Chapter 12 ~ Communicable Diseases

Question 1

what is a pathogen

Answer 1

an organisim which can cause infectious diseases

Question 2

what are the types of pathogens

Answer 2

bacteria, viruses, protoctista, fungi

Question 3

what are communicable diseases

Answer 3

diseases which can be spread directly/ indirectly from person to person by social factors/living conditions or due to climate.

Question 4

what are the pathogen modes of action

Answer 4

1) damaging the host cell directly
2) Producing toxin which damages the host tissue

Question 5

what is the plants physical defence system

Answer 5

waxy cuticle
cell wall
CALLOSE between cell wall and plasma membrane.

Question 6

How does callose defend plants

Answer 6

Callose is synthesised and depositied between cell wall and cell membrane, it acts as a barrier preventing pathogens entering.
Lignin, mechanical support
Callose blocks sieve plates in the phloem preventing spread of pathogen

Question 7

what are the chemical defences of a plant

Answer 7

insect repellent
insecticides
antibiotics (phenols)
antifungals (chintinases, these are enzymes which break d0wn chintin in fungal cell walls)
general toxins (chemicals which break down to form cyanide which is toxic)

Question 8

what are the non specific animal defences against pathogens?

Answer 8

Skin, covers most of thr body sebum which inhibits growth of pathogen
Many body tracts are lined with mucous membranes this contains mucus which traps microorganisims and contains lysosomes
lysoszymes in tears and urine
acid in stomach

Question 9

Blood Clotting and Wound repair

Answer 9

platelets come into contact with collagen in skin or wall of damaged blood vessels and secrete substance such as thromboplastin this triggers cascade of reactions resulting in formation of a blood clot and sterotonin which makes the smooth muscle in cell walls of blood vessels contract so they narrow and reduce blood supply
clot dries and forms a scab

Question 10

what is the inflammatory response

Answer 10

HISTAMINES AND CYTOKINES

Question 11

what do histamines do

Answer 11

they make the blood vessels dilate causing heat to increase preventing pathogens reproducing

Question 12

what do cytokines do

Answer 12

they attract wbc and dispose of pathogens via phagocytosis

Question 13

what is the function of phagocytes

Answer 13

to engulf and destroy patogens

Question 14

what are the two types of phagocytes

Answer 14

macrophages and neutrophils

Question 15

what is the stages of phagocytosis

Answer 15

1) pathogens produce chemicals which attract pathogens
2)phagocytes recognise non human protein on pathogen which is a response to foreign pathogen
3) phagocyte engulfs pathogen and encloses in a vacuole known as the phagosome
4)phagosome and lysosome combine to form phagolysosome
5) enzymes from the lysosome digest and destroy pathogen

Question 16

what takes longer macrophage or neutrophil

Answer 16

macrophage

Question 17

what occurs when a macrophage digests a pathogen

Answer 17

it combines antigens from pathogen surface membrane with glycoproteins in the MHC
MHC complex moves the pathogen antigens to the macrophages own surface membrane becoming an APC
APC antigens stimulate other cells

Question 18

what do cytokines do

Answer 18

cell signalling molecules
increase body temp
stimulate specific immune system

Question 19

what do opsonins do

Answer 19

chemicals which bind to pathogens and tag them so that they can be more easily recognised by pathogens

Question 20

what is the specific immune response system based on

Answer 20

T lymphocytes and B lymphocytes

Question 21

where do T lymphocytes mature

Answer 21

Thymus Gland

Question 22

where do B Lymphocytes mature

Answer 22

Bone Marrow

Question 23

what are the 4 main T lympohocytes

Answer 23

1) T killer
1) T memory
3) T regulatory
4) T helper

Question 24

what do T helper cells do

Answer 24

they produce interleukins which stimulates activity of B cells this increases antibody production and stimulates production of other T cells

Question 25

what do T killer cells do

Answer 25

they produce perforin which kills pathogen by making holes in cell membrane so it is freely permeable

Question 26

what do T regulatory cells do

Answer 26

supress the immune system
make sure that the body recognises self antigens and does not set up an autoimmune response

Question 27

what does T memory cells do

Answer 27

they are apport of the immunological memory, if they meet an antigen again they divide rapidly forming a huge number of clones of the T killer cells and destroy the pathogen

Question 28

when are B cells activated

Answer 28

when cytokines are released from T helper cells
when antibody molecules on their cell surface binds to a complementary antigen

Question 29

what are the main types of B lymphocytes

Answer 29

plasma cells, B effector cells, B memory cells

Question 30

what are plasma cells

Answer 30

produce antibodies which complementary shape to antigen

Question 31

What are b effector cells

Answer 31

divide to form plasma cell clones

Question 32

what are B memory cells

Answer 32

immunological memory

Question 33

cell mediated immunity

Question 34

Humoural immunity

Question 35

what is an auto immunine disease

Answer 35

it is a disease which occurs when a persons immune system fails to distinguish self antigens from forein antigens and begins to attack normal body cells eg type 1 diabetes, lupus

Question 36

what is the structure of antibodies

Answer 36

it is a glycoprotein which can bind to a specific antigen on patjpgrn or toxin which has triggered the immune response
it is made up of 2 poly peptide chains which are joined by disulfidr briges.

Question 37

how do antibodies defend the body

Answer 37

1) antigen-antibody complex acts as opsonin so the complex is engulfed and digested
2) pathogens cant invade any host cells
3) antiobodies act as agglutinins causing pathogens carrying antigen-antibody complexes to clumo oreventing spread easier for phagocytres to engulf