“ THE BASIC THING IS THAT EVERYONE WANTS HAPPINESS, NO ONE WANTS SUFFERING; AND HAPPINESS MAINLY COMES FROM OUR OWN

ATTITUDE RATHER THAN EXTERNAL FACTORS. IF YOUR OWN MENTAL ATTITUDE IS CORRECT,

EVEN IF YOU REMAIN IN A HOSTILE ENVIRONMENT, YOU FEEL HAPPY.”

-TENZIN GYATSO, 14TH DALAI LAMA

CHOOSE HAPPINESS!

PLEASE REFER TO PAGES 1-5 OF YOUR COMMON DISEASES OF

COMPANION ANIMALS BOOK AND CHAPTER 9 IN YOUR CLINICAL

ANATOMY AND PHYSIOLOGY BOOK

THE IMMUNE SYSTEMSystem of defense against

pathogens

Immunology

Immune System The system in the body responsible for

maintaining homeostasis by recognizing harmful from non-harmful organisms and producing an appropriate response.

Immunity The ability of the body to fight infection and/or

foreign invaders by producing antibodies or killing infected cells. DIVIDED INTO 2 LARGE CATEGORIES: NONSPECIFIC AND

SPECIFIC IMMUNITY

Foreign Invaders

Pathogens– Viruses, bacteria or

other living thing that causes disease/immune response.

• Antigens– Soluble substances:

Toxins & foreign proteins

– Particulate: Bacteria/ tissue cells

Parts of the Immune System

1. Blood - particularly White Blood Cells 2. Bone Marrow – Produces B Lymphocytes and T

lymphocytes3. Thymus Gland – consist of T Lymphocytes

(originally produced in the bone marrow)– T lymphocytes learn to recognize self from non-self– Mature and then move to spleen, lymph nodes looking

for invaders

4. Other factors: nutrition, stress, sanitation, and age

Nonspecific Immunity vs. Specific Immunity

NON-SPECIFIC IMMUNITY

NONSPECIFIC IMMUNITY includes species resistance, mechanical/chemical barriers, inflammation, & interferon/complement

First Line of Defense – The Skin - Provides Physical/mechanical and Chemical barriers Physical – hard to penetrate, made of indigestible

keratin, hairs Chemical – tears, sweat, mucous, saliva , enzymes,

sebum

Second Line of Defense –Inflammation When invaders gain access to the body there is an

inflammatory responseSIGNS OF INFLAMMATION:

REDNESSHEATPAINSWELLING

*cells of the invaded tissue release enzymes called mediators that attract white blood cells via chemotaxis. Blood vessels dilate and become more permeable. Specific white blood cells, usually neutrophils, begin to “gobble up” the foreign material (phagocytosis).

NON-SPECIFIC IMMUNITY

NONSPECIFIC IMMUNITY

• Inteferon– Substance that prevents replication of virus in the

host cell

• Complement– Group of enzymes activated during infections– Act on cell wall > pores in membranes > rupture/lysis

of the cell

NONSPECIFIC IMMUNITY

SPECIFIC IMMUNE RESPONSE

3RD Line of Defense: Specific Immune Response Conducted by cells known as lymphocytes

T lymphocytes and B lymphocytes

SPECIFIC IMMUNE RESPONSE

This is a specific response to a specific pathogen/antigen.

B-cell lymphocytes are responsible for humoral immunity, which involves the creation of Antibodies. Upon contact with a specific antigen, cloning of

B-cells creates some plasma cells which make ntibodies, while others become memory cells

Response time is slower on the first exposure to the antigen (7-10 days)

Subsequent exposure to the antigen initiates a quicker response due to the presence of memory cells

SPECIFIC IMMUNE RESPONSE

T-cell lymphocytes carry out cell-mediated immunity by directly combining with the foreign cell and destroying it or rendering it incapable of causing disease T-cells learn “self” from “non-self” in the thymus Macrophages will present foreign antigen to the

T-cell T-cells will repeatedly divide and begin to destroy

the invading organisms. Faster response

The Pathway of Specific Immune Response

Pathogens

Pathogens eaten by Macrophage

Displays portion of Pathogen on surface to T cells

Helper-T cell recognizes Pathogen

Step 1

Step 2

Step 3

Activates B- CellActivates Cytotoxic

T- Cell

Memory B-CellMemory T-Cell

Kills Infected CellsAntibodies

Immune Response Summary

Antigen

Macrophage

Helper T - Cell

Active Cytotoxic T-Cell Active B - Cell

Kills Infected Cells Plasma Cell Memory B-Cell

Antibodies

Deactivates AntigensHarmless/agglutinate/destruction

Memory T-cell

Displays copy of antigen on surface of cell

Cellular Immunity Antibody Immunity

Cellular Immunity vs. Humoral Immunity

Carried out by T-CellsInfected cells are

killed by Cytotoxic T –Cells.

Carried out by B-cellsAntibodies are

produced and dumped into blood stream.

Antibodies bind to antigens and deactivate them.

Cellular Immunity (cell-mediated) Antibody (Humoral) Immunity

Antibodies

Y-shaped protein molecule.

Made up of variable and constant regions.

Made up of Heavy and Light chains.

Produced by B-Lymphocytes

Function: Recognize antigens, bind to and deactivate them. Note: Variable region

recognizes the antigens.

How an antibody operates/works

Deactivation of a bacterium by an antibody.

Primary vs. Secondary Immune Response

Primary Immune Response This is a response to an invader the First time the

invader infects the body. No measurable immune response for first few days. Next 10 – 15 days antibody production grows steadily

Secondary Immune Response A more rapid response to an invader the 2nd time

it invades the body. Antibody production increases dramatically and in a

much shorter time period..

Primary .vs. Secondary Immune Response

Development of Immunity

Inherited immunity Genetic factors that affect baby before birth

Acquired Natural – occurs every time the animal is exposed to a

pathogen. Artificial – the result of deliberate exposure to a pathogen

such as with vaccinations.

Passive Antibodies formed in one infected animals are transferred to

another animals that is not infected.

Active Occurs when the animal’s own immune system encounters a

pathogen and produces an immune response