Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BMS 752 (Medical Physiology) > Cardiac contraction > Flashcards

Cardiac contraction Flashcards

You may prefer our related Brainscape-certified flashcards:
USMLE® Step 1 flashcards
1
Q

what are the two key elements of excitation-contraction coupling

A

structure

CICR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what two structures are most important to EC coupling

A

T tubules

sarcoplasmic reticulum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the general process of calcium induced calcium release CICR

A

Calcium enters the the cell during phase two, triggering the release of calcium from the SR and producing a contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

trigger calcium

A

calcium that enters the cell through a calcium channel that bings to ryanodine receptors and triggers CICR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the function of a ryanodine receptor

A

binds with calcium to allow for the release of calcium from the SR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what does SERCA do

A

uses ATP to pump calcium back into the SR afer a contraction to allow the muscle to relax

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is necessary for cardiac muscle relaxation

A

a decrease in intracellular calcium concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

T/F contractility is dependent on preload and afterload

A

false, it is an intrinsic capability of the heart dependent on calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

contractility

A

the intrinisic contractile force of the heart a given preload and afterload

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Frank-Starlings law

A

increased ventricular filling (preload) will increase tension in the heart muscle and increase contraction force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the difference between contractility and Frank-Starlings law

A

contractility is intrinsic and Ca dependant

Frank-Starling is dependent on preload, not calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the calcium signalling process

A

Ca enters the cell

trigger calcium binds to ryanodine triggering CICR

depolarization and muscle contraction

repolarization through calcium sequestering by SERCA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what protein regulates SERCA activity

A

phosopholamban

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe how phospholamban works

A

at rest phospholamban inhibits SERCA

stimulation of beta adrenergic receptors releases cAMP

cAMP phosphorylates phospholamban

phosphorylation allows SERCA to function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the function of phospholamban at rest

A

inhibition of SERCA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the function of phospholamban in response to sympathetic beta receptor stimulation

A

phosphorylation by cAMP will disassociated phospholamband from SERCA to allow calcium to be removed from the cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what are the functions of cAMP in regards to contractility of the heart

A

it stimulates L type calcium channels to increase Ca influx

phosphorylation of phospholamban to increase SERCA activilty

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how does SERCA allow for enhanced contractility

A

increased SERCA activation will increase the amount of Ca in the SR and allow for a greater release, whch will trigger a stronger contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the effect of digitalis on the heart

A

it increases contractility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how does digitalis (digoxin) produce greater contractility in the heart

A

it increases intracellular Na concentration, decreasing the activty of the Ca/Na exchanger and increasing the amount of intracellular calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

why does intracellular calcium increased contractility

A

more calcium means there are more Ca bound to troponin which will allow for more myosin binding sites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

describe the path of blood through the heart

A

vena cava

right atrium

tricuspid valve

right ventricle

pulmonary semilunar valve

pulmonary artery

lungs

pulmonary vein

left atria

mitral valve

left ventricle

aortic valve

aorta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

two phases of the cardiac cycle

A

systole

diastole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

two parts of systole

A

isovolumic contraction

ejection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

three parts of diastole

A

isovolumic relaxation

passive ventricular filling

atrial systole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what are the four phases of the ventricular cycle

A

filling

isovolumic contraction

ejection

isovolumic relatxation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is the driving force behind the movement of blood during the cardiac cycle

A

pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

ejection fraction

A

the amount of blood ejected from the left ventricle each beat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is the formula for EF

A

SV/EDV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what is a normal ejection fraction

what would it mean if EF were low

A

+50%

lower values indicate heart failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

EDV vs ESV

A

EDV: the amount of blood in heart during ventricular filling

ESV: the amount of blood remaining in the heart after a contraction

32
Q

when is pressure the highest in the ventricles and aorta

A

during ventricular systole

33
Q

incisura

A

the point on a ventricular pressure graph where the aortic valve closes, indicated by a small increase in pressure followed by a stedy decline

34
Q

what would a high slope on a pressure/time graph indicate

A

increased contractility

35
Q

what is measured by a pressure/volume loop

A

the efficiency and work performed by the heart

36
Q

what is this?

define the variables

A

a pressure time graph of the left ventricle

A diastolic filling

M1 mitral valve closes

B isovolumic contraction

A1 aortic valve opens

C ejection

A2 aortic valve closes

D isovolumic relaxation

M2 mitral valve opens

37
Q

what is this?

