Human Body Cell Atlas

Red blood cells

Job

Carry oxygen from your lungs to every part of your body.

Lives in

Your blood

Wow! You have about 25 trillion of them, more than any other kind of cell!

What are Red Blood Cells? · Lumina Learning

Platelets

Job

Rush to a cut and stick together to make a plug, so you stop bleeding.

Lives in

Your blood

Wow! They're not whole cells! They're little pieces that break off giant cells in your bone marrow, and each one lasts about a week.

What Makes Your Blood Clot? | Operation Ouch | Science for Kids · Operation Ouch

White blood cells

Job

Find and fight germs. There are a few different kinds on the team.

Lives in

Your blood and all over your body

Wow! For every white blood cell, you have about 700 red blood cells.

How White Blood Cells Fight Infections · The Magic School Bus

Macrophages

Job

Big eaters that swallow germs and clean up old, worn-out cells.

Lives in

All over your body

Wow! Their name means "big eater"!

The Immune System Explained I – Bacteria Infection · Kurzgesagt – In a Nutshell For older kids

B cells

Job

Make antibodies, sticky tags that grab onto germs so other defenders can find them.

Lives in

Your blood and your glands

Wow! Some B cells remember a germ for years, so if it comes back you can fight it off fast.

What Is the Immune System for Kids | Learn all about how the body fights off bad germs · Learn Bright

T cells

Job

Some hunt down cells that germs have taken over. Others are team captains that tell the other defenders what to do.

Lives in

Your blood and your glands

Wow! They get their training in a small organ in your chest called the thymus. That's where the "T" comes from!

How The Immune System ACTUALLY Works – IMMUNE · Kurzgesagt – In a Nutshell For older kids

Stem cells

Job

Blank cells that can turn into other kinds of cells.

Lives in

Your bone marrow and other places in your body

Wow! Stem cells in your bone marrow make all your blood cells: red, white, and platelets!

What Are Stem Cells? 🔬 | Science Made Easy | Operation Ouch · Operation Ouch

Megakaryocytes (Platelet Makers)

Job

They make platelets by letting tiny pieces of themselves break off into the blood.

Lives in

Bone marrow

Wow! One megakaryocyte can make thousands of platelets.

What Makes Your Blood Clot? · Operation Ouch

Endothelial Cells (Blood Tube Lining)

Job

They line the inside of blood tubes, keep blood flowing smoothly, and control what passes in and out.

Lives in

Inside every blood tube

Wow! The tiniest blood tubes have walls only one endothelial cell thick.

Exploring the Heart - The Circulatory System! · AboutKidsHealth - The Hospital for Sick Children

Pericytes (Capillary Huggers)

Job

They wrap around tiny blood tubes and help keep them strong, steady, and working well.

Lives in

Around the tiniest blood tubes

Wow! The name pericyte means a cell that sits around something, because it wraps around blood tubes.

Exploring the Heart - The Circulatory System! · AboutKidsHealth - The Hospital for Sick Children

Neutrophils (First Responders)

Job

They rush to germs first and gobble them up.

Lives in

In the blood

Wow! Neutrophils can throw out sticky nets made from their own DNA to trap germs.

How White Blood Cells Fight Infections · The Magic School Bus

Eosinophils (Parasite Fighters)

Job

They fight parasites that are too big to eat and also take part in allergies.

Lives in

In the blood and gut lining

Wow! They are named after a pink dye called eosin, which makes their grains look bright orange-pink.

How White Blood Cells Fight Infections · The Magic School Bus

Basophils (Rare Alarm Cells)

Job

They release alarm chemicals like histamine that call in other helpers.

Lives in

In the blood

Wow! Fewer than 1 out of every 100 white blood cells is a basophil.

Why Do We Get Allergies? | The Dr. Binocs Show · Peekaboo Kidz

Mast Cells (Allergy Alarm Cells)

Job

They release alarm chemicals like histamine when they sense germs or, in allergies, harmless things like pollen.

Lives in

Skin, nose, lungs, and gut

Wow! The itchy bump from a bug bite is partly caused by histamine from mast cells.

Why Do We Get Allergies? | The Dr. Binocs Show · Peekaboo Kidz

Monocytes (Macrophages in Training)

Job

They travel in the blood, then move into the body's tissues and become macrophages.

Lives in

In the blood

Wow! Monocytes are the biggest white blood cells in your blood.

What Is the Immune System for Kids · Learn Bright

Alveolar Macrophages (Lung Dust Cleaners)

Job

They eat dust, pollen, and germs that reach the tiny air sacs in your lungs.

Lives in

Tiny air sacs in the lungs

Wow! They are sometimes called dust cells because they eat so much dust.

How Your Lungs Work · Nemours KidsHealth

Histiocytes (Tissue Cleaners)

Job

They eat germs, dead cells, and junk in the body's tissues.

Lives in

Tissue under the skin and around organs

Wow! Macrophages like these help clean up the old blood in a bruise, which is part of why a bruise changes color.

The Immune System Explained I – Bacteria Infection · Kurzgesagt – In a Nutshell For older kids

Kupffer Cells (Liver Cleaners)

Job

They catch germs and old red blood cells in the blood flowing through the liver.

Lives in

Blood channels in the liver

Wow! They are named after Karl von Kupffer, a scientist who studied them in the 1800s.

What Does The Liver Do? · Peekaboo Kidz

Dendritic Cells (Germ Messengers)

Job

Grabs pieces of germs and shows them to T cells so they know what to fight.

Lives in

Skin, nose, lungs, and gut

Wow! Dendritic cells were discovered in 1973, and their discoverer later won a Nobel Prize.

How The Immune System ACTUALLY Works – IMMUNE · Kurzgesagt – In a Nutshell For older kids

Langerhans Cells (Skin Lookouts)

Job

Catches germs that get into the skin and shows pieces to T cells.

Lives in

Top layer of the skin

Wow! Paul Langerhans found them as a student in 1868 and thought they were nerve cells.

How Your Skin Works · Peekaboo Kidz

Helper T Cells (CD4+)

Job

Sends signals that tell B cells, killer T cells, and other defenders how to fight.

Lives in

Blood and lymph nodes

Wow! The T in T cell stands for thymus, the small organ where they finish growing up.

How The Immune System ACTUALLY Works – IMMUNE · Kurzgesagt – In a Nutshell For older kids

Cytotoxic T Cells (Killer T Cells)

Job

Finds cells taken over by viruses and makes them shut down.

Lives in

Blood, lymph nodes, and body tissues

Wow! Some killer T cells become memory cells that remember a virus for a long time.

How The Immune System ACTUALLY Works – IMMUNE · Kurzgesagt – In a Nutshell For older kids

Regulatory T Cells (Tregs)

Job

Calms down other defender cells so they don't attack your own body.

Lives in

Blood and lymph nodes

Wow! In 2025, scientists won a Nobel Prize for discovering how these cells keep the peace.

What Is the Immune System for Kids · Learn Bright

Plasma Cells (Antibody Factories)

Job

Makes huge numbers of antibodies that stick to germs.

Lives in

Bone marrow, lymph nodes, and gut

Wow! Some plasma cells keep making antibodies in your bone marrow for many years.

What Is the Immune System for Kids · Learn Bright

Natural Killer (NK) Cells

Job

Checks other cells and stops ones that look sick.

Lives in

Blood, liver, spleen, and lymph nodes

Wow! NK cells are ready to fight without meeting a germ first.

How White Blood Cells Fight Infections · The Magic School Bus

Thymic Cortical Epithelial Cells (T Cell Test Givers)

Job

They test young T cells to check that they can recognize the body's own ID tags.

Lives in

Outer part (cortex) of the thymus

Wow! Most young T cells do not pass the thymus tests. Only the ones that will work well and safely get to leave.

What Is the Immune System for Kids · Learn Bright

Thymic Medullary Epithelial Cells (Body Picture Showers)

Job

They show young T cells tiny pieces of proteins from all over the body, so T cells that would attack the body can be removed.

Lives in

Inner part (medulla) of the thymus

Wow! These cells can make tiny bits of proteins that are normally found in faraway body parts, like the eye or the pancreas.

What Is the Immune System for Kids · Learn Bright

Splenic Sinusoidal Endothelial Cells (Stave Cells)

Job

They line the spleen's blood spaces and make narrow slits that red blood cells must squeeze through.

Lives in

Spleen (red pulp)

Wow! These cells are long and lined up side by side, a bit like the wooden planks of a barrel.

