Oxygen in the blood

Question 1

solubility factor for oxygen? is oxygen soluble?

Answer 1

Oxygen is not very soluble in water

– Solubility factor for O2 = 0.01 mmol.l-1.kPa-1

Question 2

how can u calculate the amount of Oxygen dissolved in plasma?

Answer 2

O₂ dissolved = solubility x pO₂

_{At pO2 of 13.3 kPa only 0.13 mmol.l-1 is dissolved}

_so

_{0.01 mmol.l-1.kPa-1}

Question 3

how much is CO?

Maximum CO?

Answer 3

5l/min

Max CO= 25l/min

Question 4

CO cannot meet the needs of the body by just dissolved oxygen alone.

so we need some kind of transport system to transport that oxygen

Answer 4

ok

Question 5

Oxygen binding pigments?

which one has the highest affinity for oxygen?

Answer 5

• Haemoglobin – present in blood
– Tetramer – binds 4 oxygen molecules

• Myoglobin – present in muscle cells

– Monomer – binds 1 oxygen molecule

myoglobin!!

Question 6

structure of hemoglobin!

Answer 6

Question 7

Draw an oxygen-haemoglobin dissociation curve, label the axes correctly &

indicate the normal values of

(i) alveolar pO2
(ii) capillary pO2 in a typical tissue.

Answer 7

alveolar pO₂= 13.3

Question 8

Moods of Haemoglobin

Answer 8

Question 9

When PO2 is low Hb is in the tense or relaxed state?

Answer 9

When pPO2 is low Hb is tense

which means its hard for the first molecule of hemaglobin to bind!

Question 10

Hb saturated above ______

unsaturated below _______

Half saturated at ______

Answer 10

Hb saturated above 9-10kPa

Virtually unsaturated below 1kPa

Half saturated at 3.5 – 4 kPa

Question 11

what is normal hemoglobin concentrations

how can u calculate the oxygen content of arterial blood

Answer 11

If Hb concentration is normal ≈ 2.2 mmol.l-1

Each Hb molecule binds 4 O₂ molecules

Therefore oxygen content = 8.8 mmol.l-

Question 12

if a patient is anaemic,

what will happen to pO_{2 ?}

what about oxygen content ?

Answer 12

pO₂ will be normal, but oxygen content will be lower

huh why? ask alaa ask

Question 13

what is the pO_{2 in the tissues?}

Answer 13

typically 5 kPa

cuz its given up all its oxygen!

Question 14

The lower the tissue pO2, the more O2 will dissociate from Hb

ok?

Question 15

How low can tissue pO₂ get?

Answer 15

• Tissue pO2 must be high enough to drive diffusion of O2 to cells
• It cannot fall below 3 kPa in most tissues

Question 16

what is capillary density?

which muscles have it high?

Answer 16

defined as the number of capillaries per unit cross-sectional area of muscle.

metabolically active tissues!

Question 17

If u have a high capillary density (ex: in heart muscle) you can get the Po2 in that tissue to be low… why?

Answer 17

bc u dont need the oxygen to diffuse over a LARGE ditance!

Question 18

Draw the effects on the haemoglobin oxygen dissociation curve of

(i) a fall in pH (ii) a rise in temperature. Iii) an increase in 2-3 DPG

↓pH promotes _____state of Hb

Answer 18

shift graph to the RIGHT causing higher chance for o2 to dissociate

T state

Question 19

Explain the difference between oxygen saturations (‘Sats’) partial pressure of oxygen PaO2 and oxygen content of blood

Question 20

Over the whole body about _____% of oxygen from arterial blood is given up

Answer 20

27

Question 21

when does 2,3-Bisphosphoglycerate increase?

Answer 21

2,3-BPG levels increase with anaemia or at altitude

Question 22

describe CO poisoning and graph

Answer 22

Question 23

Hypoxemia vs hypoxia

Answer 23

• *• Hypoxemia** - low pO₂ in arterial blood
• *• Hypoxia –** low oxygen levels in body or tissues

• If pO2 levels are low not all the Hb will be saturated

if Hb levels r low, not enough O2 will be present in the blood

Question 24

what conditions can cause hypoxia?

Answer 24

shock> peripheral vasoconstriction

places where tissues r using oxygen faster than it is delivered!

• peripheral arterial disease
• raynaud’s disease

Question 25

Define cyanosis and explain its significance

Answer 25

Bluish colouration due to unsaturated haemoglobin

Can be peripheral (hands or feet) due to poor local circulation

Question 26

Raynaud’s phenomenon

Answer 26

where the blood supply to certain parts of the body, usually the fingers and toes, becomes temporarily reduced when exposed to cold temperatures

Question 27

what type of cyanosis is this?

Answer 27

central (more serious)

(mouth, tongue, lips, mucous membranes) due to poorly saturated blood in systemic circulation

(maybe prob with lungs, cardiac,….)

Question 28

which congenital disease can cause cyanosis

Answer 28

Question 29

how does the pulse oximeter work?

Answer 29

O2 Saturation is estimated using a pulse oximeter.

Detects pulsatile arterial blood, and ignores the venous blood

saturated Hb is gunna absorbs less of the red spectrum

doesnt say how much is Hb concentration!

Question 30

Arterial Blood Gas Analysis

Answer 30

This requires an arterial blood sample (as opposed to a venous blood sample obtained by venepuncture).

This is obtained by arterial puncture usually from the radial artery.

Hence it is an invasive technique.

Question 31

Would pulse oximetery be useful in assessing a patient w/ suspected CO poisoing?

Answer 31

NO

they will look very rosy cheeked, cuz Carboxyhemoglobin is BRIGHT RED

Question 32

Answer 32