Blood components Flashcards
What are the four main components of blood?
RBC
WBC
Platelets
Plasma
What is contained in plasma?
RBC
WBC
Platelets
Soluble fibrinogen
What is the role of platelets?
Coagulation
How are platelets produced?
Budding off multinucleated megakaryocytes
What is the main purpose of RBC?
O2 transportation
Buffer CO2
What are some structural peculiarities of the RBC?
Biconcave disk Full of haemoglobin No nucleus No mitochondria High surface area/volume ratio Flexible
Why are RBC full of haemoglobin?
To carry O2
What problem does haemoglobin cause for the cell?
Gives high oncotic gradient
How does the cell cope with the oncotic gradient associated with haemoglobin?
NaK ATPase
What is the structure of haemoglobin?
Tetrameric globular protein
Haems (Fe2+) group
What is the Haems (Fe2+) group made of?
Flat porphyrin ring
1 Fe2+
How much O2 does one Fe2+ bind?
Binds 1 O2
Can O2 bind to Fe3+?
No
What is needed to prevent Fe3+?
Antioxidants
What are the two main variants of Hb?
HbA- Adult
HbF- Foetal
What are the subunits of HbA?
Alpha
Beta
What are the subunits of HbF?
Alpha
Gamma
How many globin SU make up a Hb molecule?
4
Why don’t RBC have nucli?
More deformable
More room for Hb molecules
Why do RBC need power?
To maintain NaK ATPase
How does a RBC generate ATP?
Gylcolysis
Why can RBC only do glycolysis?
No mitochondria
Why do RBC have a high surface area to volume ratio
Allow for gas exchange
Why are RBCs flexible
To squeeze through capillaries
What makes RBC flexible?
Spectrin ‘spar’ proteins
How long does a RBC live for?
120 days
What is the process of forming new RBC called?
Erythropoiesis
From differentiation what are the steps of RBC formation?
Pronormoblast/Proerythroblast
Normoblast/Erythroblast
Reticulocyte
RBC
Where are Pronormoblast/Proerythroblast found?
Restricted to bone marrow
What is the first cell morphologically recognisable as a RBC?
Pronormoblast/Proerythroblast
What RBC progenitor leaves the bone marrow?
Reticulocyte
How long do reticulocytes last outside the bone marrow before becoming RBC?
3 days
How is RBC formation regulated?
Erythropoietin
Quality control
Where is EPO released from?
Kidney
What regulates EPO?
Hypoxia inducible factor 1 gene
When do kidneys release EPO?
In response to hypoxia
Where in the kidneys sense hypoxia?
Juxtaglomerula apparatus
What percentage of RBC are destroyed before leaving the bone marrow and why?
10%
Due to defects
Where is Hb formed?
Cytoplasm of developing RBC
Where do RBC get iron from?
Macrophoage stores
Where does RBC breakdown occur?
Spleen
Occasionally liver
What breaks down RBC?
Macrophages
What contents of RBC are recycled?
Globin chains
Haem groups
What are globin chains recycled to?
AA
What are haem groups broken down to?
Iron
Bilirubin
Describe Haem to bilirubin
Haem -> Porphyrin -> Biliverdin -> Bilirubin
What happens to bilirubin?
Taken to liver and conjugated then excreted as bile
