Topic 11: Cardiovascular System - Cardiac Cycle - Mechanical Activity + blood flow through heart

Question 1

What are 2 main events of mechanical activity? What are they initiated by?

Answer 1

• systole and diastole
• electrical activity

Question 2

What is systole?

Answer 2

• contraction and emptying

Question 3

What is diastole?

Answer 3

• relaxation and filling

Question 4

What is one complete heartbeat composed of? (2)

Answer 4

• diastole and systole of Atria
• diastole and systole of ventricles

Question 5

What is the average HR?

Answer 5

75 bpm

Question 6

How many seconds per beat, aka per one cardiac cycle?

Answer 6

0.8 seconds
(60sec/min divided by 75 beats/min)

Question 7

In that time for a cardiac cycle, starting with atrial contraction at time 0, what occurs? (4)

Answer 7

1) Atria in systole for 0.1 second, then diastole for 0.7
2) ventricles enter systole after atria (0.1 second delay at AV node)
- therefore ventricles begin systole as atria begin diastole
3) ventricles in systole for 0.3 sec and diastole for 0.5

Question 8

What is blood flow to the heart due to? (3)

Answer 8

1. emptying pressure changes (high to low P_
2. Valves
3. myocardial contraction (raises P)

Question 9

Path of blood flow diagram

Answer 9

Question 10

What occurs during ventricular systole? (2 steps, 5 points)

Answer 10

1) higher P in ventricles than atria forces AV valves shut
- turbulence of blood gives first heart sound (LUB)
- shortly after QRS wave starts

2) P rises, so higher P in ventricle than aorta/pulmonary trunk pushes semilunar valves open
- blood enters vessels

Question 11

What occurs during ventricular diastole? (2 steps 5 points)

Answer 11

1) Pressure drops
- higher pressure in aorta/pulm trunk than ventricle forces semilunar valves to shut
- turbulence, thus causing 2nd heart sound (Dub)
- mid T wave

2) AV valves open when P in ventricles drops below P in atria

Question 12

What are three types of heart sounds?

Answer 12

• turbulent flow
• laminar flow
• korotkoff sounds

Question 13

What is turbulent flow?

Answer 13

noisy due to blood turbulence when valves shut

Question 14

What is laminar flow?

Answer 14

• no sound (smooth flowing fluid)

Question 15

What is laminar flow?

Answer 15

• no sound (smooth flowing fluid)

Question 16

What are korotkoff sounds? (4)

Answer 16

• turbulence heard in brachial artery during blood pressure measurements
  begin - systolic pressure
  ends - diastolic pressure
• due to cardiac cycle events