Heart Contraction

Question 1

4 Valves

Answer 1

1. Tricuspid (right AV)
2. Bicuspid (mitral valve)
3. Aortic semilunar valve
4. Pulmonary semilunar valve

Question 2

What helps the direct the flow of blood?

Answer 2

• valves
• if the cuspids are closed then the semilunar will be open
• they work opposite of each other

Question 3

What supports the tricuspid (right AV)?

Answer 3

• -papillary muscle

- chordae tendineae

Question 4

Chordae Tendineae

Answer 4

-connect the papillary muscles to the tricuspid valve

Question 5

Systole

Answer 5

• ventricular contraction
• blood ejection
• lasts about 0.3 sec

Question 6

Diastole

Answer 6

• rest of chamber
• period of relaxation
• ventricular filling
• lasts about 0.5 sec

Question 7

tricuspid valve

Answer 7

-directs blood from the right atrium to the right ventricle

Question 8

mitral (bicuspid) valve

Answer 8

-directs blood flow from the left atrium to the left ventricle

Question 9

aortic semilunar valve

Answer 9

-between the left ventricle and aortic artery

Question 10

pulmonic semilunar valve

Answer 10

-between the right ventricle and pulmonary artery

Question 11

Semilunar valves

Answer 11

• are thicker

- not supported by fibrous cords

Question 12

Function of Valves

Answer 12

• open and close according to pressure gradients

- pressure stops the blood from flowing back through the vena cava’s

Question 13

Blood Return to the Heart (2 ways)

Answer 13

1. Superior vena cava
2. Inferior vena cava
   - both go to the right atrium

Question 14

Blood Flow through Heart

Answer 14

• right atrium through tricuspid valve
• into right ventricle through pulmonary valve
• ejected to pulmonary arteries passes through lungs = oxygenated
• returns to left atrium through mitral valve
• left ventricle through aortic valve to aorta

Question 15

Preload

Answer 15

• blood in atria moving to ventricles
• stretches ventricles
• related to sarcomere length
• this is the beginning stretch and only force that can stretch the sarcomeres of the heart
• affected by venous blood pressuer

Question 16

Afterload

Answer 16

• tension or stress on ventricles to push blood out to lungs or the aorta
• aortic pressure

Question 17

Cardiac Cycle

Answer 17

• any events related to the flow or blood pressure from the beginning of one heartbeat to the beginning of the next
• both systole and diastole
• lasts about 0.8 sec

Question 18

Why is there a slight delay at the AV node?

Answer 18

-so the after and preload can fill up!

Question 19

When HR increases

Answer 19

• the time in diastolic phase decreases
• fast beating heart my not remain relaxed long enough for adequate filling
• stroke volume will be decreased

Question 20

Mechanically systole

Answer 20

-defined as the interval between the closing of the AV valves and the opening of the semilunar vales

Question 21

Electrically Systole

Answer 21

-defined as the time between Q-T interval

Question 22

Isovolumetric Contraction

Answer 22

-systole
atrioventricular valves: closed
semilunar vales: closed
-the sarcomeres shorten but the intraventricular pressure has not exceeded arterial pressure

Question 23

Rapid Ventricular Ejection

Answer 23

• pulmonic
• semilunar valve is forced open, AV valve closed
• left ventricular pressure exceeds 80mmHg
• blood is rapidly ejected as sarcomeres shorten

Question 24

Reduced Ventricular Ejection

Answer 24

• aortic pressure rises and ventricular pressure and volumes fall
• ventricules are full contracted - force blood to flow out!
• semilunar and AV valves are closed

Question 25

Cardiac or Ventricular Systole

Answer 25

- electrical impulses spread through the myocardium across intercalated discs - action potentials result in excitation-contraction coupling and ventricular sarcomere shortening - ejection of blood from the ventricles occurs

Question 26

Ventricular Diastole (4)

Answer 26

1. Isovolumetric Relaxation 2. Rapid Ventricular Filling 3. Reduced Ventricular Filling 4. Atrial systole - end of diastole

Question 27

Phases of Diastole

Answer 27

1. Passive Filling - blood enters ventricle due to pressure gradient 2. Active filling phase - atrial systole, blood forced into ventricle by atrial contraction

Question 28

Pressure Changes

Answer 28

-reflect the alternating contraction and relaxation of the heart

Question 29

Which pressure is larger?

Answer 29

Atrial pressure slightly exceeds ventricular pressure even when both chambers are relaxed

Question 30

When does myocardial excitation occur?

Answer 30

- during diastole - the SA node is the pacemaker (by right atrium) - the impulse emitted from the SA node travels to the AV node by the intranodal pathway

Question 31

Lubb

Answer 31

- 1st sound is low pitched, soft, long | - closure of the AV valves (onset of systole)

Question 32

Dub

Answer 32

- 2nd sound is higher pitched, shorter, and sharper | - closure of semilunar valves (onset of diastole)

Question 33

Opening of AV Valve

Answer 33

-diastole

Question 34

Closing of AV Valve

Answer 34

-onset of isovolumic contraction

Question 35

Opening of semilunar valve

Answer 35

-onset of ejection

Question 36

Closing of semilunar valve

Answer 36

-end of systole

Question 37

How is ECG composed?

Answer 37

- einthoven triangle - heart is the center of this triangle - gives 3 leads - combining these gives us a normal tracing