MDGAR EVERS COLLEGE CITY UNIVERSITY OF NEW YORK DEPARTMENT OF BIOLOGY BIO 351 TE
ID: 301570 • Letter: M
Question
MDGAR EVERS COLLEGE CITY UNIVERSITY OF NEW YORK DEPARTMENT OF BIOLOGY BIO 351 TEST #1 ANSW/ER ALL QUESTIONS 1. The primary purpose of the endocrine system is A. Body repair B. Maintenance of homeostatsis C. Coordination of movement. D. Response to external stimuli E. Information storage 2. Which of the following statements supports the view that the endocrine system and the nervous system are closely connected structurally and functionally? 1. The posterior lobe of the pituitary is a downward growth or extension of the hypothalamus. 2. Two hormones of the pituitary are actually synthesized in the hypothalamus. 3. ADH release by the pituitary depends on stimulation of the hypothalamus by high blood solute levels. 4. Stimulation of the mammary gland nipples or the female genitalia causes oxytocin release. A. 1 and 2 only. B. 2 and 4 only. C. 1, 2, and 3 only D. 2, 3, and 4 only. E. 1, 2, 3, and 4Explanation / Answer
1. B
The endocrine system plays an important role in homeostasis because hormones regulate the activity of body cells. The release of hormones into the blood is controlled by a stimulus. For example, the stimulus either causes an increase or a decrease in the amount of hormone secreted.
2.E
The posterior lobe of the pituitary gland develops as an extension of the hypothalamus. As such, it is not capable of producing its own hormones; instead, it stores hypothalamic hormones for later release into the systemic circulation.
There are two sets of nerve cells in the hypothalamus that produce hormones. One set sends the hormones they produce down through the pituitary stalk to the posterior lobe of the pituitary gland where these hormones are released directly into the bloodstream. These hormones are anti-diuretic hormone and oxytocin.
The most important variable regulating antidiuretic hormone secretion is plasma osmolarity, or the concentration of solutes in blood. Osmolarity is sensed in the hypothalamus by neurons known as an osmoreceptors, and those neurons, in turn, stimulate secretion from the neurons that produce antidiuretic hormone.
The myoepithelial cells contract under the stimulation of oxytocin, excreting the milk secreted by alveolar units into the lobule lumen toward the nipple. As the infant begins to suck, the oxytocin-mediated "let down reflex" ensues and the mother's milk is secreted — not sucked from the gland — into the baby's mouth.
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