Exam 3 Kirk L5: Mechanisms of Global Regulation Flashcards
Define the following terms
________ is a theorhetical reference point… the amount of vascular contraction found under resting conditions without neural or hormonal (extrinsic) influences
_______ is vascular constriction under resting conditions as a result of tonic SNS activity. Resistance is higher than basal tone due to the presence of tonically released NE
Basal tone is a theorhetical reference point… amount of vascular contraction found under conditions with no extrinsic influences
Resting sympathetic tone: vascular constriction under resting conditions as a result of tonic SNS activity (presence of tonically released NE increases resistance)
In your resting sympathetic tone, your resistance is _____ than that of theorhetical basal tone.
Explain why
In resting sympathetic tone, your resistance is higher than that of theorhetical basal tone.
This is because NE gets released tonically, increasing pressure via vasoconstriction and therefore increases resistance
Define what active mechanisms vs passive mechanism due to change your vascular resistance
Active mechanisms induce a change in vascular resistance away from basal tone
Passive mechanisms induce a change in vascular resistance back toward basal tone
Where are the alpha receptors located and what do they cause?
WHere is beta 1 receptors?
Beta 2 receptors?
Alpha receptors are located on the vascular smooth muscle and cause vasoconstriction
Beta 1 is on cardiac muscle and increases HR and contractility
Beta 2 are located on smooth muscle and cause vasodilation
What two types of blood vessels have little sympathetic vasoconstriction innervation?
Coronary (heart) and cerebral (brain) have very little sympathetic vasoconstrictor innervation.
Parasympathetic NS innervates ______ within circulatory system
PSNS innervates very few blood vessles
mainly affects the heart
What is the sympathetic cholinergic pathway important for with regards to exercise?
Sympathetic cholinergic pathway release ACh onto sweat glands of skin, inducing vasodilation
important to regulate temp while exercise
Which receptors cause vasoconstriction in blood vessels?
Which receptors cause vasodilation in blood vessels?
Vasoconstriction of blood vessels : ALPHA 1 (alpha two but only a little)
Vasodilation of blood vessels: beta 2
The baroreceptor is what kind of receptor?
Important for short term or long term?
Baroreceptor is a mechanoreceptor, it responds to changes in stretch
If it gets stretched, aka high bp it increases its firing
If it does not get stretched aka small bp, it decreases its firing
SHORT TERM
Baroreceptor is a ____ feedback loop
Baroreceptor is a negative feedback loop
Baroreceptors are located in which two places?
Baroreceptors in the aortic arch and the carotid sinus
Carotid sinus gets ennervated with which cranial nerve
What about aortic arch?
Carotid sinus —> IX
aortic arch : X
A decrease in arterial pressure stimulates ____ and inhibits _____
What happens to peripheral vessels?
What happens to HR?
WHat happens to contractility?
Decrease in arterial pressure stimulates activation of SNS and inhibits PSNS.
Peripheral vasoconstriction
Increase in HR
Increase in contractility
Baroreceptors are more responsive to _____ pressures than to constant ____ pressures
Blood pressure threshold for baroreceptors is ___ mmHG
What happens if you have hypertension?
Baroreceptors more responsive to pulsatile/phasic pressures than static/constant pressures
threshold is 50 mmHg
Your baroreceptors adapt and raise the threshold
The ____ is the primary mechanism responsible for long term regulation of BP
It is responsible for mitigating the effects of fluid loss, dehydration (NOT HEMMORHAGE)
RAAS system: long term regulation
RAAS system:
____ is where low blood pressure is detected
Thus, stimulating ____ release.
That then converts ____ into _____
ACE then converts ____ to ______
____ is a powerful vasoconstrictor
RAAS:
Kidneys is where the low bp is detected
Thus stimulating renin release
Renin converts angiotensinogen to angiotensin I
ACE then converts angiotensin I to angiotensin II
Angiotensin II is a powerful vasoconstrictor
RAAS system:
Angiotensin II is a strong vasoconstrictor.
Explain the ways it increases blood volume:
aldosterone
ADH
hypothalamus
Angiotension II Mechanisms:
- stimulates aldosterone release, causing kidneys to reabsorb water
- stimulates hypothalamus to release ADH, increasing kidneys ability to retain water
- Hypothalamus: increases thirst
Explain why the RAAS system is bad news for CHF patients
How do physicians remedy this?
In CHF, decreased contractility will result in low blood pressure, stimulating the RAAS pathway
Chronic stimulation of this system relults in hypertension, increased afterload, fluid retension, edema
Responses are maladaptive
TREAT by giving an ACE inhibitor (decreases angiotensin II)
There are chemoreceptors in the same place as baroreceptors (aortic arch and carotid sinus).
Explain what happens when you have low O2 and high PCo2 levels.
(Explain what happens in the “intrinsic cardiovascular response” vs the integrated response)
Low O2…. the baroreceptors will send a signal to the brain, sending a signal to the heart that causes them to slow down and conserve more O2 (GREEDY) so the intrinsic cardiovascular response is bradycardia and vasoconstriction
However, the integrated response involves the pulmonary system, and more spefically the medulla vagal control center (sends signal for lungs to ventilate faster, that increase in respiration causes an increase in HR
In real life, hypoxia causes tachycardia becayse the increase in ventilation acts via stretch receptors in the lung to centrally inhibit efferent vagal nerve activity
