IB Biology - 6.3. Defense against infectious diseases

Blood clot

a semi-solid lulmp from liquid blood that is used to seal the cut in the blood vessels and prevent further entry of pathogens into the bloodstream.

Platelets

Are cell fragments present in blood that help create a blood clot upon injury.

Clotting factors

Molecules produced by damaged tissued and platelets which set off a cascade of events that lead to the formation of a blood clot.

Pathogen

Disease-causing organism.

Types of pathogens

Virus, bacteria, fungi, protozoa

Virus

Acellular. Need a host cell to carry out functions of life. Can have DNA or RNA. Can cause flu, HIV, measels, common cold, herpes, etc.

Bacteria

Prokaryotes, divide by binary fission. Can cause food poisoning, ear infections, cholera, etc.

Fungi

Eukaryotes, reproduce with spores. Can cause athlete's foot, ringworm, allergic reactions, etc.

Protozoa

Simple parasites. Can cause malaria, leishmaniasis, toxoplasmosis, etc.

Lines of defense against pathogens

Physical barrier: skin, mucous membranes. Blood cells: phagocytes.

Atherosclerosis

Degenerative disease in which areas of the artery wall become damaged. Cholesterol builds up in these damaged areas, restricting blood flow.

Coronary heart disease

If clots occur in myocardial tissue. Coronary muscle tissue dies as a result of a lack of blood and oxygen.

Phagocytes

Attaches to the pathogen's cell surface and engulfs it. White blood cells.

Pasogome

Vesicle that contains the pathogen.

Lymphocytes

Breaks down the pathogen. White blood cells, specific immunity. Can activate other lymphocytes or produce antibodies.

Antigen

A substance or molecule that causes antibody formation. Non-self.

Antibody

A globular protein that recognizes a specific antigen and binds to it as part of an immune response.

Clonal selection

A specific lymphocyte makes many clones of itself to produce antibodies to a specific pathogen.

Memory cells

Creates immunity.

Antibiotic

Drugs used in the treatment and prevention of prokaryotic bacteria. Designed to disrupt structures or metabolic pathways in bacteria and fungi. Ineffective against viruses

Antibiotic resistance

Indiscriminate use of antibiotics leads to this.

HIV (human immunodeficiency virus)

Gradually attacks the immune system. Retrovirus.

AIDS

A syndrome caused by HIV.

Specific immunity

Triggered by lymphocytes, which produce a response when in contact with a specific pathogen.

Mucous membrane

Parts of the skin covered in a secretion called mucous, keeps the skin moist and prevents growth of bacteria.

Red blood cells

Can be passed between individuals without causing immune rejection, but they do posses basic antigen markers. (ABO system).

Disease

Any condition that disturbs the normal functioning of the body.

Illness

Deterioration in the normal state of health of an organism.

Disease transmission

Direct contact, contamination, airborne, vectors.

Antibody actions

Precipitation, Agglutination, Neutralization, Inflammation, Complement activation.

Allergen

Environmental substance that triggers an immune response despite not being intrinsically harmful.

Histamine

Causes allergic reactions (such as inflammation).

Vaccination

Induce long-term immunity to specific pathogenic infections by stimulating the production of memory cells

Types of vaccines

Live attenuated, inactivated, toxoid, subunit/conjugated, RNA

Epidemic

Increased occurrence of a particular infection within a given region.

Pandemic

Epidemic that has spread across a large geographical area.

Herd immunity

When individuals who are not immune to a pathogen are protected from exposure by the large amounts of immune individuals within the community

Epidemiology

Study of patterns, causes and effects of health and disease conditions in a defined population.

Monoclonal antibodies

Antibodies artificially derived from a single B cell clone. Commonly used to provide immune protection for individuals who contract harmful diseases.

Humoral immunity

The pathway by which antibodies are produced by B lymphocytes to target exogenous antigens.

Cell-mediated immunity

Pathway that does not result in antigen production but instead targets endogenous antigens

Active immunity

Production of antibodies by the body itself and the subsequent development of memory cells. Will result in long-term immunity.

Passive immunity

Results from the acquisition of antibodies from another source and hence memory cells are not developed.

Hypersensitivity disorders

An excessively disproportionate immune response to a substance that is not inherently harmful (allergen).

Autoimmune disorders

Occurs when the immune system fails to recognize body cells as ‘self’ and begins targeting its own cells and tissues

Immunodeficiency disorders

Is a state in which the immune system’s capacity to fight infection is compromised or absent entirely

Macrophage

Large phagocyte. Finds antigens and eats them by secreting enzymes.