IC2 RBC, platelets & haemostasis

Question 1

Facts about blood:
pH of blood - ?
% of of weight - ?%
Volume of blood in males - ?
Volume of blood in females - ?
Temperature of blood in our body - ?

Answer 1

pH of blood - 7.35-7.45
% of of weight - 8%
Volume of blood in males - 5-6L
Volume of blood in females - 4-5L
Temperature of blood in our body - 38℃

Question 2

What type of tissue is blood?

Answer 2

Connective tissue

Question 3

What is plasma is made up of?
(Include percentages of its components)

Answer 3

1. Water - 92%
2. Proteins - 7%
3. Other solutes - 1%

Question 4

What are the 3 main types of protein present in the plasma?

Answer 4

1. Albumin
2. Globulin
3. Fibrinogen

Question 5

What are the 2 functions of albumin?

Answer 5

1. Act as carrier protein
2. Maintain osmotic pressure

Question 6

What are the 2 functions of globulin?

Answer 6

1. Immune function
2. Clotting

Question 7

What is the main function of fibrinogen?

Answer 7

To be converted into fibrin, which assist in clotting.

Question 8

What is the function of RBC?

Answer 8

To carry O2 to the cells and CO2 away from the cells

Question 9

What is haematocrit?

Answer 9

Haematocrit is the percentage of blood that is RBC.

Question 10

What are the haematocrit levels in males and females?

Answer 10

Males - 46% haematocrit

Females - 42% haematocrit

RBC makes up 46% of blood in males’ bodies.

RBC makes up 42% of blood in females’ bodies

Question 11

What is the definition of anaemia in terms of haematocrit?

Answer 11

Anaemia is when haematocrit is too low

Question 12

What is the definition of polycythemia in terms of haematocrit?

Answer 12

Polycythemia is when haematocrit is too high

Question 13

Describe the process of haemostasis.
(There are 3 stages)

Answer 13

Stage 1:
- Breakage in smooth muscles of the blood vessel will lead to vasoconstriction.
- Constriction of blood vessels reduces the amount of blood flowing through the damaged region, reducing blood loss

Stage 2:
- Breakage in the smooth muscle of the blood vessel exposes collagen fibers.

      - Collagen fibers will then attract platelets to bind to it via Von Willebrand's factor (vWF). This leads to the formation of the platelet plug.

      - When platelets bind to the collagen fibers:
                  - It releases granules containing ADP, thromboxane A2 and etc.
                  - ADP attracts more platelets to bind
                  - Thromboxane A2 promotes aggregation & further vasoconstriction.
                  - Secretes factor II which activates other factors, leading to activation of factor X, which converts prothrombin into thrombin.
                  - Secretes factor XIII

      - Thrombin then activates fibrinogen into fibrin
      - Thrombin also activates factor XIII to XIIIa 

Stage 3:
- Fibrin helps to reinforce the clot but it is not strong enough
- Factor XIIIa helps to form cross-links between fibrin to strengthen it
- Blood vessel wall is no longer bleeding
- Remodeling occurs to fix the breakage, repairing the blood vessel

Question 14

Summary of the things produced by platelets

Answer 14

Platelets releases:

1. Granules - contains ADP, Tbx A2, Factor III, Factor XIII

ADP - attracts more platelets
Tbx A2 - promote aggregation & further vasoconstriction
Factor III - activates other factors which leads to activation of factor X. Factor X activates prothrombin to thrombin.
Factor XIII - helps in formation of cross-links between fibrin

Question 15

What are the 2 components that make up haemoglobin?

Answer 15

1. Heme
2. Globin

Question 16

What are the 4 characteristics of heme?

Answer 16

1. Heme is a pigment, not a protein
2. It contains 1 Fe atom which can bind to 1 O2 molecule
3. Binding is weak and reversible
4. A Hgb molecule contains 4 heme group, which allows it to bind to 4 O2 molecule

Question 17

What are the 3 characteristics of globin?

