Describe the general functions of the major systems of the human body.

Integumentary System: acts as a barrier to protect the body from the outside world (ie. skin, hair, and nails)

Circulatory System: carries oxygen and nutrients to cells, carries waste away from cells (ie. heart and blood vessels (veins and arteries))

Digestive System: converts food into molecules that can be used by cells (ie. mouth, esophagus, stomach, small intestine, large intestine)

Respiratory System: provides oxygen to the blood and removes carbon dioxide from the body  (ie. nose, mouth, pharynx (throat), trachea, and lungs)

Immune System: fights off illness and disease  (ie. lymph nodes, white blood cells, and spleen)

Muscular System: allows for movement  (ie. cardiac muscles, skeletal muscles, and smooth muscles)

Nervous System: coordinates all body functions, sends signals to and from all parts of the body  (ie. brain, spinal cord, and neurons)

Skeletal System: support the body, protect internal organs, store minerals  (ie. bones and joints)

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.