Physiology

Question 1

The strength of contraction is regulated by what 2 things?

Answer 1

1. intracellular Ca levels during the action potential

2. initial length of cardiac fibers which determines sensitivity of myofilaments to Ca2+

Question 2

what ion is the principle regulator of contraction

Answer 2

Ca2+

Question 3

What 3 things do catecholamines accelerate the rate of regarding contraction?

Answer 3

accelerate the rate of: 1. cardiac contraction (inotropy)

2. Intracellular calcium decline
3. Cardiac relaxation (lusitropy)

Question 4

which volume determines the preload

Answer 4

End diastolic volume

Question 5

EDV-ESV=

Answer 5

stroke volume

Question 6

what happens when you stretch cardiac muscle fibers

Answer 6

you increase the calcium sensitivity and increase the contractility

Question 7

preload

Answer 7

end diastolic volume

Question 8

afterload

Answer 8

aortic pressure on the ventricles (or pressure restricting movement of blood)

Question 9

systolic pressure

Answer 9

peak pressure in the aorta, not the ventricle

Question 10

diastolic pressure

Answer 10

minimum pressure in the aorta, not the ventricle

Question 11

what happens when you increase your preload

Answer 11

you increase stroke volume

Question 12

what happens to shortening velocity when you increase the afterload

Answer 12

when you increase the afterload you have greater resistance and this slows the contraction event, so less blood will be pumped

Question 13

what does a cardiac function curve show generally show you

Answer 13

as you increase venous return you will increase right atrial pressure and increase end diastolic volume and increase end diastolic fiber length

Question 14

whats the frank starling relationship

Answer 14

basically says that the volume of blood ejected by the ventricle depends on the volume present in the ventricle at the end of diastole (so stroke volume and cardiac output correlate directly with end diastolic volume)

Question 15

what are the 4 factors that set the cardiac function curve? which one is most important

Answer 15

1. sympathetic and parasympathetic activity (MOST IMPORTANT)
2. intrinsic ventricular effectiveness
3. afterload (aortic pressure)
4. Intrapleural (intrathoracic pressure)

Question 16

increasing the afterload has what effect on stroke volume

Answer 16

increasing the afterload decreases the stroke volume

Question 17

what variable sets the X-axis intercept on a vascular function curve

Answer 17

systemic filling pressure (aka mean systemic filling pressure)

Question 18

what sets the slope of a vascular function curve

Answer 18

resistance to venous return

Question 19

equation for venous return

Answer 19

Venous Return = (difference in pessure)/(resistance to venous return)

Question 20

what is filling pressure

Answer 20

pressure that is required to fill the blood vessels beyond their intrinsic volume (AKA overfilling pressure), pressure required to fill the blood vessels beyond their intrinsic capacity

Question 21

what causes a greater change in the vascular function curve, changing the filling pressure or changing the TPR

Answer 21

changing the filling pressure

Question 22

what are the 2 independent reasons to make veins smaller during vigorous exercise

Answer 22

1. sympathetic venoconstriction

2. mechanical compression

Question 23

important vasodilator metabolites are thought to include

Answer 23

adenosine
ATP
ADP
AMP
CO2
Lactic Acid
K+

Question 24

What 3 things can increase the Kf in capillaries

Answer 24

1. vasodilating the precapilary sphincters (allows greater surface area for filtration)
2. more fenestrations
3. inflammation-increase capillary permeability

Question 25

What happens if the lymphatic system can't keep up with all the fluid coming into the interstitium

Answer 25

EDEMA

Question 26

what is the only way for protein to return to the circulation

Answer 26

return via lymph flow to venous system

Question 27

what are 5 major causes of edema

Answer 27

``` increased capillary pressure increased interstitial pressure decreased plasma oncotic pressure increased interstitial oncotic pressure increased permeability-inflammation ```

Question 28

what is the strongest stimulus for the baroreceptors

Answer 28

rapid changes in arterial pressure

Question 29

what are 3 things that baroreceptors tell the CNS about

Answer 29

MAP pulse pressure heart rate

Question 30

what happens to systemic arterial pressure as you increase the isolated carotid sinus pressure

Answer 30

it goes down

Question 31

if you have really high pulse pressures what will your CNS be doing to systemic arterial blood pressure

Answer 31

CNS will actively try to decrease arterial pressure with high pulse pressures, detected in carotid sinus

Question 32

What is a very important function of the baroreceptors in the carotid sinus

Answer 32

buffer the pressure fluctuations

Question 33

if there is a blood pressure change that lasts more than a day what is going to happen to the baroreceptor setting

Answer 33

it will change to a new setpoint

Question 34

what is the cushing reaction?

Answer 34

when intracranial pressure in the brain increases-->compression of cerebral arteries-->decreased perf. of brain-->activates medullary chemoreceptors-->increase sympathetics-->increase TPR and increase BP

Question 35

what are the 4 classes of rapidly responding systems

Answer 35

baroreceptors chemoreceptors reg. of SV by arterial pressure cerebral Ischemia-induced response

Question 36

what are the less rapidly responding systems (1 mi-30mins)

Answer 36

``` low pressure receptor-mediated reflex mechanisms (via stretch receptors) ANP capillary fluid transfer vascular stress relaxation RAAS ```

Question 37

what are 6 things that cause right shift of renal function curve

Answer 37

``` ATII aldosterone symp. activity ADH renal disease obesity ```

Question 38

what are 3 things that cause left shift of renal function curve

Answer 38

ANP NO some prostaglandins

Question 39

what happens when the slope of a renal function curve decreases

Answer 39

you are becoming more and more salt sensitive (small changes in fluid intake cause increasingly larger changes in BP)

Question 40

what 2 factors cause renal function curves to shift to the right

Answer 40

disease and age (causing HTN)

Question 41

changes in TPR cause equal and opposite changes in CO but have no effect on _______________

Answer 41

arterial pressure