Cardiovascular Reflexes Flashcards
Where are Baroreceptors located?
Carotid Sinus!!!!
And minimally in aortic arch.
With decreased arterial pressure, is there decreased or increased baroreceptor firing?
Increased arterial blood pressure?
Decreased blood pressure=decreased baroreceptor firing.
Increased blood pressure=increased baroreceptor firing.
What is activated when there is decrease baroreceptor firing?
Increase Sympathetic innervation to increase Cardiac Output and SVR.
And decreased parasympathetic firing.
What change do baroreceptors sense?
Changes in blood pressure in the carotid sinus.
Does the baroreceptor reflex have more effect on rapidly changing BP or long term BP changes?
Rapidly changing pressure. especially postural changes in BP.
What is the Bainbridge Reflex?
Infusion of volume causes an increase in heart rate due to activation of atrial stretch receptors which causes medullary center activation of sympathetic output to the SA node.
How does degree and direction of HR change depend on prevailing HR?
Slow baseline HR will see increased HR with infusion.
High baseline HR will see decreased HR with infusion.
Which nerve innervates Carotid sinus?
CN-IX
What do atrial stretch receptors sense changes in?
Changes in volume.
Location of stretch receptors?
Vena Cava/right atrial junction.
Pulmonary vein/left atrial junction.
Stretch receptor activation causes three other related results, What are they?
Decreased sympathetic activity to kidneys.
Decrease vasopressin, Increased atrial natriuretic peptide.
(all of these are trying to get rid of blood via increased urine output.)
What is the other name of Bezold-Jarisch Reflex?
Ventricular Receptor Reflex.
What does this reflex play a role in?
Blood pressure regulation.
Describe the Bezold-Jarisch Reflex:
Strong contraction of an underfilled ventricle elicits the reflex.
What is best way to limit the Bezold-Jarisch Reflex with spinal anesthesia?
Give preload prior to spinal anesthetic.
The Bezold-Jarisch Reflex is probably involved in what?
Bradycardia and hypotension during coronary reperfursion,
Bradycardia and hypotension with myocardial ischemia/infarction, Bradycardia with profound hypovolemia, Syncope in severe aortic stenosis.
What are the “big three” symptoms of aortic stenosis?
CHF, Angina, Syncope.
2 Take aways from Bezold Jarisch Reflex:
- Give epi if severely hypotensive/bradycardic
2. Give preload prior to spinal anesthesia.
Where are peripheral Chemoreceptors located?
Aortic and Carotid bodies.
Hypoxemia/hypercarbia result in excitation of vasomotor center which causes what?
Increase in SVR»>Increase in MAP.
Peripheral Chemoreceptor involvement in BP is not stimulated strongly until what arterial pressure is reached?
Until arterial pressure falls below 80mmHg.
How is CNS ischemic response mediated?
Result of decrease blood flow to vasomotor center in medulla.
What is the result of the CNS ischemic response reflex?
Increase in BP, Contractility, and HR.
What is an example of CNS Ischemic Response?
Patient shocked out of ill-perfusing rhythm, they will typically have sever hypertension following even if drugs were not given.
What is Cushing Response a result of?
Increased intracranial pressure.
What will you typically see with Cushing triad?
Increased ICP, Hypertension, Bradycardia, irregular breathing.
Which happens first, increased MAP or decreased HR in Cushing Response?
Increase MAP from CNS Ischemic response, which then causes baroreceptor reflex which causes decrease in HR.
Where are Diving reflex receptors located?
Facial thermoreceptors.
What two things do the diving reflex have on the body?
Decrease HR and Increased peripheral vasoconstriction.
What stimulus causes Atrial stretch reflex?
Increased Blood volume.
What is the response to increased blood volume via atrial stretch reflex?
Makes you pee to decrease blood volume.
What stimulus causes Bezold-Jarisch Reflex?
Strong contraction of an empty ventricle
Where are receptors located for Bezold-Jarisch Reflex?
Ventricles.
What stimulus causes the CNS Ischemic response?
Decreased MAP (blood flow to medulla).
Where are the baroreceptors located?
Carotid sinus.
What stimulates baroreceptors?
Decreased MAP.
What is the response elicited from Diving reflex?
Decreased HR and vasoconstriction.
What stimulates Cushing Response?
Increased ICP.
What Stimulates Diving Reflex?
Cold water to face
Where are Diving reflex receptors located?
Facial thermoreceptors.
What stimulates the Bainbridge reflex?
Increased blood volume.
What is the response elicited from the Bainbridge reflex?
Increased HR.
Where are Bainbridge receptors located?
Atrial/venous junction.
What stimulates Peripheral chemoreceptors?
Decreased MAP.
What response is elicited from peripheral chemoreceptor reflex?
Increased MAP.
Where are peripheral receptors located?
Aortic and Carotid bodies.
