The immune system Flashcards
what is the immune system
the body’s defences system use to protect the organism from pathogens
what are the three lines of defence
the first line of defences
- barriers that prevent entry of the pathogens
second line of defences
- non-specific responses to a pathogens
the third line of defences
- the adaptive/ specific immune response
for the first layer of defence what are the difference physical barriers
- skin
-coughing and sneezing reflexes
-mechanical protection
-mucus
-stomach acid
explain the skin as a physical barrier
-physical barrier
-is made up of tissues and is the largest organ of the human body
- the upper layer, epidermis consists of dead cells containing keratin forming a protective layer
-lipid molecules are secreted from glands which provide a waterproofing agent to prevent access to microbes
what happens if the skin is breached
cells called platelets initiate clotting factors that seal the point of entry for pathogens
explain the coughing and sneezing reflexes as a physical barrier
- physical barrier
- although it is a method of transmission, this involuntary action helps expels the pathogens
explain mechanical protection as a physical barrier
- blinking is initiated as a response to irritation in the eyes
-tears particles and pathogens are mixed so they can be eliminated from the eye
explain mucus as a physical barrier
- physical barrier
- is a slippery secretion found on the surface of several body organs and systems
-produced by specialised epithelial cells that line the organs eg:bronchi of the respiratory system - on the surface of these cells are small hair like structures called cilia that have a rhythmic motion which directs mucus and foreign particles in the respiratory organs to the pharynx and mouth to be swallowed or expelled
on the surface of the mucus cells there are…
- on the surface of these cells are small hair like structures called cilia that have a rhythmic motion which directs mucus and foreign particles in the respiratory organs to the pharynx and mouth to be swallowed or expelled
explain stomach acid as a physical barrier
- physical barrier
- the cells lining the stomach secrete acid (HCI) giving the stomach a low pH
- this is considered an extreme environment and if a pathogen gets this far into the system, either by swallowing them or carried by mucus the acid will destroy them
what is immunity
the term immunity refers to the ability of a host to resist infectious disease
what happens if any microorganisms that can penetrate the physical barriers encounters two levels of resistance
non-specific (innate)
- second line of defence
specific (acquired)
- third line of defence
example of non-specific
cells
physical barriers
examples of specific
cells
chemical mediators
the second line of defence is characterised by being..
- non-specific
- a rapid non learned response
- responds in a similar matter
what does the second line of defences involve
- phagocytes and phagocytosis
-non-self recognition
-white blood cells and killer cells
-chemicals Eg: histamine - inflammatory response
what is phagocytosis
process that certain white blood cells use to ingest pathogens
what are natural killer (NK) cells
provide protection against cells infected with a pathogen
Natural killer cells carry out their actions by…
- recognising protein marked ‘non-self’ on cells that need to be destroyed
-releases cytokines which are cell-signalling molecules that guide other responses
what is the complement system
it is a group of about 30 proteins that are secreted by cells in the body. They are active when binded with pathogens and bring around a cascade affect, stimulating a range of chemicals and effects
how is the inflammatory response characterised
- swelling
- redness
- pain
- heat that accompanies a wound from psychical injury and pathogen of wound site
what is histomines
histomines increases blood flow to increase permeability of capillaries in the inflammatory response
histomines increases blood flow to increase permeability of capillaries in the inflammatory response- what does this cause?
this causes mast cells to release histamine which causes blood vessels to dilate at the site of infection, bringing extra blood to the region. this carries while blood cells to engulf the microbes
what does blood clotting do in the inflammatory response
blood clotting factors are also released and seals the wound leaving a scab
what can form around the wound
pus can form around and in the wounds by the action of white blood cells called neutrophils
what are neutrophils
white blood cells
what is the lymphatic system
primary- where lymphocytes develops such as bone marrow and thymus glands
secondary- lymph nodes, spleen and tonsils, this is where white blood cells recognises pathogens and mount responses
what does bone marrow create
WBC -white blood cells
what does thymus allow
WBC to mature
what does the lymph nodes and the spleen do
filter pathogens through and exposes WBC
what are antigens
a substance that triggers specific defences in the immune system( protein fount on pathogens cell surface)
what are antibodies
a substance that is produced within an organism’s body to help fight and recognise pathogens
what is lymphocytes
- white blood cells of the immune system are called lymphocytes. these are found in spleen and blood
-there are two tyeps b cells and t cells
what are the two lymphocytes
B-cells and T-cells
what are B-cells
B-lymphocytes
-produced and matured bone marrow, responsible for producing antibodies
- vital for the development of immunity
what are T-cells
T-lymphocytes
- produced in bone marrow and mature in thymus
-stays in lymph nodes for filtration
-removes pathogens in the body
- T-cells trigger B-cells to develop killer cells
what are produced by T-cells and B-cells
helper cells or killer cells
major histocompatibility complex (MHC) are…
-a set of protein makers found on the surface of the cell.
