inquiry question 2 module 7 Flashcards
How does a plant or animal respond to infection?
what system do plants use to respond to infection
innate immune system
passive (physical and chemical barriers) and active defence (systemic acquired resistance, hypersensitive response, basal resistance)
physical barriers of plants
- Thorns and spikes
- Thick bark
- stomata opens in rainy weather, cooler weather
- Tough waxy cuticle
- Trichomes: Fine hairs, spines, outgrowths found on plants
- Thick cell wall
Resin: Thick sticky substance produced in response to an insect attack, fungal infection eg. eucalyptus
Leaf dropping: Infected leaves may drop off the plant, Prevents disease from spreading to other parts of the plant
chemical barriers/ defence in plants
- enzymes that break down pathogen-derived toxins chitanase that breaks down cell wall of fungi
lemon myrtle: distinct smell due to oil it produced that has microbial and insect repelling properties - saponins: Produced in the cell membrane of plants Degrade the cell membranes of fungal cells
- caffeine: Toxic to fungi and insects
Systemic acquired resistance
Pattern recognition receptors
triggers the thickening of the cellulose wall of the cell which prevents pathogen from spreading to the next cell
hypersensitive response
triggers cell suicide (apoptosis) at the infected site if a pathogen infects a cell
- the plant detects the presence of specific pathogen proteins and kills the infected cell
basal resistance
natural inherent defences of the plant
animal disease control in agriculture
australia = strict quarantine procedures in place → prevent introduction of contaminated animals/plants
- intensive farming
disadvantages: More animals being kept in smaller places
advantages: more efficient production
animal diseases in australia
foot and mouth disease
- virus that affects sheep, cattle
- spread through saliva etc
- symptoms: ruptured blisters on feet and mouth
impact on australia:
- Effect on australia if outbreak → livestock industry makes up a large part of the economy → reduce the value of potential livestock exports
- prevention of spread: vaccinations
mad cow disease:
- caused by prion in nervous system
- spread through contaminated soil etc.
impact on australia:
- meat exports cancelled
- prevention of spread: Infected animals are destroyed → prevent the spread of disease
anthrax
- bacterium causing sudden death and bleeding
- prevention: affected farm is quarantined
avian influenza:
- virus - flu like symptoms
- effect on agriculture: infected birds destroyed
- affected farm is quarantined
animal immune response
first - innate, physical and chemical barriers to entry
second - innate, inflammatory response and phagocytosis
third - adaptive, specialised B-cells, T-cells and antibodies, response specific to pathogen
antigen vs pathogen
antigen : molecule that signals immune response , usually on surface of pathogen which the body recognies as harmful
pathogen: disease causing organism or agent
first line of defence
protects against the entry of pathogens into the body and is non-specific such as areas with opening like the mouth, eyes, ears
physical barriers: skin, sticky mucous membrane, cilia
chemical barriers: lysosomes, enzymes, acidity
skin
physical barrier
- top layer of dead keratinised cells that prevent pathogens from penetrating
- basal layer = undergoes mitosis to continuously grow new skin cells and maintain the barrier
- microflora present on skin: competes with pathogens for space and nutrients which prevents them from growing
cut or wound: controlled bleeding, blood clotting and scab formation to it can heal underneath
mucous membrane
physical barrier
Sticky layers of tissue that line the body where it needs to remain moist like digestive and respirtory tracts that trap pathogens and stop them from progressing any further into the body
- pathogens are trapped in the mucous which is swept away with cilia
- coughing and sneezing expels the mucous
what produces mucous
goblet cells
cilia
physical barrier
- Tiny hair-like projections on the surface of a cell found on respiratory surfaces eg. bronchial tubes, nose
- Beat and sweep mucous away so it can be removed from the body and moved from lungs to be expelled through coughing
sebum
chemical barrier
- water resistant
- oily barrier that is broken down to become acidic
sweat
chemical barrier
- secreted by skin and contains enzymes with lysozymes that destroy pathogens
lysozymes
enzymes that break down the cell walls of some bacteria
cerumen
chemical barrier
- ear wax
- secreted by cells in the ear canal
- Trap and eventually remove pathogens or particles that have entered the ear
acids and enzymes
chemical barrier
- exist in secretions from gastric juice, tears, saliva, vaginal excretions
acids:
- Speeds up the chemical breakdown of proteins and carbohydrates
- Vagina: microflora break down cells shed from walls of the vagina and create acidic conditions → inhibits growth of pathogenic bacteria and fungi to prevent thrush
