Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

2023 Systems Phys > Cardiac - Excitation Coupling - Cardiac Cycle > Flashcards

Cardiac - Excitation Coupling - Cardiac Cycle Flashcards

1
Q

Which phase is the relaxation phase?

A

Diastole

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

Which phase is the contraction phase?

A

Systole

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

How does relaxation occur in the cardiac muscle?

A

Remove Ca2+ from the system to relax
1. Ca2+ pump uses ATP to move Ca2+ back inro SR and decrease Cystolic Ca2+
2. Na+-Ca2+ exchanger moves 1 Ca2+ out for 3 Na+ in
3. Ca2+ pump uses ATP to pump Ca2+ back into the extracellular space

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

How does contraction occur in the heart?

A
  1. L-Type Voltage-gated Ca2+ channels open during phase 2
  2. Ca2+ flows in
  3. Ca2+ binds to Ryr channels on SR - causes Ca2+ induced Ca2+ release
  4. Ca2+ binds Troponin C
  5. Tropomyosin moves, binding site opens on actin
  6. Contraction occurs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where is the most Ca2+ located?

A

Outside the Cell

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

How does Ca2+ effect SV and CO?

A

When Ca2+ release is enhanced SV and CO increase

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

How do catecholamines effect cardiac contraction and relaxation?

A
  1. Catecholamines bind B1 Receptors
  2. Stimulates Adenylyl Cyclase
  3. Adenylyl Cyclase increases cAMP
  4. Increased cAMP stimulates cAMP-PK
  5. cAMP-PK causes phosphorylation of Ca2+ Channels on the membrane, Phospholamban, and Troponin I
    Phosphorylation of these results in increased uptake or removal of Ca2+ and relaxation of the cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What occurs when cAMP-PK phosphorylates phospholamban?

A

It reduces the phospholamban inhibition of ATP on the Ca2+ pump on the SR
This increases reuptake of Ca2+ in SR and relaxation

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

What occurs when cAMP-PK phosphorylates L-Type Voltage-Gated Calcium Channels on the cell membrane?

A

The Ca2+ channels close and prevent Ca2+ from entering the cell
This decreases cystolic Ca2+ and causes relaxation

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

What occurs when cAMP-PK phosphorylates Troponin I?

A

It decreases the affinity of Ca2+ for Troponin C -> decreasing Ca2+ binding to TnC
TnC releases calcium more easily resulting in the reuptake and removal of Ca2+ quicker and relaxation

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

How do Cardiac Glycosides effect Cardiac Contraction?

A

Cardiac Glycosides inhibit the Na+-K+ pump
Extracellular Na+ decreases -> reducing the ion gradient
This results in less Na+ availability for Na+-Ca2+ exchanger to exchange for cystolic Ca2+
This results in more Ca2+ being left in the heart and enhances heart contraction

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

What does the Ca2+ pump do for cardiac contraction

A

It uses STP to pump Ca2+ out of the cell and cause relaxation

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

What increases stroke volume?

A

Contractilty
Preload

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

What decreases stroke volume?

A

Afterload

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

What determines Preload?

A

End Diastolic Volume

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

What determines Preload In vitro?

A

Varies with resting length of muscle

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

What determines Preload In Vivo?

A

Venous Pressure and End Diastolic Pressure

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

When preload increases, cardiac output…

A

Increases

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

What happens when cardiac muscle goes beyond optimal length?

A

It decreases the function of the muscle

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

How is afterload determined in vitro?

A

By the applied load

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

How is afterload determined in vivo?

A

By arterial pressure
Systemic arteriaal pressure in the LV
Pulmonary arterial for the RV

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

Which part of the heart has the highest afterload?

A

LV

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

Why does the LV have the highest afterload?

A

It has to overcome aortic valve pressure

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

At any length, if you enhance Ca2+ availability….

