non-specific defences

Question 1

What are primary defences and how do they work?

Answer 1

-The skin physical barrier secretes, sebum which inhibits growth of pathogen

-Mucous membranes, Trapp organisms contain lysozymes and phagocytes

-Lysozymes in tears and urine

all prevent entry of pathogenic organism are non-specific

Question 2

Explain the process of blood clotting

Answer 2

platelets release chemicals
Cascade of reactions occur
Fibrin is produced
Fibrin forms network, that traps platelets this forms, a clot

The cascade of reaction turns, soluble, fibrinogen, = insoluble, fibre in

Question 3

explain the process of skin repair

Answer 3

blood clot, dries out and forms a scab

Scab, dries and shrinks, drawing sides of a cut together

Deposition of fibrous, collagen under scab

Stem cells in epidermis divide by mitosis form new cells

Cells migrate to edges of cut and differentiate to form new skin

New blood vessels grow to supply oxygen nutrients to new tissue

Tissue contract to help draw edges of cut together

Question 4

what happens to swallowed mucus?

Answer 4

Goes to stomach where the acid destroys trapped pathogen

Question 5

give examples of expulsive reflexes

Answer 5

Cough
Sneeze
vomitting
diarrhoea

Question 6

explain the process of inflammation

Answer 6

A tissue infected with organism pathogen detected by mast cells

Mast cells release histamine, which causes vasodilation

Capillary walls are more permeable to white blood cells and some protein so blood plasma and phagocytic white blood cells live blood and enter tissue fluid

Increased production of tissue fluid causes, oedema (swelling)

Excess tissue fluid drains into lymphatic system, where pathogen comes in contact with lymphocytes, which triggers specific immune response

Question 7

what type of defence is phagocytosis?

What are the two types of phagocytes? How are they different?

Answer 7

secondary non-specific defence
Occurs when pathogen gets past primary defence and enters body

Neutrophil -lobed nucleus
Macrophage- larger, round nucleus

Question 8

Explain the process of phagocytosis

Answer 8

-neutrophils binds to the opsonin attached to antigen on the pathogen
-Pathogen engulfed by endocytosis, forming phagosome
-Lysosomes fuse to phagosome and release lytic enzymes into it forming phagolysosome, hydrolysing pathogen broken down into amino acids/ sugars
-After digestion, harmless product can be absorbed into cells or exocytosis

Macrophages can go on to become antigen presenting cells with a MHC complex

Question 9

what is opsonin?

Answer 9

Protein molecule type of antibody attaches to antigens on surface of pathogens to enhance ability of phagocytic cells to bind and engulf the pathogen