8 Special Circulations

Question 1

What are the diastolic and systolic pressures in the right ventricle?

Answer 1

Diastolic: 0-8mmHg
Systolic: 15-30mmHg

Question 2

What are the diastolic and systolic pressures in the aorta?

Answer 2

Diastolic: 60-90mmHg
Systolic: 100-140mmHg

Question 3

What are the diastolic and systolic pressures in the left ventricle?

Answer 3

Diastolic: 1-10mmHg
Systolic: 100-140mmHg

Question 4

What is the mean:

i. ) Arterial pressure
ii. ) Capillary pressure
iii. ) Venous pressure

Answer 4

i. ) 12-15mmHg
ii. ) 9-12mmHg
iii. ) 5mmHg

Question 5

What are the diastolic and systolic pressures in the pulmonary artery?

Answer 5

Diastolic: 4-12mmHg
Systolic: 15-30mmHg

Question 6

How is ventilation of the alveoli matched to the perfusion of the alveoli?

Answer 6

Blood is diverted away from alveoli that are not well ventilated to maintain the V/Q ratio.

Question 7

What is the optimum V/Q ratio?

Answer 7

0.8

Question 8

What can chronic hypoxic vasoconstriction cause?

Answer 8

Ventricular failure in the right heart

Question 9

In the upright position, where is the most pressure experienced in the lung?

Answer 9

Lower part

Question 10

What pressure forces fluid OUT of the capillaries?

Answer 10

Hydrostatic pressure

Question 11

What pressure pulls fluid back INTO the capillaries?

Answer 11

Oncotic pressure

Question 12

What drugs are given to treat oedema?

Answer 12

Diuretics

Question 13

What blood vessel adaptations are present in the brain?

Answer 13

High capillary density
Reduced diffusion distance
High basal flow rate
High O2 extraction

Question 14

How long does it take for a neurone to be irreversibly damaged when no oxygen is supplied?

Answer 14

4 minutes

Question 15

How is blood supply to the brain secured structurally?

Answer 15

Anastomoses between the basilar and internal carotid arteries

Question 16

What molecule are cerebral vessels very sensitive to?

Answer 16

CO2

Question 17

What do the vessel muscles do when the PCO2 is increased?

Answer 17

Vasodilation

Question 18

What is the Cushing’s reflex?

Answer 18

The rigid cranium protects the brain but also does not allow for expansion. Increases in intracranial pressure result in haemorrhaging or tumours.

Question 19

When does blood flow in the left coronary artery usually occur?

Answer 19

Diastole

Question 20

Which circulation has an important role in regulating arterial blood pressure?

Answer 20

Skeletal muscle circulation

Question 21

How is heat loss via the skin regulated?

Answer 21

Cutaneous circulation

Question 22

What does a decreased temperature induce in the cutaneous circulation?

Answer 22

Increases sympathetic tone in the anastomoses.

Question 23

What does a increased temperature induce in the cutaneous circulation?

Answer 23

Allows the anastomoses to dilate so heat is dissipated.