Human Health and Disease

Antibody

A substance produced in response to a specific antigen; combines with the antigen to neutralise or destroy it

Antigen

Any substance capable of causing the formation of antibodies when introduced into the tissues

B-Cell

A type of lymphocyte that develops into either a plasma cell that produces antibodies or a memory cell

Endemic

A disease that is always present in a population or region

Epidemic

An increase in the occurrence of a specific disease above the baseline level for a particular population

Immunisation

Programming the immune system so that the body can respond rapidly to infecting micro-organisms

Immunity

Resistance to infection from invading micro-organisms

Infection

The invasion of a host by a pathogen, where it establishes itself and replicates

Infectious (communicable)

Caused by an invading pathogen and able to be transmitted from one organism to another

Macrophage

A phagocytic cell derived from a monocyte (a type of white blood cell)

Micro-organism

A microscopic organism

4 types of micro-organism

Bacteria, virus, fungi, protists

Bacteria

majority are non-pathogenic, essential to life on earth (Decomposition of organic material)

prokaryotic - no membrane bound organelles or nucleus

DNA - single circular molecule, can contain plasmids

Made of a capsule, cell wall (comprised of peptidoglycan, important for protecting the bacteria)

plasmid

small circular double stranded DNA separate from chromosomal DNA

types of bacteria

spherical = coccus

rod shaped = bacillus

curved spiral = spirilla

comma = vibrio

cholera

vibrio bacteria living in salt water and human hots, highly motile (moves using flagella)

causes acute diarrhoeal infection when ingested through contaminated food or water

virus

sub-microscopic, non-cellular, can’t make proteins or replicate on its own so depends on a host cell to synthesise proteins and replicate, can contain either DNA or RNA

what do viruses consist of? (cellular structure)

Nucleic acid core (DNA OR RNA) surrounded by a protective protein coat (capsid)

Sometimes they have a lipid envelope covering the capsid - enveloped virus

DNA virus

•DNA can be linear or circular

•Usually double‐stranded DNA

•Rarely single‐stranded DNA

•Can encode up to hundreds of viral proteins

RNA virus

•RNA can be linear or circular

•Usually contain single-stranded RNA

•Sometimes contain double-stranded RNA

•Have smaller genomes that usually encode only a few proteins

Fungi

Most are multicellular heterotrophs, cell walls made of chitin, cell membrane has phospholipid bilayer, eukaryotic, microscopic to macroscopic

fungal disease - pneumocystis pneumonia

Mostly affect immunocompromised people

Symptoms: fever, cough, difficulty breathing, chest pain, chills, fatigue

protists

large group of eukaryotes that are’t animals, plants or fungi, microscopic to macroscopic, unicellular, multicellular or colonial

most protists are aquatic

animal-like protists = protozoa

single-celled eukaryotes, can move, are heterotrophs

plant-like protists

algae, autotrophs, no stems roots or leaves, most live in water bodies, can be unicellular or multicellular

fungi like protists

heterotrophs, reproduce by forming spores, cell walls made from cellulose, two major types - slime molds, water molds

slime molds - grow as slimy masses on decaying matter

water molds - live in moist soil

flagellates

move using large flagella (Tails) that rotate like a propeller, example is Trypanosoma causing African sleeping sickness

pseudopodia amoebae

Extends projections of cytoplasm out to form feet-like structures that propel the cell forward, example is naegleria fowleri (the brain eating amoeba)

ciliates

move using tiny tail-like projections that beat back and forth, example is paramecium

apicomplexa

don’t move but use enzymes to penetrate the host’s tissues, example is plasmodium spread by mosquitoes as malaria

Outbreak

A sudden, unexpected increase in the prevalence of a particular disease above the baseline level for that population

Pandemic

A disease that has spread rapidly throughout the world; an epidemic that has crossed international borders

Phagocyte

Cells that are able to engulf micro-organisms and cell debris

T-Cell

A lymphocyte that can differentiate into a number of cells that are involved in cell-mediated response

Vaccination

The introduction of antigens to a person so they acquire immunity without suffering from the illness

Vaccine

An antigen preparation used in artificial immunisation

Vector

An agent that transmits pathogens from one host to another

Virulence

The measure of the ability of a pathogen to cause disease within its host