Chapter 22- Immune System

what are the 5 immune cell types

granulocytes- neutrophils, eosinophils, basophils

agranulocytes- monocytes and lymphocytes

what do monocytes differentiate into?

macrophages- live in the alveoli of the lungs

dendritic cells- live in the skin and mucousal membranes

microglial cells- live in the brain

what are mast cells?

cells in CT releasing histamine and heparin and are abundant near blood vessels and mucous linings

what do immune cells secrete?

cytokines- soluble proteins that regulate the immune system by communicating between cells involved in the immune response

what is innate immunity?

immunity that you are born with, immediate response. broken into…


1. skin/mucous membranes
2. non-specific internal defense

what are some examples of skin/mucous membranes being the first line of defense?

* skin; being a multi-layered physical barrier
* chemicals on mucous membranes; like sweat, lysozyme, hyaluronic acid in the skin, lactic acid in sebum, mucus, hair/cilia, acidic vaginal enviornment
* eyes; tears have lysozyme which is an antibacterial enzyme
* ears; earwax protects eardrum from bacteria and waterproofs

what is involved in the internal defense system category of innate immunity?

Cells, chemicals, and physiological responses

what cells are involved in the internal response section of innate immunity

leukocytes

what are the phagocytic cells?

neutrophils- arrive first at the site of injury

macrophage- some travel to the site of injury but some stay in the tissue

dendritic cells- work to take in the pathogen, process it and place a portion of it on the cell surface

what are the proinflammatory chemical-secreting cells?

basophils- heparin (anticoagulant) and histamine (vasodilator/increases permeability)

mast cells- reside in CT to increase fluid movement from the blood to injury

what are the Natural Killer cells?

destroy unwanted cells with release of chemicals

* perforin- makes hole in enemy cells
* granzymes- enter through the holes and trigger apoptosis

what are eosinophils?

they target parasites by releasing cytotoxic chemicals to destroy them, involved in allergic or parasitic infections

what is the second part of the internal responses (2nd line of defense)

chemicals (specifically cytokines)

what are interferons (IFNs)?

released by a variety of cells including those infected by a virus by binding to nearby cells to prevent them from being infected

what is the complement system?

proteins that are formed by the liver and become activated when needed, usually during bacterial infections

What is O-Ice?

This is how the proteins act

Opsonization- opsonin protein binding to the pathogen to mark it for destruction

Inflammation- activates basophils and mast cells to promote inflammation

cytolysis- complement proteins create a channel in enemy cell membrane causing it to lyse (makes a hole in cell membrane)

elimination- proteins connect immune complex to RBC bringing it to liver for removal

what are the two physiologic factors of internal 2nd line of defense responses?

Inflammation and fever

what is inflammation?

local, immediate, nonspecific response to injury caused by external stimuli (like a bug bite, or cut to a body part)

what is the first step of inflammation?

1. chemical release from mast cells and basophils (heparin and histamine) as well as prostaglandins which stimulate pain through reception

what is the second step of inflammation?

2. vascular changes- vasodilation occurs, permeability of capillaries increases, cell-adhesion molecules activate for leukocyte attachment at site of injury

what is the third step of inflammation?

3. leukocyte recruitment- occurs through three steps


1. margination- leukocytes go to the open area
2. diapedesis- leukocytes squeeze out of capillaries through the openings
3. chemotaxis- leukocytes move toward injury

what is the fourth step of inflammation?

4. delivery of helpful plasma proteins like complements, clotting, and pain receptor kinans

what is exudate?

extra tissue fluid formed fluid proteins and immune cells that left the capillaries during inflammatory response

what are the cardinal signs of inflammation

redness/heat (increased blood flow), swelling (from exudate), pain (chemicals stimulating pain reception), loss of function (from pain and swelling)

what is a fever caused by?

release of pathogens, tissue trauma or drug reaction

what does a fever do?

inhibits viruses and bacteria, enhances interferons and tissue repair

what is adaptive immunity (third line of defense)

a delayed response to specific antigens (like a few days), stimulated by antigens which will trigger immune response by binding to antibody of T cell

some antigens produce disease called…

pathogens

what is immunogenicity

determined by size quantity, complexity and degree of foreignness of antigen

what are epitopes?

projections on antigens serving as binding sites for the lymphocytes or antibodies

what are haptens?

molecules too small to act as an antigen alone (like bee pollen and animal dander)

how do T and B cells become activated?

through binding to an antigen through receptors on surface cells

what is a coreceptor?

helps present the antigen present itself to the T cell can look at the antigen and bind to it if needed

what is a major histocompatibility complex molecule?

transmembrane proteins making the surface of cells, where the antigen will be placed right on top and presented to lymphocyte

what is MHC class I

found on all nucleated cells. presents as a self-antigen

what is a MHC class II

surface of antigen presenting cells which are dendritic cells, macrophages, and B cells. They will take in the antigen and process it and then present it with a MHC class II molecule