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Unformatted text preview: the production and secretion of
androgens and cortisol from the adrenal cortex.
(b) Humoral stimulus: High blood glucose
stimulates release of insulin from the endocrine
tissue of the pancreas. Low blood glucose levels
stimulate release of glucagon.
(c) Neural stimulus: Sympathetic nervous
stimulation of the adrenal medulla causes the
release of norepinephrine (noradrenaline). the body to direct its efforts towards maintaining
activity throughout the stressful period.
(b) Unrelieved stress leads to elevated levels of
glucocorticoids (especially cortisol) which leads
to prolonged immune suppression, lowered
resistance to disease, and elevated levels of
blood sugar. Eventually, the capacity of glands
and the immune system is exhausted making the
subject susceptible to illnesses such as ulcers,
depression, diabetes, digestive trouble, and
cardiovascular disease. Hormones of the Pituitary (page 99) 1 (a) Growth hormone has generally anabolic effects.
It stimulates the proliferation of chondrocytes and
deposition of bone, it stimulates muscle growth
through protein synthesis and proliferation of
myoblasts, and it promotes the utilization of fats.
(b) Chronic or total growth hormone deficiency in
infancy results in the child being small, with an
immature face and chubby body build. Rate of
growth of all body parts is slow so that the child's
proportions remain normal.
(c) In the rare case of chronic hypersecretion of
growth hormone in infancy, the child exhibits
rampant growth or gigantism (a condition called
(d) Secretion of GH hormone is regulated through
(1) negative feedback of IGF-1 to suppress
secretion of GnRH from the hypothalamus and
(2) high levels of IGF-1 stimulating release of
hypothalamic somatostatin which also supresses
GH secretion. 2. The pituitary produces GH and TSH. TSH controls
the release of hormones from the thyroid which
are involved in the regulation of metabolic rate. GH
stimulates the liver and other tissues to secrete
IGF-1, which is both an endocrine and an autocrine/
paracrine hormone and mediates the metabolic
effects attributable to GH (see 1a). 3. Release of...
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- Winter '13