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Cardiovascular > Session 9 > Flashcards

Session 9 Flashcards

0
Q

What is the function of the Bronchial lung circulation.

A

Part of the systemic circulation and meets the metabolic needs of the lungs

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1
Q

What are the 2 circulations in the lungs?

A

Bronchial

Pulmonary

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2
Q

What is the function of the pulmonary lung circulation?

A

Blood supply to the alveoli and is needed for gas exchange.

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3
Q

What is the pressure in the right atrium?

A

0-8mmHg

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4
Q

What is the pressure in the right ventricle?

A

15-30mmHg systolic

0-8mmHg diastolic

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5
Q

What is the pressure in the pulmonary artery?

A

15-30mmHg systolic

0-8mmHg diastolic

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6
Q

What is the pressure in the left atrium?

A

1-10 mmHg

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7
Q

What is the pressure in the left ventricle?

A

100-140mmHg systolic

1-10mmHg diastolic

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8
Q

What is the pressure in the aorta?

A

100-140mmHg systolic

60-90mmHg diastolic

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9
Q

What is the mean arterial, capillary and venous pressure in the pulmonary circulation?

A

Arterial - 12-15 mmHg
Capillary - 9-12 mmHg
Venous - 5 mmHg

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10
Q

How does the pulmonary circulation ensure low resistance?

A

Has short and wide vessels
Has many capillaries in parallel
Has very little smooth muscle

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11
Q

How does the pulmonary circulation ensure efficient gas exchange?

A

Has a large surface area due to high density of capillaries in th alveolar wall
Thin layer of tissue to create a short diffusion pathway

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12
Q

What does the alveoli need for efficient oxygenation?

A

Must match the ventilation with perfusion

An optimal Q : V ratio is 0.8 for one alveoli.

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13
Q

How can the pulmonary circulation ensure there is an optimal Q : V ratio?

A

Hypoxia pulmonary vasoconstriction - diverting blood away from the alveoli that are not well ventilated. Possibly due to disease.

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14
Q

What can chronic hypoxia vasoconstriction cause?

A

Right ventricular hypertrophy because increase in vault resistance –> pulmonary hypertension –> right ventricle having to work harder.

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15
Q

When can chronic hypoxia vasoconstriction occur?

A

At high altitudes

Consequence of lung disease

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16
Q

What is capillary transit time?

A

How long it takes for red blood cells to move along a vessel. (Flow)

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17
Q

When can capillary transit time decrease?

Extra point - How?

A

During exercise. There is NO compromise to gas exchange.
Extra point - an increase in cardiac output –> increase in pulmonary arterial pressure –> opening of apical capillaries –> increase O2 uptake of lungs –> increased blood flow –> decreased capillary transit time.

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18
Q

What determines fluid formation?

A

Starlings forces

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19
Q

What influences capillary hydrostatic pressure more, arterial or venous pressure in the systemic circulation?

A

Venous pressure in systemic circulation.

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20
Q

What pressure causes fluid to leave pulmonary capillaries?

A

Hydrostatic pressure

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21
Q

What pressure causes fluid to enter pulmonary capillaries?

A

Colloid oncotic pressure.

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22
Q

What happens if the hydrostatic pressure is too high and too much lymph is formed in the lung?

A

It will impair gas exchange

23
Q

What is the typical movement (in/out) of fluid along a pulmonary capillary?

A

More fluid moves out at the arterial end

More fluid moves in at the venous end

24
Q

At what atrial pressure will you get oedema?

A

20-25

25
Q

When could you have high pressure in theft atrium?

A

Mitral valve stenosis.

Left ventricular failure.

26
Q

What can relieve the symptoms of pulmonary oedema?

A

Diuretics as they reduce the blood volume which reduces hydrostatic pressure.

27
Q

How does posture effect pulmonary oedemas?

A

The fluid is at the base of the lung when standing and spread out over the lung when lying down

28
Q

How does the effect of hydrostatic pressure on pulmonary vessels vary with gravity?

A

Top vessels collapse during diastole
Vessels in line with the heart continuously open
Vessels at the bottom distend

29
Q

How does the structure of the cerebral circulation secure O2 supply?