- Creates hostile environment for entering pathogens
enzymes:
- Lysozymes in tears, saliva, sweat, nasal secretions that help kill pathogens
- Dissolve the cell membranes of pathogens
microflora
- first line of defence
- diverse mixture of microorganisms that are regularly present on our bodies and necessary for the proper functioning and good health
- mutualistic relationship with humans
Microflora = gain from host → supply of nutrients, stable environment, constant temperature, protection and transportation
Humans = presence of microflora → difficult for pathogenic microorganisms that could cause disease to establish themselves and multiply in the host
second line of defence
If first line of defence was breached body resorts to second line of defence that is non-specific and apart of the innate immune system
inflammatory response
A chemical response that helps wound repair and leads to pathogen destruction
1. chemical signal such as histamines is released
2. increasing permeability of blood vessels, leakiness and increasing dilation to increase circulation in the area, phagocytes migrate to the area, Endogenous pyrogens are released
3. phagocytes consume bacteria and cell debris
five signs of inflammation
- redness
- pain
- swelling
- heat
- loss of function
histamines
released by mast cells trigger vasodilation and increase vascular permeability
what are released by mast cells
histamines
vasodilation
increase in diameter of blood vessels → increasing the blood flow to the site of infection to increase the amount of fluid and number of white blood cells that can move to the area and destroy pathogens;
how does increasing permeability help the immune response
allows certain white blood cells to move from the blood into the tissues to attack the invading pathogens
function of inflammation
- destroy any pathogens present
- limit pathogen from spreading
- repair/replace and damaged tissues
phagocytes
specialised white blood cells that engulfs and destroys foreign particles, bacteria ad dying cells
- attracted to the site of inflammation due to presence of chemotactic factors
- exit blood vessels and move into tissues to destroy invading pathogens
- neutrophils
- macrophages
- dendritic cells
- natural killer cells
mast cell
- releases histamines
- recruits neutrophils and macrophages
macrophage
- phagocyte involved in phagocytosis of pathogens
- antigen presenting cells: After the macrophage has destroyed the foreign particle, parts of the antigen are displayed on the surface of the macrophage
- lives up to several months
- migrates from blood vessels into tissues (chemotaxis)
- differentiated from monocytes
neutrophils
-phagocyte involved in phagocytosis of pathogens
- short lived
- releases toxins that kill or inhibit bacteria and fungi
- migrates from blood vessels into tissues (chemotaxis)
dendritic cells
antigen -presenting cells
- triggers adaptive immune system
- in epithelial cells
- differentiated from monocytes
natural killer cells
kills tumour cells and virus-infected cells
-circulates in blood and migrates to tissues (chemotaxis)
phagocytosis
is the process by which phagocytes change their shape so they can surround a foreign particle, such as a bacterium, and completely enclose it
- Once the foreign particle is inside the cell, enzymes are released to destroy it
process of phagocytosis
1.Phagocyte moves to the bacterium.
2.Phagocyte changes shape so it completely encloses bacterium.
3. Lysosomes contain destructive enzymes.
4.Enzymes are released and destroy bacterium.
5. Harmless particles are released from phagocyte
Endogenous pyrogens
released during inflammatory response → chemicals that increase the body temperature → inhibit the growth of pathogens and inactivate some enzymes and toxins made by pathogen, Increases rate of biochemical reactions
monocytes
differentiate into phagocytic cells –> dendritic and macrophages
- stored in the spleen and move to infected tissue though blood vessels
fever response
slows rate of infection and increases activity of immune cells by increasing temperature
- The body may react to pathogens by altering the hypothalamic set point of body temperature and allowing the tissue to heat up
lymphatic system
System of vessels and nodes that return body fluid and proteins back into the blood system and filters cell debris
- plasma seeps out of blood stream into tissues –> interstitial fluid –> taken to lymphatic vessels –> lymph –> lymph is emptied into the bloodstream
spleen
Reservoir for blood
Filters and purifies the lymph and blood that passes through it
If damaged → more susceptible to infections
major lymph organs
spleen, bone marrow, lymph nodes, thymus, tonsils, adenoid
lymph nodes
act as filters as lymph fluid passes through –> Produced additional lymph fluid, lymphocytes, antibodies and memory cells indicate site of infection
bone marrow
Produces lymphocytes (white blood cell which are important for the immune response and are capable of producing antibodies)