What Is the Immune System for Kids · Learn Bright

Splenic Reticular Cells (Spleen Net Builders)

Job

They make a net of thin fibers that holds the spleen's blood and immune cells in place.

Lives in

Inside the spleen

Wow! Their long arms touch each other, so together they form a 3D web.

What Is the Immune System for Kids · Learn Bright

Lymph Node Fibroblastic Reticular Cells (Road Builders)

Job

They build a net of fibers in lymph nodes that immune cells crawl along to find each other.

Lives in

Lymph nodes

Wow! They also send out signals that help immune cells find their way, a bit like road signs.

What Is the Immune System for Kids · Learn Bright

Follicular Dendritic Cells (Germ Clue Holders)

Job

They hold bits of germs on their branches so B cells can learn to make better antibodies.

Lives in

Lymph nodes, spleen, tonsils

Wow! They can hold on to germ bits for a long time, weeks or even longer.

What Is the Immune System for Kids · Learn Bright

Nerve cells

Job

Send tiny electric messages between your brain and your body.

Lives in

Your brain, spinal cord, and nerves

Wow! Your brain has about 86 billion of them!

How do nerves work? · TED-Ed For older kids

Glial cells

Job

Helper cells that feed, protect, and clean up after nerve cells. Some wrap nerve cells in a fatty coat.

Lives in

Your brain and nerves

Wow! Your brain has about as many glial cells as nerve cells.

Glia Are Your Brain's Most Mysterious Cells · SciShow For older kids

Granule Cells (Tiny Balance Brain Cells)

Job

They pass movement and balance messages on to Purkinje cells in the cerebellum.

Lives in

Cerebellum, at the back of the brain

Wow! Scientists think more than half of all the nerve cells in your brain are these tiny granule cells.

2-Minute Neuroscience: The Neuron · Neuroscientifically Challenged For older kids

Enteric Glia (Gut Nerve Helpers)

Job

They support and protect the nerve cells in the walls of your gut.

Lives in

In the walls of the gut

Wow! Your gut's nerve network can control the squeezing of your intestines even without orders from your brain.

Glia Are Your Brain's Most Mysterious Cells · SciShow For older kids

Microglia (Brain Cleaners)

Job

They guard the brain, clean up waste and germs, and trim extra connections between nerve cells.

Lives in

Brain and spinal cord

Wow! Microglia's thin arms keep moving and feeling around, even while you sleep.

Glia Are Your Brain's Most Mysterious Cells · SciShow For older kids

Upper Motor Neurons (Move Command Senders)

Job

Sends the "move!" message from your brain down to the spinal cord.

Lives in

Motor cortex of the brain

Wow! Some of their axons stretch from the top of your brain down into your spinal cord.

How do nerves work? - Elliot Krane · TED-Ed For older kids

Lower Motor Neurons (Muscle Movers)

Job

Carries the "move" message from the spinal cord to a muscle.

Lives in

Spinal cord and brainstem, reaching out to muscles

Wow! The ones that move your foot muscles start in your lower back.

How Your Muscles Work · Nemours KidsHealth

Pseudounipolar Sensory Neurons (Touch Feelers)

Job

Carries touch, heat, cold, and pain messages from your skin to your spinal cord.

Lives in

Ganglia beside the spinal cord

Wow! Its message can skip right past the cell body on the way to the spinal cord.

How do nerves work? - Elliot Krane · TED-Ed For older kids

Bipolar Sensory Neurons (Two-Armed Messengers)

Job

Passes messages for seeing, hearing, and smelling on toward the brain.

Lives in

Retina, inner ear, and nose

Wow! Your body keeps making new smell neurons, even though most nerve cells last your whole life.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Interneurons (Message Connectors)

Job

Connects neurons to each other and helps decide which messages go on.

Lives in

Brain and spinal cord

Wow! Most of the neurons in your brain are interneurons.

2-Minute Neuroscience: The Neuron · Neuroscientifically Challenged For older kids

Purkinje Cells (Balance Brain Cells)

Job

Helps your cerebellum keep your balance and make your movements smooth.

Lives in

Cerebellum of the brain

Wow! Their dendrite trees are wide but flat, like a paper fan.

2-Minute Neuroscience: The Neuron · Neuroscientifically Challenged For older kids

Pyramidal Cells (Thinking Cells)

Job

Helps you think, plan, and remember by linking parts of the brain.

Lives in

Cerebral cortex and hippocampus

Wow! They are the most common kind of neuron in the cerebral cortex.

2-Minute Neuroscience: The Neuron · Neuroscientifically Challenged For older kids

Betz Cells (Giant Movement Cells)

Job

Sends strong movement commands from the brain down to the spinal cord.

Lives in

Motor cortex of the brain

Wow! They are some of the biggest nerve cells in your whole brain.

How do nerves work? - Elliot Krane · TED-Ed For older kids

Spindle Neurons (von Economo Neurons)

Job

Scientists think they help with feelings, getting along with others, and quick choices.

Lives in

Deep in the front part of the brain

Wow! They have also been found in great apes, whales, dolphins, and elephants.

2-Minute Neuroscience: The Neuron · Neuroscientifically Challenged For older kids

Protoplasmic Astrocytes (Bushy Star Helpers)

Job

Feeds, cleans up after, and helps the neurons in gray matter.

Lives in

Gray matter of the brain and spinal cord

Wow! Each one looks after its own little patch of brain, with hardly any overlap.

Glia Are Your Brain's Most Mysterious Cells · SciShow For older kids

Fibrous Astrocytes (Long-Armed Star Helpers)

Job

Supports the long axon wires in white matter and connects them to blood tubes.

Lives in

White matter of the brain and spinal cord

Wow! Their arms are packed with tiny threads that make them strong.

Glia Are Your Brain's Most Mysterious Cells · SciShow For older kids

Oligodendrocytes (Wire Wrappers)

Job

Wraps axons in myelin so messages travel fast.

Lives in

Brain and spinal cord

Wow! One oligodendrocyte can wrap pieces of many different axons.

Glia Are Your Brain's Most Mysterious Cells · SciShow For older kids

Schwann Cells (Nerve Wrappers)

Job

Wraps nerve fibers in a fatty coat so messages travel fast.

Lives in

Nerves in your body

Wow! Schwann cells can help a hurt nerve in your arm or leg grow back.

Glia Are Your Brain's Most Mysterious Cells · SciShow For older kids

Ependymal Cells (Brain Fluid Movers)

Job

Lines the brain's fluid spaces and waves tiny hairs to keep the fluid moving.

Lives in

Inside the brain and spinal cord

Wow! The clear fluid they line works like a water cushion for your brain.

Glia Are Your Brain's Most Mysterious Cells · SciShow For older kids

Satellite Glial Cells

Job

Wraps around nerve cells in ganglia and keeps them healthy.

Lives in

Nerve bunches near the spine

Wow! They were named satellites because they circle a nerve cell like moons around a planet.

Glia Are Your Brain's Most Mysterious Cells · SciShow For older kids

Meningeal Arachnoid Barrier Cells (Brain Wrap Seal)

Job

They join tightly together to make a barrier that keeps the fluid around the brain separate from the outer layer.

Lives in

Arachnoid, the middle wrapping of the brain

Wow! The arachnoid is named after spiders, because thin strands stretch from it like a spider web.

How Your Brain Works? - The Dr. Binocs Show | Best Learning Videos For Kids | Peekaboo Kidz · Peekaboo Kidz

Meningeal Pia Mater Cells (Brain Hugging Layer)

Job

They make the thin, delicate pia mater, which covers the brain's surface and guides blood vessels into it.

Lives in

Pia mater, right on the brain's surface

Wow! Pia mater is Latin for "tender mother," because it is so thin and gentle.

How Your Brain Works? - The Dr. Binocs Show | Best Learning Videos For Kids | Peekaboo Kidz · Peekaboo Kidz

Meningeal Dural Fibroblasts (Tough Brain Cover Builders)

Job

They make the strong collagen fibers of the dura mater, the tough outer wrapping of the brain.

Lives in

Dura mater, just under the skull

Wow! Dura mater is Latin for "tough mother."

How Your Brain Works? - The Dr. Binocs Show | Best Learning Videos For Kids | Peekaboo Kidz · Peekaboo Kidz

Choroid Plexus Epithelial Cells (Brain Fluid Makers)

Job

They make cerebrospinal fluid, the clear liquid that cushions and cleans the brain and spinal cord.

Lives in

Choroid plexus, inside the brain's fluid-filled spaces

Wow! Floating in this fluid makes your brain act much lighter than it really is, a bit like how you feel lighter in a pool.