A

Anastomoses between the basilar and internal carotid arteries
Circle of willis

30
Q

How can the function of the cerebral circulation ensure secure O2 supply?

A

The brain stem can regulate other circulations
The metabolic factors
Myogenic autoregulation

31
Q

How is the cerebral circulation adapted to meet the high demand for O2?

A

Has a high capillary density so there is a large surface area and slow diffusion rate.
Has a high basal flow rate.
Has high O2 extraction.

32
Q

How does myogenic auto regulation work?

A

An increase in blood pressure causes vasoconstriction.
A decrease in blood pressure causes vasodilation.
Only works above 50mmHg
Maintains blood flow with changing pressures.

33
Q

What is Hypercapnia?

A

An increase in CO2 causes vasodilation

34
Q

What is Hypocapnia?

Extra point - What can cause it?

A

A decrease in CO2 causes vasoconstriction.

Extra point - By hyperventilation

35
Q

How can regional activity in the cerebral circulation alter blood flow?

A

Increases the concentrations of metabolites eg K+ which cause vasodilation and therefore an increase in blood flow.

36
Q

What is the Cushings reflex?

A

It is a response to increase in inter cranial pressure (cold be de to a haemorrhage or tumour)
There is an increase in sympathetic output so contraction of arteries occur and increases the arterial blood pressure - maintained cerebral blood flow.

37
Q

When does blood flow in the left coronary artery?

A

Mainly Diastole.

38
Q

How does the coronary circulation ensure adequate blood flow and O2 supply?

A

High capillary density
Short diffusion pathway - smaller diameter than skeletal capillaries
Continuous production of NO by the endothelium which is a vasodilator.

39
Q

What is the relationship between coronary blood flow and myocardial O2 demand?

A

Almost linear.

40
Q

How can blood flow be increased more in coronary circulation?

A

Metabolic hyperaemia due to vasodilators such as adenosine, K+, H+

41
Q

What are functional end arteries prone to?

Extra point - What can this cause?

A

Atheromas
Extra point - Stable Angina as blood flow is most during exercise, but diastole is reduced so coronary vessels fill less.

42
Q

What can cause unstable angina?

A

Stress and cold due to sympathetic vasoconstriction of the coronary vessels.

43
Q

What are vessels in the skeletal circulation rich in?

A

Innervation by sympathetic vasoconstrictor fibres.

44
Q

How can the skeletal circulation increase O2 and nutrient delivery/removal of metabolites during exercise?

A

Only half of the vessels are perfused at rest so in exercise there is increased recruitment which allows increased flow and a decreased distance of diffusion.

45
Q

What are the important vasodilation molecules?

A 
K+
H+
Inorganic phosphates
Osmolality
Adenosine
46
Q

What causes vasodilation?

A

Adrenaline acting on beta 2 adrenoreceptors

47
Q

What causes vasoconstriction?

A

Noradrenaline acting on alpha 1 adrenoreceptors.

48
Q

What is the metabolic requirement of the cutaneous circulation?

A

Low

49
Q

What is the cutaneous circulation responsible for?

A

Temperature regulation

Blood pressure maintenance

50
Q

How does the cutaneous circulation control blood pressure?

A

Vasoconstriction can cause an increase in total peripheral resistance which leads to an increase in arterial pressure.

51
Q

What is Apical skin?

A

An area that has a high surface area to volume ratio.

52
Q

What structure is in apical skin?

A

Artereovenous anastomoses. (Glomus body in Spring like shape)

53
Q

How can artereovenous anastomoses regulate heat loss?

A

They can increase the surface area to volume ratio so more heat is lost.

54
Q

What controls artereovenous anastomoses?

A

NOT controlled by metabolites
Sympathetic vasoconstriction.
Decrease in core temperature increases the sympathetic tone.
Increase in core temperature decreases the sympathetic tone so relaxation and shunt to Venus plexus.

55
Q

How does non apical skin regulate heat loss?

A

Has the vasodilator Bradykinin which comes from the ACh sympathetic innervation of sweat glands.

Cardiovascular (15 decks)

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