Arterial pressure regulation Flashcards
which fibers terminate at the heart and vessels?
SNS and PNS postganglionic fibers
Efferent fibers
What is the afferent pathway of the baroreceptor reflex?
Sensory mechanoreceptors sense arterial pressure via stretch in arterial wall
*** Active at normal pressure means Tonic Signal
Increasing stretch does what to AP generation on the baroreceptor reflex?
Increases it
Why are baroreceptors only good in the short term?
Adaptation
- continually elevated pressures can lead to gradual decrease in firing
Where do the parasympathetic fibers come from?
Nucleus ambiguus of medulla
Where do the sympathetic fibers come from?
- Rostral ventrolateral medulla
2. Raphe nucleus of medulla
How do the afferent fibers of the baroreceptor reflex enter the brain?
Enter medulla via nucleus tractus solitarius
What does a carotid message do?
increases pressure in carotid sinus to trick body into increasing parasympathetics to decrease pressure!
Can fix some atrial tachyarrhythmias
What is the current theory of long term regulation?
Long term pressure regulation crucially involves the kidneys, their NA+ handling and ultimately the regulation of blood volume
How would increased arterial pressure affect urinary output rate?
Increases it and thus decreases fluid volume, CO and later decreases arterial pressure
How does one calculate the urinary output rate?
Glomerular filtration rate- renal fluid reabsorption rate?
What is significant of glomerular filtration?
Transcapillary fluid movement dependent on hydrostatic and onconic pressures!
What does most resorption in the kidneys follow?
Sodium
- Water follows Na+ via osmosis
What happens when we increase renal tubular Na+ reabsorption?
Increases water reabsorption and thus decreases urinary output
Where is angiotensinogen produced?
liver
What is RAAS?
Renin
Angiotensin
Aldosterone system
Where is renin produced and what is its purpose?
Kidneys
- Catalyzes conversion of angiotensiongen to angiotensin I
What converts Angiotensin I to angiotensin II?
Angiotensin converting enzyme (ACE)
What is the role of angiotensin II?
controls release of aldosterone
What is the role of aldosterone? Produced where?
primary regulator of rate of Na+ reabsorption by renal tubular cells
Adrenal glands
what affects the release of Renin from kidneys?
- Increase in renal sympathetics
- lowered glomerular filtration rate
- activation of sympathetics vasoconstrictor nerves in renal arterioles
increase in all causes increase Renin and increased Na+ reabsorption and thus decrease urinary output
What is another major affector of urine production?
Vasopressin (anti-diuretic hormone)
- release from post pituitary gland
whats the relationship between baroreceptors and ADH?
Increased afferent input from baroreceptors means decreased release of ADH and less water retention
Where and how does ADH work?
On renal collecting ducts via V2 receptors to increased water perm (cAMP dependent)
Leads to increase water retention
What is a secondary function of ADH?
Vasoconstriction in severe hypovolemia via IP3 signal transduction pathway on VSM
