Blood And Blood Components Flashcards
(24 cards)
What are the constituents of blood?
-Plasma, approx 55%
(inculding plasma proteins, electrolytes, ezymes, nutrients and serus (straw-coloured water)
-Erythrocytes (red blood cells), approx 45%
-Leucocytes (white blood cells), <1%
-Thrombocytes (platelets), <1%
Describe erythrocytes?
-Biconcave discs, flexible membrane, so can squeeze through capillaries
-Carry Hb (a protein that carries O2), found in the cytosol of cell
-Membrane made of glyolipids (antigens),
responsible for different blood types
-Lack nucleus and organelles so can’t reproduce nor synthesis new components
-Live for only 120 days due to wear ad tear
Explain the process for erythropoiesis
-Starts in bone marrow as pluripotent stem cell
-Differentiates into pro erythroblast
-Synthesis of Hb and nucleus is expelled-reticulocytes
-Reticulocyte matures over 1-2 days after leaving bone marrow, becomes erythrocyte
How is erythropoiesis stimulated?
By low O2 levels
What type of cells detect the low O2 levels?
-Juxtaglomerular cells of kidneys
-They secrete erythropoietin into blood which increases speed of maturation process in bone marrow to produce more RBCs Leucocytes
Describe leucocytes?
-Have a nucleus
-Plasma membranes have proteins called major histocompatibility (MHC)
antigens used for
immunological purposes
What are the different classifications of MHCs?
-Granular, filled with granules (eosinophils, basophils and neutrophils)
-Agranular (lymphocytes and monocytes), monocytes develop into macrophages in tissues
What are the monocytes and granular leucocytes developed from?
Myeloid stem cells, lymphocytes from lymphoid stem cells
Describe the functions of leucocytes?
-Can live for months/ years, most just for a few hours/ days
-Combat infections by phagocytosis (neutrophils, macrophages and eosinophils) or by immune response (predominantly lymphocytes)
-Can leave blood stream to deal with having pathogens
-Granulocytes never return, lymphocytes circulate in and out of blood vessels
Describe thrombocytes?
-Formed from fragments of megakaryocytes under influence of thrombopoietin in red bone marrow, then enter circulation.
-Disc shaped
-No nucleus, many vesicles
-Life span 5-9 days
-Involved in homeostasis by forming platelet plug, vasospasm and blood clotting
What is present on the surface of erythrocytes?
-A genetically predetermined coating of glycoproteins and glycolipids
-These acts as antigens(have immunogenicity and reactivity to antibodies)
-Antigens also known as agglutinogens or isoantigens
How is blood groups categorised?
-By presence or absence of antigens on the cell surface
-At least 24 blood groups and over 100 surface antigens
-One blood group may contain different blood types
What are two major blood groups ?
ABO and rhesus
Explain ABO blood groups and types?
-Based on two antigens, A and B to determine the type
-Surface A antigen on erythrocytes are blood type A
-Surface B antigen on erythrocytes are blood type B
-Surface A and B antigen on erythrocyte are blood type AB
-No surface antigen are blood type O
What do blood plasma contain?
-Antibodies
-Also known as agglutinins or isoantibodies
-Specific antibodies will react with specific antibodies
Which antibodies will react with which antigens?
-Anti A antibody reacts with antigen A
-Anti B antibody will react its antigen B
-The plasma does not contain antibodies that will react with antigens of it own erythrocytes
-The plasma may contain antibodies which will react with antigens that the body’s own RBCs lack
What is the inheritance of blood type due to?
-Multiple allele inheritance
-Blood type A and B are dominant to blood type
-Blood types A and B are co-dominant
Explain the rhesus blood group?
3 inherited alleles responsible for coding the rhesus antigen: C,D and E
What is the D antigen specifically responsible for?
-The rhesus statue of an
individual
-If the D antigen is present on the surface of the RBC the individual is
Rh+
-Rh+ is dominant to Rh- in the inheritance pattern for this group
Why is type
AB classed at the
universal recipient?
And Why is Type O negative the safest blood type to be donated?
It has both antigens
It has no antigens, but it shouldn’t be given to individuals with anti C antibodies
When does ABO incompatibility occur?
-When a mother’s blood type is O and her baby’s blood type is A or B.
-Mother’s immune system may react and make antibodies against baby’s red blood cells
-It’s very rare
Which classification does Anti A and Anti B antibodies belong to?
-IgM due to their molecular size
-These are very unlikely to cross placenta where mother (usually type O) is of a different blood group to foetus (usually type A or B)
When does Rhesus incompatibility occur?
-When mother is Rh- and foetus is Rh+
-RhD antigens from foetus mix with maternal blood
-Mother makes D
antibodies
-IgG antibodies due molecular size can cross placenta
-These anti D antibodies will attack and haemolyse foetal erythrocytes carrying D surface antigens
What can this cause?
-Can cause iso-immunisation, foetal anaemia and hydrops fetalis (severe liver swelling and fluid build up in foetus)
-May lead to jaundice in first 48 hours of life
