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Cardioresp > 12 > Flashcards

12 Flashcards

1
Q

what are the two physical circulations int he lungs and what does each supply

A

pulmonary –> lungs

bronchial (part of systemic) –> trachea and bronchial tree

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2
Q

what is the venous drainage of bronchi

A
  • bronchial veins (azygos and hemiazygous) to the right atrium
  • pulmonary veins to left atrium
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3
Q

where does bronchial circulation arise from

A

aorta

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4
Q

where does pulmonary circulation arise from

A

right ventricle

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5
Q

what percentage of left ventricular output does bronchial circulation receive

A

2%

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6
Q

what percentage of right heart cardiac output does pulmonary circulation receive

A

100%

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7
Q

do bronchial arteries bracnch the same way from the aorta

A

no they vary in their branching pattern

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8
Q

are there any links between bronchial and pulmonary circulation

A

yes they have arterial AND venous anastomoses

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9
Q

where does the right bronchial vein drain

A

azygous vein

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10
Q

where does the left bronchial vein drain

A

hemiazygous vein AND ACCESRORRY Hemiazygous

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11
Q

where do the azygous vein hemiazygous vein AND ACCESRORRY Hemiazygous run?

A

posterior to the heart and anterior to spinal cord. along the spinal cord

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12
Q

how long does it take for blood to pass through the lungs (pulmonary circulation)

A

5s

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13
Q

what blood vessels do bronchial arterioles from the aorta supply

A

capillaries around bronchi and bronchial smooth muscle

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14
Q

whats the surface area for gas exchange

A

50 – 100 m2​

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15
Q

what are some key anatomical features of pulmonary arteries that allow them to do their job well

A

Thin walled (less smooth muscle than systemic arteries.)
​
Larger diameter than systemic arteries. ​
​
Vessels are highly distensible and compressible​
​
High compliance–> pulmonary arteries stretch during systole: this smooths the blood flow through the lungs

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16
Q

whats the mean pulmonary arterial pressure when STANDING

A

15mmHg

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17
Q

whats the mean pulmonary venous pressure

A

8mmHg

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18
Q

which of systemic or pulmonary has a greater resistance

A

systemic.

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19
Q

what pathology arises from constant pulmonary arterial resistance increase

A

pulmonary arterial hypertension –> right heart enlargement and failure.

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20
Q

which is worse, systemic or pulmonary hypertension

A

​Pulm hypertension bc it produces rise in afterload of right heart.

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21
Q

whats the function of the somatic supply to the lung

A

carry pain and touch sensation from the lungs to the spinal cord segments T2-T6

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22
Q

what types of nervous system exists int he lungs

A

somatic

auatonomic

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23
Q

whats the function of the sympathetic supply to the lung and where do sy pathetic nerve fibres arise from

A

from T2 to T4-6

sympathetic fibres innervate smooth muscle in walls of bronchi and small pulmonary vessels. Activation causes bronchodilation via beta 2 receptors. Bronchial muscle relaxation due to sympathetic nerves is greatly augmented by circulating adrenaline

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24
Q

whats the function of the parasympathetic supply to the lung and where do parasympathetic nerve fibres arise from

A

vagus nerve

This contains both afferent and efferent fibres. The afferent fibres detect stretch of lungs during inspiration; efferent fibres produce bronchoconstriction and stimulate secretion of mucus in the bronchi.

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25
Q

where do sympathetic nerves run

A

along blood vessels (pulmonary artery)

26
Q

where do parasympathetic nerves run

A

as separate nerve plexi ending on local postganglionic nerve cells.​

27
Q

is pulmonary pressure low or high

A

low

28
Q

does gravity impact pulmonary BP

A

YES

29
Q

when you’re standing up which part of the lung has greatest pressure? least=

A

greatest in base

least in apex

30
Q

whats the pressure in lung apex when STANDING

A

2mmHg

31
Q

whats the pressure in lung base when STANDING

A

25mmHg

32
Q

why is pressure in the base of the lungs greater than that in apex when standing

A

gravity

33
Q

whats the three zone model of lung perfusion in upright state

A 
The  apices (zone 1) have  intermittent flow; flow occurs during systole only​
but really flow is intermittent in inspiration and only stops in expiration when lungs air pressure is maximal (above capillary pressure)
The centres (zone 2) have pulsatile flow; flow greater in systole than diastole. (flow changes due to changes in alveolar pressure)
​
The bases (zone 3) have continuous flow of blood.
34
Q

what can you use to measure blood flow distribution in the upright human lung

A

radioactive xenon injected into venous blood and evolves into alveolar gas from the pulmonary capillaries. Radiation counters measure the amount of xenon passing though each part of the lung

35
Q

when can TOTAL cessation of flow int he apices be noted

A

when a person is passively ventilated with positive pressure.

