6.3 Defence Against Infectious Disease

Question 1

The first line of defense against infectious disease

Answer 1

Surface Barriers; intact skin & mucous membrane

Question 2

Skin protects…

Answer 2

External structures (outer body areas)

Question 3

The second line of defense

Answer 3

Innate immune system (Non specific response)

Question 4

Difference between 2nd and 3rd line of defense

Answer 4

2nd is non-specific in response, 3rd is specific

Question 5

Role of white blood cells in the 2nd line of defense

Answer 5

Engulf and digest forgiven bodies

Question 6

Other components of innate immune system

Answer 6

Inflammation, fever and anti microbial chemicals (complement proteins)

Question 7

Two key properties of innate immune system

Answer 7

1. Does not differentiate between different types of pathogens (non specific)
2. Responds to infections the same way every time (non-adaptive)

Question 8

Phagocytes

Answer 8

Type of white blood cell, provide no specific immunity

Question 9

Phagocytosis

Answer 9

Process by which solid materials(I.e pathogens) are ingested by cells (‘eaten’ via endocytosis)

Question 10

Process of Phagocytosis

Answer 10

1. In response to infection; phagocytes leukocytes circulate in blood and move into body tissue
2. Damaged tissues release chemicals to draw blood cells to site of infection
3. Cellular extensions surround and engulf Pathogens, then fuse to form internal vesicle
4. Vesicle fuses to lysosome and pathogen is digested
5. Pathogen fragments (antigens) may present on surface of phagocyte to stimulate 3rd line of defense

Question 11

Structure of Virus

Answer 11

Antigens on the surface outside casing called envelope, once it enters body - uses as host to replicate itself

Question 12

Third line of defense

Answer 12

Adaptive immune system (specific response)

Question 13

Characteristics of adaptive immune system

Answer 13

Can differentiate between particular pathogens and target specific response.
Can respond rapidly up re-exposure to specific pathogen to prevent symptoms from developing (memory cell)

Question 14

Adaptive immune system are coordinated by

Answer 14

Lymphocytes

Question 15

Effect of HIV on the immune system

Answer 15

Decrease in number of active lymphocytes

Question 16

What occurs as a result of a cut in the skin

Answer 16

Clotting factors are released from red blood cells

Question 17

Why isn’t penicillin used against HIV

Answer 17

Penicillin is an antibiotic. antibiotics do not affect viruses

Question 18

What is the reason for the faster rise in antibody concentration after the second infection

Answer 18

Lymphocytes rapidly reproduced to form plasma cells

Question 19

What is a feature of phagocytic white blood cells

Answer 19

Form part of non-specific immunity

Question 20

What is a non-specific immunity defense to disease

Answer 20

Endocytosis of pathogens by white blood cells

Question 21

Characteristic of antigens

Answer 21

They stimulate the production of antibodies

Question 22

Why is using a combination of antibiotics and bioengineered antibodies to treat infections more effective than antibiotics alone

Answer 22

Bacteria becomes more noticeable to phagocytes

Question 23

Reasons antibiotics aren’t always effective against pathogens

Answer 23

1. Antibiotics interrupt processes found in some but not all pathogen cells
2. Some pathogens have no metabolic processes to interrupt
3. Some pathogens have developed genetic resistance to specific antibiotics

Question 24

Explain the formation of a blood clot

Answer 24

1. Platelets are recruited to site of injury (chemical signal)
2. Cologne activates platelets, platelets change size
3. More platelets come to the site. (Positive feedback)
4. Platelets release thrombin.(prothrombin that turns into thrombin)
5. Thrombin catalase turns fibrinogen into fibrin
6. Fibrin forms web, holding the platelets together