SCIENCE FORM 2 CHAPTER 4 HUMAN HEALTH

COMPREHENSIVE AND EFFECTIVE

SCIENCE FORM 2

CHAPTER 4

HUMAN HEALTH

CONTENT

4.1 INFECTIOUS DISEASES

WATERBORNE DISEASE

HOW CHOLERA IS TRANSMITTED

AIRBORNE DISEASE

DISEASE THROUGH CONTACT

DISEASE THROUGH VECTORS

4.1 NON - INFECTIOUS DISEASES

SELF CHECK 4.1

4.2 BODY DEFENCE

SELF CHECK 4.2

EXAM FOCUS

by Amelia Bashahruddin

4.1

INFECTIOUS DISEASES

1. Infectious diseases are normally caused by pathogens.

2. Pathogens are microorganisms like bacteria, virus,fungus and harmful protozoa.

3. Parasitism, a type of symbiosis which occurs between a pathogen and a person who contracts an infectious disease caused by the pathogen in which

(a) the pathogen is the parasite that obtains food from its host.

(b) the person who contracts the infectious disease is the host that is harmed.

4.Infectious diseases are spread to humans in the following ways.

(a) Waterborne - Example of a disease is cholera.

(b) Airborne - Examples of diseases are tuberculosis (TB), flu, H1N1 and SARS.

(d) Vectors - Examples of diseases are leptospirosis (rat urine disease), dengue fever, zika and malaria.

by Amelia Bashahruddin

CONTENT

by Amelia Bashahruddin

WATERBORNE

DISEASE

1. Waterborne diseases often occur during and after floods.

2. Cholera is an infectious disease transmitted through water.

3. Cholera is caused by the cholera bacterium,Vibrio cholerae.

4.Modes of transmission of cholera include

(a) food and drinks contaminated with cholera bacteria,

(b) sewage system, rubbish and faeces,

(d) houseflies which land on contaminated food and drinks.

CONTENT

by Amelia Bashahruddin

HOW CHOLERA

IS TRANSMITTED ?

The symptoms of this disease can be identified when the patient

experiences the following symptoms.

(a) Diarrhoea

(b) Vomiting without nausea

(d) Muscle cramps

When a person has contracted cholera, the patient needs to be given treatment such as taking a saline solution to overcome the problem of dehydration and taking antibiotics like tetracycline and erythromycin to reduce the symptoms of the disease.

Preventive steps that can be taken to avoid contracting this disease are as follows.

(a) Drink or eat food that is clean or thoroughly cooked.

(b) Drink boiled water.

(d) Store food and drinks properly so that houseflies cannot land on the food or drinks.

CONTENT

White Card Stock Paper with One Ripped Edge

1. Airborne diseases can be spread in two ways.

(a) Through droplet transmission

(b) Through dust transmission

2. Infectious diseases that are spread through the air include tuberculosis (TB), influenza A(H1N1),Severe Acute Respiratory Syndrome (SARS) and flu.

3. Pathogens like TB bacteria, H1N1 virus, SARS virus and flu virus are spread in the water droplets from the patient's mouth and nose through sneezing, coughing and speaking or from the phlegm spit by the patient that has dried and formed spores, which are then spread through the air to the surroundings.

by Amelia Bashahruddin

AIRBORNE

DISEASE

CONTENT

Infection of Diseases through Contact

1. Infectious diseases spread through contact include ringworm and tinea.

2.Ringworm and tinea are caused by fungus or spores of fungus which normally get attached to personal belongings like combs and towels. When these personal belongings are shared, the fungus will infect the skin of the other user.

by Amelia Bashahruddin

CONTENT

Infection of Diseases through Vectors

by Amelia Bashahruddin

There are diseases transmitted by animals which transfer pathogens from one host to another new host. The animals are known as vectors. Examples of vectors are rats, mosquitoes, flies and cockroaches.

A. RATS

1. Infectious diseases spread by vectors like rats are leptospirosis (rat urine disease) that results from infection of the bacterium, Leptospira sp.

2. The Leptospira sp. bacteria is spread through rat urine which has been infected and remains infectious long as the urine is still moist.

How rat urine disease or leptospirosis infects

CONTENT

Torn Paper Background. Ripped Paper Sheet. Note Paper.

B. MOSQUITO

1. Infectious diseases spread by vectors like mosquitoes are dengue fever, zika and malaria.

2. Pathogens like the dengue virus and zika virus are spread through bites by the Aedes mosquito while the parasite, plasmodium malariae (parasitic protozoa) is spread through bites from the Anopheles mosquito.

by Amelia Bashahruddin

How infectious disease like dengue fever, zika and malaria are spread

CONTENT

4.1

NON -INFECTIOUS DISEASES

by Amelia Bashahruddin

1.Non-infectious diseases are chronic diseases that cannot be spread from one individual to another.

