ToB - Blood Cells

Question 0

What do the membranes of RBCs contain and what is the function of some of these?

Answer 0

Antigens
Glycoproteins
Spectrin and actin - aids with shape change = flexibility through capillaries

Question 1

What is the function of RBCs?

Answer 1

Maintain osmotic equilibrium
Generate ATP via anaerobic glycolysis
Maintain Hb in its reduced state
Deliver O2 by carrying Hb

Question 2

What is the function of Hb?

Answer 2

Confers solubility
Protects haem from oxidation
Permits variation in O2 affinity by changing shape

Question 3

What is the reason that RBCs are a biconcave disc?

Answer 3

To allow flexibility so an 8um RBC can pass through a 3.5um capillary

Question 4

What are the 2 ways in that metabolism can occur in RBCs?

Answer 4

1) . Embeds Meyerhof pathway
- Glucose is converted into lactate
- Uses ATP
- Anaerobic

2) . Hexose monophosphate pathway
- G6P is metabolised
- Uses NADPH
- Anaerobic

Question 5

How are RBCs catabolised?

Answer 5

1) . RBCs are broken down to give Hb.
2) . Hb is broken down to give haem.
3) . Haem is converted into bilirubin which can be:
- -> conjugated by liver and stored in gall bladder
- -> taken up by the kidney as urobilinogen and excreted.
- -> released into the small intestine via the bile duct.

Question 6

How does a RBC spend its life and how long is its lifespan?

Answer 6

Lifespan ~ 120days

1) . Produced in bone marrow via erythropoeisis.
2) . Lives in circulation.
3) . Removed via spleen once damaged/old.

Question 7

What hormone controls RBC production?

Answer 7

Erythropoietin

Question 8

How is RBC production controlled?

Answer 8

1). Interstitial peritubular cells of the kidney detects low pO2 = stimulate secretion of erythropoietin.
2). Erythropoietin stimulates bone marrow to produce RBCs
= pO2 increases as number of RBCs does
= interstitial peritubular cells of the kidney detects this and stop the production of erythropoietin.

Question 9

Where is the bone marrow found?

Answer 9

It is extensive in childhood but retracts as an adult, and is found in the pelvis, skull, sternum, ribs and top of long bones.

Question 10

How are platelets formed?

Answer 10

Megakaryocytes grow in size and replicate their DNA
Platelets bud off from the cytoplasm
–>2-3um
–> cell fragments so have no nucleus

Question 11

Where are platelets stored?

Answer 11

The spleen

Question 12

What hormone controls platelet production?

Answer 12

Thrombopoietin

Question 13

What is the function of platelets?

Answer 13

Aggregate to each other

Phospholipid membrane facilitates the clotting cascade

Adhere to connective tissue exposed in tissue damage

Question 14

What is the structure of platelets and their function?

Answer 14

1) . Phospholipid membrane - contains glycoprotein receptors which aid in the aggregation of platelets to each other and to clotting factors.
2) . Alpha granules - produce the glycoprotein that form the receptors that aid aggregations (e.g. Von Willebrand Factor)
3) . Dense bodies - contain Ca2+, ADP and serotonin, all which aid aggregation.

Question 15

How do platelets work?

Answer 15

1) . Damage to the endothelial lining of the capillaries exposes collagen.
2) . Platelets bind to the collagen via vwf.
3) . ADP is released from dense bodies, which makes the glycoprotein receptors on the platelet membrane exposed = primary and secondary aggregation.
4) . This provides a surface for clotting factors to bind and interact = held together by a mesh.

Question 16

What cells stem from lymphocytes?

Answer 16

T cells
B cells
Natural killer cells

Question 17

Where do T cells migrate?

Answer 17

To the thymus, where they differentiate

Question 18

What can T cells differentiate into and what is the function of these?

Answer 18

CD4+ (helper)

• induces proliferation and differentiation of T/B cells
• activates macrophages

CD8+ (suppressor)
- cytotoxic activity= instant cell destruction

Question 19

How do T cells work?

Answer 19

1) . An infected macrophage displays foreign antigens
2) . Suppressor cells (CD8+) interact and make a hole in the cell membrane = it lyses
3) . T helper cells produce cytokines to activate B and memory cells

Question 20

What do B cells express and what do they have once they mature?

Answer 20

They express antigen specific immunoglobulins.

When mature, they have different antigen receptors in their plasma membrane. They then recirculate

Question 21

How do B cells work?

Answer 21

They interact with T cells via cytokine response. They can then:

• Transform into plasmablasts = produce antibodies
• Transform into memory cells

Question 22

What do natural killer cells do?

Answer 22

Recognise and kill non self antigens via lysis (making a hole in the cell).

Question 23

What organs does the reticuloendothelial system consist of?

Answer 23

Spleen
Liver
Lymph nodes

Question 24

What cells are included in the reticuloendothelial system and what is their job?

Answer 24

Kupffer cell - locked in tissues
Microglia - in CNS
Macrophages
Monocytes

These identify and amount a response to antigens.

Question 25

How many lobes does each type of white blood cell have?

Answer 25

Neutrophil - many
Basophil - 2/3
Eosinophil - 2
Monocyte - 1(kidney shaped)

Question 26

What is the function of basophils?

Answer 26

Active in allergic reactions by containing granules of heparin, histamine, serotonin etc

Question 27

What is the function of eosinophils?

Answer 27

Mediate allergic reactions by performing phagocytosis, and releasing cytotoxic particles to kill larger foreign particles onto epithelial surfaces such as the gut and lung.

Question 28

Why do eosinophils stain well?

Answer 28

They contain granules of phospholipid and arginine.

Question 29

How long are eoisionophils in circulation and what is their lifespan?

Answer 29

3-8h in circulation with 8-12h lifespan.

Question 30

What is the function of monocytes?

Answer 30

They respond to inflammation and antigenic stimuli by moving out of capillaries via diapedesis and forming macrophages.

Question 31

What do monocytes contain?

Answer 31

Lysosomes containing CSF, lysozyme and complement.

Question 32

How is maturation of neutrophils controlled and what does this achieve?

Answer 32

By the hormone G-CSF in the bone marrow.
This:
Enhances phagocytosis
Enhances chemotaxis
Increases neutrophil production
Reduces time it takes for bone marrow to release neutrophils

Question 33

What is the function of neutrophils?

Answer 33

It moves out of the circulation to the site of infection.