BRS PHYSIOLOGY EXAM QUESTIONS WITH COMPLETE SOLUTIONS VERIFIED 2024/2025
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BRS PHYSIOLOGY EXAM QUESTIONS WITH COMPLETE SOLUTIONS VERIFIED 2024/2025
During thyroid hormone synthesis, how is iodide transported into the cell?
I pump or Na-I cotransport These transporters actively transport iodine into the cell Inhibited by thiocynate and perchlorate anions
How are adren...
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BRS PHYSIOLOGY EXAM QUESTIONS WITH COMPLETE
SOLUTIONS VERIFIED 2024/2025
During thyroid hormone synthesis, how is iodide transported into the cell?
I pump or Na-I cotransport These transporters actively transport iodine into the cell
Inhibited by thiocynate and perchlorate anions
How are adrenal androgens excreted?
Lost as 17-ketosteroids in the urine
How are estrogens produced?
The A ring of testosterone is oxidized (aromatization) This occurs in the ovaries and
placenta, but not in the adrenal cortex or testes
How are protein and peptide hormones synthesized?
Preprohormone synthesis occurs in the ER The signal peptide is cleaves to give the
prohormone The prohormone trafficks to the Golgi Additional proteolytic cleavages
occur to give the mature hormone The hormone is packaged into secretory granules for
later use
How are the endocrine cells of the pancreas organized within the pancreas?
Beta cells -- center of the islet Alpha cells -- periphery of the islet Delta cells -- scattered
throughout
How are the posterior pituitary hormones made?
,They are synthesized in hypothalamic nuclei and packaged into secretory granules with
their respective neurophysins Travel down the nerve axons for secretion by the
posterior pituitary
How are thyroid hormones produced?
Thyroglobulin is synthesized from tyrosine in the thyroid follicular cells It is then
packaged into secretory vesicles and exocytosed into the follicular lumen Iodide is
transported into the follicular cells and oxidized to iodine Tyrosine residues of
thyroglobulin react with I2 to form monoiodotyrosine (MIT) and diiodotyrosine (DIT) Two
molecules of DIT combine to form thyroxine (T4) One molecule each of DIT and MIT
combine to form triiodothyronine (T3) Iodinated thyroglobulin is stored as colloid in the
follicular lumen until needed When the cells are stimulated by TSH, colloid is
endocytosed into the follicular cells Lysosomal enzymes digest thyroglobulin to release
T3 and T4 into circulation Leftover MIT and DIT are deiodinated and the iodine is
recycled In the circulation, T3 and T4 is usually bound to thyroxine-binding globulin
(TBG)
How can neonatal hypothyroidism-associated mental retardation be avoided?
Hormone replacement therapy There is only a narrow window when this is effective, so
screening for neonatal hypothyroidism is both necessary and mandatory
How could diabetes produce hypotension?
Hyperglycemia causes the blood glucose concentration to exceed the Tm of the kidney
Unabsorbed glucose acts as an osmotic diuretic in the urine Causes excess water to be
lost in the urine, resulting in ECF volume contraction
How could diabetes produce metabolic acidosis?
,Overproduction of ketoacids Patients will increase their ventilation rate in order to
compensate
How do accessory sex organs synthesize DHT?
They contain 5a-reductase This converts testosterone to its active form, DHT
How do dilation of the cervix and orgasm regulate oxytocin production?
They both stimulate secretion
How do excitatory hormones work?
Increase the number or affinity of receptors for itself or other hormones
How do glucocorticoids contribute to the maintenance of vascular response to
catecholamines?
Cortisol upregulates alpha1 adrenergic receptors on arterioles This increases their
sensitivity to norepinephrine
How do glucocorticoids mediate anti-inflammatory effects?
Induce lipocortin synthesis, which inhibits phospholipase A2 Recall that PLA2 liberates
arachidonic acid, a precursor for prostaglandins and leukotrienes, from membrane
phospholipids They also inhibit histamine and serotonin degranulation in mast cells and
platelets
How do glucocorticoids stimulate gluconeogenesis?
Increase protein catabolism in the muscle Decrease protein synthesis (these two things
provide amino acids for gluconeogenesis) Decrease glycolysis Decrease insulin
sensitivity of adipose tissue Increase lipolysis, which provides glycerol to the liver for
gluconeogenesis
How do glucocorticoids suppress the immune system?
, Inhibit the production of IL2 Inhibit T cell proliferation These are both important in
cellular (T cell-mediated) immunity
How do hormones determine the sensitivity of a target tissue?
They regulate the number or sensitivity of receptors
How do inhibitory hormones work?
They decrease the number or affinity of receptors for itself or another hormone
How do people with ACTH-secreting tumors of the anterior pituitary respond to
the dexamethasone suppression test?
Low doses have no effect High doses inhibit cortisol secretion This is because you are
reducing the stimulus (ACTH) for cortisol production
How do people with adrenal cortical tumors respond to the dexamethasone
suppression test?
Not even a high dose inhibits cortisol secretion This is because the cells have lost
responsiveness to ACTH and just churn out cortisol
How do sulfonylurea drugs work?
Similar to ATP, these drugs close ATP-gated K channels This causes pancreatic beta
cells to depolarize Ca influx triggers insulin exocytosis
How do the Sertoli cells inhibit FSH secretion?
After being stimulated by FSH, they produce inhibin, which inhibits further FSH
secretion
How do the symptoms of secondary adrenocortical deficiency differ from those of
Addison's disease?
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