Blood Flashcards
what make ups 90% of the cells in the blood?
Erythrocytes
What is the structure of an erythrocyte?
Typical lipid bilayer membrane of globular proteins
Biconcave disc shape
Elasticity/deformability
What are erythrocytes shaped like biconcave disks and why have they got elasticity?
- increases surface area (20-30%)
- Allows passage through capillaries with diameters as small as 3-4μ (erythrocytes are 7μ)
What would cause erythrocytes to swell and lose their normal biconcave disc morphology?
Damage to the membrane leading to a failure of Na+ ion movement across erythrocyte cell membranes
What causes the short lifespan of erythrocytes?
Moving through capillaries they are too large for, this stresses them out
When the membrane of the erythrocyte gets damaged it causes residue on the surface, what does this then lead to?
Removal and recycling of lots of red blood cell components
What properties do dog erythrocytes have?
- Uniform in size
- Central pallor (pronounced concave shape which you can see under the microscope)
What properties do cat erythrocytes have?
- Anisocytosis (variation in cell size)
- Smaller
- Scarce central pallor (less concave)
What properties do horse erythrocytes have?
- Rouleaux formation (Clustering of RBCs in standing blood – most other species would be a sign of inflammation)
What properties do ruminant erythrocytes have?
- Crenation (spiky appearance – can show rogh handling of blood OR disease in dogs and cats)
- Variation in size
What properties do camelid erythrocytes have?
Elipsoid shape - unusual in mammals, common in birds and retiles
What properties do chicken and reptile erythrocytes have?
- Nucleated – not as specialised for transporting O2 like mammals are
- Larger
- Early stages are rounded and may be binucleate
- Occasional cells lose their nucleus and are termed erythroplastids
- Elipsoid shape
Why are erythrocytes metabolically active?
To maintain electrolyte gradients across the plasma membrane and of haemoglobin molecules (95% of erythrocyte proteins)
Why don’t erythrocytes have organelles?
If they don’t have mitochondria how do they get their energy?
To avoid consumption of any oxygen they are carrying
It is derived by the anaerobic metabolism of glucose
Erythrocytes don’t have a nucleus (in mammals) so how does division occur?
What are the benefits to having no nucleus?
Division happens at stem cells
Increased space for haemoglobin and allows biconcave shape
What is the main role of erythrocytes?
Transport of O2 from the lungs to the cells
How much oxygen is stored in haemoglobin and how much is dissolved into the blood?
Haemoglobin: 98.5 %
Dissolved in blood: 1.5%
What is the other role erythrocytes have?
Transport of CO2 from the cells to the lungs
How much CO2 becomes bicarbonate, binds to haemoglobin or is dissolved in the blood?
Bicarbonate: 70-85%
Haemoglobin: 10%
Dissolved in blood: 5-15%
CO2 diffuses into the capillaries and then into erythrocytes, it then becomes bicarbonate. What is the equation for this?
Carbonic anhydrase (CA)causes carbon dioxide and water to form carbonic acid (H2CO3), which dissociates into two ions: bicarbonate (HCO3–) and hydrogen (H+).
In adult erythrocytes how many of units of haemoglobin are there and how many oxygen and bind to each?
4 haemoglobin units - 1 oxygen binds to the iron atom of the ham group
In adult erythrocytes haemoglobin, what are the most common pairs of globin polypeptides?
What is highly unusual?
What is found in foetal?
What is found in embryonic/yolk sac?
Alpha and beta
Delta
Gamma
Epsilon
What happens to blood depending on the amount of oxygen bound to it?
What is the name given to haemoglobin in areas of high oxygen concentration (eg. in lungs)?
Why has it got this name?
oxyhaemoglobin
because globin releases CO2 and iron binds to O2
What is the name given to haemoglobin in areas of low oxygen concentration?
Why has it got this name?
Carbaminohaemoglobin
O2 is released and CO2 bound
What is hypoxic tissue?
What does it do?
When the tissue is lacking in O2
Additional carbohydrate (2,3-diphosphoglyceride) is released, it facilitates release of O2 from erythrocytes
What can haemoglobin also bind to that causes the dilation of blood vessels and what does this permit?
