Lecture 3 Flashcards
1
Q
Immunity
A
a collection of mechanisms that defend the human body against disease
2
Q
Physical Barriers
A
- intact skin
- mucus, cilia, coughing, sneezing
- tears, saliva, urine
3
Q
Chemical Barriers
A
Skin secretions- acid pH disrupts bacterial growth
Hair follicles- sebum is anti-microbial and protects from bacteria and fungi
Tears, saliva, nasal, perspiration have lysozome
Stomach has HCl and enzymes which digest ingested pathogens
4
Q
Lymphoid system functions
A
- self/non-self recognition
- protection from foreign invader
- B-cells, T-cells, and antigen presenting cells initiate and participate in the immune response
5
Q
Lymphoid system organs
A
- lymph node
- thymus (T cell maturation)
- spleen
- diffuse lymphoid tissue
6
Q
MALT
A
Mucosa associated lymphoid tissue
- Gut associated lymphatic tissue (GALT)
- Bronchus associated lymphatic tissue (BALT)
- appendix, tonsils, anal region
7
Q
Primary Lymphoid Organs
A
Thymus, fetal liver, pre & post-natal bone marrow
- development and maturation of lymphocytes –> immunocompetent cells
8
Q
Secondary Lymatic organs
A
Lymph node, spleen, diffuse lymphoid tissue, post-natal bone marrow
- provide the proper environment for immunocompetent cells to react
9
Q
Lymphatic vessels
A
- carry lymph through an open circulation (no pump, open ended capillaries)
- sucks up all extracellular fluid in a given area after fluid exudation
10
Q
Spleen
A
filters blood
- enters artery, leaves through vein
- sinusoids all throughout, lined with macrophages
- every RBC is checked, any with a marker are killed immediately
11
Q
Lymph node
A
- contains lymph nodules
- filtration units all along the pathway
- pathways lined with macrophages for phagocytosis of antigens
- filters out the lymph concentrated in the knee, groin, under the arm, neck
- paracortex-region is between the cortex and medulla
- in through the convex side, out through the concave side
12
Q
Lymph nodule
A
aggregation of B-cells
13
Q
Peyer’s Patch
A
Located in the ileum, permanent lymph nodules
- primary lymph nodule not stimulated
- secondary lymph nodule stimulated
14
Q
Lymph node swelling
A
Indication of infection
- antigen gets in
- lymphocytes proliferate (B cells @ cortex, T cells @ paracortex region)
- creation of memory B and T cells
15
Q
Thymus
A
- located in the superior mediastinum
- encapsulated organ, two lobes
- originates early in the embryo and continues to grow until puberty
- T cells migrate to the thymus to become immunologically competent
16
Q
Thymus structure
A
- outer cover made up of collagen
- tribecula
- connective tissue inside the entire organ for complete compartmentalization
- two lobules, no communication between them
17
Q
Effects of Thymus removal
A
In early development, it causes irreversible damage to the body’s immune system
18
Q
Major components of the Thymus
A
Parenchyma (cellular)
Stroma (connective tissue)
19
Q
Thymus Cortex
A
- dense population of lymphocytes, mainly T-cells
- macrophages and epithelial reticular cells (ERC: 3 in cortex; 3 in medulla)
20
Q
Type I ERC
A
- separates the capsule and scepta from the cortex
- surrounds the vascular elements of the cortex
- forms blood-thymus barrier
- isolates the thymus from the body via occluding junctions
- polymorphous nuclei and a well defined nucleolus
21
Q
Type II ERC
A
- located mid cortex
- long wide processes that form desmosomal unctions with each other which further subdivides the cortex
- large, pale nucleous
- no nucleolus
22
Q
Type III ERC
A
- deep in the cortex near the medulla- corticomedullary junction
- long wide processes similar to type I
23
Q
ERC and T cells
A
- Type II and III present self-antigens MHC I and II to developing T-cells
24
Q
T cell education process
A
- naive T cell leaves bone marrow and enters thymus through outer thymic cortex
- MHC I and MHC II are presented to the T cells
- weak and extremely strong signals are sent for apoptosis
- T cells with stronger signals enter the thymic cortex and are given etiher CD4 or CD8 receptors
- T cells migrate to the thymic medulla to test recognition of self
