15964751 Body Defence Mechanism

7/29/2019 15964751 Body Defence Mechanism

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TRANSPORT

CIRCULATORY SYSTEM IN

BODY DEFENCE MECHANISM


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BODY DEFENCE MECHANISM

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

Transmission of pathogens:

Air Contaminated food

Animal vectors

Contact

patho: disease

gens: agents


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LINES OF NATURAL DEFENCE

First Line

Second Line

Third Line


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BODYS DEFENCE MECHANISM

NON-SPECIFIC SPECIFIC

1ST LINE 2ND LINE 3RD LINE

SKIN : sweat, sebum

MUCOUSMEMBRANES :

secretion of mucus

Phagocytosis by

phagocytes

Antibodies produced by

lymphocytes


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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


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Skin A physical barrier

It has dead keratinisedlayer that is hard to

penetrate

Continual shedding of

dead skin cells prohibit

growth of pathogens

If there is a cut, the

blood clots quickly toseal the wound

To prevent blood loss

and entry of pathogens


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Sweat and Sebum

Produced by skin as

chemical barrier

Protective film over skin

Acidic sebum secretedby sebaceous glands

contain lysozymes,

which destroy cell walls

of certain bacteria


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Tears and Saliva

Tears and saliva

contain lysozymes,

which destroy bacteria

(protect eyes andmouth)


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Mucous Membranes

Lines trachea, respiratory passageways, digestiveand urogenital tracts.


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Mucous Membranes:Methods of Defense

Mucussecreted in the nasal cavity and

trachea

traps dust particles and microbial spores

contains lysozyme to destroy bacteria

The ciliain the respiratory tract sweep the

trapped particles to the pharynx.

The hydrochloric acidin gastric juice can killmany microorganisms


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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.


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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


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Lymphocyte

Lymphocytes

B Lymphocytes

produce antibody

T Lymphocytes

attack infected cells

or secrete certain

chemicals to

coordinate immune

response


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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.


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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 tostimulate phagocytosis by macrophages

Lysis binds to surface of antigens to form poreson cell membrane, which leads to cell rupture


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OPSONIZATION


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AGGLUTINATION


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Memory Lymphocyte

After recovery, some lymphocytes remain fora 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.


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Types of Immunity

Naturally Acquired

Active

Passive

Artificially acquired

Active

Passive


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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

4Your A4 paper must be divided into 4

equal parts for this assignment


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HIV and AIDS


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HIV Replication


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Effects


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Symptoms

Some people get fever, headache, sore muscles and joints,stomach ache, swollen lymph glands, or a skin rash for one or twoweeks. Most people think it's the flu. Some people have nosymptoms (AIDS.ORG 2003). In the later stages of HIV symptomsmay include:

Persistent, unexplained fatigueSoaking night sweats

Shaking chills or fever higher than 100 F for several weeks

Swelling of lymph nodes for more than three months

Chronic diarrhoea

Persistent headaches


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Transmission


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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, youshould use a condom.

For medical procedures, you can donate your

own blood in advanced.
http://www.learnitliveit.org/english/definitions.asphttp://www.learnitliveit.org/english/definitions.asp


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World AIDS Day 1st Dec


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CV disorders (eg.)

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

Arteriosclerosis (ar-tir-ee-o-skle-ROW-sis): Diseased condition inwhich the walls of arteries become thickened and hard, interfering withthe 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 whichthe blood lacks one or more of the clotting factors, making it difficult tostop 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 andlymphatic system with immature and abnormal white blood cells.

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


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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.


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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.)

15964751 Body Defence Mechanism

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