Binds to nitric oxide, a neurotransmitter
Maximal tissue perfusion for supply of oxygen/removal of waste products
What has a greater affinity for haem than oxygen?
Why is this problematic?
Carbon monoxide
Carbonmonoxyhemoglobin gives off the cherry red colour of the mucous membrane when really its carbon monoxide poisoning
Why is haematopoiesis a continuous replenishment process?
Cells cannot divide once in the blood so must be replenished in the bone marrow
What blood cellular components are formed during haematopoiesis?
red blood cells (erthrocytes)
white blood cells (leukocytes)
platelets (thrombocytes)
What are the following?
erthrocytes
leukocytes
thrombocytes
erthrocytes = red blood cells
leukocytes = white blood cells
thrombocytes = platelets
What is erythropoiesis?
The production of erythrocytes/red blood cells
Where does erythropoeisis occur in adult and later foetal stages?
Where does it occur in special circumstances?
Where does it occur in embryos?
Red bone marrow (contains blood stem cells) found at ends of long bones and in flat bones (e.g. ribs, pelvis + skull)
spleen
Yolk sac, liver (spleen)
What is highlighted in green?
Nucleated immature RBCs
What are sinusoidal capillaries?
Capillaries with larger intercellular gaps within their ednotheliums and incomplete basement membranes to allow passage of cells
What happens to marrow that is inactive?
Can it still produce RBCs?
Replaced by fat (yellow marrow)
Can regain activity by extension from active tissue and from circulating stem cells (if requiring RBC)
Identify the following cells:
What are retculocytes?
blood cell that has nucleus remnants (not fully matured) and can be used in an emergency were red blood cells are required
What organ is important for haematopoetics in fish?
The kidney, so if there is kidney problems there will potentially be RBC issues going on as well
What does pluripotent mean, what cell is pluripotent that’s involved in erythropoesis?
Pluripotent
Stem cells
What happens to RBCs as they mature?
Nucleus becomes progressively smaller
Cell size becomes progressively smaller
Haemoglobin levels gradually increase
During erythropoiesis where would be the following cells be found, in the bone marrow or in the blood sample (in order of development)?
Erythrocyte
Erythroblasts/normoblast
Reticulocyte
Stem cell
BM - Stem cell
BM - Erythroblasts/normoblast
BM + BS - Reticulocyte
BS - Erythrocyte
What happens to the nuclear material in immature RBCs as they mature?
Nuclear material will be transported out of cell and engulfed by macrophages
What does the formation of erythrocytes require?
Adequate amounts of:
- protein
- iron
- copper
- folic acid
- vitamins (B2, B6, B12)
Why are folic acids and vitamins essential for the formation of erythrocytes?
Essential for DNA synthesis to allow mitosis and therefore erythropoiesis
Why is iron essential for the formation of erythrocytes?
Mainly involved with haemoglobin
In the body, what is iron split between?
~ 70% as haemoglobin;
~ 30% bound to ferritin in macrophages and hepatocytes, insoluble
~ Some (<0.1%) bound to transferrin
Why is iron tightly bound to protein/transferrin in the plasma when moving to the liver, spleen or bone marrow?
Free iron is toxic to cells (damages DNA and protein) as it acts as a catalyst in the formation of free radicals from reactive oxygen species so must be bound at all times
Why is iron bound to ferritin found in the liver, spleen and bone marrow?
Liver and spleen: longer storage
Bone marrow: to produce RBCs
What are the causes of an iron deficiency?
- Physiological anaemia in newborns
- Blood loss
- Internal or external parasites - Haemorrhage
What is a good example of physiological anaemia in newborns and how it is treated?
Example: piglets
Markedly reduced RBC numbers in first 2-3 days of life
- Iron store used up within 1-2 days
- Sow milk contains very little iron
- Rapid growth due to selective breeding
What is Erythropoetin (EPO)?
Hormone that controls rate of erythrocyte production
(“Blood boosting drug”, doping horse racing to produce more red blood cells)
What stages of erythrocyte production is Erythropoetin (EPO)involved in?
All but especially during:
Erythroid cells precursors (CFU-Es) (stage prior to erythroblasts)
Where can EPO be found during early embryonic/foetal/early neonatal life?
