Anatomy and Physiology Answer Key

Anatomy and Physiology Answer Key

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Unformatted text preview: it may be a reflex (an automatic response to a stimulus involving only 2 or 3 neurons), e.g. pain withdrawal. 8. 9. Principles of Homeostasis (page 37) 1. Maintaining water and ion balance by: (a) Water and ions are taken in with food and drink, helping to replace that lost through urine, faeces, and sweat. The digestive organs and all of the digestive hormones (e.g. amylase in the mouth, pepsin in the stomach, trypsin in the small intestine) are all involved in breaking down food and facilitating absorption into the bloodstream. (b) The kidney is the primary regulator of fluid and ions. When large quantities of fluid must be excreted, the kidney produces large amounts of dilute urine. When water must be conserved, small amounts of concentrated urine are produced. ADH (antidiuretic hormone) causes more water to be reabsorbed from the kidney (causing a more concentrated urine). ADH increases when blood water levels are low. Essential ions (and glucose) are retained by active reabsorption from the kidney tubules. Another hormone, aldosterone from the adrenal glands, increases the absorption of sodium ions. Note: Water and ions are lost via sweat and water is lost in breathing. These losses are compensated for by the homeostatic role of the kidney. Note that sweating is a mechanism for thermoregulation. It is not usually an important way to rid the body of excessive water and salts. 4. Regulating respiratory gases during exercise by: (a) Increasing breathing rate. This increases both the rate of oxygen entering the lungs and the rate Receptors (detect stimuli), control and coordination centre (integration of signals and coordination of response), effectors (implement an appropriate response). 2. 3. Negative feedback mechanisms enable maintenance of a steady state internal environment despite fluctuations in the external environment (e.g. rising air temperature). Negative feedback mechanisms are self-correcting so that physiological systems are stabilized against excessive change. Body Membranes and Cavities (page 38) 1. (a) (b) (c) (d) A=parietal pleura B=visceral pleura C=visceral pericardium D=pariet...
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This document was uploaded on 01/28/2014.

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