Disease Flashcards
Infectious vs Non infectious disease
Infectious - caused by pathogen and can be transmitted from one host to another
Non infectious - Genetic, nutritional and environmental diseases (not caused by a pathogen)
Prions
Non cellular pathogenic agent (protein) which is abnormally refolded, located on surface of brain and spin al chord. Prion Proteins aggregate together to form plaques which lead to neuronal deaths
Viruses
Non living and very small- nucleic acid in protein coat. Only infect cells which possess receptors to which the virus can bind. Viruses can often change.
Protozoans
Single celled eukaryotic cells - not always pathogenic - can release toxins
Parasites
An organism that lives and feeds off of a host organism and benefits at the host’s expense.
Can be ectoparasites or endoparasites.
Fungi
Decomposers which can be mulit or unicellular. Usually attack body’s surfaces.
Bacteria
Unicellular prokaryotes - most are harmless.
Can release toxins and cause disease even after bacteria dies
Adherence factors
Allow pathogen to bind to receptors on host cell’s surface.
Invasion Factors
Receptors which interact with host cell receptors and can instigate endocytosis.
Capsules
Prevent pathogen from immune system and may prevent phagocytosis.
Toxins
Substance secreted by pathogen which damages host cell or disables immune system .
Can be exotoxins - substance secreted onto host tissue
or endotoxins - components of pathogen which is released when pathogen breaks down.
Lifecyle Changes
Dormancy stages where they exist in slow growth state. This enables them to evade immune defences.
Define vector
living thing that carries disease from reservoir to host
4 steps of Inflammation (second line of defence)
Mast cells release histamines which increase the permeability of blood vessels so that phagocytic cells can leave the capilleries into the infected site.
Damages cells release prostaglandin which makes blood vessels bigger
Chemokines - chemical communicators recruits more phagocytic cells to the area
Phagocytosis becomes more effective
Describe phagocytosis
A type of endocytosis where phagocytic cells (macrophages) identify non self markers and engulf and destroy pathogens.
The pathogen is engulfed into an internal vesicle, which fuses to a lysosome to destroy the pathogen.
Describe the first line of defense
surface barriers that prevent pathogens entering
such as:
- skin
- mucus
-cilia
- stomach acid
Parts of second line of defense
Phagocytosis
Natural KillerCells/Eosinophils
Inflammation
Fever
Interferons (release protein to stop virus replication)
Complement Proteins
Antigen
Surface makers on pathogen which immune system identifies as foreign
MHC ll vs MHC l markers
MHC ll - only found on antigen presenting cells
MHC l - found on all cells with a nucleus
Describe fever
- Macrophage releases cytokine which resets the body’s thermostat to 37 celsius
This reduces the growth rate of pathogens as well as activating heat shock proteins with strengthens the immune response,
Describe interferons
a cytokine secreted by virally infected cell, and recruits leukocytes to site
Cell mediated immune response
Involves T lymphocytes (T helper cells, cytotoxic T cells, T suppressor cells), which are stored in lymph nodes
Role of T Helper cells
Binds with antigen fragment on MHC ll marker (if it had complementary T cell receptor) and is then activated
Replicates though clonal expansion and selection
Role of cytotoxic T cells
Activated by cytokines released by T helper cells
They bind to infected cells and release cytokines which kill infected cells as well as storing memory cells.
Also causes clonal expansion of cytotoxic T cells
