Cells and the Immune System Flashcards
definitions of
1-antigen
2-pathogen
3-abnormal body cells
4-toxins
1- molecules ( usually proteins)that can generate an immune response
2-organsims that cause disease. (bacteria, virus, fungi) they all have antigens that is identified as foreign and the immune system cells respond to kill.
3-cancerous or pathogen infected cells have abnormal antigens on their surface which triggers an immune response
4- poisons molecules that are antigens
what are the 4 stages of an immune response
phagocytosis
t-cells
b-cells
antibody production
explain the steps of phagocytosis
phagocyte recognises the foreign antigens , cytoplasm moves to engulf the foreign antigen
the pathogen is then contained in a phagocytic vacuole, a lysosome then fuses with the phagocytic vacuole and breaks down the pathogen, the phagocyte present the pathogens antigens on its surface membrane to activate other immune system cells - this phagocyte acts as an antigen presenting cell
what is a T-Cell
T-lymphocyte (white blood cell) that has receptor proteins on its surface that bind to complementary antigens presented to it by phagocytes , which then activates the T-cell
what are the different types of T-cells and what do they do
helper T-cells: which release chemical signals that activates and stimulates the phagocytes and cytotoxic T-cells also stimulates B-cells
cytotoxic cells : which kills abnormal and foreign cells
what a phagocyte
a type of white blood cells phagocytosis , found in blood and tissues and are the first cells to respond to an immune trigger
What is a B-Cell
B-lymphocytes are a type of white blood cell that secretes/covered in antibodies
in B-cells when proteins bind to the antigens what is formed
antigen-antibody complex-m each b cell has a different shaped antibody so different ones bind do different shaped antigens
describe clonal selection
when an antibody on the surface of a b-cell meets it complementary shaped antigen and binds to it , then together the substance released from the helper T-cells activates the B cells.
what are the B-cells that are activated through clonal selection called and function
plasma cells- secrete antibodies
what is it called when pathogens become clumped together
agglutination
2 types of immune responses and what they mean
Cellular - T-cells and other immune system cells that interacts with phagocytes from the cellular response
Humoral - B-cell, clonal selection and the production of monoclonal antibodies from the humoral response
what is active immunity
immune system makes its own antibodies after being stimulated by a pathogen
2 types of active immunity and what they mean
Natural- become immune AFTER catching the disease
Artificial- become immune after getting a VACCINATION containing a harmless dose of an antigen
what is passive immunity
get from being given antibodies made by a different organism
IMMUNE SYSTEM DOES NOT PRODUCE ITS OWN ANTIBODIES
memory cells are NOT produced and its short-term
what are the 2 types of passive immunity and what do they mean
Natural- when a baby becomes immune because of the antibodies it receives from its mother, placenta or breast mild
Artificial- become immune from being Injected with antibodies from someone else. ex; blood transfusions
what is herd immunity
when many people are vaccinated so it protects/reduces the amount of non vaccinated people that get infected
what do vaccines always contain
antigens
what is antigenic variation
when pathogens change their surface antigens
what is
Direct ELSA
Indirect ELSA
1- uses a SINGLE antibody that its complementary to the antigen its testing for and using an enzyme/substrate to produce a colour change to indicate a POSITIVE test
2- uses 2 different antibodies
steps for testing for HIV
indirect ELSA
1. HIV antigen bound to the bottom of a well
2-plasma is added
3- antibody specific to HIV antigen binds
4- secondary antibody is added
5-bind with attachment enzyme
6-substrate is added , positive -colour change
Explain what are viruses
they are not living things, they can only reproduce inside the cells of another organism
Explain what is HIV
Human Immunodeficiency virus that affects the human immune system
What can HIV eventually lead to ?
acquired immune deficiency syndrome (AIDS)
what is AIDS
a condition where the immune system deteriorates and eventually fails. which makes someone with AIDS more vulnerable to other infections
How does HIV invade cells
1- HIV infects and kills the T-helper cells , which acts as the host cell for the virus
what is the affect of the HIV infecting T-helper cells
(2 parts)
the immune system is unable to produce an effective response to infections because other immune system cells don’t behave as they should
Therefore people with HIV develops AIDS when the T-helper cells reach a critically low level
describe the initial infection period
during the initial infection period HIV replicates rapidly and the person may experience flu-like symptoms
what is the latency period for HIV
when HIV replication drops to a low level, this period can last for years and the infected host won’t experience any symptoms
what are they symptoms/stages of AIDS
( 3 steps/stages)
initial symptoms - minor infections of the mucus membranes (nose, genitals, ears) and recuring respiratory infections
as AIDS progresses the number of immune system cells decreases further, which makes patients more susceptible to more serious infections ( chronic diarrhea, bacterial infections, TB)
During the last stages patients have a low level of immune system cells and can develop a range of serious infections (parasite infection of the brain and fungal infection of the lungs) which can KILL AIDS patients NOT HIV itself
what are the 4 main factors that can be accounted for with the survival of AIDS
1- existing infections
2- strain of HIV
3-age
4-access to healthcare
describe HIV structure
has a spherical structure with RNA and reverse transcriptase included in its core genetic material
it has an outer coating made up of proteins called a capsid,
an outer layer called an envelope with attachment proteins which allow the HIV to attach to host the T-helper cells
how does HIV evade destruction by the immune system
HIV attachment proteins are foreign antigens that can be recognized by the immune system. during replication the virus can change parts of the structure of its attachment proteins which is antigenic variation
what does HIV replicate in and why ?
HIV replicates in the T-helper cells of the host
this is because HIV lacks the required organelles such as ribosomes an d enzymes to replicate in its own
what is the 6 steps for HIV replication
1- attachment proteins attaches to the receptor molecule of the cell membrane of the T-helper cell for the host.
2- The capsid is released into the cell where it uncoats and releases the genetic material (RNA) into the cell cytoplasm
3-Reverse transcriptase is used to make a complementary strand of DNA from the viral RNA template
4- the double strand stranded DNA is then inserted into human DNA
5-Host cell enzymes are used to make viral proteins from the viral DNA that was founded in the human DNA
6- the viral proteins are assembled into new viruses which then emerge from the cell to go on and infect other cells
what happens when HIV particles emerge from the cell
the cell ruptures and dies
how does antibiotics kill bacteria
it interferes with the metabolic reactions by targeting the bacterial enzymes used in these reactions
why don’t antibiotics kill viruses
Because viruses use human enzymes and ribosomes to replicate an antibiotics don’t target human ribosomes and enzyme’s
What do antiviral drugs target
They are designed to target the few virus specific enzymes that exist ( only enzymes the viruses use)
