TRANSPORTCIRCULATORY SYSTEM IN

BODY DEFENCE MECHANISM

BODY DEFENCE MECHANISM

To protect body against pathogens (disease-causing MO) that may enter.

Transmission of pathogens: Air Contaminated food Animal vectors Contact

patho: diseasegens: agents

LINES OF NATURAL DEFENCE

First Line

Second Line

Third Line

FIRST LINE OF DEFENCE

Prevention of pathogens entering the body by mean of physical and chemical barriers. Skin

Sweat Sebum

Tears and saliva Mucous membranes

Skin A physical barrier It has dead keratinised

layer that is hard to penetrate

Continual shedding of dead skin cells prohibit growth of pathogens

If there is a cut, the blood clots quickly to seal the wound To prevent blood loss

and entry of pathogens

Sweat and Sebum

Produced by skin as chemical barrier

Protective film over skin Acidic sebum secreted

by sebaceous glands contain lysozymes, which destroy cell walls of certain bacteria

Tears and Saliva

Tears and saliva contain lysozymes, which destroy bacteria (protect eyes and mouth)

Mucous Membranes

Lines trachea, respiratory passageways, digestive and urogenital tracts.

Mucous Membranes: Methods of Defense Mucus secreted in the nasal cavity and

trachea traps dust particles and microbial spores contains lysozyme to destroy bacteria

The cilia in the respiratory tract sweep the trapped particles to the pharynx.

The hydrochloric acid in gastric juice can kill many microorganisms

SECOND LINE OF DEFENCE

The non-specific killing action by phagocytic WBC (e.g. neutrophil-blood, macrophages-IF; some dissolved e.g. venom and toxin).

They are attracted by chemicals produced at the sites of infection, engulf and ingest MO or other particles (like debris) by phagocytosis.

Some phagocytes may also be destroyed by toxins of pathogens.

THIRD LINE OF DEFENCE

Immune System System triggered in response to the presence

of foreign substance (antigen = proteins / polysaccharides usually found on cell membrane of MO or foreign tissues) in our body.

Specific / targeted response Immunity

The state which the body is resistant to infections by pathogens

Lymphocyte

Lymphocytes B Lymphocytes –

produce antibody T Lymphocytes –

attack infected cells or secrete certain chemicals to coordinate immune response

Antibody

Protein produced by lymphocytes in response to the entry of an antigen into the body.

Each type of antibody is specific to a particular antigen.

They help to destroy pathogens in different ways.

Types of Antibody Action

Neutralisation – neutralizes toxins Agglutination – binds to surface of antigens and

cause clumping of bacteria cells Precipitation – precipitates soluble antigens to

form immobile precipitates Opsonisation – binds to surface of antigens to

stimulate phagocytosis by macrophages Lysis – binds to surface of antigens to form pores

on cell membrane, which leads to cell rupture

Memory Lymphocyte

After recovery, some lymphocytes remain for a period of time. Memory lymphocytes

Defend against future infection. Infection by the same type of antigen

Therefore, we are immune against particular diseases. Immunity – ability of organism to resist infection

by pathogens or their toxin effects.

Types of Immunity

Naturally Acquired Active Passive

Artificially acquired Active Passive

Homework…

Find the graphical representation of each type of immunity. Draw the line graph(s) in a piece of A4 paper Make sure there are:

Title Axis labels and units Graph labels

1

3

2

4

Your A4 paper must be divided into 4 equal parts for this assignment

HIV and AIDS

HIV Replication

Effects

Symptoms

“Some people get fever, headache, sore muscles and joints, stomach ache, swollen lymph glands, or a skin rash for one or two weeks. Most people think it's the flu. Some people have no symptoms” (AIDS.ORG 2003). In the later stages of HIV symptoms may include:   Persistent, unexplained fatigue Soaking night sweatsShaking chills or fever higher than 100 F for several weeks Swelling of lymph nodes for more than three months Chronic diarrhoea Persistent headaches

Transmission

How can you avoid infection?

The only 100% safe way to avoid HIV infection are through abstinence and never sharing needles.

If you decide to be sexually active, you should use a condom.

For medical procedures, you can donate your own blood in advanced.

World AIDS Day 1st Dec

CV disorders (eg.)

Anemia (ah-NEE-me-yah): Diseased condition in which there is a deficiency of red blood cells or hemoglobin.

Arteriosclerosis (ar-tir-ee-o-skle-ROW-sis): Diseased condition in which the walls of arteries become thickened and hard, interfering with the circulation of blood.

Atherosclerosis (ath-a-row-skle-ROW-sis): Diseased condition in which fatty material accumulates on the interior walls of arteries, making them narrower.

Hemophilia (hee-muh-FILL-ee-ah): Inherited blood disease in which the blood lacks one or more of the clotting factors, making it difficult to stop bleeding.

Hypertension (hi-per-TEN-shun): High blood pressure. Leukemia (loo-KEE-mee-ah): Type of cancer that affects the blood-

forming tissues and organs, causing them to flood the bloodstream and lymphatic system with immature and abnormal white blood cells.

Sickle cell anemia (SICK-el cell ah-NEE-me-yah): Inherited blood disorder in which red blood cells are sickle-shaped instead of round because of defective hemoglobin molecules.

Appreciating a healthy CV system Stick to a nutritious, well-balanced diet. Control your blood pressure. Control blood cholesterol. Prevent and manage diabetes. Quit smoking. Minimize stress.

An electron micrograph scan of a human aortic valve. The aorta is the main artery of the systemic circulation. (Photograph by P. Motta. Reproduced by permission of Photo Researchers, Inc.)