Immune System

Question 1

Define pathogen.

Answer 1

Any microorganism that can cause disease

Question 2

What types of substances can be pathogens?

Answer 2

Bacterium, viruses, protazoa, fungi, and worms

Question 3

How is a virus different from other pathogens?

Answer 3

Viruses require host cells to replicate and spread

Question 4

Why can antibiotics be used to treat bacterial infections but not viruses?

Answer 4

Antibiotics target DNA transcription in bacteria, but not viruses, because of the structural and metabolic differences between bacterial cells and viruses.

Question 5

What did Chain and Florey contribute to microbiology?

Answer 5

Chain and Florey tested the efficacy of penicillin in treating various diseases.

Question 6

Outline the role of skin as a primary defense.

Answer 6

Act as a physical barrier of dead cells which cannot be affected by pathogens.

Question 7

Role of hair in primary defense.

Answer 7

Sebaceous glands in hair follicles secrete sebum, which lowers pH and in turn inhibits the growth of bacteria and fungi.

Question 8

Role of mucous as primary defense.

Answer 8

Mucous membranes secrete glycoproteins which trap pathogens and harmful particles.

Question 9

Role of acidic conditions as primary defense

Answer 9

Lower pH inhibits bacterial and fungal growth

Question 10

Role of lysozymnes as primary defense

Answer 10

Lysozymes in mucous act as an antiseptic, antibacterial enzymes

Question 11

Function of erythrocytes

Answer 11

Carry oxygen to the body

Question 12

Function of platelets

Answer 12

Prevent bleeding

Question 13

Function of plasma

Answer 13

Carry proteins that help blood clot, transport substances, and other functions

Question 14

Function of plasma proteins

Answer 14

Maintains electrolyte balance, blood viscosity, helps in clotting, causes inflammation, maintains acid-base balance

Question 15

Outline blood clotting.

Answer 15

A blood vessel is damaged, triggering the release of chemicals and lead to platelets adhering to the damaged area. The chemicals then convert prothrombin into thrombin, an enzyme which in turn converts the soluble fibrinogen into the insoluble, mesh-like fibrin. The fibrin mesh fixes the wound.

Question 16

Define leukocytes.

Answer 16

White blood cells. Help fight off pathogens.

Question 17

What are phagocytes?

Answer 17

Phagocytes are leukocytes which eat other cells by phagocytosis.

Question 18

What are macrophages? Describe their shape and size.

Answer 18

Macrophages are large, spherical phagocytes.

Question 19

How do macrophages ingest pathogens?

Answer 19

They engulf pathogens by endocytosis and digest them with enzymes from lysozymes.

Question 20

What is the difference between specific and non-specific immune responses?

Answer 20

Non-specific immune responses involve cells which are not specialized to a particular pathogen. Specific immune responses involve cells which are specially adapted to a particular pathogen.

Question 21

Describe the structure of antibodies.

Answer 21

Antibodies are Y-shaped proteins composed of two heavy chains and two light chains bound together.

Question 22

What produces antibodies? How many types of antibodies can each cell create?

Answer 22

Plasma cells produce antibodies and can only produce one type.

Question 23

Explain how antibodies are produced.

Answer 23

A specific antigen type is identified and a specific plasma cell is identified that can produce an antibody which will bind to the antigen. The plasma cell clones rapidly and these new plasma cells begin antibody production. Antibodies then travel through the blood and destroy the pathogen.

Question 24

Explain what happens to the plasma cells after antibody production.

Answer 24

Some antibody-producing plasma cells remain in the bloodstream and provide immunity against a second infection by the same pathogen, called memory cells. Memory plasma cells of this type make for faster immune response should the pathogen return.

Question 25

Define antigen.

Answer 25

Any foreign molecule that can trigger an immune response.

Question 26

What are common forms of antigens? Where are they found?

Answer 26

Antigens are proteins and very large polysaccharides. They are found on all cells.

Question 27

What blood type is called a universal donor? What about universal receiver?

Answer 27

O blood type is known as a universal donor. AB blood is known as the universal receiver.

Question 28

Explain how antibodies are produced.

Answer 28

Pathogen ingested by macrophage and its antigens are displayed on the macrophage’s cell surface. Helper T-cells bind to the antigens and are activated. Activated T-cells bind to B-cells, activating them. Activated B-cells divide into plasma and memory cells. Making plasma cells is known as clonal selection. Antibodies are then produced in the extensive rER of the plasma cells.

Question 29

Describe opsonization.

Answer 29

Make pathogen more recognizable to phagocytes.

Question 30

Describe neutralization of bacteria and viruses.

Answer 30

Pathogens neutralize the pathogen and thus prevent them from entering cells.

Question 31

Describe neutralization of toxins.

Answer 31

Antibodies bind to toxins and prevent them from affecting cells.

Question 32

Describe activation of complement.

Answer 32

Antibodies activate a complement cascade which leads to the formation of a membrane attack complex that forms a pore in the membrane of the pathogen, allowing water and ions to enter the cell and thus causing it to lyse.

Question 33

Describe agglutination.

Answer 33

Antibodies stick to pathogens so they can’t enter cells and are easy to digest.

Question 34

What is zoonosis?

Answer 34

Pathogen that can cross between species.

Question 35

What is a histamine? What are their effect?

Answer 35

An amine released by mast cells when tissue is injured or in allergic and inflammatory reactions, causing dilation of small blood vessels and smooth muscle contraction. This allows for increased flow of immune components to the infected area.