How Your Brain Works? - The Dr. Binocs Show | Best Learning Videos For Kids | Peekaboo Kidz · Peekaboo Kidz

Rods and cones

Job

Light-catching cells at the back of your eye. Rods help you see in dim light. Cones see colors.

Lives in

The back of your eyes

Wow! Each eye has about 120 million rods and about 6 million cones!

Human Eye - The Dr. Binocs Show | Best Learning Videos For Kids | Peekaboo Kidz · Peekaboo Kidz

Hearing hair cells

Job

Have tiny "hairs" on top that wiggle when sound waves reach them, sending a message to your brain.

Lives in

Deep inside your ears

Wow! If very loud noise damages them, they don't grow back. That's why it's important to protect your ears!

How Your Ear Works? - The Dr. Binocs Show | Best Learning Videos For Kids | Peekaboo Kidz · Peekaboo Kidz

Taste cells

Job

Sense sweet, salty, sour, bitter, and savory (umami) tastes.

Lives in

Inside the taste buds on your tongue

Wow! Your taste cells are replaced about every 1 to 2 weeks.

How Do We Taste our Food? | The Sense of Taste | What Are Taste Buds? | The Dr. Binocs Show · Peekaboo Kidz

Smell cells

Job

Special nerve cells that catch smells floating in the air.

Lives in

The top of the inside of your nose

Wow! They're one of the few kinds of nerve cells that keep getting replaced, about every month or two.

How does the sense of smell work? - Senses for Kids · Smile and Learn - English

Olfactory Sustentacular Cells (Smell Helper Cells)

Job

They hold smell cells in place and help keep the smell lining clean and healthy.

Lives in

Smell lining, high up in the nose

Wow! Scientists found that when COVID-19 took away people's sense of smell, the virus mostly infected these helper cells, not the smell cells.

How does the sense of smell work? - Senses for Kids · Smile and Learn - English

Retinal Bipolar Cells

Job

Passes messages from the light-catching cells to the cells that talk to the brain.

Lives in

Middle layer of the retina

Wow! Some bipolar cells signal when a spot gets brighter, and others when it gets darker.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Retinal Horizontal Cells

Job

Links many light-catching cells sideways to help edges look sharp.

Lives in

Retina, just above rods and cones

Wow! They help a gray square look lighter on a dark background than on a white one.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Retinal Amacrine Cells

Job

Links messenger cells in the eye and helps you notice movement.

Lives in

Retina, middle layers

Wow! One kind is called a starburst cell because its branches spread out like fireworks.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Retinal Ganglion Cells

Job

Sends what the eye sees to the brain through the optic nerve.

Lives in

Retina, inner layer

Wow! Some of them sense light themselves and help set your sleep clock.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Vestibular Hair Cells (Balance Sensors)

Job

Feels head tilts and turns so you can stay balanced.

Lives in

Inner ear

Wow! Some of them sit under a jelly topped with tiny crystals.

How Your Ear Works? - The Dr. Binocs Show · Peekaboo Kidz

Olfactory Basal Cells (Smell Cell Makers)

Job

Makes new smell nerve cells to replace worn-out ones.

Lives in

Smell patch high in the nose

Wow! Smell nerve cells are one of the few nerve cells your body keeps replacing all your life.

How does the sense of smell work? - Senses for Kids · Smile and Learn - English

Corneal Epithelial Cells (Eye Window Skin)

Job

They make a smooth, clear, protective outer layer on the front of the eye.

Lives in

Outer surface of the cornea

Wow! The cornea has no blood vessels. It gets oxygen straight from the air and from your tears.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Corneal Keratocytes (Clear Window Keepers)

Job

They make and look after the neat layers of fibers that keep the cornea strong and clear.

Lives in

Middle layer of the cornea

Wow! The cornea is clear because its fibers are lined up very neatly, all about the same size.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Corneal Endothelial Cells (Cornea Water Pumps)

Job

They pump extra water out of the cornea so it does not swell up and get cloudy.

Lives in

Inner surface of the cornea

Wow! These cells fit together in a pattern that looks a lot like a honeycomb.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Lens Epithelial Cells (Lens Builders)

Job

They cover the front of the lens and make new lens fiber cells.

Lives in

Front surface of the eye's lens

Wow! Because these cells keep adding new layers, your lens slowly keeps growing your whole life.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Lens Fiber Cells (Clear Lens Layers)

Job

They pack together to form the clear lens, which bends light to focus a picture inside your eye.

Lives in

Inside the eye's lens

Wow! The fiber cells in the very middle of your lens were made before you were born, so they are as old as you are.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Ciliary Body Non-Pigmented Epithelial Cells (Eye Fluid Makers)

Job

They make the clear fluid that fills the front of the eye and feeds the lens and cornea.

Lives in

Ciliary body, a ring behind the iris

Wow! Tiny threads that hold your lens in place are attached to the ciliary body.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Ciliary Body Pigmented Epithelial Cells (Dark Fluid Helpers)

Job

They take in water and other things from the blood and pass them to the pale layer, which makes eye fluid.

Lives in

Ciliary body, a ring behind the iris

Wow! This dark layer connects to the dark lining at the back of the eye, behind the retina.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Choroidal Melanocytes (Eye Shade Cells)

Job

They make brown melanin, which scientists think soaks up stray light and helps protect the back of the eye.

Lives in

Choroid, at the back of the eye

Wow! When eyes look red in a flash photo, that's light bouncing off the blood-rich layers at the back of the eye.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Scleral Fibroblasts (Eye Wall Builders)

Job

They make the strong collagen fibers of the sclera, the tough white wall that protects the eye and keeps its shape.

Lives in

Sclera, the white of the eye

Wow! The sclera and the clear cornea are made of the same kind of fibers. The sclera looks white because its fibers are jumbled up.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Skeletal muscle cells

Job

Long, striped cells that pull on your bones so you can move.

Lives in

Your arms, legs, face, and all over

Wow! You have more than 600 muscles!

How Your Muscles Work · Nemours KidsHealth

Heart muscle cells

Job

Striped, branching cells that squeeze together to pump blood. They beat all by themselves!

Lives in

Only in your heart

Wow! Your heart beats about 100,000 times every day.

How Your Heart Works? - The Dr. Binocs Show | Best Learning Videos For Kids | Peekaboo Kidz · Peekaboo Kidz

Smooth muscle cells

Job

Spindle-shaped cells that slowly squeeze food through your belly and control your blood tubes.

Lives in

Your stomach, intestines, and blood tubes

Wow! Smooth muscle works without you thinking. It even gives you goosebumps!

Muscular System Video | Types of Muscles | Video for Kids · learning junction

Slow-Twitch Muscle Fibers (Type I)

Job

Squeezes steadily for a long time without getting tired.

Lives in

Muscles all over your body

Wow! Chicken dark meat has more of this steady, red kind of muscle fiber than white meat.

How Your Muscles Work · Nemours KidsHealth

Fast-Twitch Muscle Fibers (Type IIa)

Job

Squeezes fast and strong, and can keep going for a while.

Lives in

Muscles all over your body

Wow! Training can make some very fast fibers act more like these tougher in-between fibers.

How Your Muscles Work · Nemours KidsHealth

Fast-Twitch Muscle Fibers (Type IIx)

Job

Gives big, fast bursts of power for sprinting and jumping.

Lives in

Muscles all over your body

Wow! Sprinters often have more fast-twitch fibers in their legs than marathon runners do.

How your Muscles Grow? - The Dr. Binocs Show · Peekaboo Kidz

Muscle Satellite Cells (Muscle Fixers)

Job

Wakes up to fix hurt muscle and help it grow.

Lives in

On the edge of muscle fibers

Wow! They are named satellite cells because they sit at the edge of muscle fibers.

How your Muscles Grow? - The Dr. Binocs Show · Peekaboo Kidz

Atrial Heart Muscle Cells (Atrial Cardiac Myocytes)

Job

Squeezes the heart's top rooms to push blood into the bottom rooms.

Lives in

Top rooms of the heart

Wow! When they get stretched, they send out a hormone that tells your kidneys to remove extra salt and water.

How Your Heart Works? - The Dr. Binocs Show · Peekaboo Kidz

Sinoatrial Node Pacemaker Cells (Heartbeat Starters)

Job

Makes the electric spark that starts every heartbeat.

Lives in

Top right room of the heart

Wow! They make their own sparks over and over, without being told to.

