Cardio

Question 1

How may cardiac output be regulated without requiring nervous/ hormonal input?

Answer 1

Frank-Starling relationship
Increasing venous return 
Dilates ventricles more 
Increases cardiac stretch 
Increases contractile force of muscle
Increases stroke volume

Question 2

Describe the relationship between velocity and cross-sectional area

Answer 2

Linear velocity is inversely proportional to cross-sectional area
(rapids in centre parks is slower when river is wide and faster when narrow)

Question 3

Velocity equation (including flow and area)

Answer 3

Velocity (v) = Flow (Q) / Cross sectional area (A)

volume flow remains constant

Question 4

What’s the relationship between flow and pressure difference at the inlet and outlet (ΔP) for a rigid tube?

Answer 4

Flow is directly proportional to change in pressure

Question 5

What’s the relationship between flow and length?

Answer 5

Flow is inversely proportional to length

Question 6

What’s the relationship between flow and viscosity?

Answer 6

Flow is inversely proportional to viscosity

Question 7

What’s the relationship between flow and radius?

Answer 7

Flow is directly proportional to the radius to the power 4

Question 8

What is the term that describes ability to stretch and expand?

Answer 8

Compliance

Question 9

What is the term that describes ability to recoil?

Answer 9

Elasticity

Question 10

Equation for mean arterial pressure

Answer 10

Mean arterial pressure = diastolic pressure + 1/3 pulse pressure

Question 11

What is mean arterial pressure?

Answer 11

It drives blood through the vasculature from the arteries to arterioles, capillaries, venules, veins, and back to the heart

Is carefully regulated by short-term and long-term regulatory and compensatory mechanisms

Is a time-weighted average of pressure values in large systemic arteries during the cardiac cycle

Question 12

Why is a simple average of the systolic and diastolic pressure values is not an adequate estimate of the mean arterial pressure?

Answer 12

The ventricles do not spent equal lengths of time in systole and diastole
Approximately:
1/3 time is spent in systole
2/3 in diastole

Question 13

What is the mean arterial pressure a function of?

Answer 13

1) Rate at which the heart pumps blood into the large arteries
2) Rate of blood flow out of the large arteries to enter smaller arteries and arterioles
3) Arterial wall compliance

Question 14

What is pulse pressure?

Answer 14

Systolic blood pressure - diastolic blood pressure

Question 15

What effect does aortic insufficiency (aortic valve regurgitation) have on pulse pressure?

Answer 15

Increases pulse pressure
As blood leaks back into the ventricle through the aortic valve during ventricular diastole, decreasing the pressure in the aorta during diastole
Systolic blood pressure is the same/ slightly elevated
Greater difference between systolic and diastolic pressure

Question 16

How does first degree heart block usually present in an ECG?

Answer 16

Prolonged PR interval
PR interval is normally 0.12-0.20 seconds
PR interval consistently longer than 0.20 seconds (greater than 5 small boxes) in 1st degree AV block
1:1 ratio between P waves and QRS complexes maintained
Indicates conduction through the AV node is slowed

Question 17

How does second Degree AV Block Type I usually present in an ECG?
(Wenckebach block or Mobitz Type I AV block)

Answer 17

Progressive PR interval prolongation with each beat until a P wave is not conducted - increasing delay of AV nodal conduction until a P wave fails to conduct through the AV node
1:1 P wave to QRS complex ratio is NOT maintained
Irregular R-R interval
Indicates varying failure of conduction through the AVN
can be caused by AV blocking medications/ increased vagal tone/ AVN ischemia during an inferior MI

Question 18

How does second Degree AV Block Type II usually present in an ECG?
(Mobitz Type II AV block)

Answer 18

AVN becomes completely refractory to conduction on an intermittent basis - some P waves not followed by a QRS complex since it does not conduct through the AV node to the ventricles
The PR interval may be normal or prolonged, but it is always constant in length
Indicates significant conduction disease in this His-Purkinje system and is irreversible, pemament pacemaker is required

Question 19

How to work out how long each heartbeat is

Answer 19

60 (secs) / heart rate (beats per min)

Question 20

How does sympathetic stimulation have a positive inotropic effect?

Answer 20

NA and A activate beta 1 adrenoceptors
Activates adenylyl cyclase
Causes increase in cAMP
Increases intracellular Ca2+

Question 21

How does parasympathetic stimulation have a negative inotropic effect?

Answer 21

Activate M2 receptors
Linked to adenylyl cyclase
Causes decrease in cAMP
Decreases intracellular Ca2+

Question 22

How does parasympathetic stimulation have a negative chronotropic effect?

Answer 22

ACh released increases nodal cells’ permeability to K+
This decreases the slope of the pacemaker potential
and hyperpolarizes the membrane potential

Question 23

How does sympathetic stimulation shorten phase 2 of ventricular action potentials?

Answer 23

cAMP activates protein kinase A
That phosphorylates the delayed rectifier K+ channels responsible for moving phase 2 to phase 3
Means a faster repolarisation, shortening the action potential

Question 24

Cardiac output =

Answer 24

Stoke vol x heart rate

Question 25

Ejection fraction =

Answer 25

Stroke vol (EDV-ESV) ÷ end diastolic vol x 100

Question 26

Systemic vascular resistance/ total peripheral resistance =

Answer 26

SVR = (MAP - CVP) ÷ CO

MAP: mean arterial pressure
CVP: central venous pressure

Question 27

Where do the coronary arteries arise from?

Answer 27

The aorta

Question 28

Name the layers surrounding the heart from inside out

Answer 28

Endocardium
Myocardium
Visceral pericardium of serous pericardium/ Epicardium (coronary arteries on epicardium)
Pericardial cavity
Parietal pericardium of serous pericardium
Fibrous pericardium

Question 29

Which side of the heart is the mitral valve?

Answer 29

Left

mitral and left have an L in them

Question 30

The cells of the myocardium behave as a single coordinated unit called a …

Answer 30

Functional syncytium