define the variables

A

a pressure volume loop

A diastolic filling

M1 mitral valve closes

B isovolumic contraction

A1 aortic valve opens

C ejection

A2 aortic valve closes

D isovolumic relaxation

M2 mitral valve opens

38
Q

define the variables

A
  1. mitral valve opens
  2. diastolic filling
  3. mitral valve closes
  4. isovolumic contraction
  5. aortic valve opens
  6. ejection
  7. aortic valve closes
  8. isovolumic relaxation
  9. stroke volume
39
Q

what is stroke volume

how do you calculate it

A

the volume of blood ejected each beat

SV = EDV-ESV

40
Q

what is cardiac output

how do you calculate it

A

the total volume of blood ejected from the heart each minute

CO = SV x HR

41
Q

what is ejection fraction indicative of

A

the effectiveness of ventricular ejection

42
Q

normal vs impaired EF%

A

55-65%

= 40%

43
Q

what point on a pressure/volume loop indicate LVEDV and LVESV

A

mitral valve closing

aortic valve close

44
Q

what six things can be evaluated looking at a PV loop

A
  • stroke volume
  • cardiac output
  • ejection fraction
  • contracility
  • ventricular wall compliance
  • ventricular preload an afterload
45
Q

how can stroke volume be evaluated from a PV loop

A

SV = the width of the loop

46
Q

how can cardiac output be evaulated on a PV loop

A

CO = SV x HR

47
Q

how can EF% be determined using a PV loop

A

dividing the width of the loop (stroke volume) by the volume when the aortic valve closes (LVESV)

48
Q

how can you determine the contractility of the heart from a PV loop

A

the systolic pressure (upper) line will have an increased slope with increased contractility

49
Q

how can you determine ventricle wall compliance from a PV loop

A

the diastolic compliance curve (lower line) will have a flatter slope

50
Q

what would a steeper diastolic compliance curve on a PV loop indicate

A

a decreased level of compliance indicated by less volume filling at a given pressure and preload

51
Q

T/F compliance always goes up in the heart

A

false it always go down

52
Q

compliance formula

A

change in volume/change in pressure

53
Q

positive inotropic effect

what type of drugs would cause this

A

increased contractility of the heart

Beta adrenergic agonists

54
Q

negative inotropic effect

what would cause this

A

decreased contractility

beta blockers

55
Q

what effect would increased contractility have on a PV loop

what would be the result

A

the systolic pressure curve would sift to the upper left, indicating a higher pressure per volume

increasing stroke volume

56
Q

T/F increasing contractility would affect LVEDV

A

false

57
Q

Laplace Law for a sphere

A

tension in the ventricular wall is equal to the pressure multiplied by the radius divided by the width of the ventricle

58
Q

Laplace Law formula

A

T = (P x r)/w

59
Q

how can Laplace Law be manipulated to find pressure

A

P = (w/r)(T)

60
Q

what would be the effect of increased preload on a PV loop

what would be the result

A

it would increase the LVEDV, increasing the amount of tension in the wall and increasing contraction force

increased stroke volume

61
Q

T/F changing the filling (venous) pressure of the system alters stroke volume by increase LVESV

A

false, on LVEDV will be changed with an increase in venous pressure

62
Q

afterload

A

the force that opposes ventricular shortening against aortic pressure

63
Q

what will be the effect of increasing afterload on a PV Loop

what is the result

A

it will move the point of aortic valve closing to the right due to higher pressure required with less volume ejected

decreased stroke volume

64
Q

what is a condition that would cause decreased compliance in the left ventricle?

the aorta?

what would cause an increase?

A

myocardial infarction

HTN

nothing

65
Q

what would be effect of decreased compliance on a PV loop

what is the result

A

decreased compliance would require more pressure with less filling, resulting in a steeper diastolic loop

decreased stroke volume

66
Q

what is effect of compliance on end systolic volume?

end diastolic volume?

A

no effect

decreased volume

67
Q

which part of the cardiac cycle is longer?

as HR increases, which part get shorter?

A

diastole

diastole

68
Q

a patient presents with an HR +200bpm

why would this need to be treated immediately

A

because over 180bpm increasing HR causes a decrease, not an increase in CO

69
Q

what is ficks principle used for?

what is the equation

A

to determine CO by the amount of O2 consumed divided by the difference of arterial and venous PO2

CO = (VO2)/(Cpv - Cpa) *high minus low

70
Q

what are the four areas of auscultation over the heart

A

aortic

pulmonic

tricuspid

mitral

71
Q

where is the aortic area of ausculation?

pulmonic?

mitral?

tricuspid?

A

2nd right intercostal space

2nd left intercostal space

5th intercostal space at the sternm

5th intercostal space at the mid clavicle

72
Q

what is the “LUB” sound

what is the “DUB” sound

A

mitral and tricupsid valve closure

aortic and pulmonic valve closure

73
Q

three examples of conditions that might cause a murmur

A

high blood flow through a valve in pregnancy

systemic disease such as anemia

valvular heart disease

74
Q

if you hear a systolic murmur over the 2nd right sternal intercostal space, what would this most likely be

A

aortic vale stenosis

75
Q

if you hear systolic murmur over the 5th intercostal space at the midclavicular line, what would be the expected cause

what if it were at the 5th sternal intercostal space

A

mitral valve incompetance

tricuspid valve incompetence

76
Q

two systolic murmurs

A

aortic valve stenosis

mitral or tricuspid valve incompetance

77
Q

what type of murmur would be heard with aortic valve incompetance

A

diastolic murmur over the 2nd right intercostal space

BMS 752 (Medical Physiology) (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions