Blood Flashcards
How much fluid do you have in the body?
42 Litres
- 14 Litres outside cells
- 28 Litres inside cells of which 2.5 litres is RBC Volume
What is the role of blood and circulation? 4 points
- Transports nutrients to tissues
- Transports waste products away from tissues
- Carries hormones from one part of the body to another
- Maintains an appropriate environment in all the tissue fluids for optimal cell function
What is the total volume of blood in a healthy adult?
5.5 Litres
What are the proportions of the components of blood?
- Plasma (3 Litres - 55%)
- Formed Elements (2.5 Litres - 45%)
Formed elements consist of RBC (approx. 45%), WBC and Platelets (less than 1%)
What is the haematocrit?
A sample of fresh blood with anti-coagulant spun in a centrifuge for 10minutes at 2000rpm to seperate the features of blood.
The haematocrit is the percentage of blood that is made up of cells
How does the normal haematocrit vary between genders?
In males it is between 42% - 52%
In females it is between 37% - 47%
What happens if the haematocrit falls outside of the normal values?
Anaemia - Haematocrit of less than 35%
Polycythaemia - Haematocrit of greater than 70%
(more viscous blood)
Dehydration - Haematocrit of 70% but a large drop in plasma volume
How does anaemia occur?
- Blood loss (haemorrhage)
- Haemolytic Disease (sickle cell disease)
How does polycythaemia occur?
- Living at high altitude
- Bone marrow tumours
What are the components of Plasma?
- Water 90%
- Proteins (8% of weight)
- Albumin (maintain osmotic pressure)
- Globulins (Clotting proteins and antibodies)
- Fibrinogen (clotting)
What gets transported in plasma?
- Nitrogenous waste products
- Organic nutrients
- Electrolytes (Cations, Anions & Respiratory Gases)
Where do all the cells in blood come from?
They all originate from haematopoietic stem cells
This branches into Myeloid Stem Cells and Lymphoid Stem Cells
Myeloid Stem Cells can differentiate into Platelets, Macrophages and Erythrocyte
Lymphoid Stem Cells can differentiate into Lymphocytes
How many red blood cells are there in a ml of blood?
5 Billion RBCs
What shape are RBC and how does that benefit the cell?
Biconcave disk
- Large Surface Area
- Favours diffusion
What are the diameter and thickness of a RBC?
Diameter = 8micrometres
Thickness = 2micrometres
What are some characteristics of capillaries?
- Capillaries are narrower than RBC diameter so erythrocyte membrane has to be highly flexible
- 99% of blood vessels in the body are capillaries
- Capillaries only hold 5% of the blood in your body
What can the effects of osmosis have on RBCs?
If too much water enters the cell it becomes Hypotonic and loses shape (more spherical)
If the cell loses too much water it becomes hypertonic (cell collapses but cytoskeleton remains intact
How many RBC in there in a microlitre?
5 million
How many molecules of haemoglobin are on each erythrocyte? And how many oxygen molecules does that make it?
250 million per cell
1 billion oxygen molecules (because each haemoglobin binds to 4 oxygen)
How is it obvious to spot if someone has undergone large amounts of blood loss?
Their RBC’s will have a nucleus as they haven’t had the time to mature properly (can also detect if someone is doping in same way)
Negative effects of having no nucleus?
No cell repair No cell growth No division No energy generation -RBC only survive 120 days but can travel up to 700 miles
How many RBC’s in an average adult circulation?
25-30 trillion
Where are the different types of bone marrow found?
Red marrow is found in the sternum, ribs and long limb bones (Red marrow can synthesise RBC known as haematopoiesis)
Every other bone has yellow marrow which doesn’t produce RBC
How is the production of red cells maintained?
Erythrocytes are broken down in the spleen in Heme+Globin
(Eventually forms bile from bilirubin and is excreted in faeces or urine)
-Can also form T-iron which is returned to the bone marrow
-EPO’s are released by the kidneys if the oxygen carrying capacity of blood is too low (EPO’s are used this way in doping)
Where does erythropoietin work?
Rate of division is increased in cells that have been produced by the stem cells
- no direct increase to stem cells
How much of total oxygen in blood is carried in RBCs?
98.5%
How do RBCs interact with CO2?
Reversible reaction
-Enzyme Carbonic Anhydrase converts CO2 and H20 into Carbonic Acid reversibly to be carried out in circulation
RBC’s interaction with Carbon Monoxide?
-Carbon Monoxide with actively displace Oxygen when binding to haemoglobin (240times more likely)
RBC’s interaction with Nitric Oxide?
- Nitric Oxide binds to haemoglobin in the lungs which acts as a vasodilator (Relaxes and Dilates arterioles)
- Allows more blood to circulate and helps maintain blood pressure in small amounts
What is the total amount of iron in the body? how much is in haemoglobin?
4g
-65% in haemoglobin
What is a class 1 haemorrhage?
Where the body loses up to 15% blood volume
(Blood donors lose between 8-10% Blood volume)
-No medication necessary
What is a class 2 haemorrhage? How is it treated?
- Between 15-30% blood loss
- Increase in heart rate
- Systolic and diastolic blood pressure variance decreases
- Peripheral vasoconstriction so skin looks pale and cold
-Give someone saline solution to increase blood volume
What is a Class 3 haemorrhage? How is it treated?
30-40% Blood volume loss
- Blood pressure drops
- Heart rate increases
- Brain function decreases due to lack of oxygen to the brain
-Treat by increasing volume (saline) and a blood transfusion
What is a class 4 haemorrhage? How is it treated?
Greater than 40% blood volume lost
-Body can no longer compensate
-Aggressive resuscitation required
How does haemostasis (the stopping of blood flow) occur?
-Three steps
1) Vascular spasm (vessel constricting to reduce flow)
2) Platelet plug (thrombus) to plug the leak
3) Formation of a blood clot
What is the vascular spasm? How does it occur?
Intrinsic mechanism triggers a constriction which increases resistance to blood flow.
The damage also activates the sympathetic nervous system which triggers further vasoconstriction
-ONLY MINIMISES BLOOD FLOW DOESN’T STOP IT
How many platelets per micrometre?
250,000
What are platelets?
Colourless cell fragments that break off from megakaryocytes
Characteristics of platelets (Thrombocytes)?
- Smaller than erythrocytes
- Contain mitochondria, smooth ER and cyoplasmic granules (no nucleus)
How is a platelet plug formed?
von Willibrand factor (vWf) is secreted by megakaryocytes and platelets.
- upon damage, vWf binds to exposed collagen
- Platelets then bind to vWf creating stickiness
- Platelets then secrete Serotonin (vasoconstrictor), Epinephrine and ADP(used to promote platelet aggression)
How is clot formation halted so the vessel isn’t completelt blocked?
- Prostacyclin
- Nitric Acid
Both released by healthy endothelium to stop the platelet plug from growing too large on healthy endothelium
How is a blood clot formed?
- Fibrinogen is needed to form the clot
- Platelet plug is needed to form so a clot can be made as is requires activated platelets and the products made by the platelets (both stages can occur at the same time though
- The whole of the clot is triggered by the COAGULATION CASCADE
What is the coagulation cascade?
A large number of reactions that all cascade and cause cross linked fibrin to be caused for blood clotting
Involves the intrinsic (inside a blood vessel) and extrinsic (outside a blood vessel) pathways which become linked together towards the end of the cascade
How is a blood clot removed?
Activation of Factor XII initiates the cascade of reactions to from a blood clot, but also begins the slow dissolution of the clot
What prevents circulation being entirely clotted?
- Inhibition of platelet adhesion
- Inhibition of coagulation cascade and fibrin production when no clot is needed to be formed.
- Endothelial cells release anticoagulants (Heparin and Antithrombin III)
Name and explain how some anticoagulant drugs work?
- Coumarin anticoagulants (warfarin) block the action of vitamin K
- Ca2+ removal from plasma (EDTA)
- Aspirin prevents platelet plug formation as it inhibits enzymes that from Thromboxane A2
How can coagulation disorders be caused?
- Liver disease
- Vitamin K deficiency
- Haemophilia
- Low blood platelets
What is the role of the immune system?
- Protects the body from pathogens and foreign molecules such as:
- parasites
- bacteria
- viruses
- Removes dead or damaged cells
- Attempts to recognise abnormal cells
What are the two immune defences called?
- Innate
- Acquired
What tissues are involved in the lymph? Primary and secondary
Primary
- Bone marrow
- Thymus
Secondary
- Lymph nodes
- Spleen
- Lymph vessels
- Diffuse tissues
What is innate immunity? Types of innate immunity?
Bodys non-specific response to invasion
- Physical and chemical barriers
- Phagocytosis (use of oxonin as a detector cell
- inflammatory response
What are the macrophages role in phagocytosis?
They show antigens of the broken down cell so it can be identified
What are natural killer cells?
-Cells that eliminate virus-infected and tumour cells by secreting interferons (alpha and beta) to prevent viral replication. Also secretes interferon gamma which helps to activate other immune cells such as macrophages
What is the role of the inflammatory response?
- Attracts immune cells and chemical mediators to site of infection
- Produces a physical barrier to prevent infection spreading
- Promotes tissue repair
What molecules are involved in the inflammatory response?
Histamines -swelling, vasodilation
Interleukins - fever, blood vessels more permeable to WBC
Bradykinin - pain and swelling
Complement cascade (membrane attack complex)
What does the membrane attack complex do?
Complement proteins insert themselves into membranes of pathogens to create a pore. Water then flows in causing the cell to swell up and lyse
What is acquired immunity?
The body’s specific immune response which is directed and specific invaders
What are naive B-Lymphocytes?
WBC that contain one antibody complimentary to the antigens present on the pathogen.
What happens during clonal expansion?
The naive lymphocyte begins reproducing plasma cells and memory cells to fight off the infection.
Memory cells are used in the secondary response
What are the five different classes of antibodies?
IgG-Activate complement cascade IgA-Disable pathogens before entering internal environment IgE-Associated with allergic response IgM-Activate complement cascade IgD-Unclear physiological role
What is opsosins?
Things that can bind to pathogens and make them discoverable for phagocytosis
What is the role of T Lymphocytes?
Will bind to any cell to test if it has been seen before.
If it hasn’t been seen before then there is a problem and primary response begins
What is the major histocompatibility complex?
The way of working out if a cell is self or foreign. Carried out by T Lymphocytes
What are the different MHC’s and where can they be found?
MHC Class 1 - All nucleated cells (scanned by cytotoxic T cells which will destroy it)
MHC Class 2 - present on macrophages/ B Lymphocytes and Dendritic cells (scanned by Helper T Cells which will produce more antibodies to aid with the response)
What does the thymus do?
Create Cytotoxic T Cells and Helper T Cells from a T-Cell Precursor
What happens to allergic responses?
First exposure
- sensitiztion
- Activation, clone B cells, form antibodies and memory cells
Re-exposure
-Many antibodies formed, large inflammation
How does the rejection of blood occur?
Introducing the wrong blood type into the body will cause the presence of antibodies that will react to the opposing blood type causing the similar blood cells to be agglutinated
What is rhesus factor?
Transmembrane proteins that can cause rejections like blood transfusions.
Can cause problems if mother and child are diffeent resus factors as fetal blood becomes agglutinated by maternal antibodies