A

you contract more efficiently

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
If you increase contractility, you ___ output
Increase
26
Most pathways that regulate contractility involve....
Ca2+
27
How does contractility effect SV?
Increase contractility, increase SV
28
If you increase NE in the cardiac, how is output effected?
SV is increased -> increases output
29
How does an inceased SV effect heart contraction?
When you increase SV, the heart contracts more efficiently and empties the ventricle more efficiently
30
How do catecholamines effect contractility?
They increase contractility
31
How does contractility effect pressure?
Increase contractility, increase pressure -> develop pressure more quickly
32
Which one of the following would most likely occur as a direct result of applying a Ca2+ channel blocker to a ventricular myocyte? A. No effect B. An increase in contractility C. An increase in heart rate D. A reduction in the duratio of phase 2 of the action potential E. Loss of phase 1 of the action potential
D. A reduciton in the duation of phase 2 of the action potential
33
In contracting cardiac muscle, calcium... A. is present in an amount that usually saturates all intracellular calcium binding sites C. comes from both the extracellular space and from the SR D. all of the above E. none of the above
Comes from both the extracellular space and from the SR
34
The Frank-Starling relationship...
Increases preload, increases output, independent of length
35
What are the 7 phases of the cardiac cycle?
Atrial Systole Isovolumic Contraction Rapid Ejection Reduced Ejection Isovolumic Relaxation Rapid Filling Reduced Filling
36
What must happen to atrial membranes befre the atria can contrct?
Atrial membranes must be polarized
37
How does. blood flow through the heart?
From high pressure to low pressure
38
When is aortic blood flow the greatest?
During rapid ejection
39
When does ventricular volume begin to increases?
During atrial systole
40
When do the heart sounds occur?
S1 - Isovolumic Contraction S2 - Reduced Ejection S3 - Rapid Filling S4 - Atrial Systole
41
Which heart sounds are normal?
S1 and S2
42
Which heart sounds are abnormal?
S3 and S4
43
What causes the normal heart sounds?
S1 - Mitral/Tricuspid valves close S2 - Aortic/Pulmonic valves close
44
How does a pulmonary capillary wedge work?
1. Catheter is inserted into peripheral vein -> through the RA to the RV through the PV 2. Enters pulmonary circulation, balloon is inflated 3. Tip measures back pressure from LV
45
What happens to the pressure volume loop if preload is increased?
Volume increases SV increases
46
What happens to the pressure volume loop if contractility is increased?
Pressure and SV increase
47
What happens to the pressure volume loop if afterload is increased?
SV decreases Pressure increases
48
The opening of the mitral valve occurs at the beginning of which of the following phases of the cardiac cycle? A. Rapid Ejection B. Atrial Systole C. Isovolumic Relaxation D. Rapid Filling E. Isovolumic Contraction
D. Rapid Filling
49
Using the figure, which one best describes line AB in the ventricular pressure-volume loop? A. Isovolumic relaxation B. Rapid Ejection C. Rapid Filling D. Isovolumic Contraction E. SV
D. Isovolumic Contraction
50
Using the figure at the right, what is the ejection fraction?
60%
51
For any given preload and level of autonomic nerve activity, an increaae in afterload tends to INCREASE:
Metabolic activity of cardiac myocytes
52
How do you read a pressure volume loop?
One cardiac cycle is equal to one circuit around the loop Start at the lower left hand corner of the loop
53
When does the mitral valve open?
Occurs when LV pressure drops below LA pressure
54
What is rapid filling?
Blood rushes into the left ventricle as it continues to relax; the volume increases, the pressure decreases since ventricle is actively relaxing
55
When would the third heart sound be heard?
near the end of rapid filling when the ventricle reaches its elastic limit
56
What is slow (reduced) filling phase?
Ventricle continues to fill due to continuous venous return contributes to 1/4-1/3 od LVEDV Ventricular pressure rises slightly
57
What happens during atrial contraction?
Final contribution of blood to LVEDV prior to isovolumic contraction
58
When does the mitral valve close?
As ventricula pressure begins to increase the mitral valve snaps closed First heart sound
59
When is the first heart sound heard?
When the mitral valve closes
60
What happens during isovolumic contraction?
Steep rise in ventricular pressure Ventricular volum remains constant until ventricular pressure exceeds aortic pressure - aortic valve forced open
61
What causes the end of isovolumic contraction?
The opening of the aortic valve
62
When is aortic diastolic pressure recorded?
At the pressure where the aortic valve opens
63
What happens during systolic ejection (rapid and reduced ejection)?
During this phase ventricular and aortic pressure rise and fall together due to open communication provided by the aortic valve
64
When does the aortic valve close?
Near the end of systolic ejection and both ventricular volume and pressure are decreasing and drop below aortic pressure
65
What creates the 2nd heart sound?
the closing of the aortic valve
66
When does the end systolic pressure point occur?
When systole ends at the closure of the aortic valve
67
What happens during isovolumic relaxation?
Steep drop in ventricular pressure with no change in ventricular volume
68
When does the mitral valve open?
Wen ventricular pressure falls below LA pressure and the LV begins filling again
69
What is the equation for Ejection Fraction (EF)?
EF = EDV - (ESV/EDV)
70
What is the equation for SV?
SV = EDV - ESV
71
What is the effect of the SNS on heart rate?
SVS increases HR
72
What is the effect of the PSNS on heart rate?
PSNS decreases HR

2023 Systems Phys (41 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions