immune system Flashcards
what can the immune system identify?
- pathogens
- abnormal body cells
- toxins
- cells from other organisms of the same species
what are antigens?
proteins that stimulate an immune response
what are pathogens
microorganisms that cause disease
what is a phagocyte
- white blood cell
- that carries out phagocytosis
what is phagocytosis?
the engulfment of pathogens
what is the full process of phagocytosis
1) pathogen recognised as having non self antigens
- phagocyte travels towards pathogen by chemotaxis
2) pathogens antigen binds to receptors on the phagocyte cell membrane
- pathogen is engulfed by phagocyte by endocytosis
- forming phagosome
3) lysosomes fuse to phagosome to form a phagolysosome
- lysosyme released into phagosome to digest the pathogen
4) harmless products removed by exocytosis
- pahgocyte presents antigen on its own cell membrane
define chemotaxis
movement of an organism in response to a chemical stimulus
define antigen presenting cell
a cell that presents a non-self antigen on its surface
what are the two types of T cells
- T helper cells
- cytoxic T cells
what do t helper cells do?
- white blood cell involved in cellular immune response/cell-mediated response
- stimulates cytotoxic t cells, b cells, and phagocytes
- release cytokines (stimulate other immune cells)
what do cytoxic t cells do
- white blood cell involved in cellular response/cell-mediated response
- kills abnormal cells and infected body cells
outline the full process of the cell-mediated response
1) complimentary T helper cells bind to foreign antigen on APC
2) release cytokines that stimulate
- clonal expanision (rapid mitosis) of **t helper cells **, which become memory cells or trigger humoral response
- clonal expansion of cytoxic t cells which secrete perforin to destroy infected cells
outline the full process of the humoral response
- complimentary T helper cells bind to foreign antigen on antigen presenting T cells
- helper t cells stimulates conal expansion (rapid mitosis) of complemtary B cells
- B cells differentiate into plasma cells
- plasma cells secrete antibodies with complementary variable region to antigen
what do memory T-cells do?
- remember specific antigen
- recognise it second time round
what is clonal expansion?
- specific B cells divide repeatedly by mitosis
- differentiate into plasma and memory cells
what do memory B cells do?
record the specific antibodies needed to bind to the antigen
what does it mean when someone is immune?
Their immune system has the ability to respond quickly to a second infection
what is the primary immune response?
responding to a newly encountered antigen
what are lymphocytes?
white blood cells involved in the specific immune response
compare the secondary and primary immune response?
primary:
- responding to a newly encounted antigen
- slower because it takes immune system time to recognise pathogen and create response
VS
secondary:
- responding to a previously encountered antigen
- secondary is faster because memory cells are able to recognise foreign antigen when encountered again
- secondary is stronger than primary immune response because more plasma cells can be produced more quickly
- secondary, individual is unlikely to show symptoms of pathogen because pathogen pathogen is removed by immune system before it has time to cause harm (individual is immune
how do cytoxic t cells kill infected or abnormal cells?
- produce a protein (perforin)
- makes a hole in pathogn or infected cells
- hole makes cell freely permeable to all substances and quickly dies
what is cell - mediated immunity?
the type of response when T lymphocytes respond to antigens presented on a body cell
what is humoral immunity?
the type of response which involves B lymphocytes and antibodies
PRACTICE QUESTION
ADCs are molecules made of a monoclonal antibody linked to a cancer drug
the process of entering the cell and the breakdown of the antibody to release the drug is very similar to phagocytosis
use your knowledge of phagocytosis to describe how an ADC enters and kills the tumour cells
(3 marks)
- cell injests/engulfs the antibody/ADC
- lysosomes fuse with phagosome (containing ADC)
- Lysozymes breakdown/digest the antibody/ADC to release the drug
