Immunity A3.1

Question 1

What are pathogens?

Answer 1

Pathogens are microorganisms or agents that cause disease in hosts. They include bacteria, viruses, fungi, and protists.

Question 2

What is a Prokaryotic cell that can produce toxins?

Answer 2

bacteria

Question 3

what are Non-cellular entities that hijack host cells to reproduce?

Answer 3

virsuses

Question 4

what are ukaryotic organisms that cause diseases like athlete’s foot?

Answer 4

fungi

Question 5

what are Single-celled eukaryotes, such as Plasmodium?

Answer 5

protists

Question 6

what are the bodies frist line of defense against disease?

Answer 6

Skin & Mucous membranes

Question 7

how does skin help protect the body against viruses?

Answer 7

the Tough outer layer (keratinized) prevents pathogen entry. Sebaceous glands secrete sebum, creating an acidic environment that inhibits microbial growth.

Question 8

how do mucous membranes help protect the body against viruses?

Answer 8

Found in areas like the respiratory tract, they trap pathogens with mucus and expel them through ciliary action or sneezing. Enzymes like lysozyme in saliva break down bacterial cell walls.

Question 9

what is the process of blood clotting?

Answer 9

When skin is breached, blood clotting prevents further pathogen entry.

Platelets adhere to the injury site and release clotting factors.
Clotting factors convert prothrombin into thrombin.
Thrombin catalyzes the conversion of fibrinogen into fibrin, forming a mesh that stabilizes the clot.

Question 10

describe an Innate Immune System

Answer 10

Non-specific, immediate response. Includes barriers (skin, mucus) and cells like phagocytes and natural killer cells.

Question 11

describe an Adaptive Immune System

Answer 11

Specific, slower response involving lymphocytes (B-cells and T-cells). It creates memory cells for long-term immunity

Question 12

what are the key differences between an innate immune system and an adaptive immune system?

Answer 12

Speed: Innate is rapid; adaptive takes days.
Specificity: Adaptive targets specific pathogens, while innate does not.

Question 13

what is a phagocyte?

Answer 13

a type of cell within the body capable of engulfing and absorbing bacteria and other small cells and particles.

Question 14

how do Phagocytes help Infection Control?

Answer 14

Phagocytes, such as macrophages and neutrophils, engulf pathogens through phagocytosis:
Pathogen is recognized and engulfed.
The pathogen is enclosed in a vesicle (phagosome).
Lysosomes fuse with the phagosome, releasing enzymes that digest the pathogen.
Antigen fragments may be presented on the phagocyte’s surface, signaling other immune cells.

Question 15

what are Lymphocytes?

Answer 15

white blood cells central to adaptive immunity

Question 16

what do B-Lymphocytes do?

Answer 16

Produce antibodies specific to antigens.

Question 17

what do T-Lymphocytes do?

Answer 17

Include helper T-cells (activate B-cells) and cytotoxic T-cells (destroy infected cells)

Question 18

how do antibodies neutralize pathogens?

Answer 18

Antibodies neutralize pathogens by:
Binding to antigens and preventing infection.
Flagging pathogens for destruction by phagocytes.

Question 19

how are b-lymphocytes activated and cloned?

Answer 19

When a B-cell encounters its specific antigen, it binds and internalizes it. A helper T-cell recognizes the same antigen and releases cytokines, activating the B-cell. The activated B-cell undergoes clonal expansion, forming:

Plasma cells: Secrete large amounts of antibodies.
Memory cells: Provide immunity against future infections.

Question 20

what happens to b and t cells after infection?

Answer 20

After an infection, some B- and T-cells remain as memory cells. Upon re-exposure to the same pathogen:

Memory cells respond quickly, producing antibodies before symptoms develop.
This forms the basis of long-term immunity.

Question 21

how is HIV transmitted?

Answer 21

Through blood, semen, vaginal fluids, and breast milk. Targeting helper T-cells, impairing the immune system.

Question 22

what is AIDS?

Answer 22

The final stage of HIV infection, characterized by severe immune suppression and vulnerability to opportunistic infections.

Question 23

How do antibiotics help infection?

Answer 23

Antibiotics kill bacteria by targeting processes like cell wall synthesis or protein production, which do not occur in human cells. Overuse has led to resistant strains, such as MRSA. Mechanisms of resistance include:

-Mutation of target sites.
-Efflux pumps to remove antibiotics.
-Enzymes that break down antibiotics.

Question 24

what are zoonoses?

Answer 24

Zoonotic diseases that originate in animals and transfer to humans. Examples:

Rabies: Transmitted via bites from infected animals.
Avian Influenza: Spread from birds to humans through close contact.

Question 25

how do vaccines impact immunization

Answer 25

Vaccines introduce antigens (live attenuated or inactivated pathogens) to stimulate an immune response without causing disease. Memory cells form, ensuring rapid response upon future exposure.

Question 26

what is herd immunity?

Answer 26

Herd immunity occurs when a significant proportion of the population is immune, either through vaccination or prior infection. This reduces pathogen transmission, protecting individuals who cannot be vaccinated.