Skeletal System
This is the longest and strongest bone in the human body.
femur
This organ is the control center of the nervous system and sends signals throughout the body.
brain
This type of muscle is attached to bones and helps the body move.
skeletal muscle
These two organs in the chest allow you to breathe in oxygen and breathe out carbon dioxide.
lungs
This system uses glands to release hormones that control growth, metabolism, and other body functions.
endocrine system
The adult human body normally has this many bones.
206
This long bundle of nerves runs down your back and connects the brain to the rest of the body.
spinal cord
This muscle pumps blood throughout the body and is found only in the heart.
cardiac muscle
This muscle below the lungs helps you breathe by contracting and relaxing.
diaphragm
This gland is often called the “master gland” because it controls many other endocrine glands
pituitary gland
This part of the skeletal system protects the brain.
skull
These specialized cells carry electrical signals throughout the nervous system.
neurons
These muscles work automatically and control movements like digestion in the stomach and intestines.
smooth muscles
This tube carries air from the nose and mouth down to the lungs.
trachea
This gland in the neck helps regulate metabolism and energy use in the body.
thyroid gland
These flexible tissues connect bones to other bones at joints.
ligaments
This system includes the brain, spinal cord, and all the nerves in the body.
nervous system
This is the largest muscle in the human body, located in the buttocks.
gluteus maximus
Tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged.
alveoli
These are chemical messengers released by glands that travel through the bloodstream to target organs.
hormones
This mineral, found in milk and dairy products, helps keep bones strong.
calcium
This part of the nervous system controls automatic actions like breathing and heartbeat.
autonomic nervous system
Muscles are connected to bones by these strong cords of tissue.
tendons
This gas from the air is taken into the body and used by cells for energy.
oxygen
This hormone helps regulate blood sugar levels in the body.
insulin