Red Blood Cells Flashcards
What are the cellular components of blood called?
Formal Elements of Blood
What are the the three formal elements of blood?
Red Blood Cells
White Blood Cells
Platelets
What is another name for Red blood cells?
Erythrocytes
What is another name for white blood cells?
Leukocytes
What are platelets essential for?
Blood clotting
What is the term used to describe the proportion of blood made up of RBC?
Haematoocrit
What is the Haematocrit in males and females?
Males - 45%
Females - 41%
Describe the centrifugal test to used to determine the haematocrit?
Blood sample in blood capillary tube
Spun around to separate heavier element of RBC
Measure
How many RBC are there in 1 micro litre of blood?
Males - 5 million
females- 4.5 million
How many red blood cells are there in the body?
25 trillion
Describe the shape and size of red blood cells?
Flattened Biconcave Disc.
7-8 micro-metre in diametre (same size as capillaries)
2 micrometre thick
What is the reason for the shape of RBC?
Optimal shape for the diffusion of gases into and out of RBC’s and therefore a key part of gas exchange
Discuss the size of RBC in relation to the size of blood capillaries?
The diameter of RBC and blood capillaries is the same and so RBC are very flexible and able to squeeze through capillaries.
RBCs are easily deformable.
What is critical component of RBC that allows for gas transfer?
Haemoglobin
How many molecules of Haemoglobin are found in a single red blood cell?
280 Million
What are the two constituent parts of Haemoglobin?
Globin - Protein part
Haem - pigment part
What does Haem contain?
Iron which carries Oxygen
What is Globin composed of?
Several polypeptide chains (haem is nestled in amongst these protein chains)
How much Haemoglobin is there per litre of blood?
150 grams per litre of blood
Do RBC contain many organelles?
No they are anucleate and obtain energy anaerobically
What % of RBC are destroyed daily and where and by what?
1% destroyed daily in the liver, spleen and bone marrow by macrophages.
Discuss the breakdown of RBC.
At end of lifespan, RBCs are phagocytosed by macrophages in spleen, liver or bone marrow.
Globin broken down into Amino Acids which are reused for protein synthesis.
Haem is broken down into iron and biliverdin.
Iron is bound to transferin and taken to red bone marrow for erythrpoeisis.
Biliverdin becomes Billrubin.
Billirubin is further broken down in liver and excreted in bile to small intestine. From there it becomes urobiligen (yellow) and is taken to kidneys for excretion. Also in small intestine urobiligen is turned into stercobilin (brown) which is excreted as faeces. This is what gives us brown hobbies.
Rate of RBC breakdown is equal to…
The rate of RBC synthesis.
What is another name for RBC synthesis?
Erythropoesis
Where does erythropoiesis take place?
It varies depending on age.
In adults in bone marrow, ribs, sternum, vertebrae, pelvis, long bones
Discuss erythropoiesis.
It occurs over several stages:
- Begins with Stem cells
- Reticulocytes formed & nucleus ejected
- Erythrocyte formed
What are three factors required for erythropoiesis?
Iron
Folic acid (vit B9)
Cobalamin (vit B12)
What controls erythropoiesis?
The hormone Erythropoeitin (EPO)
Where does Erythropoeitin come from in the body?
Kidneys - 90%
Liver - 10%
What could damage to the liver or more likely the kidneys result in?
Anaemia due to EPO malfunction
What stimulates the release of Erythropoeitin? (EPO)
Reduced Oxygen intake via: -haemorrhage -Decreased cardiac efficiency -being at high altitude All stimulate production of EPO stimulating production of RBCs increasing O2 carrying capacity
What is the result of the release of Erythropoeitin?
Increased RBC synthesis which increases Oxygen carrying capacity
Also increases blood viscosity (clot risk)
What are the four key blood types?
A, B, AB, O
What determines blood type?
The type of antigen (A or B) present on the RBC surface
What is the role of plasma with regards to blood type?
Plasma contains the A and B antibodies to the A and B antigens. The plasma antibodies within a person will not match the RBC antigen
Discuss what antigens and antibodies are present with respect to blood type
Type A - A antigen - B antibody
Type B - B antigen - A antibody
Type AB - both antigens - no antibodies
Type O no antigens - both A and B antibodies
If a transfusion occurs delivering the matching antibody to a persons naturally occurring antigen what occurs?
Agglutination
Discuss what transfusion are therefore appropriate with regards to blood type.
A cannot accept B or AB
B cannot accept A or AB
AB can receive from any
O can receive only from O
Must blood type always be checked prior to transfusion?
Yes, because there are in reality many antigens that can be present on the surface of RBC
Discuss Haemolytic Disease of Newborn and the Rhesus antigen.
Some humans (84% in europe) RBC contain an antigen called Rhesus. Few humans have the Rhesus antibody If a father is Rhesus positive and mother does not. then their baby will be positive.
If there is blood contamination between mother and baby then the mother may produce Rhesus antibodies in response to it.
If the mother has a second baby that is Rhesus positive then the Rhesus antibodies in her body can cross placenta and attack foetus RBC’s.
What is another name for blood clotting?
Haemostasis which is a coordinated response
What are the three elements to Haemostasis?
Vascular Spasm
Formation of Platelet Plug
Coagulation
What is vascular spasm with regards to blood clotting?
Damage to blood vessel stimulates smooth muscle contraction, vaso constriction, maintained by chemicals released by platelets
What is the formation of a platelet plug with regards to blood clotting?
- Platelets come into contact with damaged blood vessel and exposed collagen fibres
- Platelets stick to damaged area
- Platelets release chemicals
- Vascular Spam induced by chemicals
- platelet stickiness increased
- platelets clump and plug hole
- reduced blood loss
What is coagulation with regards to blood clotting?
It is the formation of a gel over damaged area that consists of a network of the soluble protein fibrin
This network traps the cellular components of blood = blood clot
What are some key factors for blood clotting to occur?
Vitaming K
The clotting factors in plasma
Calcium ions
Liver enzymes
What are the two pathways for blood clotting to occur?
Intrinsic and Extrinsic
What is the extrinsic pathway?
It is a fast process
What is the intrinsic pathway?
It is a slow process. Involves the reaction when platelets come into contact with collagen fibres.
What is the buffy coat?
In centrifuged blood the RBC = 45%, the Plasma = 55% and the BUFFY COAT is a thin line in the middle that is composed of WBC and platelets
What is total blood volume?
5 Litres
8.8 Pints
What is the function of red blood cells?
To transport gases in the circulation, O2 and CO2
What is the lifespan of a red blood cell?
120 Days
They are anucleate and therefore have short life span.
What does pre-natal erythropoiesis take place?
1-4 months - yolk sack
2-9 months - Liver
4-6 months - spleen
5-9 months - Bone marrow
Where does post-natal erythropoiesis take place?
It falls off rapidly in the tibia and femur.
It gradually decreases in vertebrae, pelvis, ribs, sternum
What maintains the normal level of RBC synthesis?
The circulating levels of erythropoietin hormone
What would inhibit the release of Erythropoietin?
Oxygen Excess
