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Human Body Systems

Major organ systems of the human body

20 cards · science

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Cards (20)

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Circulatory SystemTransports blood, oxygen, nutrients, and removes wastes
Heart, arteries, veins, capillaries; a closed double circuit delivers oxygen and returns CO2.
Respiratory SystemExchanges oxygen and carbon dioxide with the environment
Lungs and airways; gas diffusion occurs across alveoli with a large surface area.
Digestive SystemBreaks down food and absorbs nutrients
Tract from mouth to anus; liver, pancreas, and gallbladder aid chemical digestion.
Nervous SystemCoordinates body activities via electrochemical signals
Central and peripheral divisions; integrates sensory input and controls effectors.
Muscular SystemProduces movement and maintains posture
Skeletal, smooth, and cardiac muscle; also generates heat, e.g., shivering.
Skeletal SystemProvides support, protection, and mineral storage
Bones, cartilage, ligaments; bone marrow makes blood cells and stores calcium.
Endocrine SystemRegulates body processes via blood-borne hormones
Pituitary, thyroid, adrenals, pancreas, and gonads; slower, longer-lasting signals.
Immune SystemDefends against pathogens and abnormal cells
Innate and adaptive arms; lymphocytes, antibodies, and lymphoid organs coordinate defense.
Reproductive SystemProduces gametes and enables reproduction
Ovaries and testes make gametes; ducts and glands support fertilization and development.
Urinary SystemEliminates wastes and regulates fluid and electrolytes
Kidneys, ureters, bladder, urethra; filters blood to form urine and maintain pH.
Integumentary SystemProtects the body and regulates temperature
Skin, hair, nails, glands; barrier to injury and microbes; helps synthesize vitamin D.
HeartPumps blood through systemic and pulmonary circuits
Four chambers; right side to lungs, left to body; SA node sets the pace.
LungsFacilitates gas exchange between air and blood
Millions of alveoli create vast surface area; diaphragm drives ventilation.
BrainCentral control of perception, movement, homeostasis
Cerebrum, cerebellum, brainstem; uses ~20% of resting oxygen supply.
LiverMetabolism, detoxification, and bile production
Processes nutrients, stores glycogen, makes plasma proteins; largest internal organ.
KidneysFilters blood to form urine and balance electrolytes
Nephrons reabsorb and secrete; also release renin and erythropoietin.
StomachStores and digests food with acid and enzymes
Parietal cells secrete HCl and intrinsic factor; churning forms chyme.
Small IntestineAbsorbs most nutrients from digested food
Duodenum, jejunum, ileum; villi and microvilli vastly increase surface area.
PancreasReleases digestive enzymes and controls blood glucose
Exocrine acini secrete enzymes; islets release insulin and glucagon.
SkinBarrier organ and regulator of body temperature
Epidermis, dermis, hypodermis; sensory receptors and sweat glands; largest organ.