Lecture 2 - Blood Constituents Flashcards
What does blood do?
Transports material between cells and external environment to maintain homeostasis
Transports O2 and CO2
Some blood cells are part of the immune system
Some constituents help stop bleeding
What are the functions of blood?
Transport Maintain body temperature Controls pH (buffer) Regulation of body fluid electrolytes Removes toxins from the body Regulates blood clotting
What makes up the blood?
Plasma - 55%
Erythrocytes - 44%
Leukocytes (WBC) - 1%
Thrombocytes (platelets)
What is haematrocrit?
The total volume of blood occupies by red blood cells
The blood plasma:
> 90% water
Transports material in blood
Can hold and distribute much of the heat generated metabolically
What is the most plentiful organic constituent of plasma?
Plasma proteins (8%)
How are plasma proteins identified?
By electrophoresis
What is the primary function of erythrocytes
Transport O2
Facts about erythrocytes
Transport O2 but cannot use it Last 120 days Formed in bone marrow 2 trillion RBC’s at one time 2-3 million are made per second
Erythrocyte structure and function
Contain Hb that allow it to carry O2
Concave shape to be more efficient at carrying O2
Hb molecule consists of two parts
The globin part - a protein made up of four chains
Four iron containing haem groups
Haemoglobin structure
Four globin protein chains
Four iron containing haem groups (each iron atom can combine with one molecule of O2)
Therefore, 4 haem groups = 4 iron atoms. Therefore, each haemoglobin can pick up four O2 passengers
What is it called when oxygen is bound to haemoglobin?
Oxyhaemoglobin
In addition to being able to bind with oxygen, what else can Hb bind with?
CO2
Carbon monoxide
Carbonic acid
What is haemoglobinopathies?
Where abnormal globin chains are made: - sickle cell anaemia
What is sickle cell anaemia?
The gene code for the Beta chain of Hb is mutated
Resulting in Hb polymerising at low pO2 levels forming long crystals of HbS.
This causes RBCs to deform and become sickle shaped
What is haemostasis?
The arrest of bleeding from a broken blood vessel
What are the three steps of haemostasis?
Vascular spasm (blood vessel constriction)
Formation of platelet plug
Blood coagulation
(Platelets have a role in all 3 steps)
What is vascular spasm in haemostasis?
Blood vessel constriction
The smooth muscle layer constricts to slow blood flow and minimise blood loss
Platelets release potent vasoconstrictors to cause this
As the ends of the inner surfaces are pushed together, they become sticky and adhere to each other
What is the platelet plug in haemostasis?
When the lining is disrupted due to injury, platelets stick to the exposed area and to each other
How do platelets stick to each other?
Using Von Willebrand factor (vWF) a plasma protein secreted by platelets
What happens to plateletsbthat are bound through vWF?
They release serotonin, causing the surface of nearby platelets to become sticky and stick to the first platelets
The platelet plug seals the break and performs three other functions, which are?
Compaction/strengthening
Further vasoconstriction
The plug releases other chemicals which play a role in blood clotting
What is blood coagulation (clotting)
Liquid blood to a solid gel (clot or thrombus)
