LP #102 Fxn Of The Heart Flashcards
1
Q
- Enables flow of fluid in 1 direction
* d/t P differences on both sides of the valve
A
Valves
2
Q
- Endothelial extensions
* Integral part of heart wall
A
Cardiac valves
3
Q
Orderly BF through heart depends on?
A
- Rhythmic myocardial contractions
- Timely opening/closing of valves
- ensures bld flow in correct direction
4
Q
*1 way BF through heart
A
Atrioventricular (AV) valves
5
Q
*Ensure 1-way BF out of heart & into aorta or pulmonary trunk
A
Semilunar (SL) valves
6
Q
AV valves location
A
- b/w atria & ventricles
- Tricuspid (right AV) valve has 3 flaps
- Bicuspid (mitral or left AV) valve has 2 flaps
7
Q
AV valves fxn
A
Allows BF from atria into ventricles
- valves open when the heart is relaxed (diastole)
- prevent back flow into atria as ventricles are filling up & ventricular P increases
- prevent blood back flow into atria during systole (flaps close)
8
Q
How the AV valves work
A
- Valve closes when atrium is full
- Blood then moves into ventricle
- P decreases in atrium as P increases in ventricle
- Changes in P pushes the flaps up, press up against each other & close atrial entrance
9
Q
SL valves location
A
- b/w ventricles & aa that exit the heart
- Aortic valve: b/w L ventricle & aorta
- Pulmonary valves: b/w R ventricle & pulmonary trunk
10
Q
SL valves fxn
A
Prevent back flow of blood from aorta & pulmonary trunk into ventricles
- ventricles contract: P opens valves 7 blood moves out into aa (aorta & pulmonary trunk)
- aa fill w/blood: increase P w/in aa, which pushes flaps back & closes opening b/w ventricles & aa
11
Q
- Short, branched & interconnected
- Fxnally coupled (syncytium)
- Myofibres held together by inercalated discs & desmosomes
- w/stands substantial P
- Gap jxns enable ions to flow freely b/w cells
A
Properties of Myocardial cells
12
Q
Time when cells cannot be further excited?
A
Refractory period
13
Q
Long AP (contraction) & refractory period
- Skeletal m (1-2 msec) vs cardiac m (~250 msec)
- Prevents tetany of heart m
A
Myocardial cells
