Immune System Flashcards
1
Q
Ograns of the immune system
A
- Tonsils are diffuse lymphoid tissue
- Lymph nodes protect lymph and contain lymphocytes and macrophages
- Spleen is the largest lymphoid organ; produces and stores immune cells; filters blood
- Gut-associated lymphoid tissue (GALT) is a diffuse lymphoid tissue
- Thymus produced T lymphocytes
- Bone marrow produces RBC
- Lympthatic vessels contain valves and have thin walls composed of smooth muscle and connectibe tissue; flexible to accommodate excess fluid
- The lymphatic system is a network of vessels that transport lymph, which contains excess fluid diffused into tissues from capillaries
- Lymph nodes are positioned along these vessels and filter the fluid transported via the system
2
Q
Lacteal
A
A lacteal is a small lymphatic vessel found in a villus of the small intestine epithelium
- Plays major role in absorption of fats, which are first taken up by the lympathic system in the form of chylomicrons
3
Q
3 lines of defense
A
- Physical barrier: skin, mucous, etc.
- Innate immunity: rapid, non-specific
- Macrophages, neurophils, mast cells, dendritic cells, NK cells, inflammation
- Aquired/specific immunity
- Lymphocytes (T & B cells)
4
Q
B lymphocytes
A
B lymphocytes create and express antibodies (immunoglobulins) that have a high affinity for the antigen expressed by T cells
- B cells also stimulate the formation of memory cells
- Unlike T cells, B cells are produced and matured in the bone marrow
- Plasma and memory B cells
5
Q
Innate immunity – inflammation
A
- Capillary permeability increases, allowing immune cells to access the infected sites
- Results in redness and swelling
- The infected area becomes warm
- The infected area is often painful due to swelling and presence of certain chemicals
- Function is to slow the spread of pathogens and mobilize local defense
- Fever are caused by pyrogens
6
Q
Lysozyme
A
- Found in tears
- Catalyzes the breakdown of bacterial CW
- Part of innate response
7
Q
Leukocyte
A
A leukocyte is a WBC, divied into:
- Monocyte
- Eosinophil
- Basophil
- Neutrophil
- Lymphocytes
8
Q
Innate immunity – monocytes
A
Monocytes can differentiate into macrophages and dendritic cells
-
Macrophages phagocytize (by phagocytosis) dead cells and pathogens
- If a pathogen is ingested, its antigens are then presented on the surface of the macrophage to stimulate other immune cells to mount a specific immune response to invading pathogen
- Spleen contains a very high number of macrophages
-
Dendritic cells are focused on processing antigens and presenting them to other immune cells
- Found in areas of body where contact with external environment
9
Q
Innate immunity – granulocytes
A
Granulocytes are attached to the site of injury, where they phagocytize antigens
-
Neutrophils are the first responders to sites of inflammation
- Attracted to cytokines and attract more WBC once they arrive at the site of tissue damage
- Particularly adapted to attack bacteria; main component of pus
- The most abundant WBC (50-70%)
-
Eosinophils are responsible for allergic and asthmatic responses
- Elevated eosinophils count indicates an allergic reponse or infection by a parasite
- Basophils and the related mast cells are involved in allergic response and parasite infections and the release of histamine
10
Q
Granulocytes vs agranulocytes
A
- Granulocytes contain cytoplasmic granules, while agranulocytes do not
- Granules are small vesicles that contain enzymes and other cytotoxic substances
- Agranulocytes: monocytes, B and T lymphocytes
11
Q
2 types of specific immunity
A
Cell-mediated and humoral immunity
- Humoral immunity involves antibodies (B cells)
-
Cell-mediated immunity involves Tc cells
- It allows the destruction of body cells that have been marked for destruction after viral infection
12
Q
T lymphocytes
A
Each T cells is reactive to only one random antigen type, presented by a major histocompatibility protein complex (MHC) (MHC I + MHC II) (glycoproteins on cell surface)
- In antigen presentation, MHC binds to antigens adn display them for T cells to recognize
- Most T cells undergo apoptosis (programmed cell death) bc either do not react with MHC or react too well and would attack self cells
- The ones that are not destroyed stay in circulation
-
Cytotoxic (Tc) cells (killer) recognize and respond to antigen presented by MHC I complexes
- MHC I complexes come from cells infected with viruses or developing tumors and signal Tc cells to destroy those cells
- Contains CD8 surface protein
-
Helper (TH) cells respond to antigens presented by MHC II complexes
- Releases cytokines to stimulate the immune response, causing WBC to mature and attack
- Chemically facilitate B cell and Tc cell activity
- Contains CD4 surface protein
- Natural killer (NTK) cells behave similarly to both Tc and TH cells but respond to antigens presented by other types of cells
- Once a reaction has occurred, memory T cells specific to the antigen are formed and remain in circulation for long periods of time
- Regulatory or suppressor (Treg) cells have counteracting effect that tones down the activation and continuation of immune responses
- T cell are formed in bone marrow and mature in the thymus, and then released into lymph
- Patients with AIDS have very low level of certain type of T cells
- HIV infects helper T cells
13
Q
Role of MHC I receptor proteins
A
- MHC I receptors bind to normal proteins that are produced within the cells of the body
- When a cell becomes infected or cancerous, it triggers recognition as ‘non-self’ and can be marked for destruction by a T cell
- Antigens presented by MHC I are recognized only by Tc cells that contain the CD8 surface protein
- They are present on every body cell, except for those that do not contain nuclei (RBC)
14
Q
Role of MHC II receptor proteins
A
- MHC II receptors bind to foreign antigens that have been broken down by phagocytosis
- When fragments of these antigens are presented on immune cells, helper T cells recognize a threat and can activate other immune responses
- Antigens presented by MHC II are recognized only by helper T cells that contain the CD4 surface protein
15
Q
Antibody vs antigen
A
Antigens are attacked
by the attacking antibodies
16
Q
Antibodies
A
- Variability of Fab fragments’ shape make immunity possible
- The Fab regions (two arms) are antigen-binding sites that offer the antibody’s specificity
- The Fc region the Ig class of the antibody
- When an antibody binds an antigen, it signals via the Fc chain