- these are coded by genes unique for all individuals
what does MHC stand for
major histocompatibility complex
cells display two different groups of MHC on the cell surface these are
- self proteins- that are unique for that individual
-short section of PROTEIN ANTIGENS from pathogens, these groups play vital role in the adaptive immune response, these are NON SELF
the display antige enables…
Recognition and binding by T-lymphocytes which acts as a further immune response
if a pathogen comes along
it breaks past the first line of defence and it is able to bypass the second line of defences but once in enters the blood stream the 3rd immune response comes into play
if the body recognizes the antigen…
- antibodies already in the blood stream (memory B cells)
- antibodies ‘tag’ and disable the pathogen
-T-cells notify killer cells to destroy the pathogen
if the body doesn’t recognises the antigen…
-B-cells and T-cells are present in the blood stream
- B-cells with identify non-self antigen on the pathogen
- this will active killer T-cells
- Provide memory T-cells for subsequent exposure to the same antigen
-activate specific B-cells to secrete antibodies
what are killer T-cells
they are know as cytotoxic T-cells, they identify infected cells and secrete chemicals to destroy them
what are memory T-cells
if an individual is exposed to the same antigen a second time, the memory cells detect this and begin a response quicker
the memory T-cells contributes to the secondary immune system
what is passive immunity
-protection against a protent antigen where immediate action is needed to prevent death Eg; snake bite
why is passive immunity important
this can be important in several circumstances
- proving protection for unborn and newborn infants who have yet to fully develop their immune system. antibodies can be transferred from the mother via placenta tor breast milk
what is the two different acquired immunity
primary and secondary
what is the primary response for acquired immunity
the primary response is smaller and slower due to the action of the first two lines of defence and the stimulation of the B-cells and production of the antibodies while the secondary response is faster and larger due to the memory cells being created
what is the secondary response for acquired immunity
- is the basic of vaccinations
-an individual is exposed to a part or a dead part of the virus - the body raises an unneeded immune response and the different memory cells are created
- this lessens the time needed for the immune response if they were to be infected by the real virus
what is pathogenicity
-is the ability if a pathogen to cause infectious disease
- this is ability of a pathogen to be transmitted from one host or source to another- transmission
how can transmission occur
- airborne
- vector-borne
- contact
- contaminated food and water
- body fluids
transmission via airborne is becuase
-air is not suitable medium foe the growth of pathogens but it can carry them between organisms
-airbron disease is often caused by sneezing or coughing
example of airborne disease
influenza
- airborne pathogens are contained in fluids and droplets in the respiratory tract
-can infect another host why inhaled
transmission via vector borne…
- they carry the pathogen but do not suffer the disease
-are commonly arthropods (ticks and mites) and vertebrate (rats and bats)
what are vectors
vectors are living transmitters of pathogens
when does external transmission of vector borne diseases occur
it occurs when the pathogen is on the surface of the body
when does internal transmission of vector borne diseases occur
it occurs when the pathogens is carried inside the vector
transmission via contact…
- it occurs when the pathogen is transmitted to the host by direct or indirect contact
what is direct contact
it refers to the pathogen being transmitted from person to person touching, kissing and sexual contact
what is indirect contact
refers to the pathogen being transmitted from the sources to the host through non-living objects called vehicles
transmission via food and water
-Certain communities struggle to keep their water ways clear, therefor are prone to disease. laws are requited in order to keep our food preparation safe for consumption
-microorganisms feed on the same nutrients as humans
what water can cause serious disease if consumed
water that has been contaminated by fecal matter either by humans or animals and contain pathogens
