Cardiovascular control system

Question 1

systemic aterial baroreceptors

Answer 1

• Found in carotid sinus, and aortic arch, also in arteries
• Innovated by cranial nerves
• have stretch sensitive ion channels
• senses changes in pressure
• increase in BP, will result in increase firing, then will get a reduction in sympathetic nerve activity and an increase in parasympathic activity (vagus nerve) and vice versa
• however when you become hypertensive, then the changes are not as good because it becomes sensitised to new BP state
• can get an increase in baroreceptor sensitivyt with increase NO

thershold, saturation and rate sensitiviey (graph)

Question 2

cardiac receptors

Answer 2

• found in heart - veno-aterial junctions
• influenced by changes in VR and blood volume

mylenated fibers

• respond to filling of atria
• provide afferent information about the extent of cardiac filling (stretch)
• is influenced by changes in venous return or blood volume
• results in increase HR, reduced renal sympathetic stimulation

unmylenated fibers - similar to systemic arterial baroreceptors
-reduced sympatehtic outflow to heart and vessels, increase vagal activity, reduce dcatecholamine secretion, reduce adh and angiotensin 2

Question 3

chemoreceptors

Answer 3

aortic and carotid bodies - regulate blood pH

• increase in paco2 and H+ conc, and decrease pa02
• low o2 will stimualte sympathetic drive to heart and vessels

Question 4

Why do we have the cardiovascular control system?

Answer 4

• to maintain BP, CO and to distribute blood around the body to get oxygen to different regions
• this lecture is about how the body senses the changes in BP

Question 5

What happens when atrial pressure falls?

Answer 5

• increase heart rate and inotropic state
• constriction of precapillary blood vessles in skeletal muscle, splanchnic, renal, cutenous ciruclations - to get blood going away
• venoconstriction
• increased catachloamine secretion (NA, Adrenaline)
• increased ADH, AII, other hormones