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Flashcards in RESPIRATORY PHYSIOLOGY Deck (57):
1

what does the binding of O2 cause in Hb subunits

change from tense to relaxed state

2

What causes the Bohr effect

chloride shift increasing salt bridge formation

3

what effect does BPG have on the 02 dissociation curve

reduces affinity as resists salt bridge formation

4

how does BPG differ in foetal Hb

BPG level are decreased therefore Hb has higher affinity

5

How much O2 is associated with Hb and how much is dissolved

5% dissolved
95% HB

6

how long does it take for blood to be saturated with 02 in the alveoli

0.25 seconds

7

At rest blood spends 0.75 seconds in the alveoli, how does this change with exercise

time reduced to 0.25 seconds
progressive lung diseases will affect people during exercise first

8

methods of automatic neural control of breathing

PRE BOTZINGER COMPLEX in medulla --> rhythmical breathing

STRETCH RECEPTORS in lungs inhibit inspiration to protect lungs

PROPRIOCEPTORS in muscles, tendons and joints --> increase ventilation

9

Chemical control of ventilation

CENTRAL chemoreceptors (sensitive to PCO2 via H+ ions)

PERIPHERAL chemoreceptors
(sensitive to love PO2 [and ph])

10

what is resting O2 consumption

250ml/min

11

How does the global part of Hb modify the properties of haem

Makes reaction reversible
O2 can bind co-operatively

12

What is Henry's law

content of dissolved gas X in liquid Y= solubility of XinY. pp of X

13

3 mechanisms of CO2 transport in the blood

1. dissolved in blood
2. carbaminos
3. as carbonic acid in RBCs

14

What is the Haldane effect

deoxy blood can carry more CO2 as Hb mops up H+ ions forming carbamino groups

15

what is the normal PO2 in arterial blood

100mmHg (roughly same as mean alveolar)

16

what is the Bohr effect

reduced affinity for O2 owing to:
1. fall in pH
2. rise in PO2
3. Rise in temp
4. 2,3-BPG

17

what is the PO2 in capillary beds

40mmHg

18

What is Ficks law?

measures rate of diffusion.
Directly proportional to area, diffusion constant, partial pressure gradient
Inversely proportional to thickness

19

The alveolar gas equation

PAO2= PIO2 -(PACO2/0.8)

20

what is starling's equation

measures the flow of blood
F=Kfc[^P-reflection coef .^colloid]

21

what is the total blood volume in the pulmonary circulation

500ml
(10% of total)

22

what cause active and passive changes in perfusion

Passive:
- recruitment
- distension
Active:
- hypoxic pulmonary vasoconstriction

23

what is the normal VQ ratio

0.8

24

what is the V/Q at the base of the lung

<1

25

what is the V/Q at the apex

>1 (~3)

26

how much of the CO is shunted via the bronchial and mediastinal veins into the pulmonary veins

2-3%

27

how does venous pooling occur in the standing position

1. veins expand --> greater capacity unto 600ml
2. hydrostatic forces force fluid out

can mimic effect of haemorrhage

28

how music water is in the average adult male

64% (42L)

(53% in females)

29

explain the 20:40:60 rule

20 ECF
40 ICF
60% of body weight is water

30

what is the osmolarity of blood

300-310 mOsm/L

31

what is the osmolarity of 0.9% NaCl

308 mOsm/L

32

what is the osmolarity of intracellular fluid

290 mOsm/L

33

what percentage of a unit of 5% dextrose would stay in the plasma after equilibration

7%

34

what is the osmolarity of 5% dextrose

252mOsm/L

35

which 2 systems regulate body fluid compartments

osmoregulation
volume regulation

36

how does osmoregulation work

osmoreceptors in the hypothalamus (OVLT, SO) communicate with the posterior pituitary to secrete ADH when osmolarity falls

37

how does volume regulation help maintain body fluid compartments

sensed by ECV, carotid sinus, afferent arterioles and atria

acts on: RAAS, SNS, SNP, ADH, pressure natriuresis

38

what is oedema

osmotic expansion leading to increased ECW vol

39

what might cause hyPERosmotic expansion

Oral rehydration therapy

40

what might cause hypOsmotic expansion

water retention

41

what might cause osmotic contraction

cholera
osm stays the same

42

what might cause hyPERosmotic contraction

loss of water

43

what might cause hypOsmotic contraction

loss of solute e.g. in adrenal disease

44

what is starling's law of the heart

decreased blood volume leads to decreased cardiac output

45

how long is the normal PR interval

120-200ms
3-5 small squares

46

how long is the normal QRS

120ms
3 small squares

47

how long should the QT interval be

350ms
proportional to HR

48

what is the duration of a ventricular action potential

400ms (4 in muscle)

49

how would you calculate HR from an ECG

300/RR or 1500/RR for small squares

50

what are the difference between atrial/nodal APs and ventricular APs

atrial has shorter plateau phase, slower upstroke and uses a different Na channel in depolarisation

51

in a normal axis what would you expect to see on an ECG

Positive:
I, II, aVL, AVF

Negative:
III, aVR

52

what are the short term, intermediate and long term controls of blood pressure

SHORT: baroreceptor

INT: transcapillary shift
vascular stress relaxation (10-60min)
RAAS (after 20mins)

LONG : kidney --> aldosterone, ADH

53

Which cells mostly fire during expiration

The VRG

54

Which cells most fire during inspiration

The DRG also inhibits VRG

55

What is the role of the pontine respiratory group

To fine tune breathing
Transaction at this level leads to abnormal gasping pattern

56

Which cells in the cerebral cortex are involved in the conscious modification of breathing

The pyramidal tracts

57

Which 4 reflexes are present in the lung and modify breathing

Irritants in nose and upper airways --> vagus --> coughing, aspiration reflex, diving reflex

Pulmonary stretch detectors --> vagus --> decr resp via herring breuher

Irritant receptors: noxious gases --> bronchoconstriction

J receptors detect fluid in lungs --> dyspnoea in left sided heart failure