How Your Heart Works? - The Dr. Binocs Show · Peekaboo Kidz

Atrioventricular Node Cells (Heartbeat Gatekeepers)

Job

Holds each heartbeat signal for a split second so the heart's rooms take turns.

Lives in

Middle of the heart

Wow! If the main heartbeat starter stops, AV node cells can make a slower backup beat.

How Your Heart Works? - The Dr. Binocs Show · Peekaboo Kidz

Cardiac Purkinje Fibers (Heartbeat Wires)

Job

Carries the heartbeat signal super fast through the heart's bottom rooms.

Lives in

Walls of the bottom heart rooms

Wow! They are named after scientist Jan Purkinje, who also has brain cells named after him.

How Your Heart Works? - The Dr. Binocs Show · Peekaboo Kidz

Myoepithelial Cells (Gland Squeezers)

Job

Squeezes tiny glands to push out sweat, tears, and spit.

Lives in

Around sweat, tear, and spit glands

Wow! They are part lining cell and part muscle cell.

Why Do We Sweat? | Sports Science | SciShow Kids · SciShow Kids

Myofibroblasts (Wound Closers)

Job

Pulls the edges of a wound together and fills it with collagen.

Lives in

Healing wounds

Wow! They start out as fibroblasts and change jobs when you get a cut.

How Do Cuts Heal? · SciShow Kids

Skin cells

Job

Build a tough, waterproof outer layer that keeps germs out and water in.

Lives in

The outside of your body

Wow! You grow a whole new outer layer of skin about every month.

How Your Skin Works · Peekaboo Kidz

Melanocytes

Job

Make melanin, the brown color in your skin, hair, and eyes. It helps protect you from the sun.

Lives in

The bottom of your skin's outer layer

Wow! Everyone has about the same number. Skin color depends on how much melanin they make.

The science of skin color - Angela Koine Flynn · TED-Ed For older kids

Epidermal Basal Cells (New Skin Makers)

Job

They divide to make new skin cells that move up and replace the old ones.

Lives in

Bottom of the outer skin layer

Wow! The skin cells on your surface today started down here a few weeks ago.

How Your Skin Works · Peekaboo Kidz

Merkel Cells (Touch Sensors)

Job

They work with nerve endings to sense light touch, pressure, and texture.

Lives in

Bottom of the outer skin layer

Wow! Your fingertips and lips have lots of Merkel cells, which is why they are so good at feeling.

How Your Skin Works · Peekaboo Kidz

Corneocytes (Skin Shield Cells)

Job

They form a tough, waterproof wall that keeps water in and germs out.

Lives in

Very top of your skin

Wow! Corneocytes are no longer alive, but they still protect you every day.

How Your Skin Works · Peekaboo Kidz

Trichocytes (Hair Cells)

Job

They divide and fill with keratin to build a strand of hair.

Lives in

Hair roots under the skin

Wow! The hair you can see is made of cells that are no longer alive, so a haircut doesn't hurt.

How Your Hair Grows? - The Dr. Binocs Show · Peekaboo Kidz

Nail Matrix Cells (Nail Makers)

Job

They make new nail cells that harden and push the nail forward.

Lives in

Under the skin at the base of each nail

Wow! Fingernails grow faster than toenails.

How Your Nails Grow? | The Dr. Binocs Show · Peekaboo Kidz

Nail Bed Cells

Job

They hold the nail in place and let it slide forward as it grows.

Lives in

Under each nail

Wow! Your nails look pink because of tiny blood tubes in the nail bed under them.

How Your Nails Grow? | The Dr. Binocs Show · Peekaboo Kidz

Bone cells

Job

Build, clean up, and look after your hard bones.

Lives in

Inside your bones

Wow! A grown-up's skeleton gets rebuilt almost completely about every 10 years.

Bones for Kids · Learn Bright

Cartilage cells

Job

Make cartilage, the bendy stuff in your ears, the tip of your nose, and the cushions between bones.

Lives in

Your ears, nose, and joints

Wow! Cartilage has no blood tubes, so it heals very slowly.

The Skeletal System - Bones for Kids (Updated Version) · Smile and Learn - English

Fat cells

Job

Store energy for later, and help keep you warm and cushioned.

Lives in

Under your skin and around your organs

Wow! A fat cell is mostly one big drop of fat. It can grow bigger or shrink.

What is fat? - George Zaidan · TED-Ed For older kids

Fibroblasts

Job

Make collagen, strong stretchy threads that hold your body together. They also help heal cuts.

Lives in

All over your body, between other cells

Wow! A scar is extra collagen that fibroblasts made while fixing a cut.

How Do Cuts Heal? · SciShow Kids

Osteoclasts (Bone Recyclers)

Job

They break down old bone so it can be replaced with new bone.

Lives in

On the surface of bones

Wow! One osteoclast can have many nuclei, because it forms when several cells join together.

How do broken bones heal? · But Why Kids

Fibrocytes (Resting Fiber Cells)

Job

Looks after the tough fibers in connective tissue and can wake up to help fix injuries.

Lives in

Tendons, skin, and other connective tissue

Wow! A fibrocyte is a resting fibroblast. When you get hurt, it can wake up and start making new fibers again.

How Do Cuts Heal? · SciShow Kids

Brown Fat Cells (Brown Adipocytes)

Job

Burns fat to make heat and help keep the body warm.

Lives in

Neck, upper back, near the collarbones

Wow! Babies have lots of brown fat, which helps keep them warm because they can't shiver well yet.

What is fat? - George Zaidan · TED-Ed For older kids

Beige Fat Cells (Beige Adipocytes)

Job

Stores fat, but can switch on in the cold to burn fat for heat.

Lives in

Mixed in with white fat

Wow! Scientists only figured out that beige fat cells are their own kind of cell in recent years.

What is fat? - George Zaidan · TED-Ed For older kids

Chondroblasts (Cartilage Builders)

Job

Builds new cartilage by making the tough, bendy stuff around it.

Lives in

Edges of cartilage and growing cartilage

Wow! Before you were born, much of your skeleton was first made as cartilage, and later most of it turned into bone.

The Skeletal System - Bones for Kids (Updated Version) · Smile and Learn - English

Chondrocytes (Elastic Cartilage)

Job

Looks after springy elastic cartilage so it bends and bounces back.

Lives in

Outer ear and the flap in your throat

Wow! Elastic cartilage is full of stretchy fibers, which is why your ear can bend and spring back.

The Skeletal System - Bones for Kids (Updated Version) · Smile and Learn - English

Chondrocytes (Fibrocartilage)

Job

Looks after tough fibrocartilage, the shock-absorbing cushions in joints and spine.

Lives in

Knees and the discs in your spine

Wow! Each knee has two C-shaped fibrocartilage cushions called menisci.

The Skeletal System - Bones for Kids (Updated Version) · Smile and Learn - English

Osteoprogenitor Cells (Bone Starter Cells)

Job

Waits on bone surfaces and turns into bone-building cells when needed.

Lives in

The thin skin around and inside bones

Wow! When you break a bone, these cells help make the new bone that fixes it.

How do broken bones heal? · But Why Kids

Osteoblasts (Bone Builders)

Job

Builds new bone by laying down a layer that hardens with minerals.

Lives in

On the surfaces of bones

Wow! When an osteoblast gets walled in by the bone it made, it becomes an osteocyte.

Bones for Kids · Learn Bright

Type A Synoviocytes (Joint Cleaners)

Job

Cleans up tiny bits of waste and germs inside joints.

Lives in

The lining of joints like knees and elbows

Wow! Type A synoviocytes are a kind of macrophage, the same family of cells that gobbles up germs in other parts of your body.

The Skeletal System - Bones for Kids (Updated Version) · Smile and Learn - English

Type B Synoviocytes (Joint Oilers)

Job

Makes the slippery ingredients of joint liquid so bones glide smoothly.

Lives in

The lining of joints like knees and elbows

Wow! Joint liquid is thick and slippery, a bit like raw egg white.

The Skeletal System - Bones for Kids (Updated Version) · Smile and Learn - English

Odontoblasts (Dentin Makers)

Job

Makes dentin, the strong layer that forms most of each tooth.

Lives in

Inside teeth, at the edge of the pulp

Wow! Odontoblasts keep making a little more dentin for as long as the tooth is alive.

All About Teeth! | SciShow Kids Compilation · SciShow Kids

Ameloblasts (Enamel Makers)

Job

Makes enamel, the hard white outer coat of each tooth.

Lives in

Around growing teeth, before they come in

Wow! Enamel is the hardest material in the human body.