Answer 17

1. Globin is made of 4 folded polypeptide chains - 2 alpha & 2 beta chains
2. Each chain contains 1 heme group
3. Amino acid sequence at each chain determines O2 binding affinity

Question 18

How does site of erythropoiesis change with age?

Answer 18

Fetus - yolk sac, liver, spleen, lymph node
<5yo - all bone marrow
5-20yo - Bone marrow in ribs, sternum, vertebrae, proximal end of long bones
>20yo - Bone marrow in the ribs, sternum, vertebrae

Question 19

What is erythropoietin?

Answer 19

It is a hormone secreted by the kidneys to increase rate of RBC production, in response to a fall in O2 levels in the tissues.

Question 20

What are the 6 factors that can trigger erythropoietin release by the kidneys?

Answer 20

1. Hypoxia due to decrease RBC number or function
2. Decrease O2 availability
3. Increase tissue demand for O2
4. Anaemia
5. Decrease blood flow to kidney
6. Blood donation

Question 21

List the progression from erythroblast to mature RBC.

Answer 21

Erythroblast → Normoblast → Reticulocytes → RBC

Question 22

What are the 4 symptoms of anaemia?

Answer 22

1. Fatigue
2. Paleness
3. Shortness of breath
4. Chills

Question 23

What is aplastic anaemia?

Answer 23

Failure of the bone marrow to make enough RBCs

Question 24

What are the 2 causes of polycythemia?

Answer 24

1. Tumour or tumour-like condition in the bone marrow
2. Dehydration

Question 25

What is the effect of polycythemia on blood?

Answer 25

It makes blood very viscous, potentially plugging the capillaries.

Question 26

What are the definition of these 4 types of leukocyte disorders? 1. Leukopenia 2. Leukocytosis 3. Leukemia 4. Lymphoma

Answer 26

1. Leukopenia - too few leukocytes 2. Leukocytosis - higher than normal WBC count (can be a normal response to bacterial or viral invasion 3. Leukemia - cancer located in blood 4. Lymphoma - cancer located in lymphatic system

Question 27

What are the 3 pathways in fibrin activation?

Answer 27

1. Extrinsic pathway 2. Intrinsic Pathway 3. Common pathway

Question 28

What are the factors involved in all 3 pathways?

Answer 28

Intrinsic pathways - 12,11,9,10 Extrinsic - Tissue factor 3, factor 7 Common pathway - 10, 13 Tissue factor 3 is only expressed in damaged tissues or on the outside of vessels, in the extrinsic route. Platelet factor 3 is expressed by platelet in the intrinsic route https://nusu-my.sharepoint.com/:i:/r/personal/e0725451_u_nus_edu/Documents/Pharmacy/Year%203/Y3S2/PR3154/ICs/IC2%20-%20Blood%20composition%20%26%20function/Summary%20slide%20of%20the%203%20pathways.png?csf=1&web=1&e=DGDJfm

Question 29

What is clot retraction?

Answer 29

It is the shrinking & stabilization of a blood clot. This pulls the edge of the blood vessel walls closer together.

Question 30

What are the 4 agents that can prevent blood clotting?

Answer 30

1. Prostacyclin - inhibits platelet activation 2. Serotonin - inhibits ADP at high conc 3. Artificial anticoagulants - Vit K antagonist (warfarin) 4. Endogenous anticoagulants - heparin, tPA

Question 31

Describe the process of fibrinolysis:

Answer 31

1. During clot formation, plasminogen is trapped inside the clot 2. Surrounding tissue & vascular endothelial cells slowly release tissue plasminogen activator (tPA) 3. tPA activates the inactive plasminogen to plasmin 4. Plasmin digest fibrin, leading to dissolution of the clot.

Question 32

What are the 3 tests for blood coagulation?

Answer 32

1. Partial thromboplastin time (PTT) 2. Prothrombin time (PT) 3. Internationalized ratio (INR)