Cardiovascular Control Center

Question 1

Basic Cardiovascular system outline

Answer 1

Afferents: Arterial baroreceptors (carotid sinus, aortic bodies) + cardiopulmonary receptors (heart and lungs)
CNS: Medulla oblongata (arrive through nucleus solitary tract)
Efferents: Sympathetic and parasympathetic activity

Question 2

What stimulates RAAS

Answer 2

Increase symp, decreased perfusion pressure, decreased sodium conc

Question 3

AII action

Answer 3

1) potent vasoconstictor

aldosterone release, sodium reabsorption, increases sympathetic drive; ADH secretion

Question 4

Arterial baroreceptor locations

Answer 4

Aortic bodies in arch (CNX)
Carotid sinus (CNIX)

respond to distension,sense of pressure

Question 5

Carotid sinus response to increased pressure

Answer 5

Increase firing:
Increases vagal and decrease sympathetic activity
Slowed heart rate, decreased heart contractility, decreased vasoconstriction

Question 6

Carotid sinus response to decreased pressure(5)

Answer 6

Less firing:
increased HR and inotropic state
Arteriole constriction: skeletal muscle, splanchnic, cutaneous, renal circulation. NOT coronary or cerebral
Venoconstriction
Increased catecholamine secretion (NE, E) by adrenal medulla
increased ADH, AII

Question 7

Three relationships found between carotid sinus and afferent nerve activity

Answer 7

Sigmoidal relation:
Threshold: below 30-50mmHg, decrease in pressure causes no firing
Saturation: above 150-180 mmHg no further effect on firing frequency
Rate sensitivity: for a given mean pressure, rate of firing is higher for pulsatile pressure rather than steady pressure

Question 8

Cardiac vagal afferent receptors location

efferent response?

Answer 8

CNX, myelinated, veno atrial junction
A and B receptors, respond during atrial and ventricular contraction respectively.
Sensitive to volume changes
Linear relation, similar to baroreceptors. Increase volume/pressure, increased firing

efferent response: increased firing-> increase in heart rate, and decreased renal sympathetic stimulation (primarily to maintain blood volume),
rest has similar effects as baroreceptors

Question 9

Osmoreceptors, location and respond to?

Answer 9

Hypothalamus, paraventricular nuclei
Sense changes in effective plasma osmolality by altering their volume.
Modulates synthesis and secretion of ADH by PP. Reduced ADH means less water absorption.
Also potent vasoconstrictor

Question 10

Peripheral Chemoreceptors

Answer 10

Aortic and carotid bodies, central in hindbrain
Increased firing due to low PaO2, causing increased sympathetic drive to heart and vessels
When O2 delivery is compromised, reduced arterial pressure, vasoconstriction to restore

Question 11

Arterial baroreceptor pathway in the brain

Answer 11

Carotid sinus nerve firing goes to the NTS (nucleus tractus solitaris) and to the CVLM (caudal ventro laterla medulla)
This then inhibits the RVLM which decreases sympathetic drive