All About Teeth! | SciShow Kids Compilation · SciShow Kids

Cementocytes (Tooth Root Cells)

Job

Lives in the cementum on tooth roots and helps keep it healthy.

Lives in

In the cementum covering tooth roots

Wow! Cementum helps anchor each tooth, because tiny fibers tie it to the jawbone.

All About Teeth! | SciShow Kids Compilation · SciShow Kids

Tenocytes (Tendon Cells)

Job

They make and repair the strong collagen fibers that make up tendons.

Lives in

Tendons, between muscles and bones

Wow! Your Achilles tendon, at the back of your ankle, is the biggest and strongest tendon in your body.

How Your Muscles Work · Nemours KidsHealth

Ligament Fibrocytes (Joint Strap Cells)

Job

They make and look after the collagen fibers in ligaments, the straps that hold bones together at joints.

Lives in

Ligaments at joints like knees and ankles

Wow! A twisted ankle is often a stretched or torn ligament, called a sprain.

The Skeletal System - Bones for Kids (Updated Version) · Smile and Learn - English

Chondroprogenitor Cells (Cartilage Starter Cells)

Job

They can divide and turn into new cartilage cells.

Lives in

Cartilage, especially near its surface

Wow! Cartilage has no blood vessels, so it heals much more slowly than bone or skin.

The Skeletal System - Bones for Kids (Updated Version) · Smile and Learn - English

Stomach lining cells

Job

Some make strong acid and juices that break down food. Others make slime that protects the stomach.

Lives in

The inside of your stomach

Wow! Your stomach makes a new lining every few days, so the acid doesn't eat through it!

Science for Kids - The Acid Inside My Stomach | Learn About Digestion | Operation Ouch · Operation Ouch

Intestine cells

Job

Line your small intestine with tiny bumps and soak up food into your blood.

Lives in

The inside of your small intestine

Wow! They're replaced every 3 to 5 days, some of the fastest-changing cells in your body!

Digestive System | The Dr. Binocs Show | Learn Videos For Kids · Peekaboo Kidz

Liver cells

Job

Clean your blood, store energy, and make bile, a juice that helps digest fat. They do hundreds of jobs!

Lives in

Your liver

Wow! The liver can regrow! If part of it is removed, its cells divide to grow it back.

What Does The Liver Do? | Liver Functions | The Dr Binocs Show | Peekaboo Kidz · Peekaboo Kidz

Insulin-making cells

Job

Make insulin, which helps your cells take in sugar from your blood for energy.

Lives in

Little clusters in your pancreas

Wow! In type 1 diabetes, the body's defenders attack these cells by mistake, so people take insulin as medicine.

What Causes Diabetes? | The Dr Binocs Show | Best Learning Videos For Kids | Peekaboo Kidz · Peekaboo Kidz

Parietal Cells (Stomach Acid Makers)

Job

Makes stomach acid and a helper your body needs to take in vitamin B12.

Lives in

In tiny pits in the stomach lining

Wow! Parietal cells are packed with mitochondria, because making acid takes lots of energy.

Science for Kids - The Acid Inside My Stomach | Operation Ouch · Operation Ouch

Gastric Chief Cells (Protein Breakers)

Job

Makes pepsinogen, which stomach acid turns into pepsin to break down protein.

Lives in

Deep in the stomach's glands

Wow! Chief cells make their helper in a safe, switched-off form so it doesn't chop up the cell that made it.

Science for Kids - The Acid Inside My Stomach | Operation Ouch · Operation Ouch

Gastric Foveolar Cells (Stomach Slime Shield)

Job

Coats the stomach lining in thick mucus that protects it from acid.

Lives in

The surface and pits of the stomach

Wow! The cells lining the stomach surface are replaced every few days.

Science for Kids - The Acid Inside My Stomach | Operation Ouch · Operation Ouch

Gastric Mucous Neck Cells

Job

Makes mucus inside the narrow neck of the stomach's glands.

Lives in

The neck of stomach glands

Wow! They live close to the stem cells that make new stomach lining cells.

Science for Kids - The Acid Inside My Stomach | Operation Ouch · Operation Ouch

G Cells (Gastrin Makers)

Job

Releases the hormone gastrin, which tells the stomach to make acid and churn.

Lives in

The lower stomach and upper small intestine

Wow! G cells have a tiny brush on top that touches your food, so they can sense protein in your meal.

Science for Kids - The Acid Inside My Stomach | Operation Ouch · Operation Ouch

D Cells (Somatostatin Makers)

Job

Releases somatostatin, which tells nearby cells to slow down acid and other messages.

Lives in

The stomach and small intestine

Wow! Some D cells have long arms that reach right over to the cells they want to slow down.

Science for Kids - The Acid Inside My Stomach | Operation Ouch · Operation Ouch

Enterochromaffin-like (ECL) Cells

Job

Releases histamine, which tells the acid-making cells to make more acid.

Lives in

Deep in the stomach's glands

Wow! Some heartburn medicines work by blocking the histamine message from ECL cells.

Science for Kids - The Acid Inside My Stomach | Operation Ouch · Operation Ouch

Enterochromaffin (EC) Cells

Job

Senses what is in the gut and releases serotonin, which helps the gut squeeze food along.

Lives in

The lining of the stomach and intestines

Wow! Most of the serotonin in your body is made in your gut, mostly by EC cells.

Digestive System · Peekaboo Kidz

Paneth Cells (Gut Guards)

Job

Releases germ-fighting proteins that protect the stem cells of the small intestine.

Lives in

The bottom of pockets in the small intestine

Wow! Paneth cells last much longer than most gut lining cells, which are replaced every few days.

Digestive System · Peekaboo Kidz

Microfold (M) Cells (Gut Mail Slots)

Job

Picks up samples of germs and other things from the gut and passes them to immune cells below.

Lives in

Over immune patches in the small intestine

Wow! An M cell has a pocket on its bottom side where immune cells sit and wait for deliveries.

What Is the Immune System for Kids · Learn Bright

Tuft Cells (Gut Lookouts)

Job

Senses unwanted visitors in the gut and sends signals that alert the immune system.

Lives in

The lining of the intestines (and some other places)

Wow! Tuft cells use some of the same sensors that taste cells on your tongue use.

Digestive System · Peekaboo Kidz

I Cells (CCK Makers)

Job

Releases the hormone CCK, which calls for bile and digestive juices and helps you feel full.

Lives in

The first part of the small intestine

Wow! CCK helps tell your brain you've had enough to eat.

Digestive System · Peekaboo Kidz

S Cells (Secretin Makers)

Job

Releases secretin, which tells the pancreas to send out acid-calming juice.

Lives in

The first part of the small intestine

Wow! Secretin was the very first hormone ever discovered, back in 1902.

Digestive System · Peekaboo Kidz

K Cells (GIP Makers)

Job

Releases the hormone GIP, which helps the pancreas get ready to release insulin after a meal.

Lives in

The first part of the small intestine

Wow! Sugar you eat makes your body release more insulin than the same sugar put straight into the blood, partly thanks to K cells.

What Causes Diabetes? · Peekaboo Kidz

L Cells (GLP-1 and GLP-2 Makers)

Job

Releases GLP-1, which helps control blood sugar and feeling full, and GLP-2, which helps the gut lining grow.

Lives in

The lower small intestine and large intestine

Wow! Some medicines for diabetes work by copying the GLP-1 messenger that L cells make.

What Causes Diabetes? · Peekaboo Kidz

Cholangiocytes (Bile Duct Cells)

Job

Lines the bile ducts and adds water and bicarbonate to the bile flowing through.

Lives in

The bile ducts in and near the liver

Wow! Many cholangiocytes have a single tiny hair that can feel the bile flowing past.

What Does The Liver Do? · Peekaboo Kidz

Hepatic Stellate Cells (Ito Cells)

Job

Stores vitamin A in little fat drops and helps repair the liver when it is injured.

Lives in

In thin spaces between liver cells and blood channels

Wow! Most of the vitamin A in your body is stored in your liver, much of it inside stellate cells.

What Does The Liver Do? · Peekaboo Kidz

Pancreatic Acinar Cells (Digestive Juice Makers)

Job

Makes digestive enzymes that break down starch, fat, and protein in the small intestine.

Lives in

Grape-like bunches all through the pancreas

Wow! Acinus comes from a Latin word meaning berry, because the bunches look like little grapes.

Digestive System · Peekaboo Kidz

Pancreatic Centroacinar Cells

Job

Starts the pancreas duct and adds a watery, acid-calming juice to the enzymes.

