Learning the Human Body Systems for Kids

Underneath your skin, organs, muscles, nerves, and bones are hard at work. They keep you alive and healthy without you even realizing it. But how do these body systems work? Learn all about the main human body systems and how they function with helpful charts and descriptions.

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Main Systems of the Human Body

The human body has many body systems. Its main systems are the nervous system, the circulatory system, the digestive system, the respiratory system, the urinary system, the muscular system, and the skeletal system. For more details, download the printable PDF human body for kids that provides labels for the main internal parts of the body.

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The Nervous System

There are two main parts of the nervous system. The central nervous system, which includes the brain and spinal cord, and the peripheral nervous system, which branches out around the body. The brain sends and receives messages along nerves to various organs of the body, muscles and senses.

Body Part

Location

Function

brain

inside the head (skull)

processing sensory signals provided by parts of the body; sending messages to the rest of the body; regulating automatic body functions (e.g. heartbeat, breathing, cell growth); storing memories; forming speech and behavior; facilitating movement

nerves

spinal cord (central nervous system); everywhere in the body (peripheral nervous system)

transmitting signals to the brain from other parts of the body; transmitting signals from the brain to other parts of the body

spinal cord

backbone (vertebrae)

connecting peripheral nerves to the brain; coordinating reflexes in the body

The Circulatory System

The circulatory system is responsible for carrying nutrients around the body. One of its most important functions is to bring oxygen from the lungs to the body cells. People without healthy circulatory systems might have heart attacks or strokes.

Body Part

Location

Function

heart

chest

pumping blood throughout the body

arteries (blood vessels)

various places in the body 

carrying blood away from the heart; distributing oxygen to different parts of the body

veins (blood vessels)

various places in the body

bringing blood back to the heart; allowing deoxygenated blood to regain oxygen

capillaries

everywhere in the body

connecting small arteries and veins; storing blood to be taken back to the heart

blood

blood vessels

distributing oxygen and other nutrients across the body; removing carbon dioxide and other waste from cells

The Digestive System

In order for your body to have nutrients to distribute, it needs to digest food. When you chew food, it goes through a process called digestion. The body keeps nutrients that it needs and converts the rest into waste.

Body Part

Location

Function

esophagus

neck, behind the larynx

carrying chewed food from the mouth to the stomach

stomach

upper left side of abdomen

receiving chewed food from the esophagus; mixing food with stomach enzymes; holding food before it goes into the small intestine

small intestine

middle of abdomen, between the stomach and large intestine

digesting food; absorbing nutrients from food

liver

upper abdomen, above the stomach

filtering blood from the digestive tract; producing bile to take away waste

pancreas

middle of abdomen, behind the stomach

creating enzymes to break down food; creating hormones that carry messages through the body

gallbladder

right side of abdomen, under the liver

storing liver bile during digestion

large intestine (colon, bowel)

along the backside of abdomen, between small intestine and rectum

moving waste to the rectum; absorbing water for the body; absorbing vitamins for the body

rectum

at the end of the large intestine, between the large intestine and the anus

moving waste into the anus; absorbing vitamins for the body

anus

between the buttocks, at the end of the rectum

pushing waste out of the body as a bowel movement

The Urinary System

Not all waste leaves the body through the digestive system. The urinary system, which is also called the renal system, balances the body by eliminating waste through urine. There are four main parts of the urinary system.

Body Part

Location

Function

kidneys

rear back of abdomen

removing waste from the body; balancing fluids in the body; sending waste to the bladder

ureters

tubes between kidneys and bladder

bringing urine to the bladder from the kidneys

bladder

center of the pelvis

storing urine before urination

urethra

end of the bladder to exterior of the body

bringing urine out of the body during urination

The Respiratory System

A body can’t function without oxygen. The respiratory system receives oxygen through respiration, also known as breathing, and expels carbon dioxide from the body. These are the main parts of the body used for breathing.

Body Part

Location

Function

nostrils

end of the nose

inhaling air during breathing; exhaling carbon dioxide

nasal cavity

inside the nose

keeping foreign particles out of the respiratory tract (sneezing); making mucus to keep the nose moist

oral cavity (mouth)

middle of the face

inhaling air during breathing; exhaling carbon dioxide

throat

neck, behind the nose and mouth, above the trachea

connecting oral and nasal cavities to the trachea

larynx (voice box)

neck, below the throat, in front of the esophagus

creating speech sounds; protecting the airway from choking; regulating airflow into the lungs

trachea (windpipe)

bottom of neck, between the larynx and bronchial tubes

connecting larynx to bronchial tubes; passing air into the lungs

bronchial tubes

chest, between the trachea and lungs

connecting trachea to lungs; bringing air into the lungs

lungs

chest, behind rib cage

bringing oxygen into the body through blood vessels; taking carbon dioxide out of the body through exhalation (breathing out)

Parts of the Muscular System

The muscular system enables a body to move. When the brain sends a signal to a muscle in the body, neurotransmitters tell the muscle what to do. It creates the musculoskeletal system when combined with the skeletal system. The three major types of muscles are skeletal muscles, cardiac muscles and smooth muscles.

Body Part

Location

Function

skeletal muscles

attached to bones, connected to tendons

voluntary movement; breathing (diaphragm)

cardiac muscles

heart

keeping your heartbeat going (involuntary)

smooth muscles

organ walls (intestines, stomach, bladder), eyes, skin

involuntary functions in organs

Parts of the Skeletal System

When you think of a skeleton, you’re thinking of the skeletal system. Because humans are vertebrates, they have a skeletal frame built around a backbone. The skeletal system includes the body’s 206 bones, as well as connective tissue such as tendons, ligaments and cartilage.

Body Part

Location

Function

teeth

inside mouth

chewing food

skull

head

protecting the brain

backbone (vertebrae)

back

protecting the spinal cord; stabilizing the body

ribcage

chest

protecting the heart, lungs, and internal organs; stabilizing the body

pelvis

between the hips, above the legs

supporting body weight; supporting abdominal organs; protecting digestive tract

tendons

between muscles and other body structures

attaching muscles to bones; attaching muscles to organs

ligaments

between bones

connecting bones to other bones; allowing joints to move and bend

cartilage

joints, between bones

connecting bones to other bones; allowing joints to move fluidly; keeps bones from rubbing against each other

Body Systems Work Together

As you can see, none of these systems can exist without the others. If one organ fails, it can cause an entire system to stop functioning – which can affect the entire body. Learn more about the external parts of the body and how they work together to understand more about human body functions.

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