MM <3 regulators Flashcards
Only the ___ plateaus during exercise (cardiac output)
SV
The heart and vasculature are regulated, in part, by:
neural (autonomic)
humoral (circulating or hormonal) factors.
Neural mechanisms involve ______________ branches of the autonomic nervous system.
sympathetic adrenergic & parasympathetic cholinergic
In general, the sympathetic system stimulates the heart and constricts blood vessels resulting in a rise in arterial pressure.
The parasympathetic system depresses cardiac function and ___________
dilates selected vascular bed
There are several very important humoral mechanisms including __________________ (6) . Each of these humoral systems directly or indirectly alter cardiac function, vascular function, and arterial pressure.
circulating catecholamines the renin-angiotensin system vasopressin (antidiuretic hormone) atrial natriuretic peptide, endothelin
The medulla, located in the brainstem above the spinal cord, is a major site in the brain for regulating____________________, and is particularly important for short-term feedback regulation of arterial pressure.
outflow to the heart and blood vessels
The _______________ (NTS) of the medulla receives sensory input from different systemic and central receptors (e.g., baroreceptors and chemoreceptors).
nucleus tractus solitarius
In general, the sympathetic system stimulates the heart and constricts blood vessels resulting in a rise in _________.
The parasympathetic system depresses cardiac function and dilates selected vascular bed
arterial pressure
The nucleus tractus solitarius (NTS) of the medulla receives sensory input from different systemic and central receptors (e.g., ____________).
baroreceptors
The heart is innervated by vagal and sympathetic fibers. The right vagus nerve primarily innervates the _______ node, whereas the left vagus innervates the AV node
SA node
Sympathetic effects on heart function are mediated by beta-adrenoceptors
parasympathetic effects on heart function are mediated by _____________
muscarinic receptors
The release of acetylcholine (ACh) from parasympathetic nerves binds to muscarinic ACh receptors, has a direct ________ action (coupled to nitric oxide formation and guanylyl cyclase activation).
vasodilatory
The heart is innervated by vagal and sympathetic fibers. The right vagus nerve primarily innervates the SA node, whereas the left vagus innervates the _________ node
AV Node
Sympathetic effects on heart function are mediated by ______________
parasympathetic effects on heart function are mediated by muscarinic receptors
beta-adrenoceptors
Circulating catecholamines are?
epinephrine and norepinephrine
important humoral mechanisms
Epinephrine is released by the __________ upon activation of preganglionic sympathe`tic nerves innervating this tissue.
adrenal medulla
This activation occurs during times of stress
Norepinephrine is also released by the adrenal medulla (about 20% of its total catecholamine release is norepinephrine).
The primary source of circulating norepinephrine is spillover from ____________ innervating blood vessels.
sympathetic nerves
Circulating Epinephrine Causes:
Increased heart rate and inotropy (β1-adrenoceptor mediated)
Vasoconstriction in most systemic arteries and veins (postjunctional α 1 and α 2 adrenoceptors)
Circulating Norepinephrine Causes`
Increased heart rate (although only transiently) and increased inotropy (β1-adrenoceptor mediated) are the direct effects norepinephrine on the heart.
Vasoconstriction occurs in most systemic arteries and veins (postjunctional α 1 and α 2 adrenoceptors)
Overall CV response to epinephrine is increased _________ and a small change in mean arterial pressure.
Cardiac Output
The overall cardiovascular response to Circulating Norepinephrine is increased cardiac output and systemic vascular resistance, which results in an elevation in __________
arterial blood pressure.
Because catecholamines act on the heart and blood vessels through alpha and beta adrenoceptors, the cardiovascular actions of catecholamines can be blocked by treatment with ______________
alpha-blockers and beta-blockers
The renin-angiotensin-aldosterone system (RAAS) plays an important role in regulating blood volume and systemic vascular resistance, which together influence:
cardiac output and arterial pressure
Renin, released by the kidneys, stimulates the formation of angiotensin in blood and tissues, which in turn stimulates the release of ____________ from ___________.
aldosterone from the adrenal cortex
Renin is a proteolytic enzyme that is released into the circulation primarily by the kidneys. Its release is stimulated by:
1- sympathetic nerve activation (β1-adrenoceptors)
2- renal artery hypotension
3- decreased sodium delivery to the distal tubules of the kidney.
Vascular endothelium has an enzyme, angiotensin converting enzyme (ACE), that cleaves off 2 aa to form _______ from AI
angiotensin II (AII)
angiotensin II (AII) functions to:
1- Constricts vessels—> increasing systemic vascular resistance and arterial pressure
2- release aldosterone (adrenal cortex), which in turn acts on the kidneys to increase sodium/fluid retention
3- Stimulates the release of vasopressin (antidiuretic hormone, ADH)
4- Facilitates norepinephrine release from sympathetic nerves
5- Stimulates cardiac hypertrophy and vascular hypertrophy
The renin-angiotensin-aldosterone pathway regulated by the mechanisms that stimulate renin release, & also modulated by ___________ released by the heart. These act as an important counter-regulatory system.
natriuretic peptides (ANP and BNP)
The main physiological actions of natriuretic peptides ((ANP and BNP) ) is to reduce arterial pressure by ______________
decreasing blood volume and systemic vascular resistance.
__________ is a peptide hormone formed in the hypothalamus. Its two primary functions are to retain water in the body and to constrict blood vessels
Vasopressin (aka Argipressin)
Mechanisms regulating the release of Vasopressin
Hypovolemia
Hypotension
Hypothalamic
Dehydration
cardiopulmonary baroreceptors entering the atria decrease their firing rate when there is a fall in atrial pressure. Nerve fibers from these receptors synapse within the medulla, which signals to hypothalamus for A_________ by the pituitary
Vasopressin (aka Argipressin) release
Hypotension, which decreases arterial ____________, leads to enhanced sympathetic activity that increases AVP release
baroreceptor firing
___________ located in a region of the hypothalamus regulate AVP release.
Angiotensin II receptors
an increase in angiotensin II simulates AVP release.
Natriuretic peptides (ANP and BNP) is cause decrease renin release, thereby decreasing circulating levels of \_\_\_\_\_\_. This leads to natriuresis and diuresis.
angiotensin II and aldosterone
Taken together, the actions of NPs decrease:
↓ blood volume ↓ arterial pressure ↓ central venous pressure ↓ pulmonary capillary wedge pressure ↓ cardiac output.
Natriuretic peptides serve as a counter-regulatory system for the ______ system.
renin-angiotensin-aldosterone
