Blood Flashcards
What is the blood composed of and the percentages for each
Plasma 55%
Buffy coat >1%
Erythrocytes 45%
What are characteristics of erythrocytes
Biconcave
No nucleus, mitochondria or other cell organelles
Millions of haem molecules
No DNA
Cannot synthesise RNA
How big is an erythrocyte (approx)
6um
What is the average lifespan of an erythrocyte
120 days
What is blood typing
Blood typing is used to categorise individuals based on the presence or absence of antigens of the surface of the erythrocytes
What are white blood cells
White blood cells also known as leukocytes are the immune cells of the body
What are the 2 classification of leukocytes
Myeloid and lymphoid
What are the myeloid cells in the body
Neutrophils
Monocytes
Eosinophils
Mast cells
Basophils
What are the lymphoid cells in the body
T-cells
B-cells
Natural killer cells
What are neutrophils and what are there characteristics and function
They are the most common leukocyte in the body.
They are multi-lobed nuclei
There function is to phagatose at the site of inflammation
What is a monocyte and its function
Give 2 examples of monocytes in the body
Monocytes are diverse blood cells which can differentiate into macrophages and phagoctose potential pathogens.
When they differentiate they get specialised names
Eg- kupffer cells in the liver
Microglia in the CNS
What are eosinophils and what is there function
They are granular leukocytes which act as mediators to allergic reactions and cause immune response to parasitic infections
What are basophils and what is there function
Basophils are the least common leukocyte in the body
They cause an inflammatory reaction in the immune response to any allergic reactions
What is the function of B-cells
Produce circulating antibodies
What is the function of T-cells
Become cytotoxic, helper/suppressor cell mediator immune cells
Memory T-cells are there to remember the foreign body so when it invades again your body knows what to do
What is the function of natural killer cells
They eradicate virus infected cells
What is plasma
Plasma is the liquid portion of the blood often a straw yellow colour
What is the main component of blood plasma
Mostly water
What other things are found in blood plasma apart from water
Amino acids
Electrolytes
Gases
Nitrogenous waste
Nutrients such as glucose and fats
Proteins such as albumin, globulins, enzymes, clotting factors and hormones
What are platelets also known as
Thrombocytes
Where are platelets derived from
Megakaryocytes
What are platelets
They are cell fragments
What is the function of platelets
They are cells that are recruited by the site of injury within the body which they activate the clotting process to cause wound closure
What is the platelets role in immunity
They platelets interact with the antibodies which cause them to secrete pro inflammatory and procoagulant mediators which can connect the adaptive and innate immune responses
How do platelets cause wound closure at the site of injury in the body
Platelets adhere to the vascular wall of the damaged vessel and react with fibrin to build a solid clot over the open wound, this usually takes 1 to 3 minutes
What is the coagulation cascade
The coagulation cascade is a series of reactions catalysed by protein enzymes known as coagulation factors to produce fibrin which is used to help clot the blood at the site of injury
What is primary haemostatsis
The activation and adherence of platelets to the damaged endothelium and produce a vascular response to the injury such as vasoconstriction
What is secondary haemostatsis
This is the stabilisation of the active platelets due to the actions of strands of fibrin produced in the coagulation cascade
What are the 3 stages of the coagulation cascade
Extrinsic
Intrinsic
Common pathway
What is the extrinsic pathway of the coagulation cascade
This is the initiation of the coagulation cascade which is mediated by the release of tissue factors which are expressed on the surface of cells found outside the blood vessels but not in the circulating blood cells or the endothelium. When the tissue factor is released and comes into contact with the blood it combines with the circulating clotting factor, factor VII to form a complex. This complex leads to the activation of clotting factor X which triggers the start of the common pathway
What is the common pathway of the coagulation cascade
This stage is the final stage of the coagulation cascade which leads to the formation of thrombin and fibrin
This stage of the coagulation cascade begins with the activation of clotting factor X to clotting factor Xa via either the extrinsic or intrinsic pathways. Factor Xa then combines with clotting factor V, platelet membrane phospholipids and Ca2+ ions to convert prothrombin to thrombin. This then triggers fibrinogen to be converted into fibrin strands which are an important part of the structural component for the formation of a thrombus.
The production of thrombin also activates other parts of the coagulation cascade via a positive feedback loop, via the intrinsic pathway which leads to a thrombin burst (large amount of thrombin produced)
What is the intrinsic pathway of the coagulation cascade
This pathway is initiated by the common pathway by the positive feedback loop and the amplification of thrombin
This pathway is activated by surface contact, when damage to the vascular endothelium leads to exposure of the clotting factors to the negatively charged sub endothelial surface which is mediated by molecule kallikrein.
