IC2 RBC, platelets & haemostasis Flashcards
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 - ?
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℃
What type of tissue is blood?
Connective tissue
What is plasma is made up of?
(Include percentages of its components)
- Water - 92%
- Proteins - 7%
- Other solutes - 1%
What are the 3 main types of protein present in the plasma?
- Albumin
- Globulin
- Fibrinogen
What are the 2 functions of albumin?
- Act as carrier protein
- Maintain osmotic pressure
What are the 2 functions of globulin?
- Immune function
- Clotting
What is the main function of fibrinogen?
To be converted into fibrin, which assist in clotting.
What is the function of RBC?
To carry O2 to the cells and CO2 away from the cells
What is haematocrit?
Haematocrit is the percentage of blood that is RBC.
What are the haematocrit levels in males and females?
Males - 46% haematocrit
Females - 42% haematocrit
RBC makes up 46% of blood in males’ bodies.
RBC makes up 42% of blood in females’ bodies
What is the definition of anaemia in terms of haematocrit?
Anaemia is when haematocrit is too low
What is the definition of polycythemia in terms of haematocrit?
Polycythemia is when haematocrit is too high
Describe the process of haemostasis.
(There are 3 stages)
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
Summary of the things produced by platelets
Platelets releases:
- 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
What are the 2 components that make up haemoglobin?
- Heme
- Globin
What are the 4 characteristics of heme?
- Heme is a pigment, not a protein
- It contains 1 Fe atom which can bind to 1 O2 molecule
- Binding is weak and reversible
- A Hgb molecule contains 4 heme group, which allows it to bind to 4 O2 molecule
What are the 3 characteristics of globin?
- Globin is made of 4 folded polypeptide chains - 2 alpha & 2 beta chains
- Each chain contains 1 heme group
- Amino acid sequence at each chain determines O2 binding affinity
How does site of erythropoiesis change with age?
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
What is erythropoietin?
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.
What are the 6 factors that can trigger erythropoietin release by the kidneys?
- Hypoxia due to decrease RBC number or function
- Decrease O2 availability
- Increase tissue demand for O2
- Anaemia
- Decrease blood flow to kidney
- Blood donation
List the progression from erythroblast to mature RBC.
Erythroblast → Normoblast → Reticulocytes → RBC
What are the 4 symptoms of anaemia?
- Fatigue
- Paleness
- Shortness of breath
- Chills
What is aplastic anaemia?
Failure of the bone marrow to make enough RBCs
What are the 2 causes of polycythemia?
- Tumour or tumour-like condition in the bone marrow
- Dehydration
What is the effect of polycythemia on blood?
It makes blood very viscous, potentially plugging the capillaries.
What are the definition of these 4 types of leukocyte disorders?
- Leukopenia
- Leukocytosis
- Leukemia
- Lymphoma
- Leukopenia - too few leukocytes
- Leukocytosis - higher than normal WBC count (can be a normal response to bacterial or viral invasion
- Leukemia - cancer located in blood
- Lymphoma - cancer located in lymphatic system
What are the 3 pathways in fibrin activation?
- Extrinsic pathway
- Intrinsic Pathway
- Common pathway
What are the factors involved in all 3 pathways?
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
What is clot retraction?
It is the shrinking & stabilization of a blood clot. This pulls the edge of the blood vessel walls closer together.
What are the 4 agents that can prevent blood clotting?
- Prostacyclin - inhibits platelet activation
- Serotonin - inhibits ADP at high conc
- Artificial anticoagulants - Vit K antagonist (warfarin)
- Endogenous anticoagulants - heparin, tPA
Describe the process of fibrinolysis:
- During clot formation, plasminogen is trapped inside the clot
- Surrounding tissue & vascular endothelial cells slowly release tissue plasminogen activator (tPA)
- tPA activates the inactive plasminogen to plasmin
- Plasmin digest fibrin, leading to dissolution of the clot.
What are the 3 tests for blood coagulation?
- Partial thromboplastin time (PTT)
- Prothrombin time (PT)
- Internationalized ratio (INR)
