Bio f4 chap 11 Flashcards
Name two characteristics of the skin that allows the skin to react as an effective first line of defence.
- a physical defence that prevents the entry of pathogens
- pH of the skin which ranges from 3 to 5 provides an acidic environment which is unfit for microbial growth
Differentiate between antigens and antibodies.
Antigen
- a foreign substance that enters the body
- usually a protein molecule found on the wall or external membrane of a pathogen
Antibody
- protein produced by lymphocytes
- destroy the antigen
In your opinion, why must we follow and complete the immunisation plan in Malaysia?
- immunisation helps to boost the immune system by stimulating the body’s defence cells which then protect us from any possibility of life-threatening complications
- advised to comply with and complete the immunisation plan as early as possible according to the recommended schedule
Explain how HIV infection can cause someone to suffer from AIDS
- HIV virus attacks and disables the immune system of the individual infected by the virus
- attacks and destroys lymphocytes that function to destroy pathogenic microorganisms
- result in the individual contracting AIDS or acquired immunodeficiency syndrome
- the immune system of the patient becomes so weak that her body is unable to fight against diseases that would normally not infect individuals with healthy immune systems
Why is a person who is infected with HIV may not necessarily suffer from AIDS?
- a person who is infected with HIV can be a carrier without showing any symptoms for a period longer than 10 years
- this individual will only develop AIDS if his immune system becomes weak and less resistant to disease that are usually not harmful
- an example of a disease that can prove fatal to an AIDS patient is pneumonia
- someone who is infected by the HIV virus does not necessarily contract AIDS as long as his immune system stays strong and is not crippled by the HIV virus
How can AIDS be prevented?
- avoiding risky activities such as unprotected sex with infected individuals, sharing contaminated needles used for drug abuse or tattooing, or receiving transfusion of HIV-infected blood
Explain how a mother who has HIV can infect a foetus in her womb
- the mother’s placenta to the foetus in the womb
- breastfeeding
Explain how the placenta helps in the immune system of the foetus
- antibodies are able to diffuse from the mother to the foetus
- when antibodies enter the foetus, they will act on the pathogen
- this provides immunity to the foetus and prevents disease infection
Two individual acquired immunity against chickenpox in different situations. Individual X recovered form chickenpox. Individual Y was injected with a type of suspension and received immunity against chickenpox after a few months. Explain the immunity acquired by individual X.
- lymphocytes are stimulated to produce antibodies that destroy antigens
- memory cells remain in the body
- individual X acquires natural active immunity and is able to fight against the disease in the future
Two individual acquired immunity against chickenpox in different situations. Individual X recovered form chickenpox. Individual Y was injected with a type of suspension and received immunity against chickenpox after a few months. Explain the immunity acquired by individual Y.
- the suspension that is injected into individual Y is a vaccine
- vaccine is weakened pathogens used to induce lymphocytes to produce antibodies
- acquires artificial active immunity and obtains immunity against measles
A newborn baby needs to receive immunisation based on the immunisation Plan recommended by the World Health Organisation (WHO). Explain why the immunisation programme is required.
- the baby does not acquire immunity against certain disease from the mother (natural passive immunity) during the foetal stage
- after the baby reaches the age of 6 months, her natural passive immunity will recede
- the baby maybe exposed to various infectious diseases, for example measles
- babies are unable to fight infections because they do not have the immunity against the disease
- therefore, babies must be given immunisation for her to acquire immunity against diseases
Some vaccine injections require only one dose throughout the lifetime of an individual. Explain why.
- one dose is sufficient to induce the body’s immune system to produce an antibody concentration that exceeds the immunity level and permanent throughout life to prevent infections
Sinti’s mother forgot to bring Sinti to the clinic for the third dosage of the hepatitis vaccination. Explain the effects on Sinti’s immunity.
- may contract hepatitis B if she is exposed to the hepatitis B virus because the antibody level in her body has not reached the required concentration to offer complete protection from the disease
Aziman accidentally stepped on a rusty nail during a mountain climbing expedition. Describe type for injection that is suitable to be administered by the doctor. Explain your answer.
- needs to be given an antitetanus injection
- antitetanus contains antibodies that will act against tetanus
- the rusty nail stepped on by Aziman may contain Clostridium tetani that can cause tetanus (lockjaw)
- as the antibodies for tetanus is already available in the antitetanus, the antibodies can act immediately against the bacteria
- the body immune system does not need to be stimulated to produce antibodies
- the immunity acquired by Aziman is known as artificial passive immunity
- the antiserum injection can save Aziman immediately compared to immunisation that will take a long time to stimulate to produce the required quantity of antibodies
Explain how HIV can paralyse the immune system of a person infected by the virus.
- attacks and cripples the immune system (lymphocytes), rendering the body incapable of fighting diseases
- bacteria, yeasts, parasites and viruses that normally do not cause any serious diseases in individuals with healthy immune systems can now endanger and become fatal to those with AIDS
- HIV virus attacks and destroys cells that carry the CD4 molecule on their surface, for example, T lymphocyte
- the function of the T lymphocyte is to destroy pathogenic microorganisms
- in an infection, the T lymphocyte becomes a host for the HIV virus
- the HIV virus will attach itself to the plasma membrane of the T lymphocyte and start building its DNA’s genetic materials
- the viral DNA then enters the nucleus of the T lymphocyte, combines with and becomes a part of the T lymphocyte’s DNA
- in the T lymphocyte, the HIV virus can replicate to produce new HIV populations that will attack other T lymphocyte
- the HIV virus will cripple the immune system of the infected individual
