Immunology

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Questions and Answers

What process do viruses use to replicate within a host cell?

They replicate their DNA and protein coats. (correct)

They consume the host cell's nutrients.

They undergo binary fission.

They divide and reproduce.

How do fungi typically obtain nutrition?

By consuming other fungi.

By secreting digestive enzymes and absorbing the digested materials. (correct)

By absorbing nutrients from living organisms.

Through photosynthesis.

Which of the following best describes protocists?

They do not contain any membrane-bound organelles.

They are all multicellular organisms.

They exclusively have features of animal cells.

They are a diverse kingdom that includes mainly microscopic and single-celled organisms. (correct)

Which of the following diseases is primarily caused by a protoctist?

Toxoplasmosis Signup and view all the answers

What is a characteristic of multicellular fungi?

They are composed of thread-like structures called hyphae. Signup and view all the answers

Which method can facilitate the transmission of diseases caused by viruses like Norovirus?

Surface transmission to a suitable host. Signup and view all the answers

What type of organisms are responsible for causing diseases that often require a host organism to survive?

Parasites Signup and view all the answers

What distinguishes fungi from other eukaryotic organisms?

They feed through saprotrophic nutrition. Signup and view all the answers

Which method of disease transmission involves physical contact with an infected individual?

Direct contact Signup and view all the answers

What is a primary function of prions in causing disease?

Changing the shape of healthy proteins Signup and view all the answers

What type of organism causes malaria?

Protocist Signup and view all the answers

Which of the following is a characteristic of asymptomatic carriers of a disease?

Can still transmit the disease to others Signup and view all the answers

What is the size range for most microorganisms discussed?

5-50 μm Signup and view all the answers

How does ingestion lead to disease transmission?

By consuming contaminated food or water Signup and view all the answers

Which of the following diseases is associated with an environmental reservoir?

Tetanus Signup and view all the answers

What is the average size range of microorganisms such as protoctists?

1 μm - 2 mm Signup and view all the answers

Which of the following types of pathogens are recognized as major causative agents of disease?

Bacteria Signup and view all the answers

How do viruses replicate in a host organism?

By hijacking the host cell's machinery Signup and view all the answers

What is a common method of transmission for communicable diseases?

Direct contact with infected surfaces Signup and view all the answers

Which symptom is often associated with viral infections?

Persistent coughing Signup and view all the answers

Which of the following is NOT a characteristic of viruses?

They can reproduce independently Signup and view all the answers

What term describes asymptomatic carriers in the context of communicable diseases?

Individuals showing no symptoms but capable of spreading the pathogen Signup and view all the answers

What impact do protoctists have in the context of pathogens?

They can cause significant diseases in humans and animals Signup and view all the answers

What differentiates bacteria from viruses in terms of structure?

Bacteria are prokaryotic cells, viruses lack cellular components Signup and view all the answers

Study Notes

Introduction to the Immune System

The immune system is a complex network of cells and processes that protect the body against infection by pathogenic microorganisms.
Pathogens invade the body, disrupting homeostasis and causing illness.
Pathogens, such as bacteria, viruses, fungi, and protists, can cause various diseases.

Types of Pathogens

Bacteria are single-celled prokaryotic organisms.
- Average size: 0.5-5µm (micrometers)
Viruses are smaller than cells and lack cellular components.
- Composed of a strand of DNA or RNA surrounded by a protein coat.
Fungi are eukaryotic organisms, typically multicellular, with thread-like structures called hyphae.
- Average size: 5-50µm (micrometers)
Protists are eukaryotic single-celled or simple multicellular organisms.
- Average size: 1-2mm (micrometers/nanometers)
Prions are misfolded proteins that can cause disease in humans and animals.
Parasites are organisms that live on or in another organism, known as their host, and obtain resources from it.

Pathogens Cause Disease

Pathogenic microorganisms are those that can cause disease.
The top 5 communicable diseases globally vary depending on factors like time and location.

How Diseases Spread

Transmission of diseases occurs through different methods.
- Direct contact: HIV, malaria (physical touch, bodily fluids)
- Indirect contact: touching an object touched by an infected person
- Inhalation: pathogens transmitted through coughs or sneezes
- Inoculation: introducing a small amount of inactive pathogen to stimulate immune response
- Ingestion: contaminated food or water
- Vectors: living organisms that carry pathogens between organisms

Reservoirs

These are sources of infection, such as soil, animals, water, or other environments that contain microorganisms.
Example: tetanus, where soil is the reservoir for the bacteria.

Fomites

These are non-living objects that can contaminate with pathogens.
- Examples: door handles, medical instruments

Asymptomatic Carriers

Individuals carrying a disease without displaying symptoms.
Carry risks of spreading the disease, unknowingly.

Vectors

Living organisms that transmit pathogens between organisms.
Examples: mosquitoes, ticks, fleas, and aquatic snails.
Diseases carried by these vectors: malaria, dengue fever, yellow fever, Lyme disease.
Body lice transmit typhus fever

Other Organisms Contributing to Disease

Prions are misfolded proteins that cause various neurodegenerative diseases.
Parasites harm hosts but typically don't kill them. -Example: Toxoplasmosis

The Immune Response

The immune system protects the body against infection through:
- Non-specific defenses: skin, mucous membranes, phagocytosis, inflammation
- Specific defenses: T cells, B cells

Key Definitions

Antigen: Molecules that trigger an immune response (from pathogens or other sources)
Antibodies: Proteins produced by B cells to target specific antigens.

White Blood Cells

White blood cells (leukocytes) are crucial parts of the immune system, defending against pathogens.
Different types, each with specific jobs.

Phagocytes and Lymphocytes

Phagocytes: cells that engulf and destroy pathogens.
- Make up approximately 75% of white blood cells.
Lymphocytes (include T and B cells): cells involved in specific immune responses. - Unique immune response to each antigen.

Innate Immunity

A non-specific immune response involving general defenses, such as phagocytosis and inflammation.
Effective against a wide range of pathogens.

Adaptive Immunity

A specific immune response targeting particular pathogens through the production of specialized cells (like T and B cells).
Takes time to develop compared to innate immunity.
T cells and B cells contribute to a secondary immune response, giving immunity to subsequent encounters with the same pathogen.

Inflammation

A localized response to injury or infection that involves increased blood flow and chemical release.
Aids in delivery of immune cells to affected site
Promotes phagocyte activity
Creates swelling due to fluid leakage.

The Lymph System

A network of vessels and organs, complementing the cardiovascular system, crucial to immune function.
Involved in immune response (filters body fluids).

Thymus

Plays a vital role in the development and maturation of T lymphocytes.

Viral Replication

Viruses require host cells to replicate.
Follows a typical life cycle from attachment, entry, replication, assembly, and release.

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