2.Non-infectious or chronic diseases normally develop slowly in an individual's body and can withstand along time, usually a lifetime.

3.Examples of non-infectious diseases are cancer, hypertension (high blood pressure), diabetes and cardiovascular diseases like heart attack and stroke.

Cancer

1.Cancer is a disease caused by uncontrolled rapid development and cell division to form a tumor.

2. Cancer cells do not function normally and disrupt the functions and important processes of normal cells beside them. Aggressive cancer cells can spread to the entire body.

3. Among the main factors that cause cancer are as follows

(a) stress in life

(b) genetic factor

4. There are several ways to treat cancer such as chemotherapy, radiotherapy and surgery.

Hypertension, Cardiovascular Diseases and Diabetes

1.Hypertension, cardiovascular diseases and diabetes are diseases that result from

(a) unhealthy eating habits such as excessive intake of cholesterol and sugar in one's diet over a long period of time

(b) genetic factor

(d) mental stress

CONTENT

by Amelia Bashahruddin

Symptoms, treatment and preventive ways

CONTENT

SELF CHECK 4.1

by Amelia Bashahruddin

CLICK HERE FOR THE QUIZ! ENJOY..

CONTENT

4.2 BODY DEFENCE

The immune system is responsible for warding off diseases from harmful microorganisms. The three defence tiers comprise the skin and mucous membranes, phagocytosis, and the immune system.

First Line of Defence

A. Skin

1. Skin is made up of closely packed cells that form a physical barrier to prevent the entry of pathogens and protect the body.

2. Sebum and sweat are secreted on the surface of the skin to prevent the growth of microorganisms and destroy them.

3.Pathogens can only enter the body if there is an injury or a wound on the skin.

B. Mucus membrane

1.The mucus membrane is a layer that covers internal organs such as respiratory tract, digestive tract andexcretory system.

2.The mucus membrane secretes mucus to protect and trap microorganisms that enter the respiratory tract.3. There is fine hair or cilia on the respiratory tract to trap microorganisms and filter air.4. Lysosomes in tears act as an antiseptic enzyme to destroy bacteria.

by Amelia Bashahruddin

CONTENT

by Amelia Bashahruddin

Second Line of Defence

1. Second line of defence involves white blood cells to destroy microorganisms or pathogens that have successfully entered the body through the process of phagocytosis.

2. Phagocytosis is the process of engulfing, ingesting and digesting microorganisms or pathogens by whiteblood cells.

3. White blood cell will approach and surround a pathogen. Then, white blood cell will swallow and digest the pathogen.

4. Using phagocytosis, pathogens are destroyed and the body is prevented from contracting disease.

Third Line of Defence

1. Third line of defence depends on the body to resist certain diseasesby defending itself from certain pathogens.

2.This mechanism involves immune reactions.

3. These immune reactions produce special antibodies that areproduced by lymphocytes to protect the body from attacks bypathogens and antigens.

4. Antigens are foreign proteins found on the wall or outermembrane of pathogens. Antigens stimulate immune reactions.

5. Presence of antigens in the body stimulates white blood cells(lymphocytes) to produce special antibodies that act on the antigens.

CONTENT

IMMUNITY AND TYPES OF IMMUNITY

1. Immunity is the ability of the body to fight diseases that are caused by pathogens.

2. Immunity can be classified into two types, namely active immunity and passive immunity.

Active Immunity

1. Active immunity is obtained when the immunity system of an individual produces antibodies in response to immunity caused by a type of pathogen. Active immunity can normally last a long time up to several years or even a lifetime.

2. For example, a person who contracts chicken pox and then recovers will obtain active immunity from chicken pox for the rest of the person's life.

by Amelia Bashahruddin

The types of active immunity.

CONTENT

by Amelia Bashahruddin

3. Immunisation is a biochemical action through vaccination that enables the body to build immunity towards a disease.

4. Vaccination or vaccine injection is only given to a healthy individual who has not yet been infected with a certain disease.

5. Vaccine contains an antigens from a virus or bacteria that have been weakened or dead and serve to stimulate the immune system of the body and build immunity against infections diseases.

CONTENT

by Amelia Bashahruddin

Passive Immunity

1. Passive immunity is obtained when the antibodies which fight against pathogens are transferred into the

body through outside sources such as mother's milk and antiserum. Passive immunity usually does not

last long such as a few months only. For example, a baby obtains antibodies through its mother's milk.

2. Diagram below shows the types of passive immunity.