heart mechanical

Question 1

How is the hearta 2 pumped system and what is this for

Answer 1

Two pump- 1 for systematic LHS, 1 for pulmonary RHS
each pumps Atria contract first and at the same time, then ventricles second at the same time
Keeps the flow equal in each circulation
atrial blood - away from heart: venous blood towards heart

Question 2

How does Ca++ impact the contraction, contraction strength and relaxation of the heart

Answer 2

Intercellular Ca++ increase -> cross bridges form -> contraction
- engages all cariac myocytes NOT all myosin heads

increase strength: increase systolic Ca++ levels -> more myosin bind = more X-bridges = more strength

relaxation:
decrease cytosolic Ca++ via SR
- X-brdiges release when ATP binds to the myosin

Question 3

What are the phases of contraction in the cardiac cycle

Answer 3

1. Atrial systole - atria contract push blood into ventricles until pressure pushes AV valves close
   - close = Lubb sound
2. isovolumetric ventriular contraction - ventricles contract but blood doesnt move, increase ventricular pressure
3. ventricular ejection - pressure rises enough to cause SL valves to open = blood flows into the aorta + pulmonary arteys, when pressure drop below the arterys then SL closes = Dubbs sound
4. isovolumetric ventricular relaxation - rapid pressure drop in ventricles pulls AV valves open
   5.passive filling - longest phase

Question 4

What is systole + diastole and isovolumetric stages of the heart cycle

Answer 4

Systole = short phase of contraction
Diastole = long phase of relaxation

Isovolumetric is when the ventricle is not moving blood - volume is constant

Question 5

What are featuresof a blood pressure wave

Answer 5

• pulsates due to systole and diastole phases
• diastole = long - low , systole = short - high
• systemic higher than pulminary

Question 6

What information can be relayed from blood pressure wave

Answer 6

• pulse pressure: difference between highest and lowest pressure
• fraction: systole / diastole
• mean: average pressure. Bit below halfway due to diastole leangth
• hypertention = HPB, Hypotention = LBP

Question 7

What is EDV and ESV

Answer 7

edv is when the ventrciles are most full - end of diastole ventriles

esv is when the ventricles are empty - end of systole