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Flashcards in Physiology Deck (84)
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1

Boyle's Law

at any constant temperature the pressure exerted by a gas varies inversely with the volume of the gas

i.e. as the volume of a gas increases, the pressure exerted by the gas decreases

2

the 2 forces that hold the thoracic wall and lungs in opposition

intraplural fluid cohesiveness
negative intrapleural pressure

3

roots of phrenic nerve

C3,4,5

4

is inspiration or expiration a passive process?

expiration
inspiration is an active process

5

alveolar surface tension

attraction between water molecules at liquid-air interface

6

La Place Law

smaller alveoli are more likely to collapse

7

which alveoli secrete surfactant

type 2

8

what is respiratory distress syndrome of the new born

developing fetal lungs are unable to synthesise sufactant until late in pregnancy -- premature babies may not have enough surfactant and have to make strenuous efforts to overcome the high surface tension and inflate the lungs

9

which muscles contract during active expiration
e.g. after hard exercise

abdominal muscles
intercostal muscles

10

accessory muscles of respiration

sternocleidomastoid
scalenus
pectorals major + minor
latissimus dorsi
serratus anterior

11

tidal volume

volume of air entering or leaving lungs during a single breath

12

inspiratory reserve volume

volume of air that can be inspired above tidal volume

13

Inspiratory capacity

max volume of air that can be inspired at the end of a normal quiet expiration
IC = IRV + TV

14

average tidal volume

500ml

15

expiratory reserve volume

volume of air that can be actively expired beyond normal tidal volume

16

residual volume

minimum volume of air remaining in the lungs after maximal expiration

17

funcional residual capacity

volume of air in lungs at end of normal passive expiration
FRC= ERV + RV

18

vital capacity

max volume of air that can be moved out during a single breath following maximal inspiration

19

average vital capacity

4500ml

20

total lung capacity

max volume of air that the lungs can hold
- average 5700ml

21

FVC

forced vital capacity- max volume of air that can be forcibly expelled from lungs following max inspiration

22

FEV1

force expiratory volume in 1 second- volume of air that can be expired during the first second

23

obstructive pattern of spirometry

Decreased FEV1
Decreased FEV1/FVC ratio
FVC can be normal -- asthma
FVC can be low -- COPD

24

restrictive pattern of spirometry

Decreased FVC
Decreased FEV1
Normal FEV1/FVC ratio

25

conditions that decrease pulmonary compliance

fibrosis
oedema
lung collapse
pneumonia
decreased surfactant

26

what does decreased pulmonary compliance mean

more effort needed to stretch the lungs
- restrictive spirometry

27

what is increased compliance

loss of elastic recoil of the lungs
- hyperinflation of the lungs- harder to get air out of the lungs

28

what condition increases compliance

emphysema
(compliance also increases with age)

29

alveolar dead space

there is ventilation but no perfusion

30

V:Q at bottom of lungs

Greater perfusion (blood flow) than ventilation

31

Daltons Law

the total pressure exerted by a gaseous mixture = the sum of the partial pressures of each component

32

Ficks Law

the amount of gas that moves across a sheet of tissue in a unit time is proportional to the area of the sheet but inversely proportion to the thickness

33

Henrys law

the amount of gas that dissolved in a given type + volume of liquid at a constant temperature is proportional to the partial pressure of the gas in equilibrium with the liquid

34

normal arterial P02

13.3 kPa

35

things that shift O2-Haemoglobin curve to the right

High to rigHt
- increased Pco2
- increased temperatute
- increased 2,3- Biphosphoglycerate
- increased H+ -- this will cause DECREASED pH

36

things that shift O2-haemoglobin curve to the left

Low to Left
- decreased Pco2
- decreased temperatue
- decreased 2,3- biphosphoglycerate
- decreased H+ -- this will cause INCREASED pH

