4.1 Primary animal defences pathogens

Question 1

what are some non-specific animal defenses?

Answer 1

• the skin
• blood clotting
• mucous membrane
• inflammation

Question 2

how is the skin a defense?

Answer 2

its the body’s main defence, it is physical barrier to pathogen that require a hole to get into the body

Question 3

how is blood clotting a defense?

Answer 3

clotting factors are released from platelets within blood and from damaged tissue these factors activate an enzyme cascade but blood clots do not form in the blood vessel as this will stop blood from moving within body which would results in lack of oxygen and respiratory substrates

Question 4

what is the process of blood clotting?

Answer 4

1. platelets are activated they stick together to form a platelet plug
2. clotting factors are activated and join platelets to reenforce them
3. fibrin acts as glue to hold cells in place
4. other cells in the blood help support the clot
5. clot is dissolved by the blood when no longer needed

Question 5

how does the skin repair itself?

Answer 5

1. clot dries and forms a scab
2. scab shrinks drawing sides of the skin together (makes temporary seal under where the skin is repaired)
3. collagen fibres are deposited
4. stem cells form new cells by mitosis
5. new blood vessels form
6. tissues contract and pull edges together
7. scab is released

Question 6

what is a mucous membrane and where is it found?

Answer 6

a membrane that produces mucus as contain goblet cells within the epithelium and is found in the trachea, bronchus and mouth

Question 7

how is a mucous membrane a defense?

Answer 7

goblet cells produce a sticky protein called mucus that traps pathogens. The epithelium also contain cilia that waft the mucus up the trachea so that it can be swallowed.The stomach acid then kills any pathogens trapped within the mucus by denaturing the pathogen’s enzymes.

Question 8

what is an expulsive reflex?

Answer 8

an automatic response to irritation caused by pathogen or toxin released designed to remove pathogen eg. coughing, sneezing or vomiting

Question 9

the process of inflammation?

Answer 9

mast cells release histamine (cell signalling substances)
- makes capillary walls more permeable to white blood cells

Question 10

define the term: immune response

Answer 10

the way in which white blood cells respond to infection by pathogens

Question 11

define the term: antigen

Answer 11

specific chemical maker/ proteins on the outer membrane of pathogens recognized as foreign by the immune system

Question 12

define the term: antibody

Answer 12

a small globular protein secreted by B lymphocytes in response to a particular antigen

Question 13

what are the two main groups of leucocytes (white blood cells)?

Answer 13

phagocytes (neutrophils and macrophages)
lymphocytes (B-cells and T-cells)