Chapter 37: Human Defence System Flashcards
What is a pathogen?
a disease causing organism
What is immunity?
the ability to resist disease
What are the two defence systems called?
general defence system
specific defence system
What does the general defence system do?
acts against all pathogens
What is the first line of defence in the general defence system?
consists of skin, mucous membranes, secretion of skin
What are the 3 possible 2nd line of defence in the general defence system?
white blood cells
defence proteins
inflammation
explain how white blood cells act as a line of defence.
attracted to chemicals of invading micro organisms
surround and ingest pathogens
What is a phagocyte?
a cell that ingests another cell
What is a macrophage?
a large phagocyte
What is phagocytosis?
when a cell surrounds and ingests another cell
Explain how defence proteins work.
activated by infection
prevent multiplication and limit spread of viruses
Explain how inflammation works.
infection causes blood capilleries to diallate
this brings more white blood cells to an area
those cells then fight infection
What does the specific defence system do?
system attacks particular invaders
How does the specific defence system work?
produces antibodies or white blood cells that engulf a particular pathogen
What are monocytes?
white blood cells that become macrophages
they engulf invaders
How do monocytes work?
they engulf invaders
once engulfed part of the invader remains on the surface of the macrophage
What is an antigen?
a foreign molecule on the surface of a monocyte that stimulates the production of antibodies
What are lymphocytes?
white blood cell that produces antibodies as a result of antigens
How do allergies arise?
our bodies produce antibodies against non-invaders
the body perceives a harmless substance to be an invader
What is induced immunity?
using antibodies to resist specific diseases
What is active immunity?
antibodies produced in a persons body
What is passive immunity?
antibodies from another organism enter a persons body
What is natural active immunity?
pathogens enter in a natural manner and antibodies produced as a result of this e.g. catching a cold
What is artificial active immunity?
pathogens are introduced into the body as a vaccine so that antibodies can be produced
What is natural passive immunity?
getting antibodies from another organism in a natural way e.g. breast milk from mother to baby
What is artificial passive immunity?
getting antibodies in a non natural way e.g. antibody injections
What is an antibody?
proteins that are produced by lymphocytes in response to an antigen
Why do adults have a greater number of antibodies than children?
they have been exposed to more pathogens
Explain the antibody-antigen reaction.
there is a precise fit between the antigen and the antibody
each antibody is complimentary to the antigen
How can lymphocytes be identified?
They have a large round nucleus
Where are lymphocytes made?
Bone marrow
What are the two types of lymphocytes?
B-cells
T-cells
Where do b-cells mature?
Bone marrow
What do b-cells do?
Recognize a specific antigen and produce the antibody to fight it
What do b-cells usually attack?
Bacterial infections and some virus infections
Explain how b-cells work.
Comes into contact with antigen
Multiplies and produces large amount of antibodies
Antibodies attach to antigens
Cell engulfed by pathogen or cell complement system is activated
What are memory b-cells?
The remaining b-cells that produce a specific antibody that have already overcome an infection
What are the advantages of memory b-cells? (3)
Produces antibodies to small amount of antigens
Produces antibodies faster
Produces greater numbers of antibodies than first time
How much faster do memory b-cells work than regular b-cells?
B-cells produce antibodies in about 14 day
Memory b-cells produce them in 5
Where do t-cells mature?
Thymus gland
What do t-cells do?
Fight off viruses and some bacteria
What are the 4 types of t-cells?
Helper
Killer
Suppressor
Memory t-cells
What do helper t-cells do?
Recognize antigens and stimulate the multiplication of the correct b-cell
Stimulates killer t-cells to reproduce
What do killer t-cells do?
Attack and destroy abnormal body cells (cancer,virus)
How do killer t-cells work?
Release a protein perforin
Forms pores in the membrane of the cell
Water enters and the cells burst
What are suppressor t-cells?
Stimulated by specific antigens
Slow growth
They become active after the pathogen has been destroyed
Inhibits other immune response
What are memory t-cells?
Stimulate memory b-cells to produce large amounts of antibodies if the same pathogen reenters