Reactions within the pathway
Surface contact activates factor XII
Factor XIIa activated factor XI
Factor XIa activates factor IX
Factor IXa combines with factor VIIIa, platelet membrane phospholipid and Ca2+ ions to activate factor X which then activates factor Xa and the common pathway
Why does the coagulation cascade need to be regulated
Without the cascade been regulated the positive feedback loop started by the production of thrombin would continue in the intrinsic pathway causing dangerous levels of clotting within the blood
What is used to inhibit aspects of the coagulation cascade to stop dangerous levels of blood clotting in the body
Various different proteins
Protein C- which is produced in response to thrombin which binds to the receptor on the vascular endothelium which leads to the activation of Protein S which causes the breakdown of clotting factors Va and VIIIa in a negative feedback loop.
Antithrombin- this is a natural anticoagulant which is produced by the liver which destroys clotting factors XIa, Xa and thrombin
Heparin and Fondaparinux- this enhances the natural effect of Antithrombin
Tissue factor pathway inhibitor protein- this binds to and inactivates clotting factors VIIa and Xa
What are the functions of erythrocytes
Gas exchange and transport (main function)
Determining blood type
Explain how erythrocytes perform gas exchange and act as transportation
Blood travels to the lungs where in the capillaries oxygen diffuses into the cell and bings to the haemoglobin forming oxyhemoglobin (this is what gives oxygenated blood is bright red colour). The oxygen rich erythrocytes travel through the arteries until it reaches the desired tissue.
Within the tissue the oxygen is released from the haemoglobin and diffuses across into the tissue. At the same time carbon dioxide from the tissues diffuse the opposite way and binds with the haemoglobin in the erythrocyte and form deoxyhaemoglobin (this is what gives deoxygenated blood its purple/blue colour). The deoxygenated erythrocytes then travel through the veins and back to towards the heart and lungs.
When they deoxygenated blood reaches the capillaries in the lungs the carbon dioxide is release and diffuses into the capillaries for it to be exhaled.
What is the function of a neutrophil
These are the first cells to respond to bacteria and viruses in the body.
They send signals to other immune cells
What is the function of eosinophils
They fight bacteria within the body
They respond to parasitic infections
They triggers allergy symptoms
What is the function of basophils
They play a role in asthma
They mount non-specific immune responses to pathogens
They release histamine
What is the function of B-Cells
Humoral immunity
Produce antibodies
Play a role in vaccinations
What is the function of T-Cells
They are are responsible for recognising specific foreign bodies and killing them
(Memory T-Cells)
What is the function of monocytes
Clean up dead cells
What is sickle cell anaemia
This is a disorder which causes the deformation of erythrocytes caused by the inheritance of sickle cell gene
What populations is sickle cell most common in
African and Caribbean
How does sickle cell anemia occur
Sickle cell anemia is caused by a single point mutation in the beta-globin gene which is inherited which results in an amino acid replacement at position 6 in the beta-globin chain. Glutamic acid is replaced with valine which results in sickle haemoglobin
What type or inherited disease is sickle cell
This is an autosomal recessive disease
What happens to an individual if they only inherit on sickle cell gene
They would only be a Carrier for the disease but would show many if any symptoms at all
What are some of the physiological stressors for sickle cell
Hypoxia
Dehydration
Infection
Cold temperatures
Acidosis
What happens when an individual with sickle cell experiences some of the physiological stressors
The sickled haemoglobin will polymerise and cause the erythrocytes to deform
What can cause an individual who has sickle cell that would need hospital admission
Sickle cell disease can cause vast-occlusive crises where by the sickled blood cells cause an obstruction in the micro circulation leading to pain and ischemia and even infarction.
Sickle cell disease can also cause acute chest syndrome
What can be done for an individual admitted to hospital with vaso-occlusive crises suffering with sickle cell
Medication such as crizanlizumab can be used to reduce obstructions and pain as it prevents the restriction of blood flow
What is thalassaemia
Caused by an individual producing little to no haemoglobin which causes anemia
What causes thalassaemia
The globin genes are absent or mutated which limits the ability to produce the globin chains. This causes a reduction in 1 of the certain types of chains and so an excess of the opposite chain. This accumulation of unpaired chains causes the erythrocytes to become unstable and so are unable to mature and so macrophages destroy them in the bone marrow. This destruction causes the body to produce more erythrocytes to compensate this but each one produces has a reduced amount of haemoglobin and so they become hypo chromic red cells and in severe cases can cause an insufficient oxygen delivery in the body