BLOOD 2 Flashcards
Defence
– “Self” vs “Non-self”
– protect from internal damage signals
Non-specific defenses (innate immunity)
– “Physico-chemical”
• Intact skin, enzymes in saliva, tear, mucus
• Acidic gastric secretion
• Role of WBCs (mainly granulocytes and
monocytes/macrophages )
Specific defenses (acquired immunity)
– Role of WBCs (mainly lymphocytes)
inate or natural defence
- non-specific
- no memory
- fast
- (neutrophils and macrophages)
- complement system
Acquired or adapted defence
- specific
- has memory
- slow
(Lymphocytes (B and T cells))
- antibodies
- cytotoxic molecules
Appropriate (“ Good”) role of immune systems
– defence against foreign invaders (eg. bacteria, viruses)
– Removal of own old reaction (attacking “self immune abnormal or mutant system”) cells
– Identify/destroy
Inappropriate (“Bad”) role of the immune systems
– Exaggerated response to “harmless” substances (allergies)
– Autoimmune reactions (attacking “self immune system”)
Inflammation
• Non-specific innate response to tissue injury initiates inflammation
• The inducers of
inflammation may include:
– cut on skin surface – bullet wound – injuries due to sun burn – infected sutures during surgery – infection of tonsil by cold virus
Physical characteristics of inflammation
- Redness (rubor)
- Swelling (tumor)
- Heat (calor)
- Pain (dolor)
- Loss of function
What is histamine the agent for
- Redness (rubor)
- Swelling (tumor)
- Heat (calor)
What does increased blood flow the primary cause of?
- Redness (rubor)
- Swelling (tumor)
- Heat (calor)
What is Bradykinin and prostaglandin (PGE2) the agent of
Pain ( Dolor)
What’s is pressure on the nerve endings the primary cause of ?
Pain (dolor)
Changes in vasculature (blood vessel wall)
Vascular (related to blood vessels) events:
• release of inflammatory mediators
• increased blood flow
• increased permeability of small blood vessels
VASCULAR EVENTS
- release of histamine
- local blood vessels dilate
- blood vessels become leakier
- accumulation of protein and fluid in the extracellular spaces
- additional inflammatory mediators are released: eg., bradykinin, prostaglandins, complement proteins
CELLULAR EVENTS
• resident macrophages entrap and kill pathogens, release chemical signals
• increased movement of WBCs (neutrophils and monocytes) into infected area
• phagocytosis and destruction of foreign
“non-self” agent
Goal of cellular events associated with inflammation:
to accumulate leukocytes or WBCs in the inflamed tissue
and kill the “non-self” agent
Cellular events associated with inflammation
- How does this happen?
- Margination of WBCs
- Tethering and rolling of WBCs inside blood vessel
- Activation of WBCs and endothelial cells
- Arrest/firm attachment of WBCs to endothelial cells
- Emigration/diapedesis
- Chemotaxis of WBCs
- Recognition of “non-self” by WBCs
- Phagocytosis of “non-self” pathogen by WBC’s
What is chemotaxis?
The ability of WBCs to move against a concentration gradient (low to high) in response to chemical factors (chemotactic factors)
Chemotactic factors include:
– complement products (C5a)
– chemokines (IL-8)
– bacterial products
– damaged membrane products (arachidonic acid metabolites)
Sequence leading to phagocytosis:
- recognition of foreign body (using PRRs)
- attachment to the foreign body (opsonization)
- internalization
- destruction of the “non-self” pathogen
PRR
Pattern recognition recpetors
Opsonins speed up the process of
phagocytosis
Two types of opsonins
1) antibodies
2) complement proteins
Opsonization:
- process of “opsonin” addition on bacteria to enhance attachment and engulfment of the injurious agent (eg., bacteria)
• bacteria are coated with host factors (factors made by “self” or own
body) called opsonins
Steps of phagocytosis
1) engulfment
2) killing by neutrophils
Engulfment
– injurious agent surrounded by pseudopods and internalized in a membrane bound phagocytic vacuole