Oxygen in the blood

Question 1

2 oxygen binding pigments and how much oxygen they can bind

Answer 1

Haemoglobin - blood- 4 O2 molecules

Myoglobin - muscle cells binds 1 O2 molecule

Question 2

What are the two states of Hb? What does this mean for the haemoglobin dissociation curve shape?

Answer 2

T state- tense difficult for O2 to bind, when PO2 is low

As each O2 binds molecule becomes more relaxed

R state- relaxed high affinity easier for O2 to bing

Sigmoid curve as binding becomes easier

Question 3

In mixed venous blood usually how much of the oxygen is still bound at Rest?

Answer 3

Over half

About 27% arteriole blood oxygen is given up

Question 4

What’s the Bohr shift?

Answer 4

Ph affects affinity of haemoglobin

Acid condition shifts dissociation curve right (higher PO2 values more O2 is given up) by promoting T state lower affinity for O2

Increased CO2 makes blood more acidic aka more metabolically active tissues

Question 5

As well as higher PCO2 what else do metabolically active tissues have that shifts the dissociation curve right?

Answer 5

Increased temperature

Question 6

What’s the maximum unloading of oxygen as a percentage?

Answer 6

70%

Question 7

What’s the oxygen reserve?

Answer 7

About 27% arteriole oxygen given up

Can increase to 70% when exercising with improved extraction

Question 8

What molecule increases with anaemia and altitude and what does it do?

Answer 8

2,3% bisphosphoglycerate shifts Hb dissociation curve right which allows more O2 to be given up

Question 9

Explain carbon monoxide poisoning

Answer 9

Reacts with Hb- COHb

Increases affinity of other subunits for O2 so won’t dissociate

Fatal if HBCO >50%

Question 10

What is the difference between hypodermic and hypoxia? Name some conditions that can cause each

Answer 10

Hypoxia- LOS oxygen levels in body/ tissues

• shock can reduce blood flow (peripheral vasoconstriction -> peripheral hypoxia)
• tissues use O2 faster than it’s delivered e.g. peripheral arterial disease or Raynaud’a (vasoconstriction to fingers-> blue Fakeeha)

Hypoxemia- Low PO2 in arterial blood
E.g. low PO2 or low Hb

Question 11

What is cyanosis, 2 types?

Answer 11

Bluish colour due to unsaturated Hb (deoxygenated Hb less red)

Peripheral due to poor circulation OR
Central (mouth/ mucous membranes) due to poorly saturated blood in systemic circulation

Difficult to detect

Question 12

What is pulse oximetry

Answer 12

pulsatile Arterial blood only

Detects levels of Hb saturation by differences in absorption of light between oxygenated and deoxygenated (absorbs more red knight so looks less red) Hb. Red and infrared emitted light detector

Good for detecting respiratory conditions