- T cells that bind strongly with self are sent for apoptosis
25
Cells involved in Innate Immunity
Mast cells- release bioactive chemicals
Neutrophils (PMN)- signals other cells and phagocytoses pathogens
Macrophages/Dendritic cells- stimulates other immune cells and phagocytoses pathogens
26
Acute Inflammation
1. pathogens enter the wound
2. Platelets release blood-clotting proteins
3. Mast cells secrete factors that mediate vasodilation and vascular constriction
4. Fluid and cellular exudation occurs
5. Neutrophils secrete factors that kill and degrade pathogens
6. Neutrophils and macrophages remove pathogens through phagocytosis
7. Macrophages secrete cytokines that attract lymphocytes
8. Inflammatory response continues until everything is prepared
27
PAMPs
Pathogen Associated Molecular Patterns
- recognized by PRR's on phagocytes
Examples:
- LPS
- flagellin
- lipoteichoic acids
- peptidoglycan
- ds/ss vRNA, bacterial DNA
- repeating structural units
28
PRRs
Pattern Recognition receptors
29
Classes of PRR
C-type Lectin receptors- mannose, fucose, glycan carbs
Toll-like receptors- 2&4 for LPS; 3 for dsRNA; 5 for flagellin
NOD-Like receptors- MAMPs and increase pro inflammatory cytokines
RIG1- binds vRNA to increase interferon and anti-viral cytokines
30
What happens when a bacteria is in the lung?
- initial contamination (starts to grow)
- colonization (establishment)
- mast cells + macrophages enter
- mast cells are degranulated and release histamine
- AI begins
31
Fibroblast function
fix damaged areas and assist in re-epithelialization
- main role is to lay down collagen in areas of non-pathology
- lay down scar tissue in pot holes
32
Healing
- result of resolution/repair
| - return of injured tissue to normal structure and function (non-extensive injury; parenchyma capable of regenerating)
33
Fibrous Repair sequence
- cut in skin, bleeding, formation of blood clot
- rapid accumulation of neutrophil and macrophages
- macrophage wound debridement
- capillary budding from pre-existing capil, form arterioles and venules
- fibroblast enter and remodel fibrin-fibronectin matrix into scar tissue
34
Granulation
process by which the blood clot was converted into fibrous connective tissue
- pink (collagen + RBC), soft granular (capillaries) appearance
35
Antigen
Foreign body; epitope- region that reacts with an antibody, TCR, SIGs
36
Types of Immunoglobulins
IgM stops infection by toxins and viruses
IgG protects newborns
IgA defense of mucosal surfaces
IgE allergy
IgD triggers B lymphocytes
37
Antigen Presentation
- antigen enters APC
- enzyme inside cell breaks antigen into pieces (degradation starts w/ lysozome when fusing with vesicle)
- antigen pieces bind to MHC protein inside endoplasmic reticulum
- MHC-antigen complex is transported to the cell surface via Golgi apparatus
- MHC protein presents the antigen on the surface of the cell membrane
38
Effector Helper T cells function
TH1 --> cell mediated immunity
TH2 --> humoral immunity
release interleukins
- helps stimulate proliferation
some turn into memory T cells, others turn into effector T cells
39
Effector Cytotoxic T cells
- CD8 recognizes MHC molecules
- proliferates once activated
- perforin forms a pore allowing granzyme to enter, leading to apoptosis
40
B cells
- clonal selection
- proliferates into memory B cells and plasma cells
- BCR binds to T independent antigen to activate B cell
- some B cells require TH cells for T dependent antigens
41
Autoimmunity
immune system attacks self cells
- unknown etiology
- tissue/organ specific and non-specific
- arthritis, Crohn's
42
Hypersensititivity
immune system overreacts during the second response to the same antigen
- immediate
- cytotoxic
- immune complex
- delayed
- allergies
43
Delayed-type hypersensitivity
- cell-mediated hypersensitivity characterized by tissue damage due to inflammatory responses produced by TH1
44
TB
Tuberculosis
- has cord factor
- lethal to WBC
- more DTH reactions, less effective immune response
- need 2nd one for immune system to recognize
- takes months, forming granuloma as a response
