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4 Cards in this Set
- Front
- Back
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Give some examples of physiological variables maintained by Homeostasis. |
Core temperature, Water & electrolyte concentrations, pH, Blood glucose levels, blood and tissue oxygen and carbon dioxide levels, blood pressure. |
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The body can regulate its internal environment through many feedback systems or loops; what are three basic components of a feedback system? |
Receptor – monitors change and sends input (afferent pathway), nerve impulse or chemical signal, to Control centre which evaluates input received and generates commands (efferent pathway), nerve impulse or chemical signal, to the Effector which produces a response that changes the controlled condition. |
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Is the control of blood pressure maintained by a positive or negative feedback? Briefly describe the process and the hormones involved when blood pressure drops. |
Negative feedback. RAAS – Baroreceptors in the kidney arteries detect a drop in BP and release renin. This metabolises angiotensinogen to angiotensin 1 which is further metabolised in the prescence of angiotensin converting enzyme (ACE) to angiotensin 2. Angiotensin 2 is a potent vasoconstrictor and also stimulates the adrenal glands to increase the release of aldosterone which increases the reabsorption of sodium and therefore water from urine into the blood, increasing blood volume. |
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Levels of which hormone are controlled by positive feedback?
a) growth hormone b) thyroid stimulating hormone c) oxytocin d) insulin |
Oxytocin Synthesised by hypothalamus and secreted from posterior pituitary gland, oxytocin stimulates contraction of smooth muscle in the uterus which in turn stimulates the synthesis and secretion of more oxytocin increasing frequency and force of more contractions. This positive feedback loop terminates with birth. |
