communicable diseases 4.1 Flashcards
1
Q
Types of pathogens
A
- bacteria
- fungi
- viruses
- protictisa
2
Q
examples of bacterial diseases
A
- tuberculosis (TB) in humans .Spread by the bacterium Mycobacterium tuberculosis (M. tuberculosis or Mycobacterium bovis (M.bovis).
Spread through droplets of water in the air released through
sneezing/coughing
• This is then inhaled by an uninfected individual. - bacterial meningitis in humans. N. meningitidis causes symptoms such as fever, headache, neck stiffness and a characteristic rash.
- Ring rot diseases in potato plants. The bacteria infect the vascular tissue and prevent the transport of water, causing the plant to wilt and die
3
Q
examples of fungal diseases
A
- Black Sigatoka in bananas. It spreads through the leaves of the plant, reducing its ability to photosynthesises. lack of photosynthesis causes parts of the leaf to die; producing black streaks. Eventually, the whole leaf dies
- athletes foot- growth under skin of feet.
- Ringworm (cattle)- growth of fungus in skin with spore cases through the skin to cause a rash
4
Q
examples of viral diseases
A
- viruses infect host cells and hijack their machinery to replicate their own genetic material and proteins.
- Tobacco Mosaic Virus (TMV).causes a distinct yellowing of the leaves which produces a mosaic pattern
- influenza attacks the respiratory system and causes muscle pains and headaches
- HIV attacks cells in the immune system and compromises the immune response,
-
5
Q
examples of protistista diseases
A
- can cause harm by entering host cells and feeding on the contents as they grow
It is carried in the salivary glands
• This mosquito then feeds on a human by biting them
• Plasmodium parasite then passes from the saliva of the female mosquito Anopheles into the humans blood stream
• Plasmodium infects the hepatoctes (liver cells) and ervthrocytes causing disruption to the blood flow to
)
vital organs - is transmitted via spores. The first signs of potato blight are small, dark brown marks on the leaves.
The protist destroys potato and tomato crops leaving them completely inedible
6
Q
direct transmission
A
- direct physical contact e.g. touching a infected person or contaminated surface(including soil)
- oral e.g. eating or drinking foods contaminated by the pathogens
- droplets infection
- through spores (very small reproductive structures that are released into the environment. They are dispersed via wind or water known as airborne transmission), to prevent this transmission wear mask and wash the skin after coming in contact with the soil.
- social factors: overcrowding, poor ventilation, poor health,poor diet
7
Q
indirect transmission
A
-pathogens are transmitted via a vector
8
Q
how does climate have an affect on transmission?
A
-many pathogens grow and reproduce more rapidly in warm and moist conditions therefore there is a greater variety of diseases to be found in warmer climates, and animals or plants living in these regions are more likely to become infected
9
Q
passive defences
A
- defences present before infection, prevent entry and spread of the pathogens. Include physical barriers and chemical barriers.
10
Q
example of physical defences
A
- cellulose cell walls- act as a barrier + contain a variety of chemical defences which are activated when the pathogen is detected
- lignin - thickens the cell wall
- waxy cuticle-prevents water collecting on the cell surfaces.so pathogens that collect in water will not be on the cell surface
- bark-contain a variety of chemical defences
- stomatal closure
- callose- a large polysaccharide deposited around the sieve plates blocking the flow of the sieve tubes which prevents pathogens from spreading around the plant.
- tylose formation- blocks the xylem vessels preventing the spread of pathogens. tylose also contains chemicals such as terpenes that are toxic to pathogens
11
Q
active defences
A
- occurs when the chemicals such as proteins and glycolipids in the pathogens cell wall are detected by the plant cells. the plant responds by fortifying the defences already present.
12
Q
example of active defences
A
- cell walls become thickened and strengthened with additional cellulose
- deposition of callose between plant cell wall + membrane near the invading pathogen
- an increase in production of chemicals
- necrosis- few cells of the plant are sacrificed to save the rest of the plant.
13
Q
chemical defences examples
A
- tannins- create a bitter taste, found in the bark
- insect repellent
- alkaloids- nitrogen-containing compounds such as caffeine, nicotine, cocaine and morphine give a biter taste to inhibit herbivores feeding.
- hydrolytic enzymes
14
Q
primary non-specific defences against pathogen in animals (6)
A
- skin acts as a physical barrier to pathogens.
- mucus membrane. goblet cells produced mucus trapping pathogens which the cilla wafts away.
- When a pathogen irritates the lining of an airway it can trigger an expulsive reflex; a cough or sneeze which result in a sudden expulsion of air containing the pathogen.
- lysosomes. breakdown the cell wall of bacteria + hydrochloric acid
- blooding clotting- dries to form a scab which prevents bleeding
- inflammation
15
Q
describe inflammation
A
- pathogen is detected by mass cells which realises histamines and cytokines
- histamines causes the blood vessels to dilate therefore the blood vessel walls become more permeable. blood plasma and white blood cells leave the blood and enter the tissue fluid increasing tissue fluid, which causes swelling(oedema). other symptoms are swelling + localised heat inhibiting pathogen reproduction. more white blood cells in the tissue fluid near the cells can tackle the pathogen.
- more fluid enters the lymphatic system
- mass cells allow release cytokines for cell signalling which attract phagocytes for increased phagocytosis
16
Q
what are phagocytes?
A
-white blood cells that are produced continuously in the bone marrow
17
Q
3 types of phagocytes
A
- neutrophils
- macrophages
- dendritic cells
18
Q
describe the process of phagocytosis
A
- the receptor on the phagocyte recognises the antigen on the pathogen as foreign
- the phagocyte engulfs the pathogen(endocytosis) forming a phagosome
- lysosomes contain in the phagocyte fuse with the phagosome
- the lysosomes then digest the pathogen within
- phagocyte dies and may collect in an area of infection to form pus
19
Q
describe phagocytosis with a macrophage
A
- (same stages as normal phagocytosis)
- instead the lysosomes digest everything except for there antigen
- the pathogens antigen is displayed on the surface of the macrophage (through a structure called the major histocompatibility complex)
- the macrophage becomes a antigen-presenting cell
- the displayed antigens can then be recognised by lymphocytes
20
Q
difference between neutrophils and macrophages
A
- Macrophages are larger
- macrophages are longed-lived cells as after phagocytosis it migrates to the lymph node whereas neutrophils have a long life span
- macrophages rather than remaining in the blood, they move into organs whereas neutrophils remain in the blood
- After being produced in the bone marrow, macrophages travel in the blood as monocytes, which then develop into macrophages once they leave the blood to settle in the various organs
- neutrophils have a multilobed nucleus whereas monocytes have a large kidney-shaped nucleus
21
Q
t lymphocytes
A
- made in the bone marrow, but mature in the thymus
- differentiate/develop into T helper cells, T killer cells, T regulator cells and T memory cells
