Red Blood Cells Flashcards
Where is the highest blood pressure found?
Heart
What are the functions of blood?
Transport
Regulation of pH and osmosis
Maintenance of body temperature
Defence against foreign substances
Regulation of haemostasis and coagulation
What are the components of blood?
Plasma
Erythrocytes
Leukocytes
Thrombocytes
Haematocrit - Fractional contribution of erythrocytes
What cells form the “buffy coat” of a blood sample?
WBC and platelets
What percentage of plasma is water?
90%
What are the three main proteins found in plasma?
Albumin
Globulins
Fibrinogen
What is serum?
Plasma from which fibrinogen and other clotting proteins have been removed
Where do all blood cells originate from?
Pluripotential hematopoietic stem cells (PHSCs)
What is the name of the process by which PHSCs transform into RBCs
Erythropoiesis
What is the process by which PHSCs transform into WBCs?
Leucopoiesis
What is the name of the process by which PHSCs transform into platelets?
thrombopoiesis
What do most PHSCs differentiate into before becoming a specific cell type?
Committed stem cells or progenitor cells
What protein-signalling molecules drive cellular production?
Cytokines
How many erythrocytes are in the body per litre?
5x10^12 cells per L
What is the major function of erythrocytes?
Oxygen and Carbon Dioxide Transport
Why are erythrocytes flexible?
It allows them to pass through the smallest capillaries in the body
What protein is present in erythrocytes?
Haemoglobin
What is the first major cell on the path of erythropoiesis?
Proerythroblast
When does the final stage of a reticulocyte becoming an erythrocyte occur?
As it is released from bone marrow into the circulatory system
What enzymes are needed for the high rates of DNA synthesis of RBCs?
Folic acid and Vitamin B12
What do RBCs lack?
Nuclei
Mitochondria
Ribosomes
What is hypoxia?
Low O2 levels in tissue
What cells secrete erythropoietin to promote RBC production?
Hypoxic kidney cells
What does EPO do?
Increased production of proerythroblasts
Increased haemoglobin synthesis
Increases production and reticulocytes
How can hypoxia occur?
Low blood volume
Anaemia
Low Haemoglobin
Poor blood flow
Pulmonary disease
High Altitude
What mass of haemoglobin is found per litre of blood?
12-17g
What is the maximum ml of oxygen that 1g of haemoglobin can bind to?
1.34ml
What does oxygen bind to on the haemoglobin molecule?
Haeme group (iron)
What is the average lifespan of RBCs?
120 days
Why do erythrocytes only survive for this long?
Decreased glycolysis
Reduced ATP
Loss of membrane flexibility
Self-destruct in Red pulp of spleen
What is the fate of haemoglobin following cell death?
Absorbed by macrophages
Iron recycled to bone marrow or liver
porphyrin ring converted to bile pigment bilirubin
Protein subunits degraded to amino acids
What is Anaemia?
Deficiency in O2 carrying capacity of blood
How is blood’s inability to carry oxygen caused?
A low haematocrit
Low haemoglobin concentration in erythrocytes
What is the result of anaemia?
hypoxia
What are common symptoms of anaemia?
Feelings of tiredness
Lack of energy
Pale skin/pallor
What is the most common form of anaemia?
Iron Deficiency Anaemia
What are the underlying causes of Iron Deficiency Anaemia?
Blood loss
Increased demands
Malabsorption
Poor diet (contributing factor)
What is polycythaemia?
Abnormal increase in RBC count
What is Polycythaemia Vera?
Genetic aberration resulting in excessive proliferation of erythroblasts
What is secondary Polycythaemia?
Increased RBC count caused by tissue hypoxia
What do all RBCs express?
H antigen
What is the biological family to which the H antigen belongs?
Glycoprotein/Glycolipid
What is produced by humans that modify the H antigen?
A antigen, B antigen, O antigen
What does the A antigen do?
Add an alpha-n-acetylgalactosamine to the D-galactose end of the H antigen
What does the B antigen do?
Add a D-galactose to the D-galactose end of the H antigen
What does the O antigen do?
No change to the A antigen
What other functions do antigens have?
Suppressing the anti anti-bodies of the same blood type
Order the overarching blood types in regard to their frequency
O
A
B
AB
What happens in a blood transfusion of mismatched blood?
Antibodies attach to cells causing clumping or agglutination
Small blood vessels are plugged
White blood cells destroy membrane of agglutinated cells releasing haemoglobin into the plasma
What are Rh antigens?
Transmembrane proteins
What are the 6 common types of Rh antigens?
C
D
E
c
d
e
What is the most prevalent and most antigenic Rh antigen?
D
What antigens make up Rh negative blood?
dd
What happens if a Rh+ donor gives blood to a Rh- recipient?
Recipient’s blood develops anti-D antibodies
Subsequent infusions trigger agglutination
What is erythroblastosis fetalis?
Mother is Rh-, Father is Rh-, Foetus is Rh+
Causes anti-Rh antibody formation in response to foetus’ Rh+ factor
Causes red blood cell agglutination or haemolysis
What foetus is most vulnerable to erythroblastosis fetalis?
2nd and subsequent foetuses
How does the infant appear at birth following erythroblastosis fetalis?
Jaundiced and usually anaemic
How is erythroblastosis fetalis treated?
Anti-D antibody administered during pregnancy which inhibits maternal production of anti-Rh agglutinins
What blood type is the universal donor blood?
Type O-
Why is the universal blood type called such?
Donated RBCs do not express A, B or + antigens containing antibodies
What blood type is the universal recipient?
Type AB+
Why is the universal recipient known as such?
Contains all antibodies which allow it to accept all variants of blood
