Module 4: Non-specific animal defences Flashcards
The immune system is …
a group of cells . tissues , organs and mechanisms that defend an organism against pathogens and other foreign material
An immune response is …
a complex series of non-specific and specific processes involving a range of cells and chemicals
If the body successfully fights an infection , what does this mean if the same pathogen is re-encountered?
the body will respond much more rapidly and effectively to the pathogen
State and explain the 5 main physical barriers of the body that help to prevent pathogens entering the body
Skin-covers the whole body to prevent entry of bacteria
also produces sebum which is an oily substance that inhibits pathogen growth
Skin flora-are a population of natural health bacteria that out-compete pathogens for surface space
Mucous membranes-gas exchange surfaces have a layer of mucus that trap pathogens , the mucus contains lysozymes that destroy this bacteria
Lyzozyme-enzyme found in tears and urine that destroy pathogens
Stomach acid- low pH destroys any bacteria that has entered the body
What is the purpose of blood clotting?
it rapidly seals wounds to prevent pathogens entering the body
Describe the first stage involved in blood clotting and wound repair
Include the substances involved
1) Platelets are activated by the damaged tissue and rush to the site of the wound and interact with collagen in skin/wall of blood vessels causing them to adhere
The platelets release serotonin and thromboplastin
What is thromboplastin and what does it do in the process of blood clotting?
What is the role of serotonin in this first stage of blood clotting?
its an enzyme that triggers a cascade of reactions that result in the formation of a blood clot
causes smooth muscle in blood vessel walls to contract around the wound which reduces blood supply to that area
Describe the second stage of blood clotting
2)The clot dries out and forms a hard scab that stops pathogens from entering
Describe the third and final stage of blood clotting
make 4 points
3)Epidermal cells below the scab start to grow and seal the wound permanently , blood vessels also regrow
Collagen fibres are deposited to strengthen the new tissue
Once the new epidermis has reached normal thickness the scab falls off
Describe the blood clotting cascade
Starting with damaged tissue and finishing with the clot being formed
1)damaged tissue
2)activates platelets that move to the wound
3)platelets release thromboplastin
4)thromboplastin as well as Ca2+ ions catalyse the breakdown of prothrombin into thrombin
5)thrombin catalyses the breakdown of fibrinogen into fibrin which causes the clot to form
Inflammation is …
Inflammation is characterised by … (3)
the immediate swelling of the skin around a rupture
pain , heat and redness
What cells are activated in damaged tissue when the skin is ruptured and what 2 chemicals do they release?
Mast cells are activated , they release histamines and cytokines
Describe what histamines do to blood vessels in inflammatory responses and what this causes…
What does this stop from happening?
What other thing do histamines do and what does this result in?
they cause blood vessels to dilate which causes localised heat and redness
this results in high temperature which stops pathogens from reproducing
histamines also increase the permeability of cell walls , causing more tissue fluid to leave resulting in the swelling and pain
State what cytokines do in inflammatory responses
they attract white blood cells towards the pathogens so that they can dispose of the pathogens by phagocytosis
Which part of the brain controls our bodies core temperature?
What does the large presence of white blood cells during infection cause the hypothalamus to do?
the hypothalamus
causes it to reset and increase body temperature
