Haemotology Flashcards
What is Erythropoiesis?
The term is used to describe the process of RBC formation or production. It is occurs in the red bone marrow.
What is involved in the homeostatic mechanism?
- Stimulus- Hypoxia ( lack of oxygen to tissues ) due to decreased RBC count.
- The Kidney releases erythropoietin
- Erythropoitetin stimulates red bone marrow.
- This enhances erythropoiesis which increases RBC count.
- This increases o2 carrying ability of blood
What is the consistency of blood plasma?
Plasma is a straw-coloured sticky fluid made of 91% water,7% plasma proteins plus ions. Substances are transported from one part of the body to another such as hormones.
What are the functions of plasma
- Plasma albumin- made in the liver. The negative charge of plasma albumin helps control the osmotic pressure of the blood.
- Transport- plasma proteins like calcium ions are carried by albumins.
- Plasma proteins contribute to the viscosity of the blood (thickness). Increased blood viscosity can cause increased resistance to flow through blood vessels, thus increasing blood pressure.
- Plasma proteins are involved in blood clotting.
- It acts as a buffer. This creates a solution resistant to changes in pH.
Name some of the functions of blood.
- Transport-o2, nutrients,urea and hormones.
- Regulation- Body temp,pH,circulatory fluid
- Protection- preventing blood loss,preventing infection.
What is haemostais?
Is the stemming of blood loss following damage to a blood vessel.
What are the three processes that help close breaks in small vessels?
- Vascular spasm
- Formation of temporary platelet plug
- Coagulation
What is vascular spasm?
It is the most immediate protection against blood loss and is characterized by contraction of smooth muscle fibres in the walls of damaged blood vessels causing vasoconstriction, thus reducing blood flow to the area.
Describe the platelet plug formation phase.
When a blood vessel is cut, collagen fibres within its walls are exposed to blood. Within 15 seconds platelets attach themselves to the sticky lining of blood vessels causing ‘platelet plug’ that block minor bleeding.
Thromboxane makes platelets sticky and allows them to form a plug.
Describe the coagulation phase.
The goal in this phase is to convert fibrinogen present in the blood to form fibrin.
- Substances released from damaged tissue results in the formation of PROTHROMBIN activator, which leads to the activation of coagulation.
- Prothrombin converts into thrombin.
- Thrombin turns fibrinogen into fibrin.
- Fibrin forms networks of threads that trap blood cells and platelets to form a clot.
What does Aspirin do?
Aspirin is an anti-platelet medicine which reduces the ability of the platelets to stick together and reduces the risk of clots forming.
What is the effect of Aspirin if taken in small doses daily?
It inhibits thromboxane.
Thromboxane promotes platelets sticking together and it encourages vasoconstriction.
What is Ischemia?
an inadequate blood supply to an organ or part of the body, especially the heart muscles
How does Aspirin prevent Ischemia?
Aspirin is an anti-platelet drug that prevents clots. It prevents the formation of thromboxane by binding to an enzyme.
What is the key enzyme that prevents clots called?
cyclooxygenase
