Regulation of Arterial Pressure Flashcards
What is the equation for mean arterial pressure?
MAP = Cardiac Output x Total Peripheral Resistance
(Cardiac Output = HR x Stroke Volume)
(Stroke Volume = EDP - ESP)
(MAP =2/3 diastolic BP + 1/3 systolic BP)
Normal MAP=93.3mmHg (approx 100)
What cranial nerve is associated with baroreceptors in the carotid sinus?
CN IX
Glossopharyngeal
What nerurotransmitter is associated with the nucleus tractus solitarius?
Glutamate
What is the rostral ventrolateral medulla in charge of?
Sending sympathetic signals to the heart as a part of the baroreceptor reflex.
What two regions of the brain stem are in charge of sending parasympathetic nerve fibers to the heart as a part of the baroreceptor reflex?
Dorsal motor nucleus of the vagus
Nucleus abmbiguus
What is the highest mean arterial pressure that the carotid bodies can report?
About 200 mmHg
What stimulates renin to be produced by the kidneys?
Low BP
Beta 1 adrenergic receptor activation
What four things does Angiotensin II do to increase blood pressure?
Contracts smooth muscle via the AT1 receptor
Causes secretion of aldosterone
Causes secretion of antiduretic hormone
Increases thirst
What stimulates the release of natriuretic hormone?
Excessive preload
What does natriuretic peptide do?
Dilates the arterioles
Increases fluid loss
Inhibits renin
What does the body do as a response to increased blood volume?
Increase secretion of atrial natriurietic peptide
Decreases aldosterone secretion
Renal vasodilation occurs
Increases heart rate
What nerves innervate the aortic sinus?
Vagus (X)
aortic nerve
When does the carotid sinus increase firing rate and when will it decrease firing rate?
increases firing rate in response to increased stretch (higher pressure)
decreases firing rate in response to low pressure (less stretch on walls)
most responsive to rate of change; reacts immediately and can “reset” the BP set point
Where in the brain do signals from the carotid sinus go?
First to the nucleus of tractus solitarius and then PNS sends signals to the dorsal motor nucleus of the vagus and nucleus ambiguus (inhibit vasoconstriction) and the SNS sends signals to the rostral ventraolateral medulla (vasomotor/constrict)
Compare and contrast the aortic and carotid sinuses
the aortic sinus:
has a higher threshold for activation
continues to respond above saturation
less sensitive to rate/less effected by decrease in rate
What is the sympathetic response to baroreceptor firing?
SNS responds to a decrease in baroreceptor firing rate
influences atria/ventricle, SA node, vessels directly
influences adrenal gland via splanchnics
causes:
constriction of vessels (alpha rec.)
increase HR and contract. (b1)
renin secretion by kidney
What is the parasympathetic response to baroreceptor firing?
PNS responds to increase in baroreceptor firing rate
decreases HR via vagus to SA node and ach on muscarininc receptors
causes indirect vasodilation via NO release
While the baroreceptor reflex takes seconds, what is a longer term hormonal response to vascular and fluid changes?
RAAS
controls BP by regulating blood volume and TPR
overlap with SNS
uses ADH and ANP
What will be increased as a result of angiotensin II release (overall systemic changes)
Blood volume
EDV
Preload
SV
CO
BP
What are the results of angiotensin II release (small scale changes)
- increased aldosterone, Na reabsorption, ECF volume
- Na/H exchange
- thirst
- vasoconstriction and TPR, BP (AT1 receptors)
When is renin released?
What stimulated the release?
What does renin do?
released when there is a drop in BP
via B1 adrenergic receptor activation (and SNS stim.)
decreases NaCl at macula densa, converts angiotensinogen into angiotensin I which becomes II in the lungs and kidneys
angiotensin II stimulates the release of ADH which dos what?
what else can stimulate the release of ADH?
What is the result of ADH
reduces urine production and increases fluid retenton
atrial receptors during low preload (decreased atrial firing rate)
hyperosmolarity
SNS activation
increases TPR and water retention, vasoconstirction on v1 and increased fluid reabs. on V2
What are three types of natriuretic peptides?
why are they secreted?
what are their effects?
ANP, BNP, CNP (atrial, brain, c-type)
increased secretion by excessive preload of atrial and ventricles (increased blood volume)
dilate arterioles, decrease TPR
excrete fluid, decrease preload
inhibit renin
protects against overdilation/over stretchingof cardiac chambers
What are the immediate effects of blood volume loss? (hemorrhage, dehydration or other source of loss would be same)
decreased
Venous return
preload
stroke volume
CO
MAP
vascular function curve shifts to left