Then, apical blood vessels can become completely collapsed by the high alveolar pressure generated during inspiration​

36
Q

which area of the lung is best for gas exchange

A

the base so zone 3

37
Q

why does flow occur continuously in zone 3

A

bc pulmonary arterial & venous pressures always exceed alveolar pressure

38
Q

how do quickly improve oxygen intake

A

lie down

39
Q

what total lung compliance and whats the equation

A

a measure of the stretchability of the whole lung. it is the change in volume per unit pressure change.
C=dV/dP

40
Q

where is the work of breathing the least

A

in the region of highest compliance bc a small change in pressure gives a large change in lung volume bc its very stretchy so at the base

41
Q

where is compliance the highest in the lungs

A

base

42
Q

whats better ventilated, basal alveoli or apex alveoli

A

Basal alveoli bc they have a higher compliance (steeper slope of curve) and thus a bigger volume change per unit pressure change ​

43
Q

what changes more as you move form base to apex. blood flow or ventilation

A

blood flow.
it decreases A LOT as you go up
ventilation decreases too but not as much

44
Q

whats the shape of the curve showing ventilation perfusion ration Va/Q

A

The RATIO of ventilation (VA) to perfusion (Q) is a curve that increases steeply at the apex;

45
Q

whats the ventilation perfusion ratio VA/Q at the apex

A

3.3

APEX of upright lung has ventilation greater than perfusion; ventilation/perfusion ratio is greater than one.

46
Q

whats the ventilation perfusion ratio VA/Q at the base

A

0.6

BASE of upright lung has ventilation/perfusion ratio less than one.

47
Q

how does v/Q ratio change in airway obstruction

A

lower than normal
If airways completely blocked, ventilation is 0.

If blood flow is normal, then V/Q ratio is zero, whatever the perfusion. (0/x =0)​
There is no gas exchange in a lung that is perfused but not ventilated. Thus the PO2 and PCO2 of pulmonary venous blood from the affected lung will approach that of mixed venous blood.​

48
Q

how does v/Q ratio change in BLOODFLOW (embolus) obstruction

A

Higher than normal
If blood flow to a lung is completely blocked (e.g., by an embolism occluding a pulmonary artery), then blood flow to that lung is 0. If ventilation is normal, then V/Q is infinite. ​
There is no gas exchange in a lung that is ventilated but not perfused. Thus the PO2 and PCO2 of alveolar gas will approach that of inspired air.

49
Q

whats the mixed pulmonary venous blood

A

the blood before it is re-oxygenated in the pulmonary capillary.

50
Q

what are the gas levels like in mixed pulmonary venous blood

A

Mixed pulmonary venous blood contains gas levels intermediate between the apex and base

51
Q

in pulmonary circulation, what does hypoxia cause

A

vasoconstriction of local blood vessels to divert blood away from poorly ventilated, hypoxic regions of the lung (eg. following bronchial obstruction) and toward better-ventilated regions.

52
Q

what regulates local perfusion

A

local ventilation

53
Q

during exercise when CO increases three fold what happens to pulmonary output

A

must increase three fold

54
Q

does pulmonary arterial pressure increase duringg exercise to increase pulmonary output

A

NOOOOOO The pulmonary arterial pressure does not change during exercise.​
What happens is that the pulmonary arterial resistance greatly decreases during exercise

55
Q

what happens to the pulmonary artery to accommodate increase in oxygen demand due to exercise

A

when CO rises:

Pulmonary arteries and arterioles are thin walled so –> stretch

Stretching generates a reflex relaxation of the arterial smooth muscle and so the vessels relax and enlarge, reducing the vascular resistance.​
​
Some alveoli in the lungs (mainly in zones 2 & 3) are relatively poorly ventilated during quiet breathing. Thus the associated capillaries are constricted. The increased ventilation that occurs at the start of exercise increases PO2 in these alveoli. This opens up the associated capillaries and thus reduces total pulmonary vascular resistance.​
​
Arterio-venous shunts open in the lungs during exercise, allowing blood to go directly into the pulmonary veins. (this is more of a ‘safety valve’ mechanism, as shunted blood will not be oxygenated). Shunts can also open between the pulmonary and bronchial circulations. ​
​

56
Q

whats the pulmonary vascular resistance like in the fetus

A

high bc of generalised hypoxic vasoconstriction in the fetal lung. so blood flow through the fatal lungs is low

57
Q

what happens to pulmonary vascular resistance during baby first breath

A

pulmonary vascular resistance decreases
alveoli become better oxygenated
pulmonary blood flow equals CO

58
Q

what happens to most blood entering fetal right heart

A

goes from the right to left heart via foramen oval and doctors arteriosus

59
Q

function of foramen oval

A

Allows blood entering the right heart to ‘shunt’ across to the left heart instead of entering the right ventricle Thus the output of the right ventricle is much less than the left ventricle. The foramen normally closes shortly after birth.​
​

60
Q

what structures does the ductus arteriosus join

A

aorta and pulmonary artery

61
Q

function of ductus arteriosus

A

Allows part of the blood from the right ventricle to shunt (go) directly into the aorta, bypassing the lungs. It shuts immediately after birth, when the baby takes their first breath, and allows all the output of the right ventricle to pass into the pulmonary arteries.​

Cardioresp (23 decks)

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