33. Defence System

Question 1

Human Defence system function

Answer 1

Defends and fights against pathogens

Question 2

Pathogen def.

Answer 2

A disease causing organism

Question 3

Immunity def.

Answer 3

Ability to resist infection

Question 4

Characteristics of general immunity

Answer 4

1. Doesn’t produce any antibodies
2. Non specific- acts on all pathogens
3. Defends by stopping entry and attacking

Question 5

Methods of general immunity

Barriers

Answer 5

1. Skin-physically stops pathogens entering, has sebaceous glands which secretes sebum to kill bacteria
2. Platelets prevent entry of pathogens if skin is broken by clotting the blood and forming a scab.
3. Tears, Sweat and Saliva-enzyme lysozome attacks bacteria walls
4. Acid- HCL in stomach kills pathogens

Question 6

Methods of general immunity

Attack-WBC

Answer 6

1. WBCs called phagocytes and monocytes carry out phagocytosis-where pathogen is engulfed by monocyte/phagocyte and killed

Question 7

Methods of general immunity

Attack- Proteins

Answer 7

1. Complement:produces holes in wall of pathogen causing it to fill with fluid and burst. (complimentary wafer thin mint-bursts)
2. Inferon: Makes cells surrounding infected cell immune to viral pathogen, stopping spread of pathogen.

Question 8

Methods of general immunity

Inflammatory response

Answer 8

Infected cells release chemicals causing capillaries to dilate, causing swelling, redness, heat.
Attracts WBCs to the area resulting in further inflammation and heat, restriction of reproduction of bacteria and viral cells as environment doesn’t support bacterial and viral growth.

Question 9

Specific defence system def.

Answer 9

Part of our immune system that attacks particular pathogens

Question 10

Specific defence system characteristics

Answer 10

Produces antibodies.
WBCs attack the pathogen
Attacks particular/specific pathogens

Question 11

Antibody
biomolecule
produced by
attacks what

Answer 11

biomolecule: protein
produced by: lymphocyte
attacks antigens

Question 12

Antigen def.

Answer 12

(g for germ)
Antigens are any foreign molecule that stimulates the production of antibodies.
eg. Bacterial cell walls, viral coats, foreign cells, cancerous cells

Question 13

Specific defence system

Monocyte-how it defends

Answer 13

1. Recognises and engulfs antigens-phagocytosis, develops into phagocytes/macrophages
2. Displays these antigens on its surface stimulating antibody production

Question 14

SDS
Lymphocytes- T-type
Where produced and matured
types
Once activated go to

Answer 14

Produced: Bone marrow
Matured: Thymus
Types: 4 (helper, killer, memory, suppressor)
Once activated go to: Lymphatic system

Question 15

SDS
Lymphocytes- B-type
Where produced and matured
types
Once activated go to

Answer 15

Produced: Bone marrow
Matured: Bone marrow
Types: 2 (plasma, memory)
Once activated: Lymphatic system

Question 16

SDS

B lymphocytes types

Answer 16

1. Plasma: Meets antigen, produces antibodies, which attach to antigen, antigen now recognisable and can be killed by T-cells or Monocytes
2. Memory: plasma cells that dont take part in the first defence. Remain in body to recognise the antigen if it reenters the body, allowing it to react quicker.

Question 17

SDS

T lymphocytes

Answer 17

1. T-helper: Stimulate the production of B cells and T killer cells
2. T-killer: secrete chemical perforin causes pores on antigen, causing water to enter and it bursts.
3. T-Suppressor: Stops immune response after pathogen destroyed. Prevents over reacting
4. T-memory: Form during first response but stay in body, intercept antigens quicker and provide quicker response.

Question 18

Induced Immunity def.

Answer 18

Ability to resist infection by the production of antibodies to specific antigens

Question 19

Explain passive (induced) immunity

Answer 19

Has not been affected by the pathogen/antigen

Individual is given antibodies produced by another organism

Question 20

Explain Active (induced) immunity

Answer 20

Has been infected by pathogen/antigen

Production of ones own antibodies to an antigen that has entered their body.

Question 21

Example of natural and artificial passive immunity

Answer 21

Natural: Baby given antibodies from breastmilk
Artificial: given antibodies by injection

Question 22

Example of natural and artificial active immunity

Answer 22

Natural: When pathogen enters body and individual produces antibodies in response.
Artificial: When a pathogen is medically introduced into the body- given vaccination

Question 23

Vaccination def.

Answer 23

Non disease causing dose of pathogen which stimulates the production of antibodies

Question 24

Organs specific to Immune system

Answer 24

Tonsils
Thymus
Lymph node
Spleen

Question 25

Antibody def.

Answer 25

Protein produced by lymphocytes in response to an antigen