Composition of blood

Question 1

What are the 3 main components of blood?

Answer 1

Plasma (55%)
Buffy coat (4%)
Haematocrit (41%)

Question 2

What are the contents of plasma?

Answer 2

Water (90%), nutrients, vitamins, proteins, waste

Question 3

What is the most common globular protein in plasma?

Answer 3

Albumin - heart shaped with 6-7 disulphide bonds

Question 4

What is the function of albumin?

Answer 4

• Maintenance of intravascular colloid osmotic pressure (COP) through the binding of water
• Transport of cations, fatty acids, hormones and pharmaceuticals

Question 5

What are the functions of alpha 1 and alpha 2 globulins?

Answer 5

alpha 1 - transport lipids, thyroxin, corticosteroids, hormones
alpha 2 - transport of lipids and copper ions as well as antitrypsin

Question 6

What are the function of beta 1 and 2 globulins?

Answer 6

1 - transport of iron (transferrin tKDa) and antioxidants

2 - shed by cells anda involved in self-recognition

Question 7

What is the function of theta globulins?

Answer 7

immunoglobulins

Question 8

Describe the process by which fibrinogen is converted to fibrin

Answer 8

• Factor Xa is activated by the intrinsic or extrinsic pathway, catalysing the conversion of pothrombin to thrombin
• Prothrombin and factor XIII convert fibrinogen to fibrin

Question 9

What are the strucutral properties of platelets?

Answer 9

• Colourless and discshaped
• No nucleus
• Contain various granules
• Derived from megakaryocytes in the bone marrow

Question 10

What are functions of platelets?

Answer 10

• Role in clotting and inflamation where they cllect microbes and help phagocytes
• Upon activation stellate, secrete vasoconstrictors and procoagulants
• Secrete growth factors to maintain blood vessels

Question 11

What are the characteristics of the erythrocyte membrane?

Answer 11

• Elastic (thro’ complex with vertical and horizontal strcture)
• Charged inner layer and uncharged outer layer
• Associated proteins

Question 12

What are the 3 types of protein associated with the erythrocyte membrane?

Answer 12

Glycophorins - provide highly hydrophilic coat
Aquaporins - form pores for water transport
Spectrins - maintain stability and structure

Question 13

How does erythropoiesis control erythrocyte levels?

Answer 13

• Produced at low oxygen levels in the kidney
• Released into blood stimulating bone marrow to produce more erythrocytes
  Note: recombinant erythropoeitin used for blood doping

Question 14

What is the structure of haemoglobin?

Answer 14

• 4 globin chains (2* alpha 2*beta) as well as 4 haem groups
• Haem groups composed of Fe bound to porphyrin ring and bind reversibly to an oxygen molecule

Question 15

What is co-operative binding?

Answer 15

Where oxygen binding increases the affinity of haemoglobin for oxygen (same for dissociation)

Question 16

How does oxygen unload from haemoglobin?

Answer 16

Stepwise manner were the extent/rate is work/exercise dependent
Hb08 -> Hb06 -> Hb04 -> Hb02 - Hb

Question 17

Which factors can affect oxygen dissociation?

Answer 17

Altitude - ppO2 is lower, haematocrit levels increase to compensate
Weightlessness in space - decreases haematocrit levels

Question 18

How is blood pH maintained?

Answer 18

Bicarbonate ion combines with hydrogen ions to form CO2 which is exhaled

Question 19

When does alkalosis occur and what effects can it have?

Answer 19

• During hyperventilation, CO2 removed too quickly
• Accelerated degradation of bicarbonate encourages the combination of hygrogen ions with carbonate ions to make more
• This raises blood pH leading to over exitability or death