CVS

Question 1

Stroke volume

Answer 1

Volume of blood ejected from the heart per heartbeat

Question 2

Preload

Answer 2

End diastolic volume which is stretching walls of ventricles to greatest dimensions

Question 3

End diastolic volume

Answer 3

Volume of blood in ventricles before contraction

Question 4

What are the mechanisms of arrhythmia?

Answer 4

disturbances in conduction - conduction block and re-entry

disturbances in impulse formation/triggered activity - EADs and DADs

Question 5

What is a conduction block?

Answer 5

The complete block of forward movement of action potential between SAN and ventricular myocardium

arrhythmia where signal is delayed or blocked

Question 6

What occurs due to an AV block?

Answer 6

Reduced ventricular rate

Question 7

What occurs due to a bundle of His block?

Answer 7

this part of the heart will be damaged due to electrical change - asystole, brachycardia, reduced firing rate

Question 8

What occurs due to a block in a branch of the purkynje system?

Answer 8

no change in heart rate but reduced cardiac output

Question 9

What is reentry?

Answer 9

A fast heart rate (tachycardia) caused by electrical signals that loop back on themselves. Instead of waiting for another signal from the SAN, the original signal uses a separate accessory pathway to get from the ventricles back to the atria.

Question 10

Why does reentry cause tachycardia?

Answer 10

Reentry causes a continuous loop of one signal cycling through the atria and ventricles then back to the atria via the accessory pathway. As there is no delay between signals as there should be as a refractory period, this causes a much faster heartbeat.

Question 11

What causes afterdepolarisation?

Answer 11

Caused by a preceding action potential that is abnormally long.
Can be caused by QT syndrome and some drugs.

Question 12

When does an EAD occur?

Answer 12

late phase 2 or phase 3

occurs due to prolonged action potential - long QT syndrome

Question 13

When do DADs occur?

Answer 13

In late phase 3 or phase 4 when action potential is nearly or fully repolarised

Associated with high intracellular calcium concentrations - can occur due to excessive catecholamine stimulation

Question 14

What occurs to the aorta during systole?

Answer 14

70ml fills aorta

elastic wall of the aorta distends

Question 15

What occurs to the aorta during diastole?

Answer 15

elastic wall recoils

Question 16

What does systolic pressure depend on?

Answer 16

SV
Aortic/arterial distensibility
Ejection velocity
DP of previous beat

Question 17

What does diastolic pressure depend on?

Answer 17

Arteriolar resistance –> therefore vasoconstriction, arterioscelrosis and atherosclerosis increases DP
Heart rate - high heart rate increases DP

Question 18

What is the effect of ageing on pulse pressure?

Answer 18

Age causes loss of elastin in aorta so it will have a more rigid tube. This means it can’t distend or recoil as much. This means the ejection of the same SV will lead to increased systolic pressure. Reduced elastic recoil leads to a decrease in diastolic pressure. Therefore pulse pressure (SP-DP) increases with age and therefore feels stronger.

Question 19

What is the effect of NO on arterioles?

Answer 19

Vasodilation

Question 20

What is the effect of increased metabolism on blood flow?

Answer 20

Increased blood flow due to vasodilation

Question 21

Which adrenoceptor causes vasoconstriction in smooth muscle?

Answer 21

alpha 1

Question 22

Which hormones cause vasoconstriction

Answer 22

Vasopressin

Angiotensin II

Question 23

What does arterial vasodilation cause in the capillaries?

Answer 23

Increased pressure in the capillaries
More filtration
Less reabsorption

Question 24

What does arterial vasoconstriction cause in the capillaries?

Answer 24

Decreases pressure in the capillaries
Less filtration
More reabsorption

Question 25

What does increased capillary pressure cause?

Answer 25

More reabsorption

Less filtration

Question 26

What does increased venous pressure cause in the capillaries?

Answer 26

Same reabsorption

Less filtration

Question 27

What does increased interstitial protein concentration cause in the capillaries?

Answer 27

Oncotic pressure decreases
More filtration
Less reabsorption

Question 28

What does dehydration cause in the capillaries?

Answer 28

decreased filtration

increased reabsorption

Question 29

Which nerves innervate baroreceptors in the aortic arch?

Answer 29

The vagus nerve innervates the aortic nerve which innervates the aortic arch

Question 30

Which nerves innervate baroreceptors in the carotid sinus?

Answer 30

The glossopharyngeal nerve innervates the sinus nerve which innervates baroreceptors in the carotid sinus

Question 31

Where do simple reflexes occur?

Answer 31

medulla

Question 32

Where do complex reflexes occur and give some examples

Answer 32

Hypothalamus

Exercise, feeding/satiety, thermoregulation, reproduction

Question 33

Where does reflex vasoconstriction occur?

Answer 33

Skin by reflex increase in ADH, angiotensin II
Kidney
Cerebral circulation
Coronary circulation

Question 34

What activities cause AP to increase?

Answer 34

Coughing
Sneezing
Exercise
Pain

Question 35

What activities cause ABP to decrease?

Answer 35

Standing up
Dehydration
Haemorrhage

Question 36

What does the volume reflex cause if there is a decrease in blood volume?

Answer 36

• renal vasoconstriction –> decrease in renal tubular flow so increase of flow to rest of body
• renin release –> angiotensin II release –> increased reabsorption of Na+
• increase ADH release –> increase water reabsorption –> decrease urine flow rate

Question 37

Where do the neurones making up the sympathetic innervation of the heart exit the spinal cord from?

Answer 37

T1-L2