Unit 10 - Diseases & Immunity

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Questions and Answers

What is the primary role of mechanical barriers in the body's defense against pathogens?

To kill pathogens using strong acids

To prevent pathogens from entering the body (correct)

To trap pathogens in mucus

To produce antibodies

Which method of disease transmission involves the direct transfer of body fluids?

Direct contact (correct)

Airborne transmission

Indirect contact

Vector-borne transmission

What is the function of stomach acid in the immune response?

To produce antibodies against pathogens

To serve as a mechanical barrier

To trap pathogens in mucus

To kill pathogens that enter through food or swallowed mucus (correct)

How does phagocytosis contribute to the body's immune response?

By engulfing and digesting pathogens Signup and view all the answers

What is the primary purpose of antibodies in the immune system?

To agglutinate pathogens and signal for their destruction Signup and view all the answers

What is meant by the term 'active immunity'?

The body producing its own antibodies and memory cells Signup and view all the answers

Which of the following best describes pathogens?

Disease-causing organisms capable of transmission Signup and view all the answers

What role do hairs in the nose play in immune defense?

They serve as a mechanical barrier against inhaled pathogens. Signup and view all the answers

In which scenario would a pathogen be transmitted through indirect contact?

Touching a surface contaminated by an infected individual Signup and view all the answers

What differentiates antigens from antibodies?

Antigens are found on pathogens' surfaces, while antibodies are produced by the body. Signup and view all the answers

What is the main function of antibodies in the immune response?

To attach to antigens and signal for phagocyte action Signup and view all the answers

How do memory cells contribute to immunity after an initial infection?

They allow for faster antibody production during reinfection Signup and view all the answers

What characteristic of pathogens makes memory cell immunity ineffective in some cases?

The pathogens' ability to mutate and change antigens Signup and view all the answers

What is the purpose of vaccinations?

To introduce weakened or altered pathogens to provoke an immune response Signup and view all the answers

What is herd immunity?

When a significant proportion of the population is vaccinated, protecting all Signup and view all the answers

What role do phagocytes play in the immune response?

They engulf and destroy pathogens, particularly those agglutinated by antibodies Signup and view all the answers

What advantage does passive immunity provide, especially in infants?

It provides immediate but temporary protection through antibodies from another individual Signup and view all the answers

What is an antitoxin?

A protein that neutralizes bacterial toxins Signup and view all the answers

What is the primary cause of diarrhoea in cholera?

Severe ionic imbalance from bacterial infection Signup and view all the answers

How does oral rehydration therapy help those suffering from diarrhoea?

It replaces lost water and ions through a balanced formula Signup and view all the answers

What effect can a decline in vaccination rates have on a population?

Higher risk of mass infections and greater potential for epidemics Signup and view all the answers

What is active immunity?

Immunity gained through direct infection and recovery or vaccination Signup and view all the answers

During which stage does a lymphocyte take several days to react to a pathogen for the first time?

Initial infection phase Signup and view all the answers

What is a major benefit of childhood vaccination programs?

To ensure high levels of immunity in the population from an early age Signup and view all the answers

Study Notes

Pathogens

A pathogen is an organism that causes disease
Pathogens spread diseases which are known as transmissible diseases
Pathogens spread in various ways, including direct contact (e.g., transfer of body fluids like blood or semen) and indirect contact (e.g., pathogens leaving a host and being carried to another individual).

Methods of Transmission

Droplets in the air (e.g., common cold, influenza)
Food or water (e.g., cholera, typhoid, dysentery)
Contaminated surfaces (e.g., athletes foot, salmonella)
Insect bites (e.g., malaria, dengue fever)

Body Defences

There are three main ways the body defends against disease
Mechanical barriers:
- Skin acts as a barrier against pathogens.
- Hairs in the nose trap pathogens.
Chemical barriers:
- Mucus traps pathogens and can be expelled (e.g., coughing, sneezing, swallowing).
- Stomach acid kills pathogens.

Controlling the Spread of Disease

Simple hygiene and sanitation measures are used to prevent the spread of pathogens.
Food preparation: Keeping food chilled and preparing it hygienically prevents bacterial growth, hand washing is important for preventing cross-contamination
Waste disposal: Regular disposal of waste to prevent the spread of flies and contamination; rubbish bins should be covered.
Sanitation: Proper disposal systems (plumbing, drains) in homes and public places are essential to prevent the spread of pathogens.
Waste Water Disposal: Treating raw sewage removes solid waste and kill pathogens.

Active Immunity

Active immunity develops memory cells that respond to future infection
It can happen when the body is infected with a pathogen, causing lymphocytes to produce antibodies specific to that pathogen.
Another method is receiving a vaccine that contains a harmless or altered pathogen exposing the body to the pathogen's antigens; this stimulates antibody production and memory cell development.

Antigens & Antibodies

All cells have antigens (proteins) on their surface, which provide a means of identification
Lymphocytes recognise foreign antigens
Antibodies are produced to complement the antigens
Antibodies clump pathogens together for easier elimination by phagocytes
Memory cells are created that retain instructions for faster response to future pathogen encounters.

Vaccination

Vaccinations boost the body's defense against specific diseases
They introduce a harmless or altered form of the pathogen to develop memory cells, preventing infection and generating long-term immunity.
This is key for herd immunity where a large enough percentage of the population is vaccinated, providing widespread protection.

Passive Immunity & Breastfeeding

Passive immunity is short-term and gained from antibodies from a different source.
Antibodies are passed from a mother to a baby through breast milk which are important in fighting infection until the baby's immune system is fully developed
The body does not produce its own antibodies in this case.

Cholera

Cholera is a bacterial infection causing severe diarrhea.
The bacteria (Vibrio cholerae) produces a toxin that stimulates chloride ions to be released into the small intestine, lowering the water potential and causing water to move out of the cells into the intestine, resulting in severe diarrhea.

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Description

This quiz covers the fundamental concepts of pathogens, methods of disease transmission, and how the body defends itself against diseases. Learn about various transmission methods and the significance of hygiene in controlling the spread of diseases. Test your knowledge on the biology of pathogens and the immune response.