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23 Cards in this Set

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Types of Defense Mechanisms
1. Innate Immunity- (always there) rapid responses to a broad range of microbes. Ex: external defenses (skin, mucuous membranes, secretions); internal defenses (phagocytic cells, antimicrobial proteins, inflammatory response, natural killer cells(they nonspecifically target foreign cells)

2. Acquired Immunity- (slower but more specific) a slower response to specific microbes. Ex: humoral responses (production of antibodies); cell-mediated response (cytotoxic lymphocytes. It is mediated by specific T lymphocytes that attack and destroy virus-infected host cells or foreign cells. It is important in the defense against viral, fungal and mycobacterial infections)
Innate Immunity:
Phagocytic cells
- Neutrophils (60%)- self destructive (short lifespan)
- Macrophages- transient or resident (in spleen, nodes)
- Eosinophils- worm killers
- Dendritic cells
Innate Immunity:
Antimicrobial
- Complement system- 30 proteins that travel through the body and recognize antigens on bacteria (they either kill bacteria directly or inhibit them from replication)
Innate Immunity:
Inflammatory Response
- Dilation and Permeability- to bring in macrophages, etc to come and fight off infection
- Recruitment and Clotting
Cells of Innate Response
*Mast Cells
*Phagocytes:
- Macrophages
- Neutrophils
- Dendritic Cells
*Basophils and Eosinophils
*Natural Killer Cell- target host cells that have become infected (in a nonspecific manner. They are specialized to kill certain types of target cells.
Kinds of Acquired Immunity
* Humoral- antibodies from plasma cells; B cells form the plasma and produce them. It activates B lymphocytes which replicate to form plasma cells (which produce specific antibodies)

* Cell-Mediated- Cytotoxic T cells. They divide into cytotoxic (killer) T cells which kill the host cell
Three Main Cell Types of the Immune Response
- Lymphocytes (B and T)
- Natural Killer Cells
- Antigen-presenting cells
B Lymphocytes
- B= bone marrow
- 20-30% of lymphocytes
- bone and GALT maturation
- two types of cells that come from immature B cell: Memory B cells and Plasma Cells
T Lymphocytes
- 70% of lymphocytes
- they mature in the thymus (thymus maturation)
- three main types:
Memory T cells
Helper T cells (Th)
Cytotoxic T cells (Tc)
Helper T Cell
- macrophage breaks up antigen and puts it on surface. Helper T cell comes in and recognizes it and T cell becomes activated. It sends signal to either cytotoxic T cells or to B cells to have them become plasma cells
The concept of vaccines
- first exposure to antigen A: (primary immune response) body produces antibodies to antigen A. The response is characterized by a lag period of several days before antibodies can be detected in the blood. The initial response is inititaed by only one or a few B lymphocytes that have been genetically programmed to respond to that specific antigen)

- second exposure to antigen A: (secondary immune response) much higher to antigen A than the first response. It is more rapid and more intense (characterized by higher levels of secreted antibodies) because of the presence of specific memory B lymphocytes already programmed to respond ro that specific antigen.
Lymphatic System
- four places we're worried about: spleen, thymus (those are the two main organs), lymph nodes and tonsils

-there are interactions between capillaries and lymphatic
Lymphatic Components
- the difference between the two is whether or not they're encapsulated (surrounded by a capsule)

1. Diffuse Lymphatic Tissue- no capsule; ex: lymphnoid nodules

2. Nodular Lymphatic Tissue- capsule present; ex: lymph nodes, tonsils, spleen, thymus
Diffuse Lymphatic Tissue and Nodules
- diffuse tissue- located just underneath epithelium (regions prone to invasion). Diffuse area.

- Nodule- active immune response taking place. It has a more defined shape with a darker outside and a lighter germinal center
Interaction between T and B lymphocytes
look at figure
Lymph Nodes
- small encapsulated organs located along the pathway of lymphatic vessels
- filter lymph with blood
- have a convex side- where smaller lymphatic vessels enter
- have a concave (hilum) side- where the big blood vessel enters

Layers: cortex (B lymphocytes); deep cortex or paracortex (T lymphocytes); medulla
Lymph Nodes- function and flow
- septa extend into lymph node
- sinuses have lymphocytes that fight off infection (pathogens cleaned out of blood)
- the fluids are cleaned either through the circulatory system or the lymphatic system
Tonsils
- considered to be encapsulated
- three groups:
1. Pharyngeal- a single diffuse tonsil
2. Palatine- large tonsils at walls of oral pharynx; have deep crypts (these are the ones we think about when we hear the word tonsils); they are a large aggregation of nodules.
3. Lingual- at the base of the tongue
Thymus
- produces T lymphocytes and makes sure they recognize foreign antigens (education)
- it is a bilobed lymphatic organ
- usually the thymus gets smaller as we get older but in an alcoholic it gets larger
- the thymus has a cortex and medulla
Thymus Education
- lymphnodes travel from the medulla to the cortex and interact with the epithelial reticular cells (ERC).
- then they make different CD proteins.
- the T lymphocytes that bind get to move on into the deeper cortex toward the medulla.
- 2nd section: the "self antigen" cells are eliminated, leaving only active cells that act against foreign antigens.
Thymus Blood-Brain Barrier
- there are multiple barriers separating the inside of the thymus. This isolates the education process from foreign antigens that may be in the circulatory system.
- so it is not a permeable barrier
Spleen
- the largest lymphatic organ in the body
- function: filter blood from microbes and broken down RBC. Also to produce T and B lymphocytes.
- no medulla or cortex
- instead there are regions called red pulp or white pulp
- Red Pulp= open sinuses and cords (made up of macrophages, plasma cells). Red pulp contains large numbers of RBC that it filters and degrades.
- White Pulp= areas that look like nodules (have a central germinal area and darker outside area). Have a blood vessel going through the center. The white pulp consists of lymphatic tissue, mostly lymphocytes.
Spleen circulation
- no lymphatic ducts, just a circulatory system
- circulation within red pulp allows macrophages to screen antigens in the blood
- splenic nodule
- PALS- lymphocytes that aggregate around the central artery.
- sheathed capillaries
- its either an open or closed circulatory system (we don't know which one)
- the spleen performs both immune and hemopoietic functions (because it filters blood)