Week 6- Blood, Immunity And Hypersensitivity

Question 1

What are the most common manifestations of altered erythrocyte function?

Answer 1

Anaemia- the reduction in 02 carrying capacity of the blood, due to decreased erythrocytes or decreased hemoglobin.

Question 2

What are the 3 common causes of anaemia?

Answer 2

1. Iron deficiency
2. Renal disease
3. Chronic inflammation

Question 3

What are the main symptoms of anaemia?

Answer 3

Feeling tired, cold and being pale.

Question 4

How does the body compensate with anaemia?

Answer 4

Moves interstitial fluid into blood which increases plasma. This increases volume but decreases thickness.

Question 5

What does the body do to continue compensating?

Answer 5

Increase dilation in arterioles, capillaries and venules, which increases the volume of blood flow and venous return which will increase heart rate and increase stroke volume. This can lead to heart failure in some cases.

Question 6

What are the 5 different types of anaemia causes by insufficient erythrocyte production?

Answer 6

1. Iron deficiency-inadequate iron absorption
2. Folate deficiency-baby growth
3. Pernicious-absence of ‘intrinsic’ factor (used for vitamin absorption)
4. Aplastic- failure of bone marrow to produce blood cells
5. Renal- impaired ability of kidneys to detect hypoxaemia

Question 7

What are the types of anaemia causes by erythrocyte loss?

Answer 7

1. Post haemorrhagic

2. Malaria

Question 8

What is the haemolytic disease of the newborn?

Answer 8

When the fetal blood type is different from the mothers. The mother is a Rh negative carrier, with a Rh positive baby.

Question 9

What is the main function of vitamin k? Where is it produced?

Answer 9

It is produced in the liver and is required for the production of clotting factors

Question 10

What are the tests used to evaluate hemostasis?

Answer 10

1. Prothrombin time (PT): assesses extrinsic and common coagulation pathways. Prolonged PT can be caused by deficiency/dysfunction of clotting factors
2. Partial thrombosis time (PTT): Intrinsic assessment. Can be due to factor V, VIII, X, XII, prothrombin and fibrinogen
3. Platelet count: taken from coag bloods
4. Platelet function

Question 11

What number is considered low platelets and why are they so important?

Answer 11

A count less than 100,000/uL (thrombocytopenia). They are essential because they form a temporary plug which stops the bleeding and promotes key reactions in the coagulation cascade.

Question 12

What are the 4 categories in low platelets?

Answer 12

1. Low platelet production: eg HIV, leukemia, aplastic anaemia
2. Low platelet survival: autoimmune conditions
3. Sequestation: when the spleen is enlarged
4. Dilution: blood transfusions

Question 13

What causes ITP?

Answer 13

Autoantibody destruction of platelets.

Question 14

What is hemostasis? Make reference to clotting.

Answer 14

The ability to promote coagulation and develop a table fibrin clot.

Question 15

What can impair hemostasis?

Answer 15

Liver dysfunction; either a specific liver disorder or lack of vitamin K.

Question 16

What is vitamin k used for the synthesis in?

Answer 16

• Prothrombin (plasma protein)- converts to thrombin
• procoagulant factors (V, IX, X)
• anticoagulant factors (protein C and S)

Question 17

When do people get thrombocytopenia?

Answer 17

In severe liver disease such as cirrhosis

Question 18

Where does DIC take place and what is the basic pathophysiology?

Answer 18

It occurs in small and midsize vessels, creating hemorrhage and clotting to organs. It results from abnormally, continual widespread clotting which leads to ischemia and necrosis of organs, particularly the kidneys and lungs.

Question 19

What does TF bind to?

Answer 19

Clotting factors VII- this leads to conversion of prothrombin to thrombin, which leads to formation of fibrin clots.

Question 20

What are the 2 pathways activated in clotting?

Answer 20

Intrinsic- activated by trauma in the vascular system (platelets, endothelium and collagen)
Extrinsic- tissue factor activation due to endothelial damage

Question 21

What is leukocytosis and what causes it?

Answer 21

It is a normal protective response to physiologic stressors, eg. Invading organisms, exercise, temperature etc. It is present when the count of leukocytes is higher than normal.

Question 22

What is granulocytosis?

Answer 22

An increase in granulytes (neutrophils, basophils and eosinophils). It begins when stored blood cells are released

Question 23

What happens when the neutrophil demand exceeds what’s available?

Answer 23

Immature neutrophils are released into the blood, called ‘shift-to-the-left’. When it returns to normal, it is called ‘shift-to-the-right.’

Question 24

Which immune cells have CD4 on their membrane?

Answer 24

Macrophages, dendritic cells and t-helper cells. They can be attacked by HIV

Question 25

What is the basic definition of HIV?

Answer 25

It suppressed the immune response against itself and creates generalized immune deficiency by suppressing the development of immune responses against other pathogens; this leads to AIDS.
It infects and destroys T-cells (necessary for the development of plasma and cytotoxic cells.

Question 26

What are the 4 different types of hypersensitivity reaction?

Answer 26

1. Type 1-immunoglobulin e-mediated (most common)
2. Type 2- tissue specific
3. Type 3-immune complex-mediated
4. Type 4-cell mediated

Question 27

What is the most IgE mediated hypersensitivity?

Answer 27

Histamine- contracts bronchial smooth muscle, increases vascular permeability and increases dilation

Question 28

What is the main problem with anaphylactic shock?

Answer 28

Widespread dilation

Question 29

What is the main difference between type 2&3 hypersensitivity?

Answer 29

2- antibody binds to the antigen surface
3- antibody binds to soluble antigen that was released in the blood/body fluid and the complex is deposited in the tissues

Question 30

What separates type 4 hypersensitivity from the other types?

Answer 30

Their reactions are mediated by T lymphocytes and don’t involve an antibody.