Immune System Flashcards
(20 cards)
what is a pthogen?
micro-organisms that causes disease e.g. bacteria, virus, protist and fungus
Physical Barriers meaning:
we call them the surface interface that has contact with the external environment
it’s the 1st line of defence
EARS:
wax however sometimes not accepted as an interface as it’s not carrying any pathogens in, there to trap pathogens should they try to get it in
EYES:
eyelashes trap particles but unlikely to prevent pathogens entry, tears have antiseptic properties which can kill pathogens, and prevents the eye from drying which prevents cracking then becoming vulnerable to infection, conjunctiva and cornea are layers on the surface of the eye
SKIN:
thick, multi-layered difficult to penetrate, top layer of skin is dead so can shed without damaging, keratin protein for strength and stability and makes us waterproof to prevent pathogens entering, hair follicle vulnerable and next to the follicle sebaceous gland produces oils - antibacterial keeps skin supple and sweat from sweat glands have antiseptic properties
cut/crack - vulnerable area to pathogens, histamines produced by damaged cells - inflammation and swelling and redness, platelets and fibres form scab waterproof
NOSE:
hair, mucus - goblet cells, trap pathogens, metauronal beating ciliated cells trachea and bronchi produce mucus waft up so blow out or swallow into digestive system
MOUTH:
saliva (amylase, dextrose enzyme) buffer ph7, antiseptic chemicals stomach ph2 HCl perfect ph for enzyme endopeptidases kills bacteria
UTERUS and URETHRA:
-acidic environment
-bladder holding toxic chemicals hard for bacteria to enter
types of fluid:
tissue, blood, lymphatic
non-specific mechanisms
doesn’t distinguish between pathogens, first line, bacteria to entry, second line phagocytosis
specific mechanisms:
distinguishes between pathogens, less rapid but longer lasting
Phagocytosis:
1) phagocyte will try to identify antigens on the surface of the structure (cell or virus)
2) if the phagocyte doesn’t recognise the pathogen it will attach itself to the pathogens attachment proteins
3) cell membrane of the phagocyte extends and engulfs the pathogen
4) the pathogen is fully engulfed in a phagosome (vesicle containing the pathogen) lysosomes fuse with the phagosome and hydrolytic enzymes diffuse in and hydrolyse/destroy the pathogen
5) component parts of the pathogen are either exocytosed into the blood stream or they diffuse into the phagocyte to be used phagocyte displays the pathogens antigens on its surface illicit a specific immune response it’s called an antigen presenting cell
phagocytosis
-phagocytosis causes inflammation at the site of infection, the swollen area will contain dead pathogens and phagocytes (pus)
-inflammation is a result of histamines due to cellular damage which causes dilation of the blood vessels which causes high temperatures at site of damage which speeds up delivery of phagocytes to the site of infection
why are pathogens not sufficient?
can’t identify infected cells, they don’t have memory, by chance that they come across pathogens, can’t neutralise toxins
where are all blood cells made?
the bone marrow
what are the two types of lymphocytes?
B and T lymphocytes
B lymphocytes:
mature in the bone marrow, provide antibodies and anti-toxins - tissue, blood and lymphatic known as the humoral response
T lymphocytes
made in the bone marrow but they mature in the thymus gland - housed in other glands of the immune system, cell on cell response known as the cell mediated response
what are the two types of T lymphocytes?
- T-helper cells
- cytotoxic T cell (a.k.a killer T cell)
