disease🦠 Flashcards
(51 cards)
in phagocytosis, when the bacteria is engulfed, how are its antigens removed for APC
in the phagosome the bacteria is partly broken down by lysozyme so antigens still whole
how are correct t helper cells selected
receptors on plasma membrane of t helper cell are complementary to antigen
explain importance of b memory cells in immunity
- produced in primary immune response
- remain in body
- produce secondary immune response
- quickly before symptoms occur
- divide into plasma cells
- to rapidly produce antibodies
- long term immunity
describe the action of phagocytic cells at site of infection
- pathogen recognised as foreign
- binds to antigen
- phagocytosis/ pathogen engulfed
- forming phagosome
- lysosomes fuse to phagosome forming phagolysosome
- release enzymes to digest pathogen
where are b and t lymphocytes made and where do they mature
b lymphocytes- made in bone marrow, mature in bone marrow
t lymphocytes- made in bone marrow, mature in thymus gland
describe the changes that occur to t lymphocytes during an immune response. explain the roles of t lymphocytes in fighting a pathogen
- t cell with complementary receptors to antigen is selected for
- by clonal selection
- this t cell undergoes clonal expansion
- t helper cells release cytokines
- to stimulate b cells to differentiate into plasma cells
- to stimulate macrophages to carry out phagocytosis more actively
- t killer cells kill infected host cells
- secrete enzymes
- t memory cells stay in body to provide long term immunity
- secondary immune response if reinfected, rapid response
- active immunity
-cell mediated response
what is parasite
- lives in host
- gains nutrients from host
- at expense of host
how does plasmodium bypass human primary defence
- mosquito feeds on blood
- breaks skin so cannot act as barrier
why is malaria common in tropical areas
suitable climate for mosquito
why are erythrocytes that contain plasmodium more likely to be engulfed by phagocytes than healthy erythrocytes
different chemicals that attract phagocytes are released from infected erythrocytes
describe how structure of antibody allows them to perform function
- 4 polypeptides 2 light chains 2 heavy chains
- variable region allows binding to antigen
- 2 variable regions allow binding of more than one antigen
- variable region on different antibodies allows specificity to different antigens
- constant region allows binding to phagocytes
- hinge region allows flexibility
- disulfide bonds hold polypeptides together
how do antibodies neutralise
- prevent binding to host cell
- block antigen of pathogen
- bind to toxins
explain agglutination of antibodies
- clump together many pathogens
- so phagocyte can engulf many pathogens at once
- clump too large to enter host cell
why is saying that bacteria are immune to antibiotics incorrect
- do not have immune system
- resistant
- bacteria are unicellular
why are phagocytes described as the secondary defence
-involved after pathogen has entered body
why are phagocytes considered non specific
-able to digest many different pathogens
how do phagocytes pass from blood into tissue fluid
- lobed nucleus so cell can change shape
- can move through pores in capillary walls
- histamine makes capillary walls leaky
infective agent that causes tuberculosis
M.tuberculosis
how does tuberculosis pathogen spread
- droplets
- cough
- inhaled by individuals
factors that increase TB infection
- overcrowding
- poor diet
- homelessness
- not vaccinated due to no access
how does mosquito transmit malaria to human
- mosquito is vector
- plasmodium present in mosquito saliva
- infected mosquito bites human
- plasmodium passes from saliva to blood
which lymphocytes secrete substances to kill infected cells
-T
which lymphocytes activate other lymphocytes
T
why is influenza vaccine changed every year
- different antigen shape
- mutates
- antibody produced needs to match new strain
