Primary defences against disease

Question 1

what is the main primary defense

Answer 1

skin

Question 2

what is keratinisation

Answer 2

the process of keratinocytes migrating to the surface of the skin. This dries out the cytoplasm and replaces it with keratin (protein). Keratinised layer of dead cells acts as a barrier to pathogens

Question 3

What cells produce keratin (protein) in the skin

Answer 3

Keratinocytes

Question 4

is the keratinised layer of cells dead or alive

Answer 4

dead

Question 5

Why is it important that fibrinogen is converted to insoluble fibrin in the blood clot process

Answer 5

so it can form a blood clot to trap erythrocytes and platelets to stop bleeding

Question 6

what blood cell releases clotting factors and Ca2+ to trigger the enzyme cascade.

Answer 6

Platelets release ca2+ and clotting factors when an abrasion is caused

Question 7

what can abrasions cause

Answer 7

abrasions to the skin can put the body at risk to abrasions

Question 8

describe the clotting process

Answer 8

abrasion to skin puts body at risk of infection

the abrasion exposes collagen and platelets bind to the collagen to release ca2+ and clotting factors

this triggers the cascade where soluble fibrinogen is converted to insoluble fibrin by the enzyme Thrombin

this causes a clot by trapping platelets and erythrocytes

Question 9

what enzyme catalyses the fibrinogen into fibrin

Answer 9

Thrombin

Question 10

what does a clot form when it dries out

Answer 10

scab

Question 11

how is skin developed under the clot

-collagen
-stem cells
-blood vessels

Answer 11

fibrous collagen deposited under the scab.
stem cells in epidermis are then divided by mitosis to form new cells which differentiate into skin cells.
new blood vessels grow and supply o2 and nutrients to the new skin

Question 12

what is a mucous membrane

Answer 12

epithelial cells which contain goblet cells to produce mucous to trap pathogens

Question 13

which areas of our body would need a mucous membrane

Answer 13

airways - trachea
lungs

Question 14

Mucous membranes- describe ciliated cells

Answer 14

cilia tiny hair like structures which move in coordinated patterns to move layers of mucous along to be swallowed into digestive system.

Question 15

why are most pathogens killed in the digestive system

Answer 15

killed by acidity of the stomach
pH 1-2 to denature pathogen enzymes

Question 16

How does coughing and sneezing protect us from pathogens

Answer 16

when irritated by potential pathogens, our reflexes of coughing and sneezing expel air which will carry the pathogen

Question 17

What are signs of inflammation

Answer 17

swelling
redness
usually hot to touch
painful

Question 18

Inflammation- what are the specialised cells which detect the presence of pathogens.

Answer 18

Mast cells

Question 19

what substance do mast cells produce when pathogens are present

Answer 19

Histamine

Question 20

what is the main effect of histamine and describe

Answer 20

Main effect- Vasodilation

Vasodilation- makes capillaries more permeable to white blood cells.

Question 21

During Inflammation, Blood plasma and white blood cells leave blood into tissue fluid, what happens from there

Answer 21

this increases tissue fluid production to cause oedema (swelling)
excess tissue fluid is then drained into the lymphatic system.