Introduction to the Immune System

Question 1

Innate Immune System

Answer 1

any part of the immune system that fights an invader that same way each time that it encounters that invader
-rapid response
-recognizes broad range of pathogens
no “memory”

Question 2

Adaptive immune system

Answer 2

any part of the immune system that fights an invader better the second time it encounters the invader

• slower response
• recognizes specific pathogens
• have “memory”

Question 3

Immunology

Answer 3

study of the immune system

Question 4

Edward Jenner

Answer 4

late 18th century
smallpox (variola) virus could be prevented by variolation (purposfully infecting a person with the virus in a controlled manner DANGEROUS)
Jenner infected subjects with cowpox (vaccina) virus
the subjects became resistant to smallpox
1798: last case of smallpox

Question 5

Vaccination

Answer 5

the innoculation of healthy individuals with a weakened form of disease causing agent to provide protection from the disease

Question 6

Skin

Answer 6

first barrier a microorganism has to cross

tough layer of dead cells prevents entry into deeper layers where they could cause infection

Question 7

Compliment

Answer 7

set of blood proteins made by liver

assemble on the surface of a microorganism creating gaping holes and killing it

Question 8

Specialized Immune System Cells- Function

Answer 8

-recognize and send alert signals
-respond and destroy invader
most are made in the bone marrow
once developed: they are released into blood stream
some circulate, others travel to tissues

Question 9

Multipotent Stem Cells

Answer 9

in bone marrow: can give rise to Lymphoid and Myeloid stem cells

Question 10

Lymphoid Stem cells

Answer 10

give rise to lymphocytes (white blood cells)

Question 11

Myeloid Stem cells

Answer 11

give rise to red blood cells, platelets, and cells of the immune system

Question 12

Monocyte

Answer 12

resides in a tissue as a tissue-resident macrophage
one of the sentinels for the immune system
phagocyte
one of its jobs is to monitor tissues for the presence of molecules made by microorganisms/viruses
once it finds something- it triggers inflamation
this inflammation allows the body to swiftly and efficiently eliminate the microorganism

Question 13

Macrophage: Mechanism of Action

Answer 13

1. microorganism enters- molecules made are sensed by macrophage which starts signaling molecules
2. Signaling molecules diffuse away and cause nearby capillaries to widen and become leaky (why swelling and heat accompany inflammation)
   when the capillaries become leaky, other cells exit bloodstream towards infection

Question 14

Neutrophils

Answer 14

phagocyte
normally resides in blood- enters tissue in response to infection
swallow small microorganisms- phagocytosis
enclosed in a membrane compartment where the neutrophil unloads toxic chemicals killing it

Question 15

Toll-like receptor (TLR)-3

Answer 15

senses double stranded RNA from viruses

allows the innate immune system to detect a variety of viruses the FIRST TIME the virus infects

Question 16

Innate external barriers

Answer 16

skin/exoskeleton, acidic environment, secretions, mucous membranes, hairs, cilia
1st line of defense

Question 17

Innate internal defenses

Answer 17

phagocytic cells, natural killer cells, defensive proteins, inflamitory response
2nd line of defense

Question 18

Adaptive responses (lymphocytes)

Answer 18

-defense against pathogens in body fluids
-defense against pathogens inside body cells
third line of defense

Question 19

B Cells

Answer 19

defend body against any microorganism or virus that is not inside of a cell (extracellular bacteria, viruses travelling between cells)
arise from stem cells in the marrow
Exits marrow and populates the peripheral lymphoid organs (lymph nodes)
ANTIBODY RESPONSE

Question 20

T cell

Answer 20

defends body against any microorganism that is ‘hiding out’ inside of a cell (intracellular bacteria, virus infecting a cell)
arise from stem cells in the marrow
complete their maturation in the thymus before populating peripheral lymphoid organs

Question 21

Antigen

Answer 21

anything Band T cells recognize
-carbohydrates on the surface of the bacteria, proteins made by bacteria and viruses (ect)
Antigens are recognized by highly specific antigen receptors expressed on the surface of B cells and T cells

Question 22

How do B and recognize and respond to their antigens?

Answer 22

receptor on the surface will bind directly to the surface of the B cell will bind directly to its antigen
once the cell has found it’s antigen it replicates and makes clones

Question 23

Clonal selection

Answer 23

an antigen selects a B cell with a receptor that matches it and selected cells from clones
some of these clones become effector cells which destroy the antigen

Question 24

Clonal selection: Problem

Answer 24

• there are countless antigens
• there is a B cell in your body with a receptor for each and every one
• even antigens that dont exist

Question 25

How can your body make so many different B cells?

Answer 25

Solution: a single cell gives rise to a large pool of B cells
Each B cell has a unique RANDOMLY GENERATED receptor
then clonal selection can occur

Question 26

Peter Medwar autoimmune disease Experiment 1950s

Answer 26

Removed skin from one mouse strain (strain A)
skin was grafted onto genetically distinct mouse strain (mouse B)
RESULT: graft was rejected (recognized as non-self by the immune system of strain B)
Medwar then purified cells from strain A mice and injected them into neonatal strain B mice
Skin graft was repeated
RESULT: graft was accepted

Question 27

Immunological Tolerance

Answer 27

the immune system can learn to tolerate anitgens

*clonal detection

Question 28

Clonal Detection

Answer 28

self reactive B/T cells are detected during development

Question 29

Clonal Selection Postulates

Answer 29

1. each lymphocyte bears a single type of receptor with a unique specificity
2. interaction between foreign molecule and a lymphocyte receptor capable of binding that molecule with high affinity leads to lymphocyte activation
3. the differentiated effector cells derived from an activated lymphocyte will bear receptors of identical specificity to those of the parental cells from which that lymphocyte was derived
4. Lymphocytes bearing receptors specific for ubiquitous self molecules are deleted at an early stage in lymphoid cell development and are therefore absent from repertoire of mature lymphocytes