REFLEX CONTROL OF THE CIRCULATION

Question 1

what is the use of arterial baroreceptors

Answer 1

-vital to maintain blood flow to brain and myocardium

Question 2

effect of increased blood pressure on baroreflex

Answer 2

-pulse pressure falls
-vasodilation decreases TPR and BR
-decreased sympathetic nerve activity
-increased vagus nerve activity

Question 3

effect of decreased blood pressure on baroreflex

Answer 3

-increased sympathetic activity and decreased vagus activity

-increased heart rate and force of contraction so increased cardiac output

-arteriole constriction gives increased TPR

-venous constriction increases central venous pressure by starlings law increases stroke volume and cardiac output

Question 4

role of veno-atrial mechanoreceptors

Answer 4

-reduces sympathetic activity to renal arteries
-increases glomerular filtration
-secretes atrial natriuretic peptide, increasing sodium ions excretion
-

Question 5

what are veno atrial mechanoreceptors stimulated by

Answer 5

-increase in cardiac filling / CVP

Question 6

what are ventricular mechanoreceptors stimulated by

Answer 6

-over distension of ventricles
-weak reflex

Question 7

where are arterial chemoreceptors found

Answer 7

in the carotid and aortic bodies

Question 8

what are arterial chemoreceptors stimulated by

Answer 8

-low oxygen (hypoxia)
-high co2 (hypercarnia)
-hydrogen and potassium ions

Question 9

role of arterial chemoreceptors

Answer 9

-regulate ventilation
-drive cardiac reflexes during asphyxia, shock and haemorrhage

Question 10

What converts angiotensin 1 to angiotensin 2

Answer 10

ACE - angiotensin 1 converting enzyme

Question 11

What activates metaboreceptors

Answer 11

-metabolites potassium ions
-lactate
-adenosine

Question 12

Why are muscle metaboreceptors important in exercise

Answer 12

• continually contract muscle but joint angle and muscle length do not change
  -higher bp drive blood into contracted muscle to maintain perfusion

Question 13

Role of muscle metaboreceptors

Answer 13

-regulate sympathetic activation

Question 14

How is the NTS linked to the limbic system

Answer 14

-stimulates NTS
-simulates nucleus ambiguus
-increased activity on vagal nerve and depressor effect on AV and SA nodes
-leads to syncope ( fainting )

Question 15

What causes a syncope

Answer 15

-decreased cerebral blood flow due to sudden drop in arterial cardiac output and blood pressure

Question 16

Pp