Physiology: Haemoglobin and Gas Transport

Question 1

What does blood transport from lungs into tissues?

Answer 1

O2

Question 2

What does blood transport as a waste product from tissues to the lungs?

Answer 2

CO2

Question 3

How much O2 can be dissolved in a 1L of plasma?

Answer 3

3ml of oxygen

Question 4

What aids the carrying of oxygen ability in blood?

Answer 4

Haemoglobin in red blood cells

Question 5

How much O2 can be dissolve in blood with RBC containing Haemoglobin?

Answer 5

200ml/ L

Question 6

Is arterial partial pressure of O2 = to arterial concentration/ content of O2?

Answer 6

No

Question 7

Why is arterial partial pressure of O2 not = to arterial concentration/ content of O2?

Answer 7

Partial arterial pressure of O2 only refers to O2 in the plasma solution

Question 8

Why do gases not travel in gaseous phase through blood?

Answer 8

As an air embolism may occur

Question 9

How much much of the arterial O2 extracted by peripheral tissues at rest?

Answer 9

25%

Question 10

What partial pressure of arterial blood equal too?

Answer 10

Oxygen pressure within the plasma solution

Question 11

How much of the oxygen in blood bound to haemoglobin?

Answer 11

98%

Question 12

How many oxygen molecules bind to 1 haemoglobin?

Answer 12

4

Question 13

What is the most prevalent haemoglobin in RBC?

Answer 13

HbA

Question 14

What are the types of haemoglobin in RBC?

Answer 14

HbA
HbF
HbA2
HbA1a
HbA1b
HbA1c

Question 15

What is the fundamental determinant of how saturated haemoglobin is saturated with oxygen?

Answer 15

Partial Pressure of Oxygen in arterial blood

Question 16

What allows oxygen to be extracted from alveoli into arterial blood?

Answer 16

Partial Pressure gradient between the alveoli and pulmonary capillaries

Question 17

What maintains the partial pressure gradient in blood?

Answer 17

Hb taking O2 from the plasma and Hb is saturated

Question 18

When does the haemoglobin saturation fall below 90%?

Answer 18

When PaO2 is under 60mmHg

Question 19

What other forms of haemoglobin have a higher affinity of O2?

Answer 19

Myoglobin 
Foetal Haemoglobin (HbF)

Question 20

Why do myoglobin and HbF have a higher affinity for O2 than HbA?

Answer 20

As they need to extract O2 from maternal blood or require high amount of O2 due to high activity

Question 21

Define the condition Anaemia?

Answer 21

Condition where oxygen carrying capacity of blood is compromised

Question 22

What can cause anaemia?

Answer 22

Iron deficiency
Haemorrhage
Vitamin B12 deficiency

Question 23

What Chemical factors affect Haemoglobin Affinity?

Answer 23

pH - more alkaline higher affinity, more acidic less affinity
PCO2 - less CO2 higher affinity for O2
Temp - lower temp higher affinity
DPG - binding fo 2,3-DPG decreases affinity

Question 24

What is 2,3-diphosphoglycerate (2,3-DPG) produced by?

Answer 24

Erythrocytes

Question 25

When does 2,3-DPG increase?

Answer 25

When low O2 supply

Question 26

Why is Carbon Monoxide Toxic?

Answer 26

Haemoglobin has a higher affinity to CO than O2

Question 27

What are the symptoms to carbon monoxide poisoning? (6)

Answer 27

``` Hypoxia and Anaemia Nausea and Headaches Cherry Red Skin Mucous Membrane RR not affected due to normal PCO2 Brain Damage and Death ```

Question 28

What is the definition of Hypoxia?

Answer 28

Inadequate supply of O2 to tissues

Question 29

What are the 5 main Types of Hypoxia?

Answer 29

``` Hypoxaemic - most common Anaemic Stagnant Histotoxic Metabolic ```

Question 30

What is Hypoxaemic Hypoxia?

Answer 30

Reduced O2 diffusion at lungs due to decreased PO2atmos or tissue pathology

Question 31

What is Anaemic Hypoxia?

Answer 31

Reduced O2 carrying capacity of blood due to anaemia

Question 32

What is Stagnant Hypoxia?

Answer 32

Heart Disease causing insufficient pumping of blood around the body

Question 33

What is Histotoxic Hypoxia?

Answer 33

Poisoning of cells stopping O2 being delivered to them

Question 34

What is Metabolic Hypoxia?

Answer 34

O2 delivery to tissues does not meet demand

Question 35

How is CO2 transported through blood?

Answer 35

1. CO2 diffuses from tissue to blood 2. 7% dissolves in the erythrocytes and plasma 3. 23% combines with deoxyhaemoglobin in erythrocytes to form carbamino compounds 4. 70% combines with water in the RBC's to form carbonic acid which then further dissociates to form bicarbonate and H+ ions. Bicarbonate leaves erythrocytes in exchange from Cl- due the chloride shift and H+ ions binds to deoxyhaemoglobin. Reverse occurs at pulmonary capillaries

Question 36

How is pH of blood kept stable?

Answer 36

All CO2 produces is eliminated by air

Question 37

What happens to pH of plasma when Hypoventilation occurs?

Answer 37

Causes CO2 retention increasing H+ ion concentration causing Respiratory Acidosis

Question 38

What happens to the pH of plasma when Hyperventilation occurs?

Answer 38

Releases more CO2 decreasing the concentration of H+ ions and causing Respiratory Alkalosis