37

shape of O2-haemoglobin dissociation curve

Sigmoid

38

pneumonic for blood gases

ROME

- respiratory opposite
- metabolic equal

39

respiratory alkalosis

Increased pH decrease pCO1

40

respiratory acidosis

Decreased pH Increased pCO2

41

metabolic alkalosis

Increased Ph Increased HC03

42

metabolic acidosis

Decreased pH decreased HCO3

43

things that can cause respiratory alkalosis

PE
pregnancy
anxiety
altitude

44

what blood gas result do COPD and asthma cause

respiratory acidosis

45

what blood gas result do opiates cause

resp acidosis

46

things that cause a metabolic alkalosis

diuretics
vomitting

47

what blood gas result does renal failure + sepsis cause

metabolic acidosis

48

structure of fetal Hb

2 alpha 2 gamma sub units

49

how many haemoglobin groups are there per myoglobin

one

50

what does presence of myoglobin in blood indicate

muscle damage

51

what modifies respiration

the pons

52

what generates respiratory rhythm

medulla

53

where are the peripheral chemoreceptors

carotid bodies
aortic bodies
- affected by hypoxia

54

where are the central chemoreceptors

the medulla
- response to H+ concentration of the CSF

55

can H+ cross the blood brain barrier

NO

56

how is a metabolic acidosis corrected

hyperventilation to increase CO2 elimination from the body

57

how is a respiratory acidosis corrected

body reabsorbs HC03

58

what type of stimulation causes bronchoconstriction

parasympathetic

59

Cardiac output

volume of blood pumped by each ventricle per minute
CO= SV X HR

60

stroke volume

volume of blood ejected by each ventricle per heart beat

61

what is pre-load

end diastolic volume
- volume of blood within each ventricle at the end of diastole
- determined by venous return

62

Frank Starling Mechanism

the greater the EDV, the greater the SV

63

describe actin + myosin

actin = thin, lighter appearance
myosin = thick, darker appearance

64

role of tropomyosin in actin-myosin cross bridge formation

tropomysin covers binding sights on actin filaments
- when Ca binds to troponin on actin this causes a conformational change
- conformational change moves tropomyosin out the way-- cross bridge formation

65

after load

resistance into which the heart is pumping
- will result in ventricular hypertrophy if chronic

66

positive inotropic effect

increased FORCE OF CONTRACTION of the heart due to sympathetic stimulation

67

positive chronotropic effect

increased in HEART RATE due to sympathetic stimulation

68

role of myosin light chain kinase

phosphorylates the myosin light chain so that it can bind to actin

69

what activates myosin light chain kinase

calcium-calmodulin

70

what inactives myosin light chain kinase

phosphorylation

71

How does the FEV1/FVC ratio differ in stable COPD v an acute exacerbation

ratio is decreased (below 70%) in stable disease
ratio will be further decreased to a very low value in an acute exacerbation e.g. 40%

72

what is the approx functional residual capacity in a young man

2.2 L

73

management of acute HF

IV furosemide + nitrates

74

how do nitrates work

cause venodilatation -- decrease preload

75

how does COPD affect total lung capacity

increased total lung capacity due to trapping of air

76

PO2 and saturations in anaemia

normal- low Hb but normal concentration of 02.

77

what force holds the lungs in opposition

negative intrapleural pressure

78

how is intra pleural pressure affected in pneumothorax

intra pleural pressure becomes more +ve - air is entering the lungs but not leaving

79

what happens when P02 falls to below 8kPa

saturations will decrease significantly
- will remain around > 90% until below 8kPa

80

which has a higher diffusion co-efficient - CO2 or O2

CO2

81

Haldane effect

removing O2 from Hb increases its affinity for CO2 -- O2 is released at tissues + Co2 is taken up

82

which neurones generate breathing rhythm

pre-botzinger complex

83

pneumotaxic centre

area in pons that modifies breathing rhythm generated by medulla
- stimulation will terminate inspiration

84

apneustic centre

prolonges inspiration