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