8 - Innate Immunity Flashcards
What is immunity?
resistance to disease
What type of system is the immune system and why?
functional system not an organ system
- comprised of a vast array of molecules & cells
- involved in every body system
Pathogen categories
- Bacteria
- Viruses
- Fungi
- Parasites
What is lymphatic tissue?
special form of connective tissue containing lymphocytes
primary vs secondary lymphoid organs/tissues
(name, basic function)
primary:
- red bone marrow + thymus
- immune cell production & !immunocompetence
secondary:
- lymph nodes, nodules/follicles & spleen
- where most immune responses occur
!immune cell maturation & education
Red bone marrow
(where, purpose)
in flat bones & !epiphyses of long bones
- pluripotent stem cells divide & differentiate into:
- immunocompetent B cells
- pre-T cells (immature)
!inside the head
Thymus
(where, purpose)
in anterior mediastinum
- pre-T cells develop into mature T cells
Lymph nodes
(where, purpose)
throughout the body, couple centimeters large
- filters for lymph
- adaptive immune cells gather (get inflammed during sickness because immune cells multiply)
Spleen
(where, purpose)
left, between stomach and diaphragm
- removes damaged & defective RBCs
- stores platelets
- also has the functions of a lymph node
Lymphatic nodules
(where, purpose)
throughout the body (tonsils on each side of back of throat)
- not organs, organized masses of lymph tissue
- commonly associated with mucosal surfaces
- why they’re called !MALT
!Mucosal Associated Lymphoid Tissue
Innate immune system vs Adaptive
Innate:
- defence: non-specific, 1st & 2nd line
- consists of: surface barriers, internal defenses (mechanisms & immune cells)
Adaptive:
- defence: highly specific, 3rd line
- consists of: immune cells, newly generated cell types + proteins
- has memory
- humoral (B cells) & cellular (T cells) immunity
Skin
(innate or adaptive, why & how)
Innate (1st)
Epidermis:
- many layers of cells, hard for bacteria to get through
- sheds frequently, stuck bacteria will fall off
- slightly acidic (because of keratin) hostile environment to many pathogens
Mucous membranes
(innate or adaptive, why & how)
Innate (1st)
- mucous (nose, throat…):
- viscous (traps things)
- can be ejected (coughing & sneezing)
- can be swallowed (killed in stomach)
- hairs (nose, ears…):
- trap and filter microbes
- cilia (respiratory tract…):
- hair like, move mucous
Tears
(innate or adaptive, why & how)
Innate (1st)
made by lacrimal apparatus
- makes and drains tears in response to irritants
- flushes bacteria from the eye, prevents from collecting
- have lysozymes (enzymes) that break down cell wall of some bacteria
Bodily fluids
(innate or adaptive, why & how)
Innate (1st)
Saliva:
- washes teeth & mouth
- contains enzymes
Urine:
- flow cleanses urinary system
Vaginal secretions:
- expel microbes (can be stimulated by toxins)
- slightly acidic
Sebum:
- oils form protective coating on skin
- acidic
Sweat:
- flushes microbes from skin
- contains lysozymes
Gastric juices:
- highly acidic, destroys most bacteria & bacterial toxins
Microbiome
(innate or adaptive, why & how)
Innate (1st)
- crowd the skin (harder for bad bacteria to settle & grow)
- make compounds toxic to pathogens
- many other fun things :) little frens
Antimicrobial proteins
(innate or adaptive, why & how)
Innate (2nd)
enhance innate defences by attacking or hindering reproduction of microorganisms:
- interferons: interfere with viral replication
- complement: assists other immune responses
- iron-binding proteins: steal iron from bacteria
- other antimicrobial proteins: kill or sound infection alarm
Natural Killer cells
(innate or adaptive, why & how)
Innate (2nd)
- in blood and tissues
- spontaneously kill tumour or virally-infected cells:
- perforin: makes hole in cell
- granzyme: enters cell, causing apoptosis
- release cytokines: signal other immune responses
How do natural killer cells identify problems?
by the amount of MHC class 1 molecules (flags that the cell belongs to the body)
- normal cells: enough MHC
- NK cells inhibited from killing
- tumour cells: often have reduced MHC
- NK cells not as inhibited from killing
- transformed/infected cells: can activate NK cell receptors
- flag NK cells to kill it, strong response
transformed = become cancerous
Phagocytosis
(definition, stages)
goodnotes
engulfing of foreign microbes or debris by a cell via its membrane
5 stages:
1. chemotaxis (cells move to site of issue cuz of chemical stim)
2. adherence (attach to microbe)
3. ingestion (engulf microbe)
4. digestion (using digestive enzymes)
5. killing (microbe dead)
Which cells can be phagocytes?
(innate or adaptive, name, info)
Innate (2nd)
Neutrophils:
- most abundant leukocyte
- become phagocytic near infectious material
- first to move from blood to tissues during inflammatory response
- major component of puss
Monocytes(MC)/Macrophages(MP):
- MCs: in blood –> MPs: matured MCs in tissues
- MCs recruited to infection sites to differentiate into MPs
Dendritic cells:
- highly specialized, tissue resident
- antigen presenting
How do phagocytes recognize pathogens?
Inflammation
(innate or adaptive, why & basic how)
Innate (2nd)
defensive response to any tissue damage
- helps deliver molecules & cells to infection
- prevent spread to other tissues
- prepare site for repair
How does inflammation occur?
(full mechanism/feedback loop)
goodnotes flowchart
Step 1: signalling, vasodilation, permeability of blood vessels
- damaged cells signal issue: chemical ‘alarm’ & inflammatory mediators released
- nearby macrophages active: release cytokines & chemokines
- mast cells: also release inflammatory mediators
Step 2: phagocytes move from blood to infection
- more blood nearby, decreased velocity
- permeability allows immune cells to migrate
Step 3: Healing
- clots and such
How to identify inflammation & why signals occur
- rubor & calor (redness & heat caused by increased localized blood flow)
- tumor (swelling caused by increased permeability fluid collects in tissues: edema)
- dolor (pain caused by swelling, notifies us to immobilize area)
Fever
(innate or adaptive, why & how)
Innate (2nd)
is an abnormally high body temperature
- pyrogens (type of cytokine) alter hypothalamic thermostat
- increases metabolic rate (chem. rxns faster in heat)
- higher temp. helps steal minerals from bacteria (zinc, iron…)
