What is Haematopeosis?
What is Leucopoeisis? (2)
- Production of Blood cells
2. Production of Leucocytes
Where does Leucocyte formation start? (2)
From Pluripotent hematopoietic stem cell in the bone marrow.
What are the 2 major leucocyte lineages, what type of leucocytes do they form? What is the other minor lineage? (3)
In the bone marrow, the hematopoietic stem cell Divides into:
- Lymphoid Progeny - Form Lymphocytes, small and bland-looking.
- Myeloid Progeny - Form granulocytes, larger cells with cytoplasmic granules.
3. Immature dendritic cell - Forms mature dendritic cell in tissue.
What are the types of lymphocytes? (3)
In the blood:
- B cells (becomes Plasma Cell when activated)
- T cells
- Natural Killer Cells
These then move into Lymph nodes.
What are the types of granulocytes? (5)
- Monocyte (forms Macrophage in tissues)
- Unknown Precursor of Mast cell (forms mast cell in tissues)
What are the functions of Dendritic cell? (2)
Dendritic cells recognise antigens in peripheral sites of the lymph nodes, presenting them to adaptive immune cells (e.g lymphocytes) to activate.
What are the functions of:
- Mast Cells (5)
- Neutrophils - Phagocytosis and activation of antibacterial mechanisms.
- Eosinophils - Killing of antibody-coated parasites
- Basophils - Unknown
- Macrophages - recognise antigens, activating phagocytosis and other antibacterial mechanisms.
- Mast Cells - Release of granules containing histamine and other active agents.
What are the functions of:
- NK Cells
- B-cells - Produce antibodies. These antibodies bind to antigens such as Bacteria.
- T-cells - Mature in thymus gland during gestation. CD8 cells deal with intracellular (viral) infection. CD4 (helper) cells are required in direct immune activity.
- NK cells - Important with intracellular infection and tumours.
What are Cytokines? (1)
Cytokines (interleukins) are small proteins released by cells to communicate to other cells e.g immune cells.
What are Chemokines? (2)
Chemokines are small proteins released by cells to guide other cells on where they should go e.g CXCL8 guides neutrophils to site of infection.
What is the mechanism of action of phagocytosis? (3)
- Phagocyte receptors recognise microorganism antigen.
- Microorganism is engulfed and release lysosomes which contains digestive enzymes.
- Microorganism killed in ‘phagolysosome’ by low pH, digestive enzymes, toxic-free radicals and hydrogen-oxygen products.
What processes does local inflammation activate? (3)
It activates action of
- Release of soluble mediators:
* Cytokines - (TNF alpha), IL-1, IL 6.
* Chemokines: CXCL8
What can increased action of Cytokines and Chemokines when released by macrophages at an infection site do to blood vessels? (3)
- Increased Permeability
- Increased adhesion molecules on blood vessel endothelium.
Outline how the symptoms of inflammation manifest due to action of Cytokines and Chemokines? (2)
- Redness, heat and swelling is caused by increased vascular permeability and vasodilation.
- Pain is caused by inflammatory cells (e.g neutrophils) entering tissue and releasing inflammatory mediators.
What feature of the immune system causes systematic inflammation? (2)
Cytokines, as these act on distant tissues and are released into circulation.
What are the good things about inflammation? (3)
- Amplifies Immune response
- Focuses the immune response using chemokines and cytokines
- Activates next stage of immunity (B cells/Tcells)
What are the bad things about inflammation? (3)
- Can incorrectly activate immune response when no infection present.
- Can damage healthy tissue
- Can activate immune response in uncontrolled manner (septic shock)