Exam 1 Review: Chapter 19: Endocrine Regulation of Blood Pressure/Blood Volume
osmoreceptors - Receptors in the CNS, particularly in the hypothalamus, which respond to changes in the osmotic pressure of the blood.
renin-angiotensin-aldosterone system - A complex endocrine negative feedback control system which plays an important role in regulating blood volume, arterial pressure, and cardiac and vascular function; in response to sympathetic stimulation, low blood pressure or low blood sodium levels: (1) the juxtaglomerular apparatus of the kidney will release the enzyme renin, (2) renin will catalyze the activation of an inactive precursor substance, angiotensinogen, which is made by the liver, into angiotensin I, (3) angiotensin I (which has some activity of its own) will be further activated by an enzyme found in the lungs, angiotensin-converting enzyme (ACE), into active angiotensin II, (4) angiotensin I & II stimulate these physiological responses: (a) enlargement of the heart and blood vessels, (b) systemic vasoconstriction, (c) aldosterone release from the adrenal cortex, (d) activation of the hypothalamic thirst center, (e) ADH release from the posterior pituitary/neurohypophysis; processes (c, d, and e) cause retention of salt and water by the kidneys and as a result, increased blood volume; thus this system has a powerful hypertensive effect.
angiotensinogen - A peptide synthesized in the liver which is released into the bloodstream to be the substrate for the enzyme renin which converts it to angiotensin I, a moderately effective hyperensive control substance, but more importantly angiotensin I is, itself, the precursor to angiotensin II [See ACE]; these vasoactive peptide products can also stimulate aldosterone release from the adrenal cortex, ADH/vasopressin from the posterior pituitary, and stimulate the hypothalamic thirst center.
angiotensin I - The peptide product of the circulating enzyme renin which converts the inactive precursor angiotensinogen to angiotensin I, a moderately effective hypertensive regulatory substance, but more importantly, the precursor to angiotensin II.
angiotensin II - The peptide product of the lung enzyme angiotensin-converting enzyme (ACE) which converts the angiotensin I into angiotensin II, a highly effective hypertensive regulatory substance which targets the adrenal cortex for aldosterone release, the anterior pituitary for ADH/vasopressin release, the hypothalamic thirst center, and the smooth muscle in arterial walls for contraction.
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aldosterone - The main steroid hormone produced by the outermost layer of the adrenal cortex, whose release is stimulated by increased potassium levels in the plasma; this mineralocorticoid targets the kidney to actively transport sodium ions out of the urine and potassium ions into the urine (chloride ions and water passively follow the sodium ions back to the bloodstream); the net effects of this hormone are to increase blood pressure and blood volume and to adjust sodium and potassium levels in the blood.
epinephrine = adrenalin - A catecholamine neurohormone derived from the amino acid tyrosine in the same pathway which produces norepinephrine, from which epinephrine is derived; it is released by the adrenal medulla and interacts with all target cells which have adrenergic receptors to ready the body for increased skeletal muscular activity or fight-or-flight emergencies.
norepinephrine = noradrenaline - A catecholamine neurotransmitter and neurohormone derived from the amino acid tyrosine which is the neurotransmitter released by most sympathetic postganglionic neurons and by the adrenal medulla; it interacts with all target cells which have adrenergic receptors to ready the body for increased skeletal muscular activity or fight-or-flight emergencies.
antidiuretic hormone (ADH) = vasopressin - the neurohypophyseal peptide hormone which stimulates contraction of smooth muscle in blood vessel walls and stimulates the kidney tubules to reabsorb water; both target responses tend to increase blood pressure.
atrial natriuretic peptide = ANP - The peptide hormone released from special endocrine cells in the walls of the upper chambers/atria of the heart in response to the stretching of the chamber walls due to increased blood volume or increased blood pressure; ANP is the antagonist to aldosterone and thus triggers salt (NaCl) and water excretion and potassium ion reabsorption at the kidney tubules.
parathyroid hormone = parathormone = PTH - A protein hormone, produced by the principle or chief cells of the parathyroid gland which increases plasma calcium levels (mechanisms 1, 2, and 3) and decreases plasma phosphate levels (mechanism 3) by (1) targeting oseoclasts to increase dissolution of bone matrix, (2) targeting the intestinal lining to increase calcium ion absorption from the digested meal, and (3) targeting the kidney to reaabsorb calcium ions from and secrete phosphate ions into the urine; PTH is the antagonist to thyrocalcitonine.
vitamin D3= calcitriol - The activated form of the fat/oil
soluble vitamin D, activated in response to parathormone action, which is
necessary for adequate calcium absorption from food in the
intestines.
