Cardiovascular 5 Flashcards
Definition:
Specialized stretch receptors located within thin areas of blood vessels and send impulses to the cardiovascular centre in the medulla oblongata to regulate blood pressure
Baroreceptors
Where are vascular baroreceptors found?
Aorta and carotid sinuses
T/F: Parasympathetic reflexes are initiated if PB falls
False! It’s sympathetic
How to chemoreceptors responde to falling pH?
Increase cardiac output and constrict peripheral vessels to increase return to the lungs
How do chemorecptors respond to rising pH?
Decrease cardiac output and dilate peripheral vessels to decrease return to lungs
What does neurological regulation of BP depend on?
cardiovascular centres located in the medulla oblongata
How does neurological regulation decrease cardiac function?
Dec HR and SV via parasympathetic stimulation
How does neurological regulation increase cardiac function?
regulate HR and SV via sympathetic stimulation
How does neurological regulation control vessel tone?
via vasomotor centres
What is the main way the endocrine system plays a role in managing the cardiovascular system?
Catecholamines (epinephrine and norepinephrine) and several hormone that interact with the kidneys to regulate blood volume
What occurs when catecholamnies are released by the adrenal medulla?
They ehance and extend the body’s synmpathetic fight-or-flight response
- increase HR and contractile force
- increase blood flow to the liver, muscles and heart
- decrease blood flow to non-essential organs
How does ADH help control BP?
Signals to kidneys to reansorb more water, dec fluid loss in urine which increases overall fluid levels and helps restore blood volume and pressure
Also plays a small role in peripheral vessel constriction
How does the renin-angiotensin-aldosterone system aid in BP control?
- specialized cells in the kidneys screte renin in response to decreased blood flow
- renin activates angiotensinogen from the liver into angiotenis I, which is then overted into angiotensin II in the lungs which stimulates thirst in the hypothalamus
T/F: Angiotensin II is a powerful vasoconstrictor helping increase BP
True
T/F: Angiotensin II stimulates release of ADH and aldosterone
True
What triggers the thirst response?
Osmoreceptors sense an increase in the osmolaity ( concentration) of the blood
What causes a release of atrial natriuretic hormone (ANH)?
released in respoinse to stretch in the atria as this detects increased blood volume
T/F: ANH is an agonist to angiotensin II
False! Its an antagonist
What does ANH do?
- causes of loss of Na and water from the kidney
- supresses renin, aldosterone and ADH production and release
What are the differences between the renin-angiotensin-aldosterone system and ANH?
R-A-A:
- overall effects are to limit losses in blood volume, combine with vasoconstriction leading to raised BP
ANH:
- overall effect is to promote loss of fluid from the body so blood volume and BP will decrease
BP
What are autoregulation mechanism?
Mechanisms that do not require specialized nervous stimulation or endocrine control. They are local self-regulatory mechanisms that allow each region to adjust its own blood flow and perfusion
What controls precapillary sphincters?
chemical signals
What causes precapillary sphincters to dilate? Constrict?
release of nitric oxide (NO) from endothelial cells, which allows for blood to flow
Contriction is cuased by release of endothelins (vasocontrictors) released from endothelial cells
What is a largely protective function against dramtic changes in BP and blood flow?
Myogenic response which is the reaction to stretching of the arteriole smooth muscle
