Cardio Responses to Stress

Question 1

what is the equation for MAP

Answer 1

CO x TPR

Question 2

intrinsic cardiac regulation is described by what law

Answer 2

frank starling mechanism

stroke volume increases with preload and then plateaus and stroke volume begins to decline

Question 3

according to the frank starling mechanism what does changes in preload have on SV

Answer 3

more preload = more stroke volume and vice versa

but high levels of preload eventual lead to decreased SV which reduces CO

Question 4

what increase the preload

Answer 4

increase in volume 
increase in central venous pressure 
decrease in venous compliance 
increase in atrial filling or contraction 
decrease in Hr (prolongs diastole) 
increase in ventricular compliance 
increase in aortic or pulmonary pressure
increase diastole - with class 2 drugs

Question 5

what is the bowditch (tripe effect)

Answer 5

how changes in heart rate affects the force of contraction
increase in HR increases force of contraction and vice versa
high levels of HR eventually lead to decreased force of contraction

Question 6

is the bowditch effect independent of the frank starling law

Answer 6

yes

Question 7

what is the bainbridge reflex

Answer 7

increased venous return
baroreceptors in the atria detect increased stretch
HR increased via sympathetic stimulation to SAN
antagonistic to carotid baroreceptor réponse - involved in sinus arrhythmia

Question 8

what is chronotropy

Answer 8

direct cardiac affect on the SAN (positive - increase)

Question 9

what is dromotrophy

Answer 9

positive increases conduction velocity - AVN

direct cardiac effect

Question 10

what is inotrophy

Answer 10

the effect of force of contraction of the ventricles and atria
positive increase the force of contraction

Question 11

what is lusitropy

Answer 11

relaxation of the atria and ventricles

positive means more relaxation

Question 12

what are the actions of the RAAS

Answer 12

angiotensin 2 -vasoconstriction
increased Na+ and H2O retention
Aldosterone - increased Na and H2O retention
Vasopressin (ADH) - promotes H20 retention

Question 13

how does RAAS affect CO

Answer 13

it increases central venous pressure which increases SV

vasoconstriction also increases TPR which increases MAP

Question 14

which catecholamine is released from the adrenal gland which increases sympathetic actions of the heart

Answer 14

epinephrine
increases Renin
increase vasoconstriction which increases TPR
increases HR and SV

Question 15

what does the renal juxtaglomerular apparatus do

Answer 15

local baroreceptor which regulates blood pressure

Question 16

where are the common baroreceptors located

Answer 16

carotid sinus and aortic arch

Question 17

what do changes in baroreceptor firing do

Answer 17

increased firing due to increased pressure causes decrease in sympathetic tone and increase in parasympathetic tone

Question 18

what would be the body effect if someone had had excessive blood loss due to trauma

Answer 18

central venous pressure would reduce - less stroke volume and less CO
therefore there would be less baroreceptor firing and an increase in sympathetic tone and decrease in parasympathetic tone

Question 19

what is haemorrhagic shock

Answer 19

loss of blood causing tachycardia, low blood pressure, tachypnoea, confused mental state

Question 20

what does dobutamine do

Answer 20

increased force of contraction of chambers

used in cariogenic shock and severe HF

Question 21

for blood to enter the ventricle what must occur

Answer 21

pressure in the atria must be higher than the EDV of the ventricle