Lives in

The center of each acinus in the pancreas

Wow! Centroacinar cells are pale, so under a microscope they look like a light spot in the middle of each bunch.

Digestive System · Peekaboo Kidz

Pancreatic Ductal Cells

Job

Lines the pancreas ducts and adds watery, bicarbonate-rich juice that calms stomach acid.

Lives in

The ducts of the pancreas

Wow! When secretin arrives in the blood, ductal cells send out lots of their watery juice.

Digestive System · Peekaboo Kidz

Alpha Cells (Blood Sugar Boosters)

Job

Make glucagon, which raises blood sugar when it gets too low.

Lives in

Islets in the pancreas

Wow! Glucagon tells your liver to let out the sugar it has saved up, like opening a snack cupboard.

What Causes Diabetes? · Peekaboo Kidz

Delta Cells (Islet Calmers)

Job

Make somatostatin, a brake that calms nearby alpha and beta cells.

Lives in

Islets in the pancreas

Wow! Some delta cells have long thin arms that reach out to touch their neighbors.

What Causes Diabetes? · Peekaboo Kidz

PP Cells (Pancreatic Polypeptide Makers)

Job

Release pancreatic polypeptide after meals, which may help you feel full.

Lives in

Islets in the pancreas

Wow! PP cells have three names: PP cells, gamma cells, and F cells.

Digestive System · Peekaboo Kidz

Epsilon Cells (Hunger Hormone Makers)

Job

Make ghrelin, the hunger hormone, inside the islets of the pancreas.

Lives in

Islets in the pancreas

Wow! Epsilon cells are more common in babies before they are born than in grown-ups.

Digestive System · Peekaboo Kidz

Lung air sac cells

Job

Make up tiny air sacs where oxygen goes into your blood and carbon dioxide comes out.

Lives in

Deep inside your lungs

Wow! Your lungs have about 480 million tiny air sacs!

How Your Lungs Work · Nemours KidsHealth

Hairy airway cells

Job

Have tiny hairs called cilia that sweep dust and germs (stuck in slime) up and out of your lungs.

Lives in

Your nose, throat, and the tubes into your lungs

Wow! Cilia beat about 10 to 20 times every second!

What are Boogers? · SciShow Kids

Type II Pneumocytes (Air Sac Helpers)

Job

Makes surfactant, which keeps the lungs' tiny air sacs from collapsing.

Lives in

The walls of the air sacs in your lungs

Wow! Type II pneumocytes can divide and replace the thin air sac cells when they get damaged.

How Your Lungs Work · Nemours KidsHealth

Goblet Cells (Mucus Makers)

Job

Makes sticky mucus that traps dust and germs in your airways.

Lives in

The lining of your nose, windpipe, and gut

Wow! Goblet cells are named after a goblet, a cup with a stem, because of their shape.

What are Boogers? · SciShow Kids

Club Cells (Small Airway Guards)

Job

Protects the smallest airways and helps repair their lining.

Lives in

The tiny airways deep in the lungs

Wow! Club cells used to be called Clara cells, but scientists changed the name.

How Your Lungs Work · Nemours KidsHealth

Pulmonary Neuroendocrine Cells (Airway Sensors)

Job

Senses things like oxygen in the airways and sends chemical signals.

Lives in

Scattered in the lining of the airways

Wow! These cells are very rare, but some gather in little clusters that are connected to nerves.

How Your Lungs Work · Nemours KidsHealth

Pulmonary Ionocytes (Mucus Waterers)

Job

Helps control salt and water in the airway lining so mucus stays runny.

Lives in

The lining of the airways

Wow! Scientists first described pulmonary ionocytes in 2018.

What are Boogers? · SciShow Kids

Kidney filter cells

Job

Wrap around tiny blood tubes and filter waste out of your blood to make pee.

Lives in

Your kidneys

Wow! Each kidney has about a million tiny filters!

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Parietal Glomerular Epithelial Cells (Filter Cup Cells)

Job

They line the cup around each kidney filter and keep the filtered fluid inside.

Lives in

The cup around each kidney filter

Wow! Each kidney has about a million of these little filter cups.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Intraglomerular Mesangial Cells (Filter Helpers)

Job

They hold up the tiny blood vessel loops in each kidney filter and clean up stuck bits.

Lives in

Inside the kidney's tiny filters

Wow! Mesangial cells can gently squeeze, which may help control how much blood flows through the filter.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Extraglomerular Mesangial Cells (Lacis Cells)

Job

Scientists think they help pass messages between the kidney's salt sensors and its blood pressure cells.

Lives in

Next to each kidney filter

Wow! They are also called lacis cells. Lacis means lace, because they look like a lacy net.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Proximal Convoluted Tubule Cells (Kidney Recyclers)

Job

They take back most of the water, salt, and sugar from filtered fluid and return it to the blood.

Lives in

First part of the kidney's tiny tubes

Wow! Their tops are covered in tiny fingers called a brush border, which gives them lots of space to grab things.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Thin Descending Limb Cells (Water Savers)

Job

They let water leave the kidney tube so it can go back into the blood.

Lives in

Downhill side of the kidney's U-shaped loop

Wow! These are some of the thinnest, flattest cells in the kidney.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Thin Ascending Limb Cells (Salt Leakers)

Job

They let salt leave the kidney tube while keeping water inside it.

Lives in

Bottom of the uphill side of the kidney's loop

Wow! They look a lot like the downhill cells, but they do the opposite job with water.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Thick Ascending Limb Cells (Salt Pumpers)

Job

They pump salt out of the kidney tube, which helps your kidneys save water.

Lives in

Upper uphill side of the kidney's loop

Wow! They make a protein called uromodulin, the most common protein in healthy pee.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Distal Convoluted Tubule Cells (Fine-Tuners)

Job

They fine-tune how much salt and calcium go back into your blood.

Lives in

Twisty tube after the kidney's loop

Wow! They listen to hormones, so your body can tell them to keep more or less.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Collecting Duct Principal Cells (Water Gatekeepers)

Job

They add water doors when your body needs to save water, so less water ends up in your pee.

Lives in

Kidney collecting ducts

Wow! A hormone tells them when you're low on water, and they open more water doors.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Alpha Intercalated Cells (Acid Pumpers)

Job

They pump extra acid into the pee so your blood doesn't get too sour.

Lives in

Kidney collecting ducts

Wow! They are packed with mitochondria to power their acid pumps.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Beta Intercalated Cells (Base Releasers)

Job

They put extra base into the pee so your blood doesn't get too far from sour.

Lives in

Kidney collecting ducts

Wow! The base they release is bicarbonate, a close cousin of baking soda.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Juxtaglomerular Cells (Blood Pressure Guards)

Job

They release renin when blood pressure drops, which starts a chain of steps that brings it back up.

Lives in

Wall of the blood vessel going into each kidney filter

Wow! They store renin in tiny packets called granules, ready to release.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Macula Densa Cells (Salt Sensors)

Job

They sense salt in the kidney tube and send signals to adjust the filter and blood pressure.

Lives in

Where the kidney tube touches its own filter

Wow! Macula densa means dense spot in Latin, because the cells are packed so tightly.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Bladder Umbrella Cells (Facet Cells)

Job

They make a waterproof lining so pee stays inside the bladder.

Lives in

Inner lining of the bladder

Wow! One umbrella cell can cover several smaller cells below it, like an umbrella.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Somatotropes (Growth Hormone Makers)

Job

Make growth hormone, which helps bones and muscles grow.

Lives in

Front of the pituitary gland

Wow! Some of the biggest bursts of growth hormone happen while you are in deep sleep.

How Your Hormones Work? · Peekaboo Kidz

Lactotropes (Milk Hormone Makers)

Job

Make prolactin, which helps a new mother's body make milk.

Lives in

Front of the pituitary gland

Wow! In some fish, prolactin helps them handle moving between salty and fresh water.

Operation Ouch - Hormones · Operation Ouch

Corticotropes (Cortisol Bosses)

Job

Make ACTH, which tells the adrenal glands to make cortisol.

Lives in

Front of the pituitary gland

Wow! ACTH is snipped out of a much bigger protein, like cutting a piece off a ribbon.

How Your Hormones Work? · Peekaboo Kidz

Thyrotropes (Thyroid Bosses)

Job

Make TSH, which tells the thyroid gland to make thyroid hormone.

Lives in

Front of the pituitary gland

Wow! Thyrotropes are one of the rarest cell types in the pituitary, but their job is a big one.

