12

Question 1

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

Answer 1

pulmonary –> lungs

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

Question 2

what is the venous drainage of bronchi

Answer 2

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

Question 3

where does bronchial circulation arise from

Answer 3

aorta

Question 4

where does pulmonary circulation arise from

Answer 4

right ventricle

Question 5

what percentage of left ventricular output does bronchial circulation receive

Answer 5

2%

Question 6

what percentage of right heart cardiac output does pulmonary circulation receive

Answer 6

100%

Question 7

do bronchial arteries bracnch the same way from the aorta

Answer 7

no they vary in their branching pattern

Question 8

are there any links between bronchial and pulmonary circulation

Answer 8

yes they have arterial AND venous anastomoses

Question 9

where does the right bronchial vein drain

Answer 9

azygous vein

Question 10

where does the left bronchial vein drain

Answer 10

hemiazygous vein AND ACCESRORRY Hemiazygous

Question 11

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

Answer 11

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

Question 12

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

Answer 12

5s

Question 13

what blood vessels do bronchial arterioles from the aorta supply

Answer 13

capillaries around bronchi and bronchial smooth muscle

Question 14

whats the surface area for gas exchange

Answer 14

50 – 100 m2​

Question 15

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

Answer 15

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

Question 16

whats the mean pulmonary arterial pressure when STANDING

Answer 16

15mmHg

Question 17

whats the mean pulmonary venous pressure

Answer 17

8mmHg

Question 18

which of systemic or pulmonary has a greater resistance

Answer 18

systemic.

Question 19

what pathology arises from constant pulmonary arterial resistance increase

Answer 19

pulmonary arterial hypertension –> right heart enlargement and failure.

Question 20

which is worse, systemic or pulmonary hypertension

Answer 20

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

Question 21

whats the function of the somatic supply to the lung

Answer 21

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

Question 22

what types of nervous system exists int he lungs

Answer 22

somatic

auatonomic

Question 23

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

Answer 23

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

Question 24

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

Answer 24

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.

Question 25

where do sympathetic nerves run

Answer 25

along blood vessels (pulmonary artery)

Question 26

where do parasympathetic nerves run

Answer 26

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

Question 27

is pulmonary pressure low or high

Answer 27

low

Question 28

does gravity impact pulmonary BP

Answer 28

YES

Question 29

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

Answer 29

greatest in base | least in apex

Question 30

whats the pressure in lung apex when STANDING

Answer 30

2mmHg

Question 31

whats the pressure in lung base when STANDING

Answer 31

25mmHg

Question 32

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

Answer 32

gravity

Question 33

whats the three zone model of lung perfusion in upright state

Answer 33

``` 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. ```

Question 34

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

Answer 34

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

Question 35

when can TOTAL cessation of flow int he apices be noted

Answer 35

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​

Question 36

which area of the lung is best for gas exchange

Answer 36

the base so zone 3

Question 37

why does flow occur continuously in zone 3

Answer 37

bc pulmonary arterial & venous pressures always exceed alveolar pressure

Question 38

how do quickly improve oxygen intake

Answer 38

lie down

Question 39

what total lung compliance and whats the equation

Answer 39

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

Question 40

where is the work of breathing the least

Answer 40

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

Question 41

where is compliance the highest in the lungs

Answer 41

base

Question 42

whats better ventilated, basal alveoli or apex alveoli

Answer 42

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

Question 43

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

Answer 43

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

Question 44

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

Answer 44

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

Question 45

whats the ventilation perfusion ratio VA/Q at the apex

Answer 45

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

Question 46

whats the ventilation perfusion ratio VA/Q at the base

Answer 46

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

Question 47

how does v/Q ratio change in airway obstruction

Answer 47

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.​

Question 48

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

Answer 48

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.

Question 49

whats the mixed pulmonary venous blood

Answer 49

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

Question 50

what are the gas levels like in mixed pulmonary venous blood

Answer 50

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

Question 51

in pulmonary circulation, what does hypoxia cause

Answer 51

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.

Question 52

what regulates local perfusion

Answer 52

local ventilation

Question 53

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

Answer 53

must increase three fold

Question 54

does pulmonary arterial pressure increase duringg exercise to increase pulmonary output

Answer 54

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

Question 55

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

Answer 55

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. ​ ​

Question 56

whats the pulmonary vascular resistance like in the fetus

Answer 56

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

Question 57

what happens to pulmonary vascular resistance during baby first breath

Answer 57

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

Question 58

what happens to most blood entering fetal right heart

Answer 58

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

Question 59

function of foramen oval

Answer 59

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.​ ​

Question 60

what structures does the ductus arteriosus join

Answer 60

aorta and pulmonary artery

Question 61

function of ductus arteriosus

Answer 61

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.​