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RESP > O2 transport > Flashcards

O2 transport Flashcards

1
Q

How to calculate total pressure of gases?

A

P total = PH2O + ∑P consistent gases

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2
Q

How to calculate pp?

A

P gas = (Pb-PH2O) x ngas
PH2O : dry 0kPa / humidified 6kPa
Pb : atmospheric 100kPa
ngas : mole fraction, O2 at sea level 0.21

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3
Q

Define pp of gas dissolved in liquid?

A

amount of gas that would dissolve in the liquid (at eq) if the liquid was placed in contact w a gas phase of equivalent pp

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4
Q

What does the conc of gas dissolved in liquid depend on?

A

pp + solubility of gas

because conc=pp x solubility

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5
Q

Why can’t O2 transport alone?

A

low solubility = 0.2 mL/L/kPa
PA = 14 kPa can only dissolve 3mL of O2 per L
body needs 250 mL O2 per min at rest which would require CO= 80L

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6
Q

Role of Hb?

A

enables O2 to be conc within blood

binds 98% O2

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7
Q

What’s the total O2 carrying capacity?

A

3 mL/L (plasma) + 197 mL/L (Hb) = 200mL

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8
Q

Why’s O2 vs Hb dissociate curve sigmoidal?

A
  • O2 affinity increased by more binding (cooperative binding )
  • saturation + decreased free O2 binding sites
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9
Q

How’s O2 content in blood measured?

A

PaO2
CaO2 : total O2 content ml/L
O2 saturation : SaO2 (measured directly in arterial blood), SpO2 (estimated by pulse oximetry) %

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10
Q

Define PaO2

A

pp of O2 within gas phase (at a gas-liq interface) that would yield this much O2 in plasma at eq

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11
Q

Define CaO2

A

v of O2 carried by each L of blood (including plasma + bound O2)

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12
Q

Define O2 saturation

A

% of Hb binding sites occupied by O2

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13
Q

Why’s Hb effective?

A
  • structure produces high O2 affinity so high saturation at low PO2
  • conc of heme groups + Hb in 🔴
  • O2 vs Hb curve shifts to unload O2 at tissues
  • affinity changes on local environment so O2 delivery coupled to demand
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14
Q

When does saturation fall below 90% + effect?

A

when PaO2 falls below 8kPa
when PAO2 falls below 14kPa
O2 release from Hb increases as PO2 falls (tissues)

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15
Q

How is there a high carrying capacity?

A

4 O2 binding heme groups
5B 🔴/ml
270M Hb/🔴

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16
Q

Define Bohr effect

A

effect of CO2 + pH on affinity

17
Q

Why left shift?

A 
higher affinity
↓ CO2
↓ 2,3-DPG
↓ temp
↑ pH
18
Q

Why right shift?

A 
lower affinity
↑ CO2
↑ 2,3-DPG
↑ temp
↓ pH
19
Q

How does increased 2,3-diphosphoglycerate affect affinity?

A

=intermediate of glycolysis, produced within🔴

during anaerobic metabolism alters Hb structure decreasing affinity as less O2 bind

20
Q

Where’s the highest+lowest affinity Hb?

A

lungs
resting tissue
working tissue

21
Q

Role of myoglobin?

A

O2 reservoir at muscle tissue only releases O2 at low PO2 STEEEEEEEEP + left

22
Q

How is O2 transferred to baby?

A

foetal + maternal Hb in contact in placenta, O2 transferred to high affinity foetal Hb

23
Q

What’s cyanosis?

A

purple discolouration of skin/tissue when excess deoxyhaemoglobin

24
Q

What’s central cyanosis + eg?

A

blueish discolouration of core, mucous membranes, extremities
less oxygenation of blood
hyperventilation, V/Q mismatch

25
Q

What’s peripheral cyanosis + eg?

A

blueish discolouration to extremities
less O2 supply to extremities
small vessel circulation issues

26
Q

Diff ways hypoxia arise?

A
  • less ventilation
  • less perfusion
  • less O2 carried in blood to meet demands
27
Q

Cause of anemia?

A

iron deficiency

haemorrhage

28
Q

How does CO poisoning happen?

A 
-CO displaces O2 at Hb binding sites due to greater
affinity >200x
-less O2 binds + transported
-CaO2 decrease
-oxyhaemoglobin decrease
29
Q

Why does hypoxia occur is absence of cyanosis?

A

carboxyhaemoglobin is cherry red

30
Q

Anaemia readings?

A 
↓total arterial O2 conc
normal PaO2
normal SaO2
↓Hb conc
↓oxyhaemoglobin
31
Q

CO poisoning readings?

A 
↓total arterial O2 conc
normal PaO2
↓SaO2 but NORMAL pulse oximetry
normal Hb conc
↓oxyhaemoglobin
32
Q

Why does curve shift left w CO poisoning?

A

CO inhibits glycolysis in 🔴 so ↓DPG –> left–> ↑ affinity

33
Q

What’s Erythropoietin (EPO)

A

hormone secreted by kidney in response to hypoxia, induces production of 🔴within bone marrow

34
Q

How to compensate for chronic hypoxia?

A

increase Hb conc-saturation will decrease due to reduced PaO2 but compensated by greater number of Hb

35
Q

How + why does CO increase with hypoxia?

A

via increased heart rate to increase overall O2 transport - same number of Hb cycled from lungs to tissue rapidly, increasing total volume of oxygen
transported per unit time

36
Q

Define polycythaemia

A

increase in 🔴 per unit of plasma

37
Q

When does increased EPO secretion occur?

A 
chronic hypoxic respiratory disease
high altitude (due to chronic hypoxia involved)
38
Q

How do athletes use EPO?

A

altitude training

illegal doping

RESP (11 decks)

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