3. Immune system Flashcards
What is a Pathogen
Disease causing agent
What is an Antigen
Specific surface marker on pathogens that can be detected by WBC
What does Self mean
A surface marker which is detected as belonging to the human body
What does Non-self mean
A surface marker which is detected as foreign to the body
Function of Neutrophils
First responder of immune cells
What are Lymphocytes
B and T cells that defend against specific invaders
Immune system function
To protect the body against infection, illness and disease
-prevent entry then trap them and then destroy / kill them
Describe the First line of defence
Physical and chemical barriers which aim to prevent pathogens from entering the body
How does the skin provide protection
-Act as physical/ Intact barrier
-Dead cells constantly slough off
-Sebum→contain bacteriacidal / fungicidal properties
-Sweat containing salt→hostile environment for pathogens
-Hair prevents foreign bodies from entering
List the Physical barriers
Hair- ears, nose, eyelashes
Ear wax
Mucous
Skin
Identify Mucous membranes locations
Respiratory tract
Alimentary tract
Genitourinary tract
Structure of mucous membranes
Surface layer of epithelial cells over a deeper layer of connective tissue
Function of mucous membranes
Produces mucous which provides a dense barrier to trap foreign particles that can later be removed
List the Chemical barriers
Tears
Saliva
Stomach acid
Tears and saliva function
Contain lysozymes (enzymes) which break down bacteria
Stomach acid function
Contains HCl (ph of 2) which destroy pathogens that have entered the stomach eg via food
Where do Microbial barriers exist
Skin
Stomach
Vagina
How do microbial barriers work
The presence of of normal (healthy) microbes means that there is limited resources (space) for bacterial growth
What does non specific mean
Response will be the same for all invading pathogens
What does the second line of defence do
Traps pathogens by inflammation and phagocystosis
What is the mucocilliary escalator
cilia on bronchial wall that helps trap pathogens which enter via the respiratory tract (in respiratory system)
Describe the PROCESS of inflammation
-the skin is penetrated which triggers a innate, non specific response
-blood capillaries increase permeability (leakiness) and hence more WBC’s leak out into surrounding tissues // vasodilation also occurs
-Increased leakiness of capillaries means that swelling occurs (traps pathogens and may cause pain)
-Increased leakiness of capillaries means that more phagocytes migrate to the site of injury and the further release of cytokines if triggered
-Vasodilation means that there increased blood flow to site of injury (causing redness and heat)
What is the purpose of inflammation
protect, isolate and inactivate cause of (and) damaged tissue
Describe the PROCESS of phagocytosis
-Phagocyte recognises bacteria as ‘non self’
-phagocyte engulfs bacteria or pathogen
-phagosome and phagolysosome form
-enzymes within the lysosome breaks down pathogens
-unwanted cellular material is removed from the cell
Whats fever and its purpose
Fever is often a sign that the body is suffering an infection
-an increase in temperature creates a hostile environment for the pathogen to survive
Outline what is meant by specific immunity
-reacts in a specific way to each infection
-triggered by a specific antigen
-delayed at first
-greater (faster, sustained, significant ) response on 2nd encounter
-develops over time
Distinguish between cell mediated and humoral response
-The cell mediated response involves T lymphocytes whereas the humeral response involves B lymphocytes (antibodies)
Which lines of defence have memory
3rd
Which lines of defence are specific
3rd
Which line of defence has different levels of response
3rd
How do b cells vs t cells work
B cells secrete antibodies whereas T cells secrete cytokines
Where do B cells vs T cells attack invaders
B cells outside of cells whereas T ells attack inside of cells
How does the process of antibodies work
-Antibody and antigen bind (deactivates the pathogen)
-Forms lattice and agglutination occurs which triggers phagocytes for phagocytosis (engulf and destroy)
-Signals release of cytotoxins which kills cells
-Immobilise the pathogen
Distinguish between active and passive immunity
Active immunity is where antibodies are produced within the body
Antibodies are produced in one person and then introduced into another for passive immunity
eg of natural active
-infected with pathogen
eg of induced active
vaccine
eg of natural passive
breastmilk and placenta
eg of induced passive
plasma donations
define autoimmune disease
-condition in which immune system attacks own body as it is unable to differentiate between self and non self antigens
eg MS, MND
