Detecting and Responding to Pathogens: Immune System Fundamentals

Lecture notes covering the distinction between self and non-self, the Major Histocompatibility Complex, and the characteristics of various cellular and non-cellular pathogens.

Pathogen

Disease causing organisms and agents.

Non-specific immune response

An immune response to a pathogen regardless of its type.

Specific immune response

An immune response tailored specifically to a particular pathogen.

Antigen

A molecule on the surface of a pathogen that stimulates an immune response.

Self

Cells, organisms, or substances that are recognised by the immune system as belonging to the body.

Non-self

Cells, organisms, or substances that the immune system does not recognize as belonging and treats as foreign.

Major Histocompatibility Complex (MHC)

The specific genes that code for the protein markers on the plasma membrane used to identify cells as self.

MHC class I

Markers found on all nucleated cells, except red blood cells.

MHC class II

Markers found specifically on antigen-presenting cells, such as macrophages.

Autoimmune diseases

Diseases resulting from damage caused by the immune system responding to self antigens and attacking its own cells.

Allergy

A hypersensitive reaction that occurs when a person's immune response to a substance is abnormal.

Infectious disease

A disease caused by an agent that can be transmitted from one organism to another, usually considered contagious.

Non-infectious disease

A disease that cannot be transmitted directly from one person to another, such as cancer or diabetes.

Cellular Pathogens

Class of disease-causing agents that includes bacteria, fungi, protists, and parasites.

Non-cellular Pathogens

Class of disease-causing agents that includes viruses and prions.

Cocci

Spherical-shaped bacteria.

Baccili

Rod-shaped bacteria.

Exotoxin

A toxin released by bacteria into their surrounding environment.

Endotoxin

A toxic compound that forms part of the cell wall of a bacteria.

Endoparasites

Parasites that live inside the body of another organism, such as roundworms, flatworms, or flukes.

Ectoparasites

Parasites that live on the surface of another organism, such as fleas and ticks.

Incubation period

The time between initial infection and the first appearance of symptoms of disease.