4.1.1 Communicable Diseases Flashcards
what is a communicable disease?
a disease caused by a pathogen that can be passed form one organism to another
what is a pathogen?
a disease causing microorganism
what is a vector? common vectors?
an organism that carries pathogens form one organism to another
- water and insects
name the types of pathogens?
bacteria, viruses, fungi, protoctista
what do bacteria not have?
no membrane bound organelles / nucleus
ways in which bacteria are classified?
- basic shapes
- basic structure of cell wall
basic shapes of bacteria?
- rod shaped (bacilli): food poisoning
- spherical (cocci): acne
- comma shaped (vibrios): cholera
- spiralled (spiralli): stomach ulcers
- corkscrew (spirochaetae)
how to bacteria replictae?
binary fission
why do bacteria replicate using binary fission? problems with this?
- faster, exponential growth
- allows large colonies to be made
+ can cause food spoilage
+ rapid spread of disease
function of capsule in bacterial cells?
- protects cell from indigestion by phagocytosis
- helps them cling together and to various surfaces
- prevents drying out
types of cell wall in bacteria? what does the cell wall determine?
- gram positive: purple under a light microscope
MRSA - gram negative: red under a light microscope
E. Coli - how the bacteria responds to antibiotics
what is a virus?
diameter?
how much smaller than a bacterium?
basic structure of a virus?
- non-living infectious agent
- 0.02μm
- 50 x
- some genetic material surrounded by proteins
what is a bacteriophage?
what does it do?
what are they used for today?
- a virus that kills bacteria
- take over bacteria and use them to replicate and destroy bacteria
- used to identify and treat some diseases
how do bacteria cause disease?
- produce toxins
- the symptoms they cause are due to the damage to the call membrane/enzymes/genetic material
basic structure of a bacteriophage?
- looks like a spider lol
- long tube: injection tube
- tail plate attached below the injection tube
- head contains loose genetic material and protein coat
describe how viruses invade living cells?
-
what is the body’s first line of defence?
skin, clots seal wound
what is a non-specific defence?
targets any type of pathogen
non-specific defence: mucus?
contains lysosomes which destroy the cell wall of pathogens
non-specific defence: what parts of the body contain mucus? lysosomes?
mucus: air tracts, nose
lysosomes: tears, sweat, saliva, urine
non-specific defence: urine
- women?
lysosomes
allows physical washing of urinal tract
- in women, menstruation and discharge allows washing of the urinary tract
non-specific defence: expulsive reflexes
coughing, sneezing: expel mucus
vomiting/diarrhoea: expel contents of the gut
non-specific defence: what is thrush?
caused by pH change in vagina
non-specific defence: ear
contains wax which works like mucus
non-specific defence: eye
rapid eye movement moves pathogens to front of eye to be washed away by tears
- micrboes die in the salty conditions of tears
non-specific defence: gut
good gut bacteria (probacteria) and in breast milk
- compete with bad bacteria
non-specific defence: skin
sebaceous glands secrete an oily substance called sebum which inhibits the production of pathogens
non-specific defence: birth reflex?
when the baby is pushed down, it pushes against the birth canal which causes the uterus to push the baby down
non-specific defence: anus
defacating expels pathogens in diet
- ring of muscle in anus is a good physical barrier for pathogens
explain dead skin cells?
outer layer of skin called epidermis
contains layers of cells
these cells are called keratinocytes
produced by mitosis at the base of the epidermis
migrate to surface of skin
as they migrate, they dry out
the sytoplasm is replaced by the protein keratin
called KERATINISATION
takes 30 days
by time cells reach surface, no longer alive
- this keratinised layer of dead cells acts as an effective barrier for pathogens
describe what happens during blood clot formation (not cycle)
skin is breached, pathogens enter
platelets come into contact with collagen in the blood vessel, they ADHERE and secrete various substances
- thromboplastin
- seratonin
clot dries
epidermal stem cells mitose and migrate to top of epidermis and differentiate forming new cells
- scab sloughs off, wound healed :D
what is the function of thromboplastin in the blood clot response?
- enzyme that initiates a cascade of events that lead to a blood clot
(memorise the cycle)
what is the function of serotonin in the blood clot response?
- causes the smooth muscle to contract, restricting blood vessel and reducing blood flow to area
describe the inflammatory response?
presence of microorganisms detected by specialised cells called MAST CELLS
release a cell-signalling substance called HISTAMINE and CYTOKINES
(more)
what do histamines do in the inflammatory response?
- make blood vessels dilate, causing localised heat and swelling: raised temp prevents pathogens form REPRODUCING
- make blood vessels more leaky, forcing blood plasma out of capillaries, called tissue fluid CAUSES SWELLING AND OEDEMA
- drain into lymphatic system
what do cytokines do in the inflammatory response? fever?
attract phagocytes to site
- stimulate hypothalumus to reset the thermostat and temp goes up
why is a high temp useful for killing pathogens?
- high temp pathogens dotn reproduce well
- specific immune system works faster
types of phagocytes?
- neutrophils: multi-lobed nucleus, manufactored in bone marrow10 mins to engulf, get through pores in capillaries
- macrophage:
describe phagocytosis in neutrophils
1) phagocyte binds to the opsonin attached to the antigen of the pathogen
2) the cell membrane of the phagocyte fuses around the bacterium, enclosing it in a vacuole by endocytosis- phagosome
3) a lysosome fuses with the vacuole: phagolysosome and empties its digestive enzymes to digest it
4) antigens are presented on the surface, useful products are taken into the cytoplasm by diffusion / AT
describe phagocytosis in macrophages
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