Operation Ouch - Hormones · Operation Ouch

Gonadotropes (Growing-Up Hormone Makers)

Job

Make FSH and LH, which help the body grow up.

Lives in

Front of the pituitary gland

Wow! A single gonadotrope can make two different hormones.

How Your Hormones Work? · Peekaboo Kidz

Pituicytes (Pituitary Helper Cells)

Job

Support the nerve endings that store vasopressin and oxytocin.

Lives in

Back of the pituitary gland

Wow! The back of the pituitary is really part of the brain.

Glia Are Your Brain's Most Mysterious Cells · SciShow For older kids

Pinealocytes (Sleepy-Time Cells)

Job

Make melatonin at night to help you get sleepy.

Lives in

Pineal gland, deep in the brain

Wow! The pineal gland is about the size of a grain of rice and is shaped like a tiny pine cone.

How Your Hormones Work? · Peekaboo Kidz

Thyroid Follicular Cells (Energy Setters)

Job

Use iodine to make thyroid hormone, which sets how fast the body uses energy.

Lives in

Thyroid gland in the neck

Wow! The thyroid can store enough hormone to last for weeks.

Operation Ouch - Hormones · Operation Ouch

Parafollicular Cells (C Cells)

Job

Make calcitonin when blood calcium gets too high.

Lives in

Thyroid, between the follicles

Wow! When a baby is growing, C cells move into the thyroid from somewhere else.

How Your Hormones Work? · Peekaboo Kidz

Parathyroid Chief Cells (Calcium Keepers)

Job

Make parathyroid hormone (PTH) to raise blood calcium when it is low.

Lives in

Parathyroid glands, behind the thyroid

Wow! Most people have four parathyroid glands, each about the size of a grain of rice.

Operation Ouch - Hormones · Operation Ouch

Parathyroid Oxyphil Cells (Mystery Cells)

Job

Unknown! Scientists think they may help make a little parathyroid hormone.

Lives in

Parathyroid glands, behind the thyroid

Wow! Young kids have almost no oxyphil cells, and they get more common with age.

How Your Hormones Work? · Peekaboo Kidz

Zona Glomerulosa Cells (Salt Savers)

Job

Make aldosterone, which helps the kidneys keep salt and water.

Lives in

Outer layer of the adrenal gland

Wow! Their name comes from the Latin word for ball, because they sit in little round clumps.

Operation Ouch - Hormones · Operation Ouch

Zona Fasciculata Cells (Cortisol Makers)

Job

Make cortisol, which keeps blood sugar up and helps the body handle stress.

Lives in

Middle layer of the adrenal gland

Wow! Your body makes the most cortisol in the morning, helping you wake up.

Operation Ouch - Hormones · Operation Ouch

Zona Reticularis Cells (Net Layer Cells)

Job

Make DHEA, a mild hormone that helps with early steps of growing up.

Lives in

Innermost layer of the adrenal cortex

Wow! This layer starts getting busier when kids are about 6 to 8 years old.

How Your Hormones Work? · Peekaboo Kidz

Chromaffin Cells (Adrenaline Makers)

Job

Release adrenaline to get the body ready for action.

Lives in

Center (medulla) of the adrenal gland

Wow! Their name means "likes chromium" because they turn brown with a chromium stain.

Body Parts - Energy & Adrenaline · Operation Ouch

Sweat gland cells

Job

Make sweat, which cools you off as it dries on your skin.

Lives in

Tiny coiled tubes in your skin

Wow! You have about 2 to 4 million sweat glands!

Why Do We Sweat? | Sports Science | SciShow Kids · SciShow Kids

Sebaceous Gland Cells (Skin Oil Makers)

Job

They make sebum, an oil that keeps skin and hair soft and helps keep water in.

Lives in

In the skin, next to hairs

Wow! The palms of your hands and the soles of your feet have no oil glands.

How Your Skin Works · Peekaboo Kidz

Eccrine Sweat Gland Dark Cells

Job

They line sweat glands and add slippery stuff called mucus to the sweat.

Lives in

The coiled bottom of sweat glands in the skin

Wow! You have a few million sweat glands, almost all over your body.

Why Do We Sweat? | Sports Science | SciShow Kids · SciShow Kids

Apocrine Sweat Gland Cells (Armpit Sweat Makers)

Job

They make a thicker kind of sweat in places like the armpits.

Lives in

Armpits and a few other spots

Wow! Fresh sweat has no smell. Body odor comes from bacteria on the skin.

Why Do We Sweat? | Sports Science | SciShow Kids · SciShow Kids

Lactiferous Duct Cells (Milk Tube Cells)

Job

They line the tubes that carry milk from where it is made to the nipple.

Lives in

Milk tubes in the breast

Wow! The word "mammal" comes from the Latin word for breast, because all mammal moms make milk.

No video yet. Try the lessons and the Words page!

Mammary Alveolar Cells (Milk Makers)

Job

They make milk to feed a new baby.

Lives in

Tiny sacs in the breast

Wow! Milk carries antibodies that help protect a baby from germs.

No video yet. Try the lessons and the Words page!

Ceruminous Gland Cells (Earwax Makers)

Job

They help make earwax, which traps dust and keeps the ear canal clean and healthy.

Lives in

The skin of the outer ear canal

Wow! Earwax slowly moves out of your ear on its own, helped by your jaw moving when you talk and chew.

How Your Ear Works? - The Dr. Binocs Show · Peekaboo Kidz

Salivary Serous Acinar Cells (Watery Spit Makers)

Job

They make watery spit with amylase, a helper that starts breaking down starch.

Lives in

Salivary glands, around your mouth

Wow! Your biggest salivary glands are in your cheeks, just in front of your ears.

Digestive System · Peekaboo Kidz

Salivary Mucous Acinar Cells (Spit Slime Makers)

Job

They make mucus, the thick, slippery part of saliva that coats food so it is easy to swallow.

Lives in

Salivary glands under the tongue and jaw

Wow! These cells look pale and bubbly because they are packed with stored slime.

Digestive System | The Dr. Binocs Show · Peekaboo Kidz

Salivary Striated Duct Cells (Spit Salt Pumps)

Job

They line the spit tubes and pull salt back out of saliva, so the spit in your mouth is much less salty than blood.

Lives in

Tubes inside salivary glands

Wow! Their stripes come from rows of tiny power makers (mitochondria) lined up along folds in the cell.

Digestive System | The Dr. Binocs Show · Peekaboo Kidz

Lacrimal Gland Acinar Cells (Tear Makers)

Job

They make the watery part of tears, which keeps eyes wet, clean, and protected from germs.

Lives in

Tear gland above the outer corner of each eye

Wow! Tears drain into your nose through tiny holes near the inner corner of your eye. That's why your nose runs when you cry.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Meibomian Gland Cells (Eyelid Oil Makers)

Job

They make an oil that spreads over your tears and slows down drying.

Lives in

Inside the upper and lower eyelids

Wow! Each eyelid has a few dozen of these glands, lined up like the teeth of a comb.

Human Eye - The Dr. Binocs Show · Peekaboo Kidz

Spermatogonia (Sperm Stem Cells)

Job

They divide to make more of themselves and cells that will one day become sperm.

Lives in

Inside the testes

Wow! They are stem cells, so they can keep making new cells for most of a person's life.

Meiosis (UPDATED 2026) · Amoeba Sisters For older kids

Primary Spermatocytes (DNA Shufflers)

Job

They copy and shuffle their DNA, then split to start making cells with half the usual DNA.

Lives in

Inside the testes

Wow! Their DNA shuffling is part of why brothers and sisters don't look exactly alike.

Meiosis (UPDATED 2026) · Amoeba Sisters For older kids

Secondary Spermatocytes (Quick Splitters)

Job

They quickly split in two to make spermatids, the cells that will become sperm.

Lives in

Inside the testes

Wow! They last such a short time that they are hard to spot under a microscope.

Meiosis (UPDATED 2026) · Amoeba Sisters For older kids

Spermatids (Sperm in Training)

Job

They change shape, growing a tail and packing up their DNA, to become sperm cells.

Lives in

Inside the testes

Wow! They start out round and end up shaped a bit like a tadpole.

Meiosis (UPDATED 2026) · Amoeba Sisters For older kids

Spermatozoa (Sperm Cells)

Job

They carry half of the instructions (DNA) needed to make a baby.

Lives in

Made in the testes

Wow! A sperm cell is one of the smallest human cells, and an egg cell is one of the biggest.

