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Flashcards in Unit 4 Deck (30):
1

What is immunity

the ability of the body to resist infection by a pathogen
or to destroy the organism if it succeeds in invading and infecting the body

2

What are the two types of immunity?

non specific
specific

3

what is a pathogen?

a micro organism that causes disease (fungi, bacteria, virus)

4

what is an antigen?

proteins on the surface of cells.
used as a marker to identify a particular cell type

5

The First Line of Defence

epithelial cell, which form your skin, provide the first line of defence against pathogens provided they remain in tact. the form a physical barrier.

6

Chemical Defence (1)

secretions from the sebacous glands and sweat glands in the skin. keep the pH level that is too low for most pathogens

7

Chemical Defence (2)

tears and saliva contain the enzyme lysozyme which digest the cell wall of bacterial cells

8

Chemical Defence (3)

cells in the mucous membrane secrete sticky mucus that traps microorganisms

9

Chemical Defence (4)

the epithelial cells in the stomach release acid which destroys microorganisms that have been swallowed

10

Secondary line of defence - inflammatory response

when the body suffers physical injury it will respond with a localised defence called an inflammatory response

11

what are phagocytes?

white blood cells that engulf and digest bacteria in a process called phagocytosis

12

What do MAST Cells do?

release histamine causing vasodilation in blood vessels

13

what do cytokines do?

signalling molecules which stimulate recruitment of other cell types

14

Phagocytes

engulf pathogens and clean up the injured site

15

Anti microbial proteins

amplify the immune response

16

Clotting Elements

coagulation of blood helps to prevent further infection and starts tissue repair

17

Stages of inflammatory response

-Physical injury
-mast cells activated and release histamine
-histamine stimulates vasodilation of the blood vessels in injured site
-blood vessels become more permeable leak fluid into neighbouring tissues causing swelling
-cytokines secreted
-migration of phagocytes to injured area/migration of antimicrobial proteins to injured area/delivery of blood clotting factors

18

Natural Killer Cells

stimulate infected cells to commit suicide. apoptosis. infected cells are stimulated to produce a self destructive enzyme.
release cytokines that stimulate a specific immune response

19

Specific Immunity

targets one particular pathogen.
involves T & B Lymphocytes

20

Immune Surveillance

range of white blood cells move around body & constantly monitor the state of tissue.
if damage or invasion of microbes detected, white blood cells detect and release cytokines

21

Antigens

any foreign molecule that is recognised by the immune system and produces a response from a lymphocyte.

22

Antigenic Receptors

each lymphocyte has several copies of a single type of antigen receptor on the surface of the membrane.
lymphocyte specific to one antigen.

23

Clonal Selection Theory

once lymphocyte detected.
dividing repeatedly to form a clonal population of identical lymphocytes

24

Lymphocytes respond specifically to

Antigens on foreign cells
cells infected by pathogens
toxins released by pathogens

25

Autoimmunity

autoimmune disease are a result of failure in regulation of the immune system leads to a T-Lymphocyte immune response to self cells

26

Allergic Reaction

B Lymphocytes becoming hypersensitive to a normally harmless antigen
triggers an immune response which sensitises to the allergen.

27

Helper T cells

secrete cytokines that activate phagocytes, cytotoxic t cells and B lymphocytes.
specific HTC then binds to the antigen on the antigen presenting cell.
HTC becomes activated & divides to produce a clone of activated helper cells.

28

Cytotoxic T Cells

detect & destroy infected cells by several methods including apoptosis.

29

Antigen Presenting Cells

after a phagocyte destroys an invading pathogen it presents fragments of its antigens on its cell surface.
phagocyte now referred to as an antigen presenting cell

30

B lymphocytes

-the presence of an antigen triggers the production of antibodies by B Lymphocytes.
-An Antibody is a y-shaped protein, with each arm having a receptor that is specific to one antigen
-Antibody production by B Lymphocytes can occur following direct contact between the B cell & antigen
- B Cell displays molecules of foreign antigen it has taken in.