Week 2 Flashcards
Function of immune system (2)
- protect body from pathogens
- destroy abnormal cells (Cancerous)
2 systems to protect against pathogens
1) innate immune system (ade up of barriers and innate cells)
2) adaptave immune system (B - lymphocytes and T lympthocytes)
What makes up innate immune system (2)
barriers
innate cells
What makes up adaptive immune system (2)
- B - lymphocytes
- T - cells
Properties of innate immune system (7)
- Innate = int eh body since birth
- does not require/have memory
- responds immediately
- is always initiated when pathogen contacts body
- non-specific
- uses pattern recognition receptors (PRRs) that recognize microbial structures
- first and second lines of defence
How do pathogens enter our bodies (4)
- skin
- gastrointestinal tract
- respiratory tract
- urogenital tract
Barriers - physical
- skin (tight junctions of epithelial cells)
- mucous membranes (globlet cells produce mucous, ciliated epithelial cells sweep it away)
Barriers - chemical
- acidic environment
- lysosome (tears, saliva)
Barriers - microflora
- microflora = normal flora keep other bacteria in check
Microflora - benefits (5)
- can have bacteria that interact normally with the body
- associate with epithelial cells line all pathogen entry points
- produce chemicals that can inhibit growth of invading bacteria
- symbiotic relationship
- can be opportunistic (when host is weakens, or in a new place)
Second line defences (4)
- defensive cells
- defensive proteins
- inflammation
- fever
WBC of innate immune system (7)
- neutrophils
- monocytes
- mast cells
- macrophages
- natural killer cells (lymphocytes)
- basophil
- dendritic cell
Neutrophils (2)
- first responders
- live in blood
Phagocytes (3)
- neutrophils
- macrophage
- immature dendritic cells
Macrophage (2)
- arise from blood monocytes
- can consume larger particles
Immature dendritic cell
- important intermediary between innate and adaptive immune system
Eosinophils (3)
- defense against parasitic infections
- able to digest much larger particles
- also have role in allergic reactions
Lymphocytes - Natural killer (2nd line) (4)
- surveys body for abnormal cells
- kill intracellular viruses
- role in killing cancerous cells
- cytoplasmic granules = toxic enzymes that are injected into abnormal cell, degradation of viral RNA/DNA = apoptosis
Defence proteins (5)
- complement system
- 30+ plasma and cell surface proteins that work in concert to fight invading microorganisms through
- opsonization–>phagocytosis
- inflammation
- lysis
Pro-inflammatory Cytokines
- produce chemotaxis of leukocytes
- EX: chemokines, interferons (IFN)
Inflammation - what (3)
- activated phagocytes secrete chemokines and pro-inflammatory cytokines
- vasodilation and increased vascular permeability cause redness, heat, swelling
- inflammatory cells migrate into tissue, releasing inflammatory mediators that cause pain
Hypothalamus and temperature regulation
- activated = prostaglandins
–> fever (early response to an infection)
–>increased body temp kills pathogens, slow bacterial growth, speed up body defences
Phagocytosis
- macrophage/neutrophil ingest and kill invading pathogens
Phagocytosis steps (3)
1) recognition and adherence
2) engulfment
3) intracellular killing
Properties of adaptive immunity (6)
- can distinguish one specific microbe from another
- develops memory for subsequent exposures of the same microbe
- Two types (humoral immunity = B and cell mediate immunity = T)
- T cell immunity important against intracellular pathogens
- B cell immunity (Abs) help eliminate extracellular pathogens
- cannot distinguish microbial antigens from self antigens –> autoimmune disorders
Humoural immunity - function (3)
- produce specific antibodies to fight against particular extracellular pathogens
- stored in lymphoid tissue, produced in liver
- activated after exposure to antigen
Activation of humoural immunity (5)
- antigen recognition
- activation of B lymphocytes
- proliferation
- differentiation
- OUTCOME = antibody secretion, isotope switching, affinity maturation, memory B cell
Antibodies - what
- Immune Globulin (IG)
Immune Globulin - types (5)
- G = IgG
- A = IgA
- M = IgM
- E = IgE
- D = IgD
IgG - 3
- most abundant
-can cross the placenta and enter the fetus (3 months after birth - enter tissues via inflammation to destroy infection (enhance phagocytosis)
IgA (3)
- bodily secretions (tear, intestinal mucous, saliva)
- mucosal immunity in GI and resp to protect against enterence of bacteria
- importance to newborns in breastfeeding
IgM (2)
- primary pathogen response
- neutralize pathogens
IgE (3)
- hypersensitivity reaction
- some parasitic infection (mast cell)
- does not function in neutralization or phagocytosis
IgD (3)
- B cell receptor
- help to bind antigens
- currently unknown function
Role of antibodies
1) neutralization
2) Fc receptors
Role of antibodies - neutralization (1)
- block pathogen receptors that are used to gain entry in to a cell or tissues
Role of antibodies - Fc receptors (1)
- phagocytes express surface receptors that bind Abs, called Fc receptors which triggers phagocytosis
Primary response and Ig antibodies
- Ab response: IgM secreted first, then IgG/A/E later
Memory response and Ig antibodies
- high number of IgG, IgA or IgE
Lab results - differentiating between acute and previous infection
- IgM - “It’s got Me” = acute
- IgG - “It’s Gone” = previous infection
Blood types and reactions - IgM
- A antigens - blood type B
- B antigens - blood type B
- both = AB
- neither = O
- individuals with type A have pre-informed antibodies to type B antibodies, which cause glutenation and hemolysis of antibodies…different
Cell Mediated immunity (3)
- intracellular bacterias, viruses, any bacteria that are out of reach of antibodies and have escaped phagocytosis
- T cells = bone marrow, then Thymus, then maturation
- Helper T cells and cytotoxic T cells
Main defences in T cell immunity
- T helper cell (CD4+)
- Cytotoxic T cells (CD8+)
MHC
- have classes 1 and 2
- play role in adaptive branch
- presenting peptides on the cells surface for T cells
T cell receptor (TCR)
- have antigens from bacteria presented to them
- required
- expresses variable region specific for one specific peptide or antigen, creates antigen binding site
Cell Mediated Immunity
- intracellular bacteria, viruses, bacteria out of reach of antibodies and have escaped phagocytosis
- T cells arrise in bone marrow –> migrate to Thymus for multiple stages of maturation
- TCR, CD4, CD8 co-receptors
- helper T cells and cytotoxic t cells
CD4+
- T helper cells
CD8+
cytotoxic T cells
MHC molecule
- classes 1 and 2
- play role in adaptive immune system
- present peptides on cell surface for recognition by T cells
T cell receptors bind to
pROTEIN antigens presented by all antigens
How does T cell function
an MHC molecule presents a pathogen peptide
2 classes of MHC molecules and which type of T cell
- MHC class I molecules = cytotoxic T cells
- MHC class II molecules = helper T cells
Steps of T cell activation (3)
1) recognition and activation
2) proliferation and differentiation
3) effector function
T cell transformation as it activates:
1) APC
2) Naive T cell
3) activated T-cell
4) effector T-cell OR memory T-cell
Helper T-cell - CD4 - cytokines
- interferon = macrophages, apoptosis, stimulates B cells to stimulate
- alarm bells to all other cells of immune system
Cytotoxic T cells -effector
- effector = toxic enxymes that cause nucleic function to decline = apoptosis
