Physiology Semester I- Pulmonary Circulation

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1

what is the pressure and resistance in pulmonary circulation

low pressure and low resistance

2

are there any important autonomic neural influences on pulmonary vessels

no

3

what is usually used as pulmonary vascular changes

prostacyclin: vasodilator
NO: vasodilator
endothelin 1: vasoconstrictor

4

what is regional flow of lungs dependent on

gravity (hydrostatic pressure differences)

5

what are the differences of zones in the lung

zone 1 is highest in the lung and has the lowest flow

zone 3 is lowest in lung and has highest flow

6

what is true about alveolar pressure and capillary pressure in zone 1

alveolar pressure is greater than capillary pressure

7

what is true about alveolar and capillary pressures about flow

if alveolar pressure is higher than capillary pressure at the arterial and venous ends fo the capillaries, the capillaries are compressed and no flow is possible

8

what is present at zone 2 with capillary pressure and alveolar pressure

capillary pressure at arterial end is greater than alveolar pressure which is greater than capillary pressure at the venous end of the capillary, where blood flow is driven by the difference between arterial and alveolar pressure

9

what drives blood flow in zone 2

difference between arterial and alveolar pressure

10

what drive blood flow in zone 3

arterial-venous pressure differences like in most capillary beds

11

what is true about capillary hydrostatic pressure and alveolar pressure in the capillary

capillary hydrostatic pressure throughout capillary is greater than alveolar pressure

12

what is the major controller of lung blood flow besides posture

alveolar hypoxia

13

what does alveolar hypoxia cause

nearby pulmonary arterioles to constrict (hypoxic pulmonary vasoconstriction)

14

how are the effects of low PO2 in alveolar gas on pulmonary arterioles compared to systemic arterioles

they are opposite

15

what helps match ventilation with blood flow in health

hypoxic pulmonary vasoconstriction

16

what is a major factor determining flows and pressures in the fetal circulatory system

hypoxic pulmonary vasoconstriction

17

what is a shunt

channeling of blood across heart or lungs such that either systemic mixed venous blood is added directly to the systemic arteis (R to L) or blood in left atrium or ventricle moves to the right side of the heart (L to R shunt)

18

how does a L to R shunt affect PaO2

small decrease

19

how will breathing 100% O2 influence arterial pO2 of someone with a L to R shunt

increase

20

what must happen for gas exchange in the lung

V must meet Q

21

what is normal V/Q of lung

0.8

22

what happens when pulmonary capillary blood and alveolar gas don't meet in the proper proportions in any part of the lung

local V/Q mismatch

23

what do areas of local V/Q mismatch contribute to

V/Q low: systemic arterial hypoxemia

V/Q high: increased physiological dead space

24

what does gravity do to V and Q in a lung

Q increases from top to bottom

V incraeses top to bottom also, but regional differencse not as great

25

what is V/Q of an affected area in a pulmonary embolism

increased

26

in a pulmonary embolism what changes are there in PaO2

none

27

in dislodged dental work blocking airway into a lung lobe what is the V/Q of the affected area

decreased

28

is there an incraeses in R to L shunt in a pulmonary embolism

no

29

is there an increase in R to L shunt in dislodged dental work blocking airway entry into a lung lobe

yeas

30

what is V/Q's extreme cases

V/Q=0 airway obstruction (shunt)

V/Q=inf dead space

31

what can lead to respiratory failure

disruptions in somatic neural input

32

where is the central pattern generator

brainstem (medullary respiratory center)

33

what does the dorsal respiratory group in the medullary center generate

inspriation

34

what does the ventral respiratory group of the medulla control

expiration, ONLY ACTIVATED WHEN ACTIVE

35

what modifies the central pattern generator

neural groups in pons

36

what cranial nerves feed information to the medullary respiratory center

IX and X

37

where do cranial nerves that feed information from medullary respiratory center get their information from

lung mecahnoreceptors (X) and peripheral chemoreceptors (IX and X)

38

how can the respiratory pattern be disrupted

voluntarily or by altereed higher CNS or peripheral input (anxiety, apnea during sleep)

39

what is ataxic breathing

irregular inspriations usually due to medullary lesions

40

what is Cheyne-Stokes respiration

cycles of waxing and waning tidal voulme maybe seen during sleep at high altitude or in patiends with CHF

41

what is Kussmaul breathing

deep, rapid breathing seen in metabolic acidosis

42

how does vagal input modify brainstem-generated breathing patterns

lung streth receptors

irritant receptors

juxtacapillary receptors

43

how do lung stretch receptors work

limit tidal volume that leads to increased brething frequency

44

how do irritant receptors work

stimulated by vairous noxious substances, limit tidal volume while icnraesing breathing frequency

45

what are irritant receptor inputs carried by

C fibers

46

are irritant receptors slow or rapid adapting

rapid

47

where are juxtacapillary receptors

in alveolar walls

48

when are juxtacapillary receptors stimulated

when capillaries engorded

49

what do juxtacapillary receptors lead to

rapid, shallow breathing (pulmonary edema), bronchoconstriction, incraesed mucus rpoduction

rapid adapting

50

what does sleep do to breathing

depresses it

51

what depresses berathing

sleep and other brain depressants, which incrase the risk of respiratory failure

52

why do sleep apneas occur

spontaneous cessation of berathing or airflow obstruction

53

what is obstructive apnea caused by

airway closure when sleep induced reduction in pharyngeal muscle tone closes oropharynx during inspiration and supination

54

when do apneic episodes usually begin

when upper airway collapses at end of previous expiration

55

what does obesity do for obstructive apnea

increasing cmpressive factors that contribute to airway closure

56

does further inspiratory effort open or close the airway

closes

57

what stimulates the respiratroy center and brain in an apneic episode

falling PaO2 and rising PaCO2 in responsde to lack of breathing

58

what does arousal do in an apneic episode

incrases pharyngeal muscle tone and changes posture