List:
5. for
each of the following hormones, list:
(a) site of
synthesis and release
(b) target tissues/organs
which respond to the hormone
(c) the response(s) of
the target tissues/organs which help regulate blood pressure
hormones:
angiotensin
I/II
aldosterone
epinephrine
(adrenalin)/norepinephrine
antidiuretic hormone (ADH) = vasopressin
| Hormone | Site of Synthesis
and Release |
Responsive Target Tissues/Organs | Target Tissues/Organs Responses | ||||||||
| angiotensin I | liver |
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| angiotensin II | blood plasma |
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| aldosterone | adrenal cortex | kidney (tubules) | urinary retention of Na+ ions and H2O; urinary excretion of K+ ions |
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| epinephrine (adrenalin)/ norepinephrine |
adrenal medulla |
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| antidiuretic hormone (ADH) = vasopressin |
posterior pituitary
= neurohypophysis |
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Describe:
11. the hormonal regulation of blood pressure.
(A) The renin-angiotensin-aldosterone system is a complex endocrine negative feedback control system which plays important role in regulating blood volume, arterial pressure, and cardiac and vascular function; in response to sympathetic stimulation, low blood pressure or low blood sodium levels:
(1) the juxtaglomerular apparatus of the kidney will release the enzyme renin, (2) renin will catalyze the activation of an inactive precursor substance, angiotensinogen, which is made by the liver, into angiotensin I, (3) angiotensin I (which has some activity of its own) will be further activated by an enzyme found in the lungs, angiotensin-converting enzyme (ACE), into active angiotensin II,
(4) angiotensin I & II stimulate these physiological responses: (a) enlargement of the heart and blood vessels, (b) systemic vasoconstriction, (c) aldosterone release from the adrenal cortex, (d) activation of the hypothalamic thirst center, (e) ADH release from the posterior pituitary/neurohypophysis; processes (c, d, and e) cause retention of salt and water by the kidneys and as a result, increased blood volume; thus this system has a powerful hypertensive effect.
(B) Aldosterone is released from the adrenal cortex in response to angiotensin I & II (as noted above) and targets the kidney tubules to conserve Na+ ions and H2O while allowing excretion of K+ ions into the urine. Water retention increases blood volume and therefore blood pressure.
(C) Epinephrine (Adrenalin) and Norepinephrine are released from the adrenal medulla in response to Sympathetic Autonomic nervous stimulation and target (1) the myocardium of the heart to increase the rate and force of contractions, a positive inotropic effect, and (2) arterial smooth muscle causing vasoconstriction or vasodilation depending on adreneric receptor type (alpha and beta subtypes).
(D) Antidiuretic hormone (ADH) = Vasopressin is released from the anterior pituitary = adenohypophysis in response to hypothalmic recognition of increased plasma osmolarity (dehydration) and by angiotensin I & II, stimulating the following responses: (1) urinary retention of H2O by the renal tubules of the kidney and (2) vasoconstriction by arterial smooth muscle.
16. the long term regulation of blood pressure by the kidney.
The long term regulation of blood pressure by the kidney is achieved by the the renin-angiotensin-aldosterone system, which is a complex endocrine negative feedback control system which plays important role in regulating blood volume, arterial pressure, and cardiac and vascular function. In response to sympathetic stimulation, low blood pressure or low blood sodium levels:
(1) the juxtaglomerular apparatus of the kidney will release the enzyme renin, (2) renin will catalyze the activation of an inactive precursor substance, angiotensinogen, which is made by the liver, into angiotensin I, (3) angiotensin I (which has some activity of its own) will be further activated by an enzyme found in the lungs, angiotensin-converting enzyme (ACE), into active angiotensin II,
(4) angiotensin I & II stimulate these physiological responses: (a) enlargement of the heart and blood vessels, (b) systemic vasoconstriction, (c) aldosterone release from the adrenal cortex, (d) activation of the hypothalamic thirst center, (e) ADH release from the posterior pituitary/neurohypophysis; processes (c, d, and e) cause retention of salt and water by the kidneys and as a result, increased blood volume; thus this system has a powerful hypertensive effect.