Meiosis (UPDATED 2026) · Amoeba Sisters For older kids

Sertoli Cells (Sperm Nurse Cells)

Job

They hold, feed, and protect the cells that are slowly turning into sperm cells.

Lives in

Tiny tubes inside the testes

Wow! One Sertoli cell looks after many growing sperm cells at the same time.

Meiosis (UPDATED 2026) · Amoeba Sisters For older kids

Leydig Cells (Testosterone Makers)

Job

They make testosterone, a hormone that helps the testes make sperm cells.

Lives in

Between the tiny tubes in the testes

Wow! Testosterone is made from cholesterol, a kind of fat.

How Your Hormones Work? · Peekaboo Kidz

Oogonia (Egg Starter Cells)

Job

They split many times to make the cells that will become egg cells.

Lives in

The ovaries of a baby girl before she is born

Wow! Oogonia do their work before birth. A baby girl is born with all the egg cells she will ever have.

Meiosis (UPDATED 2026) · Amoeba Sisters For older kids

Primary Oocytes (Resting Egg Cells)

Job

They wait in the ovaries until it is their turn to grow into an egg cell.

Lives in

The ovaries

Wow! Some primary oocytes rest for more than 40 years before they finish growing.

Meiosis (UPDATED 2026) · Amoeba Sisters For older kids

Ovarian Granulosa Cells (Egg Helper Cells)

Job

They surround a growing egg cell, pass it food, and help make the hormone estrogen.

Lives in

Around each growing egg cell in the ovary

Wow! Granulosa cells reach out tiny arms that touch the egg cell, so they can pass it what it needs.

How Your Hormones Work? · Peekaboo Kidz

Theca Interna Cells (Hormone Team Cells)

Job

They make a starting hormone that granulosa cells turn into estrogen.

Lives in

The layer around each growing follicle in the ovary

Wow! Making estrogen takes teamwork between two kinds of cells.

How Your Hormones Work? · Peekaboo Kidz

Theca Externa Cells (Follicle Wrap Cells)

Job

They make a strong outer wrap that holds a growing follicle together.

Lives in

The outermost layer of a follicle in the ovary

Wow! "Externa" means outer, and "theca" comes from a Greek word for a box or case.

No video yet. Try the lessons and the Words page!

Luteal Cells (Corpus Luteum)

Job

They make progesterone, a hormone that keeps the womb lining ready for a baby.

Lives in

The corpus luteum, in the ovary

Wow! Corpus luteum is Latin for "yellow body" because it looks yellowish.

How Your Hormones Work? · Peekaboo Kidz

Endometrial Stromal Cells (Womb Lining Cells)

Job

They fill the womb lining and get it soft and ready for a growing baby.

Lives in

The lining of the womb

Wow! The womb lining can rebuild itself over and over again.

No video yet. Try the lessons and the Words page!

Endometrial Ciliated Cells (Womb Surface Wavers)

Job

They wave tiny hairs that scientists think help move fluid along the womb's inside surface.

Lives in

The inside surface of the womb

Wow! Cilia can beat many times every second.

No video yet. Try the lessons and the Words page!

Cytotrophoblasts (Placenta Builder Cells)

Job

They split to make more cells and help build the placenta.

Lives in

The placenta, during pregnancy

Wow! The placenta is built mostly by the baby's own cells, not the mother's.

No video yet. Try the lessons and the Words page!

Syncytiotrophoblasts (Placenta Giant Layer)

Job

It passes food and oxygen from the mother's blood to the baby, and sends waste back.

Lives in

The outer layer of the placenta

Wow! It is one giant cell with many, many nuclei.

No video yet. Try the lessons and the Words page!

Endocervical Mucus-Secreting Cells (Cervix Mucus Makers)

Job

They make mucus that helps protect the uterus from germs.

Lives in

Inside the canal of the cervix

Wow! When someone is pregnant, this mucus forms a thick plug that helps protect the growing baby.

No video yet. Try the lessons and the Words page!

Ectocervical Squamous Cells (Cervix Outer Lining)

Job

They stack in layers to make a tough lining that protects the outer cervix.

Lives in

Outer part of the cervix

Wow! This lining is a lot like the lining inside your cheek.

No video yet. Try the lessons and the Words page!

Fallopian Tube Peg Cells (Egg Feeders)

Job

They make a fluid that feeds and protects the egg cell as it travels down the fallopian tube.

Lives in

Lining of the fallopian tubes

Wow! They got their name because they look narrow, like pegs squeezed between their wider neighbors.

No video yet. Try the lessons and the Words page!

Fallopian Tube Ciliated Cells (Egg Movers)

Job

They wave tiny hairs called cilia to move the egg cell along the fallopian tube toward the uterus.

Lives in

Lining of the fallopian tubes

Wow! The egg cell is one of the biggest cells in the human body, but it cannot move on its own.

No video yet. Try the lessons and the Words page!

Prostate Luminal Cells (Prostate Fluid Makers)

Job

They make part of the fluid that carries sperm cells and helps keep them healthy.

Lives in

Prostate gland, just below the bladder

Wow! In a grown-up, the prostate is about the size of a walnut.

No video yet. Try the lessons and the Words page!

Prostate Basal Cells (Prostate Base Layer)

Job

They form a base layer under the fluid-making cells and help keep the pocket lining in good shape.

Lives in

Prostate gland, around each tiny pocket

Wow! Scientists think some basal cells can make new luminal cells.

No video yet. Try the lessons and the Words page!

Seminal Vesicle Cells (Sperm Energy Makers)

Job

They make a thick fluid with a sugar called fructose that gives sperm cells energy.

Lives in

Seminal vesicles, behind the bladder

Wow! The seminal vesicles make most of the fluid that carries sperm cells.

No video yet. Try the lessons and the Words page!

Bulbourethral (Cowper's) Gland Cells (Slippery Liquid Makers)

Job

They make a clear, slippery mucus that coats and protects the urethra.

Lives in

Two pea-sized glands below the prostate

Wow! They are also called Cowper's glands, after William Cowper, an English doctor who described them over 300 years ago.

No video yet. Try the lessons and the Words page!

Urethral Pseudostratified Columnar Cells (Urethra Lining)

Job

They line part of the urethra and protect it from urine flowing past.

Lives in

Part of the urethra

Wow! Pseudostratified means falsely layered: it looks like several layers, but every cell touches the bottom.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Squamous Epithelial Cells (Flat Lining Cells)

Job

They make thin, smooth linings and tough protective coverings.

Lives in

Skin, mouth, lung air sacs, blood vessels

Wow! Each flat cell bulges up a little in the middle, where its nucleus sits, like a fried egg.

How Your Skin Works · Peekaboo Kidz

Cuboidal Epithelial Cells (Cube-Shaped Lining Cells)

Job

They line tiny tubes and help move useful things in and out.

Lives in

Kidney tubes and glands

Wow! Cuboidal cells are about as tall as they are wide, with a round nucleus right in the middle.

Operation Ouch - What are Kidneys? | Biology for Kids · Operation Ouch

Columnar Epithelial Cells (Tall Lining Cells)

Job

They line the gut, soak up food, and help make protective mucus.

Lives in

Stomach and intestines

Wow! In the small intestine, each tall cell has a fuzzy top made of tiny finger-like bumps.

Digestive System | The Dr. Binocs Show · Peekaboo Kidz

Pseudostratified Epithelial Cells (Lining That Looks Layered)

Job

They line your airways and sweep dirty mucus up and away from your lungs.

Lives in

Nose and windpipe

Wow! Every cell touches the bottom, but only some reach the top, so it looks layered when it isn't.

What are Boogers? · SciShow Kids

Parietal Mesothelial Cells (Body Wall Lining)

Job

They line the inside of the chest and belly walls and make a slippery fluid so organs can slide.

Lives in

Inside the chest wall, belly wall, and heart sac

Wow! The lining is only one cell thick.

How Your Lungs Work · Nemours KidsHealth

Visceral Mesothelial Cells (Organ Wrappers)

Job

They cover the outside of organs like the lungs, heart, and gut and keep them slippery.

Lives in

Outside of lungs, heart, and gut

Wow! They face the parietal lining, with just a thin film of fluid in between.

How Your Heart Works? - The Dr. Binocs Show · Peekaboo Kidz

Egg cells

Job

Can join with a cell from a father to grow into a whole new baby.

Lives in

Inside the ovaries of girls and women

Wow! A human egg cell is about the size of the dot at the end of this sentence, one of the biggest cells in the body!

No video yet. Try the lessons and the Words page!