Ch 21 - Body defense Flashcards
types of hemocytoblasts (WBC’s) involved in NON-SPECIFIC defence (can attack anything)
Basophils, Eosinophils, Neutrophils, Monocytes (=macrophages)
type of hemocytoblast (WBC) involved in SPECIFIC defence
lymphocyte that form 3 major types
T and B cells attack specific antigens
‘natural killer’ lymphocytes are NON-specific and involved in 1st line of defense
some WBC’s develop further into these
monocytes to macrophages = carry out phagocytosis
B lymphocytes to plasma cells = produce antibodies
2 ways a foreign organism can be destroyed
Phagocytosis - engulfed by neutrophil/macrophage
Lysis - cell membrane attacked and ruptured
the two intrinsic defence systems of the immune system
INNATE (Non-specific) - what you are born with and are active against any sort of invader
ADAPTIVE (Specific) - what develops after birth when exposed to antigens.
Both work together to get job done! neither one works alone
two types of 1st line of defines. Innate (non-specific) defence against any type of foreign material or antigens
Surface barriers - skin (keratin resists compromising), mucosal membranes (internal organs)
Chemical barriers - skin (slightly acidic, inhibit bacterial growth), HCl and enzymes in stomach, saliva and tears, mucus (traps organisms)
Types of second line of defense
Phagocytosis - engulf and destroy antigens
Lysis by Natural Killer cells (T-cells)
inflammation - Redness / Heat / Swelling / Pain (sometimes impairment)
Antimicrobial Proteins - enhance defense, attack directly and hinder antigen ability to reproduce
3 types of WBC’s involved in Phagocytosis
Macrophages - “heavy hitters” that repeatedly kill and also release ‘respiratory burst’ of oxidizing chemicals to kill antigens. Free (wander through tissues) and Fixed (stay in place)
Neutrophils - most common first responders to infection. they are destroyed during attack on invaders (suicide killer)
Eosinophils - weak phagocytes - surround parasites and release enzymes to attack
explain the process of phagocyte mobilization (EXAM)
- Leukocytes stimulate and induce
- Margination (pavementing) - WBC’s move along capillaries and cling to CAM’s
- CAM’s (cell adhesion molecules) - mark the cite of damage/infection
- Diapedesis - WBC’s squeeze between cells and move toward the injury (by amoeboid motion)
- Positive chemotaxis - WBC’s follow increasing concentration to injury
- Neutrophils are 1st responders, then monocytes which convert to macrophages
Mechanism (process) of Phagocytosis (EXAM)
- adherence to phagocyte to pathogen
- engulfing into phagosome
- fusion with lysosome
- hydrolysis/internal digestion by enzymes
- killing by burst of free radicals or oxidizing chemicals
- killing by defensins (in neutrophils)
- exocytosis of the remaining residual body (removal)
results of phagocytosis (what do you see?)
Pus - evidence that the phagocytic cells are working
Abscess - infection not cleared and walled off by collagen fibers
Lysis by natural killer (NK) cells
- large granular T-lymphocyte involved in non-specific defines.
- found in blood, lymph vessels and other tissues and crawl/look for abnormal marker proteins
- kill cells (& cancer cells) by secreting perforin and granzymes
perforin: perforates into cell and forms pores
granzymes: enter through pores and attack membrane leading to apoptosis (natural cell death/degeneration)
NOTE: NK cells also help stimulate inflammatory response
Inflammation response
triggered whenever injury/infection and prevents spread of pathogens while it prepares for repair.
4 cardinal signs: (RHSP) Redness, Heat, Swelling, Pain (and sometimes impairment)
stimulus that triggers inflammatory response
- histamine released by mast cells in loose connective tissue is the ‘early warning system’
- Toll-like receptors (TLR’s) on macrophages recognize microbes and trigger the release of cytokines (chemical messenger)
- Kinins, prostaglandins, leukotrienes, complement - are released by injured tissues. phagocytes, lymphocytes, basophils all can trigger the process of inflammatory response
Process of the inflammatory response
- inflammatory chemicals released into extracellular fluid
- triggers dilation of arterioles - increase blood flow - REDNESS and HEAT
- increased permeability of capillaries (SWELLING and PAIN)
- release of exudate (fluid) that dilutes harmful substances and aids healing by bringing more nutrients
- damaged area walled off for repair
- foreign materials moved/swept into lymphatic vessels
- More PAIN from toxins and decreased nutrients in area (prostaglandins and kinins)
- damage to mucosa - secretion of defensins increased
- All this facilitates destruction of invaders and repairs damaged tiisues