Special Circulations

Question 1

Where do the right and left coronary arteries arise from?

Answer 1

Base of the aorta

Question 2

Where does most coronary venous blood drain?

Answer 2

Via coronary sinus into the right atrium

Question 3

What are the two branches of the left mainstem coronary artery?

Answer 3

Circumflex and left anterior descending

Question 4

What are 3 adaptations of the coronary circulation?

Answer 4

High capillary density, high basal blood flow and high oxygen extraction

Question 5

What is the only way extra O2 can be supplied to the coronary circulation?

Answer 5

By increasing coronary blood flow

Question 6

What does decreasing PO2 do to the coronary arterioles?

Answer 6

Vasodilation

Question 7

What from ATP is a potent vasodilator?

Answer 7

Adenosine

Question 8

What are coronary arterioles supplied by?

Answer 8

Sympathetic vasoconstrictor nerves

Question 9

Sympathetic stimulation of the heart results in what?

Answer 9

Coronary vasodilation

Question 10

How does circulating adrenaline cause vasodilation?

Answer 10

Activates beta 2 adrenoceptors

Question 11

When does most of coronary blood flow and myocardial perfusion take place?

Answer 11

Diastole

Question 12

What vessels supply the brain?

Answer 12

Internal carotids and vertebral arteries

Question 13

Which part of the brain is more sensitive to hypoxia?

Answer 13

Grey matter

Question 14

What arteries anastomose to form the Circle of Willis?

Answer 14

Basilar artery and carotid arteries

Question 15

What does the Circle of Willis allow?

Answer 15

Cerebral perfusion to be maintained even f one carotid artery is blocked

Question 16

What happens to resistance vessels in the cerebral circulation if MABP rises?

Answer 16

Constrict

Question 17

What happens to resistance vessels in the cerebral circulation if MABP decreases?

Answer 17

Dilate

Question 18

Autoregulation of cerebral blood flow fails when MABP is outwith what limits?

Answer 18

< 60 or > 160

Question 19

Increased PCO2 does what to the cerebral vasculature?

Answer 19

Vasodilation

Question 20

Decreased PCO2 does what to the cerebral vasculature?

Answer 20

Vasoconstriction

Question 21

What does increases cerebral pressure do to cerebral blood flow?

Answer 21

Decreases it

Question 22

What makes the tight intercellular junctions of cerebral capillaries?

Answer 22

Blood brain barrier

Question 23

Cerebral capillaries are highly permeable to what?

Answer 23

O2 and CO2

Question 24

How does glucose cross the blood brain barrier?

Answer 24

Facilitated diffusion

Question 25

What is the blood brain barrier impermeable to?

Answer 25

Hydrophilic substances

Question 26

Where does the entire cardiac output from the right ventricle go?

Answer 26

Pulmonary circulation

Question 27

What supplies the lungs?

Answer 27

Systemic bronchial circulation

Question 28

What is the pulmonary capillary pressure compared to systemic capillary pressure?

Answer 28

Low

Question 29

What does hypoxia do to pulmonary arterioles?

Answer 29

vasoconstriction

Question 30

Why is resting blood flow of the skeletal muscle circulation low?

Answer 30

Sympathetic vasoconstrictor tone

Question 31

What overcomes sympathetic vasoconstrictor activity in skeletal muscle?

Answer 31

Metabolic hyperaemia

Question 32

What does circulating adrenaline do to blood vessels?

Answer 32

Vasodilation

Question 33

What does contraction of skeletal muscle do to veins?

Answer 33

Squeezes them to aid venous return

Question 34

What does the skeletal muscle pump reduce the chance of?

Answer 34

Postural hypotension and fainting

Question 35

What compensatory change does varicose veins cause?

Answer 35

Increased blood volume