Myocyte

Question 1

Fasting energy for the heart comes from?

A Free fatty acids (FFA)
B Glucose
C Amino acids
D Glycerol

Answer 1

A Free fatty acids (FFA)

Question 2

normal blood flow to the heart

Answer 2

250ml/min or 84ml/100g/min

Question 3

what is the normal O2 consumption in a beating heart

Answer 3

9ml/100g/min

Question 4

what is the normal O2 consumption in a non beating heart

Answer 4

2ml/100g/min

Question 5

In exercise what can the O2 extraction increase by

Answer 5

The O2 extraction can increase by 100%

Question 6

In exercise what can cardiac output increase by

Answer 6

Cardiac output can increase by 700%

Question 7

what is isometric muscle contraction

Answer 7

Heart rate rises (decreased vagal tone), systolic and diastolic blood pressure rises sharply.
SV changes relatively little, and blood flow to the steadily contracting muscle is reduced as a result to the compression of the blood vessels.

Question 8

what is isotonic contracting muscle

Answer 8

Prompt increase in HR, but different to isometric contraction in that there is a marked increase in SV. In addition, there is a net fall in total peripheral resistance due to vasodilation in exercising muscle. Consequently, systolic blood pressure rises only moderately , whereas diastolic pressure usually remains unchanged or falls.

occurs in running

Question 9

During strenuous exercise, a fit 20 yr male can increase his stroke volume by?

A 400%
B 500%
C 300%
D < 200%

Answer 9

D < 200%

Normal stroke volume (SV) is 70-90mls. A fit person can increase his SV to a max of 126ml, which is, less than a 200% increase

Question 10

The cardiac output during exercise can increase by?

A600%
B700%
C500%
D200%

Answer 10

700%

Question 11

Cardiac output is changed as listed in all of the following circumstances except?

A Decreases when moving from a lying to a sitting position
B Decreased by sleep
C Increased on eating
D Increased during exercise

Answer 11

B Decreased by sleep

Question 12

During exercise in a fit, healthy young male, which of the following options is correct?

AStroke volume increases more than 700%
BStroke volume increases more than 400%
CStroke volume increases more than 300%
DStroke volume increases less than 200%

Answer 12

DStroke volume increases less than 200%

Question 12

Under basal conditions the percentage of the heart’s caloric needs which is met by fat is?

A40%
B50%
C60%
D70%

Answer 12

C 60%

Question 13

Myocardial contractility is decreased by all of the following except?

A Barbituates
B Hypercarbia
C Bradycardia
D Glucagon

Answer 13

D Glucagon

Glucagon, which increases the formation of cyclic adenosine monophosphate (cAMP), is positively inotropic, and is recommended in the treatment of some heart diseases.

Question 14

Cardiac output is decreased by which of the following?

A Sleep
B Exercise
C Pregnancy in the first trimester
D Sitting from a lying position

Answer 14

D Sitting from a lying positionCorrect

Question 15

Myocardial oxygen consumption

A Oxygen consumption in increased by parasympathetic stimulation
B The stroke work of the left ventricle is three time that of the right ventircle
C Increases more with increased preload than afterload
D Is 90ml/kg/min

Answer 15

D Is 90ml/kg/min

the stroke work of the left ventricle is 7 times that of the right ventricle

Question 16

Which is FALSE regarding coronary blood flow?

A There is blood perfusion to the right ventricle muscle and the two atria during systole
B The heart compresses its coronary vessels during contraction
C Systole and diastole shorten when the heart rate increases
D The subendocardial portion of the heart is perfused only during systole

Answer 16

D

Question 17

Regarding the oxygen consumption of the heart. Which of the following is TRUE?

A Stroke work of the left ventricle is seven times that of the right ventricle
B An increase in pre-load cause the same increase in O2 consumption as an increase in after-load
C The 02 usage of the heart at a pulse rate of 100/min is 1430ml/min
D The beating heart O2 consumption is 2ml/100g/min

Answer 17

A Stroke work of the left ventricle is seven times that of the right ventricle

Question 18

Which substance (metabolite) is vasodilatory on the heart, but not on skeletal muscle?

A Histamine
B Adenosine
C Lactate
D Potassium

Answer 18

B Adenosine

Question 19

What is the affect of histamine on heart rate and contractility?

A Decreased heart rate, increased contractility
B Decreased heart rate, decreased contractility
C Increased heart rate, increased contractility
D Increased heart rate, decreased contractility

Answer 19

C Increased heart rate, increased contractility

Histamine is known to act as a direct stimulator. In the heart, two types of histamine receptors are present: H1- and H2-receptors. H2-receptors cause an increase in heart rate and contractility as well as coronary vasodilatation, whereas H1-receptors mediate chronotropic effects and coronary vasoconstriction.