Immunology Flashcards
What is a disease?
A condition that impairs the normal functioning of the body
A disorder with specific cause and recognisable signs and symptoms
What is a communicable disease?
Disease caused by pathogens (disease causing organisms) and are transmitted from one host organism to another (infectious)
What is a non-communicable disease?
Not caused by pathogens, they can be inherited, deficiency diseases, caused by lifestyle
List some viral pathogens
Rhinovirus HIV Herpesvirus Lyssavirus Influenza virus Hepatitis Viruses Filovirus
Key points about viruses
Are non- cellular. They are not generally classed as living organisms
Have a typical size range of 20-300nm
Contain no cytoplasm or nucleus or organell s
Covered in a protein coat
Are parasitic, and depend on a host cell for both their metabolism and their reproduction
Key points about fungi
Rarely found as discrete cells
Have a nucleus and membrane bound organelles. So are called eukaryotic cells
Are plant like in appearance but lack chlorophyll
Have rigid cell walls made of chitin
List some diseases cause by fungi?
Ring worm
Athletes foot
Black Sigatoka
List some diseases caused by protoctista
Malaria
Tomato late blight
Potato late blight
What is direct transmission?
The pathogen is transferred directly from one host individual to another by direct contact e.g HIV
Coughing and sneezing can produce droplets containing pathogens which spread directly to someone else e.g influenza, tuberculosis
In direct transmission in animals
Via an intermediary or secondary host, such as a vector that transmits the pathogen in its own body E.g the vector Mosquitoes transmit the pathogen plasmodium that causes malaria
Explain who plants defend against initial attack
Callose is synthesised and deposited between cell walls in the cell next to the infected cell
In plasmodesmata between infected cells and their neighbours preventing pathogens entering
In sieve plates in the plasmodesmata sealing off the infected part and preventing spread of pathogens
Non specific immune response
1.skin
Physical barrier to prevent entry of microorganisms and secrete fatty acids to lower pH
2. Mucous membranes /goblet cells
Produce mucus which traps pathogens
Cilia
Remove pathogens/parasite
3. Expulsive reflexes
Coughing and sneezing forces mucus/ pathogens out of the nasal passages and mouth
4. Lysozyme
Enzyme in blood sweat and tears breaks down bacterial cell walls
Nasal secretions contain antibacterial chemical and ear wax traps pathogens and contains an antibacterial chemical
Second line of defence
If the skin has been penetrated and pathogens May have entered the body then there is a second line of defence Blood clotting Inflammation Wound repair Phagocytosis
Describe blood clotting
A blood clot is a mesh of protein (fibrin) fibres. Blood clots plug wounds to prevent pathogen entry and blood loss. They’re formed by a series of chemical reactions that take place when platelets
Describe inflammation
The signs of inflammation include swelling, pain, heat and redness. It can be triggered by tissue damage, the damaged tissue released molecules which increases the permeability of the blood vessels, so they start to leak fluid into the surrounding area. This causes swelling and helps to isolate any pathogens that may have entered the damaged tissue. The molecules also cause vasodilation (widening of the blood vessels), which makes the area hot brings white blood cells to the area to fight off any pathogens that may be present