Cardiovascular Receptors (Middlekauff) Flashcards
Where are arterial baroreceptors located?
Adventitial walls (outside) of aortic arch and carotid sinus
How do arterial baroreceptors travel back to the brain?
Cranial nerves IX and X
Synapse in the brain in the NTS (nucleus of solitary tract)
What do arterial baroreceptors sense?
Stretch, or CHANGES in BP (not BP itself)
How do arterial baroreceptors affect the NTS?
BP increases –> stretch occurs –> baroreceptors fire –> inhibit NTS –> inhibit sympathetic nerve activity from CNS –> decrease in HR, etc
OR
BP decreases –> decreased stretch –> decrease in baroreceptor firing –> stimulate NTS –> stimulate sympathetic nerve activity from CNS –> increase HR, etc
What exactly do arterial baroreceptors do?
Buffer ACUTE changes in BP
If they’re cut, you have same mean BP (because that’s determined by bigger things like kidneys’ RAAS, ADH, ANP, etc) but you have more fluctuation around that mean BP because you can’t buffer the changes when they occur
Where are cardiopulmonary baroreceptors located?
They are unmyelinated and located in (posterior inferior) atria and left ventricle
How do cardiopulmonary baroreceptors travel back to the brain?
Cranial nerve X
Synapse in the brain in the NTS (nucleus of solitary tract)
What do cardiopulmonary baroreceptors sense?
Stretch induced by changes in left ventricular filling pressures (LVEDP = left ventricular end diastolic pressure) and ventricular contractility
How do cardiopulmonary baroreceptors affect the NTS?
Pressure increases –> stretch occurs –> baroreceptors fire –> inhibit NTS –> inhibit sympathetic nerve activity from CNS –> decrease in HR, etc
OR
Pressure decreases –> decreased stretch –> decrease in baroreceptor firing –> stimulate NTS –> stimulate sympathetic nerve activity from CNS –> increase HR, etc
Why are cardiopulmonary baroreceptors so important?
They are important regulators of renal blood flow and volume regulation
Where are the arterial chemoreceptors located?
Small, highly vascularized nodules in carotid and aortic bodies
How do arterial chemoreceptors travel back to the brain?
Cranial nerves IX and X
Synapse in the brain in the NTS (nucleus of solitary tract)
What do the arterial chemoreceptors sense?
Changes in the blood: CO2, O2, pH
(Hypoxemia, hypercapnia, acidosis)
How do arterial chemoreceptors affect the NTS?
O2 decreases –> increased chemoreceptor firing –> stimulate NTS –> increased vagal actibity causes bradycardia –> increased sympathetic activity causes RAAS to be activated, respiratory center stimulated
Arterial chemoreceptor effects on the body when low O2
Decrease HR
Renal vasoconstriction
Increase RAAS
Vasoconstrict smooth muscle
Increase tidal volume
Vasoconstrict and venoconstrict in splanchnic circulation
Lung inflation reflex
When tidal volume increases –> pulmonary stretch receptors activate lung inflation reflex –> withdrawal of vagal activity –> increase HR
WINS over arterial chemoreflex trying to decrease HR!
Dive reflex
Initiated by ice cold water touching face –> vagal nerve activity increases –> HR decreased, increased sympathetic output (vasoconstriction) to renal, splanchnic and muscle tissues
1) Works with arterial chemoreceptors to let diving animals decrease metabolic/O2 demands and stay underwater longer
2) Can be used in humans to terminate supraventricular tachycardia
Where are muscle metaboreceptors located?
Lightly myelinated and unmyelinated type III and IV nerve endings located in skeletal muscle
How do muscle metaboreceptors travel back to the brain?
Sympathetic afferent nerve fibers go to spinal column
From spinal column, first synapse is in NTS
What do the muscle metaboreceptors sense?
Ischemic metabolides:
Interstitial K+
Acidosis
Hyperosmolarity
Hypoxia
Adenosine
(Overall sensitive to uner-perfusion of working muscle)
How do muscle mechanoreceptors affect the NTS?
Ischemic metabolites generated –> muscle metaboreceptors increase firing –> sympathetic activity increases and vagal activity decreases –> increased HR, renal vasoconstriction and activation of RAAS, etc. –> BP maintained and directs blood flow to working muscle
Systems affected by arterial baroreceptor induced sympathetic stimulation
Heart: HR up, contractility up, SV up
Kidney: Vasoconstriction, RAAS up
Muscle: Vasoconstriction
Splanchnic: Vasoconstriction, venoconstriction
Systems affected by cardiopulmonary baroreceptor induced sympathetic stimulation
Muscle: Vasoconstriction
Kidney: Vasoconstriction, RAAS up
Skin: Vasoconstriction
Systems affected by arterial chemoreceptor induced sympathetic stimulation
Heart: wants to decrease HR (however, Lung inflation reflex decreases vagal actvity and wins over and increases HR!)
Kidney: Vasoconstriction, RAAS up
Muscle: Vasoconstriction
Lungs: Increase tidal volume
Splanchnic: Vasoconstriction, venoconstriction
Systems affected by muscle metaboreceptor induced sympathetic stimulation
Heart: HR up, contractility up
Kidney: Vasoconstriction, RAAS up
Muscle: Vasoconstriction
Splanchnic: Vasoconstriction, venoconstriction
