Physiology

Template:StubPhysiology is the study of how organs function in an organism.

Organ systems

In physiology the various organs are grouped into systems based on their function. This makes it easier to understand how an organism works. More and more, however, we learn that the organs interface with one another in ways outside of the classic definitions of the systems. For example, the kidneys, generally thought of as being in the urinary system, are involved in producing hormones (endocrine system) that regulate blood pressure (circulatory system). The systems are: Circulatory, Immune/Lymphatic, Skeletal, Muscular, Digestive/Excretory, Endocrine, Respiratory, Reproductive, Nervous/Sensory, Integumentary, and Urinary. Not every physician or scientist uses the same groupings. For example, skeletal and muscular may be together, as the musculoskeletal system, and the reproductive and urinary system may be together, as the genitourinary system.

Circulatory

The circulatory system interface with the respiratory system to pump oxygenated blood throughout the body, thus supplying the organs with nutrients. The circulatory system consists of the heart and blood vessels. The heart is a special muscle which constantly and automatically pumps blood through the blodo vessels. The blood vessels consist of arteries, arterioles (smaller arteries), capillaries, venules (small veins), and veins. Arteries carry blood away from the heart, whereas veins carry blood to the heart. Normally arteries carry oxygenated blood and the veins normally carry oxygen-poor blood, but this is not always the case, as with the pulmonary arteries and veins which carry blood back and forth between the heart and lungs. Capillaries are the smallest blood vessels and are where oxygen exchange between blood and organs takes place.

Skeletal

Bones (206 in all); joints, tendons, and cartilage.

Digestive and Excretory

• Esophagus--carries food and fluids from mouth to stomach
• Stomach--digests food
• Pylorus--opens or closes the stomach
• Small intestine--allows fluids and nutrients to be absorbed into the system, by means of villi
• Cecum or caecum--absorbs more fluid into the system
• Colon or large intestine--concentrates waste for elimination
• Rectum--expels waste from the body

Endocrine

Glands including the thyroid, pituitary, pineal, gonads, thymus, pancreas, and adrenals. They produce hormones to facilitate metabolic, reproductive, and circadian cycles.

Reproductive

The reproductive system facilitates procreation, and is closely associated with the endocrine system.

• Female reproductive organs
• Uterus--Carries the fetus during gestation
• Ovaries--Produce ova; also produce hormones and thus are also classified as endocrine organs. Homologous to the testicles in the male.

• Male reproductive organs
• Testicles--Produce spermatozoa; also produce hormones and thus are also classified as endocrine organs. Homologous to the ovaries in the female.
• Prostate--Produces fluids to supply nutrients to the spermatozoa; also closes the bladder.

Each male reproductive organ is homologous, or directly corresponding, to a particular female reproductive organ.