special circulations

Question 1

what is the blood supply to the lungs

Answer 1

2 circulations
bronchial circulation- part of systemic circulation , meets the metabolic requirements of parts of the lungs
pulmonary circulation- blood supply to alveoli, required for gas exchange

Question 2

features of pulmonary circulation

Answer 2

must accept the entire cardiac output

works at low pressure and resistance

Question 3

adaptations to promote efficient gas exchange

Answer 3

high density of capillaries in alveolar wall so large surface area
short diffusion distance as there is a thin layer of tissue separating gas phase from plasma.

Question 4

what is hypoxic pulmonary vasoconstriction

Answer 4

mechanisms where vascular smooth muscle constricts when there is a relatively low oxygen level.
vasoconstriction of pulmonary vessels reduces blood supply to the hypoxic region of lungs to maintain ventilation perfusion ratio.
in systemic circulation this is the complete opposite as capillaries would dilate in response to hypoxia.

Question 5

downside of chronic hypoxia

Answer 5

leads to chronic vasoconstriction which will increase vascular resistance which leads to chronic pulmonary hypertension making it more difficult for right ventricle to pump out blood and can lead to right ventricular heart failure.

Question 6

in the upright position how is the hydrostatic pressure on vessels in the lungs

Answer 6

greater hydrostatic pressure on vessels in the lower part of the lung ( base) than at the apex

Question 7

effects of exercise on pulmonary blood flow

Answer 7

• increased cardiac output
• small increase in pulmonary arterial pressure.
• opens apical capillaries
• increased o2 uptake lungs
• as blood flow increases capillary transit time is reduced

Question 8

how is tissue fluid formed

Answer 8

starling forces determine fluid formation
hydrostatic pressure of blood within capillary pushes fluid out of the capillary and oncotic pressure which is exerted by large molecules such as plasma proteins draws fluid into the capillary.

Question 9

in what clinical conditions can you get pulmonary oedema

Answer 9

mitral valve stenosis

left ventricular failure

Question 10

how does pulmonary oedema change by posture

Answer 10

forms mainly at bases when upright and throughout lung when lying down.

Question 11

how to relieve symptoms of pulmonary oedema

Answer 11

diuretics