4.1 - Communicable Diseases - New Flashcards by Alex Phillips

Pathogen def

A microorganism that causes disease

How well did you know this?

Not at all

Perfectly

4 different types of pathogen

Bacteria
Fungi
Viris
Protoctista

How well did you know this?

Not at all

Perfectly

Different bacterial diseases

TB
Bacterial Meningitis
Ring Rot (in plants)

How well did you know this?

Not at all

Perfectly

Different diseases caused by viruses

HIV/AIDS
Influenza
Tobbaco Mosaic Virus

How well did you know this?

Not at all

Perfectly

Different fungal diseases

Black Sigatoka
Ringworm (cattle)
Athlete’s foot (humans)

How well did you know this?

Not at all

Perfectly

Diseases caused by protoctista

Blight (tomatoes and potatoes)

Malaria

How well did you know this?

Not at all

Perfectly

Direct Transmission def

Passing a pathogen from host to new host, with no intermediary

How well did you know this?

Not at all

Perfectly

Indirect Transmission

Passing a pathogen from host to new host, via a vector

How well did you know this?

Not at all

Perfectly

Transmission def

Passing a pthogen from an infected individual, to an uninfected individual

How well did you know this?

Not at all

Perfectly

Vector def

An organism that carries a pathogen from one host to another

How well did you know this?

Not at all

Perfectly

Simple pathogen life cycle

Travel from one host to another (transmission)
Enter host tissues
Reproduce in host tissues
Leave the host tissues
Infect a new uninfected person

How well did you know this?

Not at all

Perfectly

Different means of direct transmission

Direct physical contact
Faecal-oral transmission
Droplet infection
Transmission by spores

How well did you know this?

Not at all

Perfectly

Methods to decrease transmission by direct physical contact

Direct physical contact

hygiene - wash hands regularly
keep surfaces clean - especially door handles
clean and disinfect cuts and abrasions
sterilise surgical instruments
use condoms during sexual intercourse

How well did you know this?

Not at all

Perfectly

Methods to decrease transmission by faecal-oral transmission

treatment of waste water and drinking water to decontaminate and reduce risk
thorough washing of all fresh food (using treated water)
careful prep and cooking of all food

How well did you know this?

Not at all

Perfectly

Methods Methods to decrease transmission by droplet infection

Catch it - bin it - kill it
Cover mouth when coughimg or sneezing
Use tissue and dispose of correctly after use

How well did you know this?

Not at all

Perfectly

Methods to decrease transmission by transmission by spores

Use of a face mask

Washing skin after contact with soil

Social factors affecting transmission of diseases

Overcrowding
Poor ventilation
Poor health - especially with HIV/AIDS
Homelessness
Living or working with people who ahve migrated from areas where disease is common

Life cycle of Plasmodium and malaria

Person with malaria
Gametes of Plasmodium in blood
Female Anopheles mosquito sucks blood
Plasmodium develops and migrates to mosquito’s salivary glands
Uninfected person is bitten
Plasmodium migrates to liver
Plasmodium migrates to blood

What conditions are optimal for many pathogens

Warm, moist conditions

allows them to reproduce more rapidly
so greater variety of pathogens may be present in these conditions

Callose def

A large polysaccharide deposit that blocks old phloem sieve tubes

Plant physical defences, and more info on the,

Cellulose cell wall - contains many chemical defences that can be activated on detecting pathogen
Lignin thickening of cell walls - waterproof and almost completely indigestible
Waxy cuticles - prevent water colection on cell surfaces, prevents pathogens accumulating there, need water to survive
Bark - contains a variety of chemical defences against pathogens
Stomatal closure - closed, as are possible points of entry for pathogens - controlled by guard cells when pathigens detected.
Callose - large polysaccharide deposited in sieve tube at end of growing season.
blocks flow of assimlates, and pathogens in sieve tube elements
Tylose Formation - balloon-like swelling or projection that fills the xylem vessel
plugs vessel, and water (and pathogens) can longer move through the xylem

Chemical defences for plants

Terpenoids
Phenols
Alkaloids
Defensive proteins
Hydrolytic enzymes

Active defences in plants, and more info

Cell walls become thickened with additional cellulose
Deposition of callose between plant cell wall and memebrabe near invading pathogen
Oxidative bursts - produce highly reactive O2 molecules capable of damaging invading pathogen cells
Increase in production of chemicals
Canker - necrotic lesionin woody tissue - causes death of cambium tissue in bark

Inflammation def

swelling (odoema) and redness caused by infection

what is a mucous membrane?

specialiswd epithelial tissue covered by mucus

primary defences def

defences that prevent pahogens entering the body

list different primary defences in the human body

``` skin blood clotting and skin repair mucous membranes coughing and sneezing inflammation ``` Other: enzymes and antibodies in tear fluid ear canal lined by wax - traps pathogens mucus plug in cervix, relatively acidic conditions in vagina

what are the primary "non-specific" defences

defences that prevent pathogens entering the body and bloodstream, but are not specific to any one pathogen or antigen - prevent entry of any pathogen

how does skin act as primary defence

skin conists of layers of cells outer layer called epidermis acts as a barrier for pathogens

Outline the process of blood clotting and skin repair

Blood Clotting platelets bind to exposed collagen they release clotting factors this activates an enzyme cascade this causes fibrinogens to form insoluble fibres that attach to the platelets in the plug red blood cells and platelets are trapped in place this forms a blood clot Skin Repair when clot has formed dries out and forms a scab as it dries, it draws sides of the cut together makes temp. seal under which skin is repaired fibrous collagen deposited under scab stem cells in epidermis divide by mitosis to form new skin cells they migrate to edge of cut - diff. to form new skin new blood vessels grow to supply O2 and nutrients to new cells edge of cut contracts and skin is repaired - scab falls off

how does mucous membrane act as primary defence

thin layers in body, e.g. alveoli, lungs, blood vessels etc., contain mucous membranes mucus secreted by goblet cells mucus traps any pathogens epithelium also contains ciliated cells cilia can move to waft the mucus with pathogens along and out of airways enter oesophagus and is swallowed killed by stomach acid

how coughing and sneezing acts as primary defence

expulsive reflex | expels any pathogens in airway that caused the irritation

inflammation mechanism

pathogen detected by mast cells this causes release of histamines causes vasodilation makes capillary walls more permeable to white blood cells plasma and WBC leave blood vessel and enter tissue fluid causes increased prod. of tissue fluid causes swelling (odoema) excess tissue fluid drained into lymphatic system - where lymphocytes are stored can lead to pathogens coming into contact with lymphocytes causes initiation of primary immune response

what is an antigen presenting cell (APC)?

a cell (usually phagocyte) that incorporates the antigens of a pathogen into its cell surface membrane so it can be recognised by other cells in immune system

clonal selection def

selection of a specific B or T cell specific to the antigen

what are cytokines?

hormone-like molecules used in cell signalling to stimulate the immune response

what are neutrophils?

a type of white blood cell that engulfs foreign matter and traps it in a large vacuole (phagosome), which fuses with lysosomes to digest the foreign matter. - a type of phagocyte

what are opsonins?

proteins that bind to the antigen on a pathogen and then allow phagocytes to b

parasite def

an organism that: - lives in/on host - gains nutrition from host - at expense of host