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43 Cards in this Set

  • Front
  • Back
The coupling of electrical stimulation with mechanical force occurs via what?
Calcium enters myocyte during what phase?
Phase 2 depolarization
L-type voltage dependent Ca2+ channels are located where?
In sarcolemma and T tubules.
L-types voltage-dependent Ca2+ channels open in response to what? Once open what occurs?
Open in response to local AP.
Thus, Ca2+ diffuses into cytosol from ECF across T tubule membrane during cardiac AP.
Calcium into a cell causes the sarcomere to do what?
Ca2+ out of the cell causes the sarcomere to do what?
What is a phospholamban?
A protein associated with a SERCA pump.
What is a SERCA pump?
The most important pump involved in Ca2+ coupling. Pumps Ca2+ out of sarcoplasmic reticulum. It removes 80% of Ca2+ from muscle.
What is inotropy?
The force of contraction.
Too much Ca2+ constantly stimulates ?.
A rise in ECF [Ca2+] does what to AP?
Prolongs the plateau of AP.
A rise in ECF [Ca2+] does what to contraction?
Augments the strength of contraction. Heart contracts spastically, however, little time between contractions.
How do some drug alter cardiac function?
Some drugs alter cardiac function by changing Ca2+ movement across myocardial cell membranes.
There is no re-stimulation of cardiac muscle to contract before what?
Before first contraction is almost over. There is a LONG refractory period.
What is a refractory period?
Time after AP during which excitable tissue's membrane is unresponsive.
What is tetany?
a state marked by severe, intermittent tonic contractions and muscular pain, due to abnormal calcium metabolism.
Tetany in ? muscle, unlike ? muscle, cannot occur.
Tetany in cardia muscle, unlike skeletal muscle, cannot occur.
Contraction and relaxation are what kind of events?
Mechanical events (related to important sounds of the heart)
Cardiac tissue must contract in a responsive, controlled, and reliable manner to create what?
To create the pressure difference that drives blood through the cardiovascular system.
The cardiac cycle is the time period between what?
The period from the start of one ventricular contraction to the beginning of the next.
What are 3 important (general) phenomena that repeat during the cardiac cycle?
Physical, electrical, and audible phenomena.
What are 3 mechanical (phsyical) events of the cardiac cycle?
1. Contraction

2. Relaxation

3. Resultant changes in blood flow
The mechanical events of the cardiac cycle result from what?
Result from rhythmic changes in cardiac ELECTRICAL activity.
The cardiac cycle has alternate periods of what?
1. Systole (contraction and emptying)

2. Diastole (relaxation and filling)
List the phases of the Cardiac-cycle (contraction and relaxation).
1. Late Diastole

2. Atrial Systole

3. EDV (end-diastole volume)

4. Isovolumic ventricular contraction

5. Ventricular ejection

6. ESV (end-systolic volume)

7. Isovolumic ventricular relaxation

(she stated that late diastole, isovolumic contraction, ventricular ejection, and isovolumic relaxation are the 4 main phases)
What occurs during the late diastole phase of the cardiac cycle?
Both sets of chambers are relaxed. Passive ventricular filling. Heart is 'just resting'. ~80% filling of ventricles occurs.
What occurs during the atrial systole phase of the cardia cycle?
Atrial contraction forces a small amount of additional blood into ventricles.

Ao the atrial contraction compels the last 20% of blood into both ventricles of the heart. So mitral and tricuspid close.
What occurs during the EDV (end-diastolic volume) phase of the cardiac cycle?
The max amt of blood in the ventricles occurs at the end of ventricular relaxation. (EDV = 135 mL).
What occurs during the Isovolumic contraction phase of the cardiac cycle?
First phase of ventricular contraction pushes AV valves closed but does not create enough pressure to open semilunar valves.

So Calcium induced contraction starts, closes valves (tricuspid and mitral) but does not open semilunar valves.

So volume does not change although contraction starts.
Describe the ventricular ejection phase of the cardiac cycle.
As ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is ejected.

The volume ejected = STROKE VOLUME (SV)

So pressure opens up the semilunar valves and blood is injected into the aorta and pulmonary arteries.
What is Stroke Volume?
The volume of blood ejected during the ventricular ejection phase of the cardiac cycle.


(end-diast. vol) - (end-syst. vol.)

~70 ml

(only a portion of the blood is ejected, about 65 mL (ESV) remains)
Describe the ESV of the cardiac cycle?
The end-systolic volume or minimum amount of blood in the ventricles.

ESV = 65 mL
Describe the isovolumic ventricular relaxation phase of the cardiac cycle?
As ventricles relax pressure in the ventricles drops and blood flows back into cups of semilunar valves and snaps them closed.

This is the relaxation phase. So vent. pressure drops. But aorta and pulm. artery pressure increase and shut the semilunar valves and AV valves are shut so no volume-exchange takes place.
When using a stethoscope what does the S1 sound represent?

Mitral valve closes.

Aortic valve opens.

Beginning of systole.
Using a stethoscope what does the S2 sound represent?

Mitral valve opens.

Aortic valve closes.
What are heart murmurs?
Abnormal heart SOUNDS.
What are heart murmurs usually associated with?
Heart disease
Heart murmurs that are not associated with disease are referred to as what?
These are usually seen in young persons.

'functional heart murmurs'
Heart murmurs result from ?, rather than ? flow.
Result from turbulent, rather than laminar flow.
List some possible causes of turbulent flow that may lead to heart murmurs.
1. Stenotic valves

2. Insufficient (leaky) valves
What are stenotic valves?
Stiff, narrowed valves that don't OPEN completely. Can lead to heart murmurs.
What are insufficient (leaky) valves?
Valve that doesn't CLOSE completely. Usually involves scarring of valve edges so that they don't fit together properly. Can lead to heart murmurs.
What is often a culprit for both insufficient (leaky) valves and stenotic valves?
Rheumatic fever.