Where can EPO be found during adult life?
Why is it important to know where EPO is produced?
expressed in yolk sac, liver and kidney (also spleen and bone marrow)
produced in the kidney (and renal interstitium area between renal cells)
Damage to these areas can lead to a negative impact on RBC production
Where can EPO be found during adult life?
produced in the kidney (and renal interstitium area between renal cells)
What regulates the secretion of EPO in the body?
The tissues need for oxygen
Fill in the blanks:
Low 1. oxygen
- Circulatory failure or 2. (normal O2, 3. delivery)
- Hypoxia (low O2)
Stimulates production of 4.
EPO transported by 5. to 6.
EPO binds to receptors on CFU-E (7.Erythroid cells precursors )
EPO also accelerates release of 8. blood
Low 1.tissue oxygen
- Circulatory failure or 2.anaemia (normal O2 but 3.low delivery)
- Hypoxia (low O2)
Stimulates production of 4.EPO
EPO transported by 5.blood to 6.bone marrow
EPO binds to receptors on CFU-E (7.)
EPO also accelerates release of 8.reticulocytes blood
What is the average erythrocyte life spans:
Cat
Dog, human
Horse
Cattle
Cat = 70 days
Dog, human = 120 days
Horse = 145 days
Cattle = 160 days
As RBCs age their surface becomes damaged, what are the 3 impacts of this?
- lose sialic acid residues from their surface
~ exposing galactose moieties that induce their phagocytosis - become more fragile.
- may become swollen due to failure of normal membrane function
What is the normal lifespan of compatible transfused erythrocytes in dogs?
Why is it the length it is?
Approximately 21 days. – temporary, gives the animal more time to restore own cabibility of RBC production
Stress of collection and insertion and transport all contribute to short lifespan
What happens to damaged RBCs?
Phagocytized by macrophages breaking apart the harm and global into iron, bilirubin and amino acids and then these components are recycled
What happens to iron when haemoglobin is recycled?
What happens to bilirubin when haemoglobin is recycled?
Iron
- Goes to bone marrow for erythrocyte production
- Stored as ferritin
Bilirubin
- goes to the liver where it is excreted in bile
Amino acids
- goes into blood
What is happening in this diagram?
- Transferrin synthesised in liver, binds to an iron to transfer it
- Transferrin-iron complex binds to cell-surface receptors, the complex is then internalised (flips in the membrane so iron inside cell)
- Lower pH inside cell, causes conformational change in transferrin and the iron is released
- Receptor flips back, pH change to higher, causes conformational change to receptor and transferrin
- Transferrin released ready to collect another iron
constant cycling system!
What are the two ways in which iron can be stored?
Ferritin
- primary intracellular storage protein, keeps iron soluble and non-toxic
- controls iron release, buffer against iron deficiency or overload
Haemosiderin
- Intracellular complex of ferritin (denatured ferritin and other material)
- Iron within deposits is poorly available to supply iron when needed (hard to resolualise)
- Large deposits cause organ damage as changes cell function
What is mycoplasma haemofolis?
What is neonatal erythrolysis?
Common in kittens
Bacteria attached to red blood cells causes removal of erythrocytes leading to anaemia
Common in kittens and foals (cause of really early disease)
Blood group incompatible with mother, when it takes maternal antibodies from colostrum it recognises the red blood cells as foreign and will coat them for removal, lysing them and causing anemia
What does PCV stand for?
Packed cell volume
What does a Microhaematocrit measure?
Why is it used often in practice?
Fill in the missing information from the capillary tube showing the results of Microhaematocrit:
The ratio of the volume occupied by packed red blood cells to the volume of the whole blood
Rapid & cheap in house test that gives large amount of information
Fill out the missing information (causes that give said results):
Eat lots of carrots = yellow platelets
Haemolysis can instead be an artefacts if rapidly expelled through needle or handled roughly
Fatty diet = grey
What is Coulters principle?
How do automated cell counters work?
To establish the number of and identify blood cell populations
A stream of cells passes through an opening between two chambers, across which there is an electrical current. Passing cells disrupt the electrical flow, causing a pulse:
- Pulse frequency = cell number
- Amplitude is proportional to cell volume
