Events of the Cardiac Cycle

Question 1

General functions of the cardiovascular system

Answer 1

Heart - Pump that generates pressure gradient to move fluids
Blood Vessels - Passageways through which blood is distributed to different body parts
Blood - Transport medium for delivery of gases, nutrients and hormones

Question 2

Events of the Cardiac Cycle

Answer 2

Cardiac Excitation

–>
(Pacemaker Cells [SA Node]; Conduction pathways [AV Node, Bundle of his, etc.])
–>

Excitation-Contraction coupling

–>
(Ventricular Myocyte Action Potential; Calcium influx)
–>

Cardiac Contraction

Question 3

Describe blood flow along the heart

Answer 3

Question 4

Compare the volume output of the LHS vs RHS of the heart with numbers

Answer 4

LHS = RHS

~5L/min
70ml/beat

Question 5

Compare the pressure generated of the LHS vs RHS of the heart with numbers

Answer 5

LHS ~ 4 x RHS

~120 cf 30mmHg

Question 6

Systole and Diastole

Answer 6

Systole - Contraction

Diastole - Relaxation

Question 7

How does pressure affect fluid (blood) travel

Answer 7

Fluid flows from region of high to low pressure

Question 8

How do valves affect the flow of blood with regard to pressure

Answer 8

Direction of flow is determined by unidirectional valves; they open/close due to pressure differences across them

Question 9

Describe the pressure of the aorta, LV, LA as well as volume of LV during atrial systole

Answer 9

Short delay period is as a result of AV node

Question 10

Describe the pressure of the aorta, LV, LA as well as volume of LV during isovolumetric ventricular contraction

Answer 10

Question 11

Describe the pressure of the aorta, LV, LA as well as volume of LV during ventricular ejection

Answer 11

LV pressure exceeds Aortic pressure

Question 12

Describe the pressure of the aorta, LV, LA as well as volume of LV during isovolumetric ventricular relaxation

Answer 12

(Check around 30 minutes into lecture)

Question 13

Ventricular Filling

Answer 13

Describe the pressure of the aorta, LV, LA as well as volume of LV during ventricular filling

Question 14

Compare the timings of an ECG and heart pressure

Answer 14

ECG spikings slightly precede contraction and changes in heart pressure

Question 15

Jugular Venous Pulse

Answer 15

Pulsations in the internal jugular vein reflect right atrial pressure changes (no valves)

Question 16

Describe the heart sounds and when they occur

Answer 16

1st - Low pitched ‘lub’ associated with AV Valve closure
2nd - Brief high pitched ‘dup’ associated with aortic/pulmonary valve closure

3rd - Vibration of ventricular wall when filling
4th - Associated with ventricular filling during atrial systole

Question 17

Describe the sequence of Lub Dup sounds and systole/diastole

Answer 17

Question 18

Stenosis

Answer 18

Narrowing of the heart vessels/valves; creates a steep pressure gradient causing turbulence across the valve (makes a sound)

Question 19

Leaky/Incompetent/Insufficient Valve and associated sound

Answer 19

Flow can occur in different directions (regurgitation)

Murmur when valve should be closed

Question 20

Causes of heart murmurs (abnormal heart sounds)

Answer 20

High Flow

Flow in different directions