The Immune System: Infectious Diseases and Immune Responses

A comprehensive set of vocabulary flashcards covering the components, functions, and disorders of the human immune system based on the lecture notes.

Infectious Disease

A disease caused by a pathogen passed from one organism to another which disrupts homeostasis in the body.

Pathogen

Organisms such as some bacteria, viruses, protozoans, fungi, and parasites that are capable of causing disease.

Germ Theory

The theory stating that some microorganisms are pathogens, which was demonstrated through the development of Koch's postulates.

Koch's Postulates

A series of four steps used to prove that a specific pathogen causes a specific disease by isolating it from a host, growing it in pure culture, and infecting a healthy host.

Reservoir

A source of a pathogen in the environment, which can include humans, animals, or inanimate objects like soil, water, and food.

Carrier

A symptom-free person who can pass a pathogen to others without knowing they are infected.

Vector

Arthropods, such as mosquitoes and ticks, that carry and transmit pathogens causing diseases like Lyme disease and malaria.

Endemic Disease

A disease that is continually found in small numbers within a population, such as the common cold.

Epidemic

A large outbreak of a disease that occurs in one area and affects many people.

Pandemic

An epidemic that spreads through a large region, such as a country, continent, or the entire globe.

Antibiotic

A substance, such as penicillin, erythromycin, or neomycin, that can kill or inhibit the growth of microorganisms.

Lysozyme

An enzyme found in saliva, tears, and nasal secretions that breaks down bacterial cell walls to kill pathogens.

Phagocytosis

The process by which phagocytic cells like neutrophils and macrophages surround, ingest, and destroy foreign microorganisms.

Complement Proteins

A group of approximately $20$ proteins in blood plasma that enhance phagocytosis or form pores in a pathogen's membrane to destroy it.

Interferon

A protein secreted by virus-infected cells that stimulates neighboring cells to produce antiviral proteins, preventing viral replication.

Lymph

The watery part of blood plasma that leaks out of capillaries, filters through tissue, and is returned to the circulatory system via lymphatic vessels.

Lymphocytes

A type of white blood cell produced in red bone marrow that includes B cells and T cells and is responsible for specific immunity.

Spleen

A lymphatic organ that stores blood and destroys damaged red blood cells.

Thymus Gland

A lymphatic organ located above the heart where T cells mature and are activated.

Antigen

A foreign substance that triggers an immune response in the body.

Antibodies

Proteins produced by B lymphocytes that react specifically with foreign antigens.

Cytokines

Chemicals released by activated cytotoxic T cells that stimulate immune cells to divide and recruit more immune cells to the infected area.

Passive Immunity

Temporary protection occurring when antibodies made by other people or animals are transferred or injected into the body.

Active Immunity

Long-term immunity that occurs after the immune system is exposed to disease antigens and produces memory B and T cells.

Immunization

The deliberate exposure to an antigen using killed or weakened pathogens to stimulate an immune response without causing disease.

Human Immunodeficiency Virus (HIV)

An RNA virus that infects helper T cells by binding to the $CD4^+$ receptor, eventually leading to Acquired Immune Deficiency Syndrome (AIDS).

Genetic Disorders

Diseases caused by the inheritance of non-functioning genes, such as albinism, sickle cell anemia, or hemophilia.

Degenerative Diseases

Diseases resulting from the natural aging process or the body wearing out, such as degenerative arthritis and arteriosclerosis.

Metabolic Disease

A disease resulting from an error in a biochemical pathway, such as Phenylketonuria (PKU) or Type 2 diabetes.

Anaphylactic Shock

A life-threatening inflammatory response to an allergen that causes a massive release of histamine, leading to constricted bronchioles and restricted airflow.

Autoimmunity

Diseases like Rheumatoid arthritis or Lupus where the immune system forms antibodies that attack the body's own healthy tissues or joints.