Lecture 4

Question 1

A Fiber location/time of action

Answer 1

in the right atria/fires during atrial systole

Question 2

B fiber location/time of action

Answer 2

at the atriocaval junctions (SVC and IVC/right atria junction)/fires during atrial filling

Question 3

B fiber reflexes (3)

Answer 3

1) Bainbridge reflex - increase HR by action on SA node cells
2) decrease release of angiotensin II and ADH (vasopressin) which decreases volume and salt
3) decreased firing of sympathetics in the renal arteries which causes vasodilation and therefore increased glomerular filtration

Question 4

Arterial chemoreceptors sense/action

Answer 4

pH pCO2 balance/affect respiration, peripheral vasoconstriction and indirectly HR

Question 5

Other sensors affecting vascularature (3)

Answer 5

1) Skeletal muscle - can increase HR and BP when contracted
2) Stomach - algesics like capsaicin/bradykinin can cause increased HR and BP
3) CNS/emotions - can cause incr. HR/BP

Question 6

Hormonal Control (3)

Answer 6

1) epi - from adrenal medulla - acts on B2 receptors to vasodilate during exercise
2) renin-angiotensin-aldosterone - potent vasoconstrictor but only relevant in people with low salt diets or who have hemorrhaged
3) ANP - some vasodilation effect, secreted from right atrium

Question 7

Volume control sensors (3)

Answer 7

1) Right atrial volume sensors
2) Osmolarity sensory hypothalamus
3) juxtaglomerular pressure sensor

Question 8

Volume control effectors (2)

Answer 8

1) thirst (volume gain)

2) kidney diuretics (volume loss)

Question 9

R- where from/importance?
A- where converted?/effects? (3)
A- effects? (1)

Answer 9

R- renin from juxtaglomerular cells/rate limiting step
A- converterd to A2 in lung epithelium/vasoconstrictor; acts on adrenal medulla to produce aldosterone; thirst sensation
A- increased salt/water retention by incr. expression of transporters

Question 10

ADH - where from?/when released?/action?/receptor?

Answer 10

hypothalamus hormone secreted when volume is low/osmolarity is high and takes its effects on aquaporin expression on the collecting tubule (incr. expression)/Gs receptor cAMP

Question 11

ANP - mechanism of action?/action?

Answer 11

cGMP/increases salt/water filtration and excretion also a vasodilator

Question 12

Four types of circulatory shock

Answer 12

hose, pump, block, volume
hose- vasodilatory shock - can be brought on by spinal nerve injury, anaphylaxis, sepsis
pump - cardiogenic - post MI
block - obstructive
volume - plasma/post burn, ECF/post diarrhea, whole blood/hemorrhage