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20 Cards in this Set

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What is the relationship between T4 and pregnancy/
T4 is highly bound to plasma proteins, especially to thyroxin binding globulin, which increases during pregnancy. an increase in this globulin tends to decrease free T4, which leads to an increase in TSH secretion, causing the thyroid to increase thyroid hormone secretion.
Regarding question 1, how are levels of TSH affected?
Plasma levels of TSH are normal, b/c there is no further stimulus for TSH secretion. However, total T4(bound + free) is elevated. Because free T4(and not bound T4) enters cells and produces biological effects, and b/c the conc. of T4 is normal, the patient would be euthyroid.
What is the negative feedback signal associated with sperm cell production that inhibits pituitary formation of FSH?
The Sertoli cells of the seminiferous tubules secrete inhibin at a rate proportional to the rate of production of sperm cells. Inhibin has a direct inhibitory effect on anterior pituitary secretion of FSH.
in the male, FSH binds to which receptors?
FSH binds to specific receptors on the Sertoli cells, causing the cells to grow and secrete substances that stimulate sperm cell production. Inhibin provides the negative feedback control signal from the seminiferous tubules to the pituitary gland.
Leutinizing hormone peaks app. how much time prior to ovulation?
The rate of secretion of LH from the anterior pituitary increases markedly, rising 6-10 fold and peaking about 12 hours before ovulation. In response to the increase in LH conc. the follicle undergoes changes that lead to ovulation. if this surge does not occur, ovulation will not occur.
In the female, for the most part, what is the only source of progesterone production.
The corpus luteum is the only source of progesterone production, except for minute quantites secreted from the follicle before ovulation.
When is the CL functional?
It is functional between ovulation and the beginning of menstruation, during which time the conc. of LH hormone is suppressed below the level achieved during the preovulatory LH surge.
What is paracrine communication?
It refers to cell secretions that diffuse into the extracellular fluid to affect neighboring cells.
What are the delta cells of the pancreas/
They secrete somatostatin, which inhibits the secretion of insulin and glucagon.
Estrogen is required for normal reproductive function in the male. Where is the principal site of estrogen synthesis in the male?
Large amounts of estrogen are formed from testosterone and androstenediol in the liver, accounting for as much as 80% of the total male estrogen production.
Secretion of adrenal cortical hormones is deficient in patients with Addison's disease. True/False
True. As well, low plasma levels of both aldosterone and cortisol would be reported. Due to low levels of aldosterone, plasma conc of potassium would be increased.
What is Conn's syndrome?
These patients have tumors of the zona glomerulosa that secrete large amounts of aldosterone. Plasma levels of aldosterone are elevated, causing hypokalemia. The secretion of cortisol from the zona fasciculata is normal.
What is the relationship between aldosterone and sodium?
Aldosterone secretion is elevated when dietary sodium intake is low, yet cortisol secretion is normal. Although aldosterone increases the rate of potassium secretion by the principal cells of the collecting tubules, this effect is offset by a low distal tubular flow rate. Consequently, there is little change in either potassium excretion or plasma potassium concentration.
What is diabetes insipidus/
In patients with nephrogenic diabetes insipidus the kidneys do not respond appropriately to ADH, and the ability to form concentrated urine is impaired.
Is there a relationship between amino acids and insulin secretion?
Both Amino acids and glucose stimulate insulin secretion. Somatostatin inhibits insulin secretion.
What is the relationship of HCG and interstitial cells in the male?
HCG also binds to LH receptors on the interstitial cells of the testes of the male fetus, resulting in the production of testosterone in male fetuses up to the time of birth. This is what causes the fetus to develop male sex organs instead of the female apparatus.
A patient has an elevated plasma T4 conc., a low plasma level of TSH conc. and a thyroid gland that is smaller than normal. What is the most likely explanation?
The patient is taking thyroid extract. If a patient were taking sufficient amounts of exogenous thyroid extract to increase plasma levels of T4 above normal, feedback would decrease TSH secretion. Low plasma levels of TSH would result in atrophy of the thyroid gland. In Graves disease, the same changes in plasma levels of T4 and TSH would be present, but the thyroid gland would not be atrophied. In fact goiter is often present in patients with Graves disease. A lesion in the anterior pituitary that prevents TSH secretion or the taking of propylthiouracil or large amounts of iodine would be associated with low plasma levels of T4.
Free ion activity of calcium in the ECF will be increased within 1 minute by which process?
Reduction in extracellular pH. If the extracellular pH is reduced, the additional H+ ion in solution will bind with negatively charged phosphate ions and negatively charged portions of protein molecules, thereby reducing the number of potential ionic partners for positively charged calcium ions. As a result, the free calcium ion activity in the solution will increase.
Menstruation ends when the endometrium and epithelium begin to regrow and reline the surface of the uterus. What stimulates the regrowth of the cells of the epithelium?
Estrogen. Post menses, only a thin layer of epithelium remains and the only epithelial cells left are those in the deeper portions of the gland in crypts of the endometrium. under the influence of estrogen, which is secreted in increasing quantities by the follicles during the first part of the monthly cycle, epithelial cells and endometrial cells proliferate rapidly.
What is the relationship between LH and FSH and steroids?
The cells of the anterior pituitary that secrete Lh and FSH, and the cells of the hypothalamus that secrete gonadotropin releasing hormone, are inhibited by both estrogen and testosterone. Steroids taken haphazardly by individuals would result in cessation of the monthly menstrual cycle.