Blood

Question 1

What is blood composed of?

Answer 1

Cells (45% of blood volume)- ‘formed elements’
Red blood cells (erythrocyte)
White blood cells (leucocytes)
Platelets (thrombocytes)

Plasma (55% of blood volume) - extracellular fluid; water, electrolytes, organic molecules (glucose, fatty acids, glycerides, amino acids, etc); plasma proteins

Question 2

Which proteins are present in the plasma?

Answer 2

Albumins (60%): oncotic pressure, transport of lipids
Globulins (35%): transport of ions, hormones, lipids. Immune function
Firbinogen (4%): key component of blood clot
Regulatory proteins (1%): enzymes and hormones

Question 3

Red blood cells make up what percentage of all cells in the blood?

Answer 3

99%

Question 4

What is the diameter of a red blood cell?

Answer 4

6-8 micrometers

Question 5

What shape is a RBC and what does this confer?

Answer 5

Biconcave shape: gives large surface area relative to volume
This permits rapid gas (O2, CO2) transfer across cell membrane
Allows RBC to bend in narrow capillaries
Enables RBC to expand to accommodate fluid in hypotonic solutions

Question 6

Where are RBCs formed?

Answer 6

In the red bone marrow

Question 7

What is the average lifespan of a RBC?

Answer 7

120 days

Question 8

How are old RBCs broken down?

Answer 8

Old RBCs are removed from circulation and broken down by MPS (monocyte/phagocyte system) - in the spleen, mainly
Breakdown products are recycled

Question 9

What is haemoglobin made up of?

Answer 9

Protein - amino acid pool

Haem -> contains iron. Converted into biliverdin and bilirubin (waste products)

Question 10

Where is bilirubin conjugated?

Answer 10

In the liver and excreted as bile pigment

Question 11

What are the symptoms of excess bilirubin in the blood?

Answer 11

Jaundice (yellowing of skin) and itchy skin

Question 12

What percentage of RBCs are non-functional?

Answer 12

10%

Question 13

What happens to non-functional RBCs?

Answer 13

Broken down by haemolysis

Eliminated through urine or picked up by macrophages

Question 14

What is transferrin?

Answer 14

A carrier protein made in the liver

Picks up iron and drops it off at the bone marrow -> transferrin circulates iron

Question 15

What is anaemia caused by?

Answer 15

Iron deficiency in the blood

Question 16

What is the main symptom of anaemia?

Answer 16

Chronic fatigue

Question 17

How are RBCs formed?

Answer 17

Formed in red bone marrow, regulated by erythropoietin
Series of stages involved
During development there is a reduction in cell size and regression of nucleus
Requires folic acid and vitamin B12
Requires iron (for haemoglobin)

Question 18

What are the stages in RBC formation?

Answer 18

Day 1: Proerythroblast (huge nucleus, big cell)
Day 2: Basophilic erythroblast 
Day 3: Polychromatophilic erythroblast 
Day 4: Normoblast 
Days 5-7: Reticulocyte 
Day 7: Mature RBC

Question 19

What happens if RBC numbers are low?

Answer 19

Decreased oxygen delivery to cells
Decreased oxygen to kidney 
Erythropoietin released
Acts on red bone marrow 
Increases production of RBCs

Question 20

Why are RBCs never 100% saturated with oxygen?

Answer 20

Because they also carry CO2

Question 21

What is the molecular weight of haemoglobin?

Answer 21

68,000 Da

Question 22

Describe the structure of haemoglobin

Answer 22

2 alpha chains and 2 beta chains
4 hame groups (porphyrin ring, iron atom)
Fe reversibly binds O2

Question 23

What type of haemoglobin does a foetus have?

Answer 23

Hb-F

Question 24

How many molecules of haemoglobin does each RBC contain?

Answer 24

200-300 Hb molecules per RBC

Question 25

What percentage of cells in the blood do white blood cells make up?

Answer 25

1%

Question 26

What type of cells make up the majority of white blood cells?

Answer 26

Neutrophils (50-70%)

Question 27

What do neutrophils do?

Answer 27

Fight infections
Non-specific
General immune response
Phagocytic

Question 28

What do neutrophils do?

Answer 28

Fight infections
Non-specific
General immune response
Phagocytic

Question 29

What are eosinophils?

Answer 29

Immune cells involved in allergy

Question 30

What is the precursor for macrophages?

Answer 30

Monocytes

Question 31

What are the 2 types of lymphocyte?

Answer 31

T cells and B cells

Question 32

What are the 2 types of lymphocyte?

Answer 32

T cells and B cells

Produce a specific immune response

Question 33

What are platelets derived from?

Answer 33

Megakaryocytes

Question 34

What is the role of platelets?

Answer 34

Involved in haemostasis
Release vasoconstrictors (thromboxane A2)
Form platelet plug
Source of phospholipid (‘platelet factor’) for coagulation

Question 35

What is the normal platelet count?

Answer 35

150-400 x 10^9/litre

Question 36

What are blood groups?

Answer 36

RBCs carry antigens on their membranes
AB antigens and Rhesus antigens important for determining blood group/important in blood transfusions
A, B, AB, O
Rh+ or Rh-

Question 37

What happens if a Rh- person receives Rh+ blood?

Answer 37

They will develop anti-Rh antibodies

Question 38

What happens to a Rh- female if they conceive a Rh+ foetus?

Answer 38

Some of the foetal RBCs can enter maternal circulation during childbirth
Anti-Rh antibodies are formed
These can attack and haemolyse RBCs of a subsequent Rh+ foetus
Haemolytic disease of the newborn

Question 39

Which blood group is the universal donor?

Answer 39

O

Question 40

Which blood group is the universal recipient?

Answer 40

AB