Chapter 14:Defence Against Diseases

Question 1

Flashcard 1:
Q: What is a pathogen?

Answer 1

A: A disease-causing organism, such as a bacterium, virus, fungus, or protozoan.

Question 2

Flashcard 2:
Q: What is active immunity?

Answer 2

A: The defense against a pathogen by antibody production in the body.

Question 3

Flashcard 3:
Q: What is immunity?

Answer 3

A: The state in which the human body is protected from the invasion of pathogens and therefore infectious diseases.

Question 4

Flashcard 4:
Q: What are the body’s defense mechanisms against pathogens?

Answer 4

A: Mechanical barriers, chemical barriers, antibody production, and phagocytosis (white blood cells).

Question 5

Flashcard 5:
Q: What is the role of mechanical barriers in the body’s defense?

Answer 5

A: They represent the first line of defense by blocking the entry of pathogens.

Question 6

Flashcard 6:
Q: How does the skin act as a mechanical barrier?

Answer 6

A: The intact skin blocks the entry of pathogens into the body.

Question 7

Flashcard 7:
Q: How do mucous membranes protect against pathogens?

Answer 7

A: They prevent invasion by microorganisms with the help of epithelium and mucous secretions forming a protective covering.

Question 8

Flashcard 8:
Q: What role does the respiratory system play as a mechanical barrier?

Answer 8

A: The respiratory epithelium traps microorganisms and transports them away from the lungs by ciliary action.

Question 9

Flashcard 9:
Q: How do coughing and sneezing help with the body’s defense?

Answer 9

A: They remove microorganisms from the respiratory tract.

Question 10

Flashcard 10:
Q: What are chemical barriers in the body’s defense system?

Answer 10

A: Gastric juice in the stomach, acidic environment of the vagina, lysozyme in tears, perspiration, and saliva.

Question 11

Flashcard 11:
Q: How does the gastric juice in the stomach act as a chemical barrier?

Answer 11

A: It destroys many pathogens that reach the stomach.

Question 12

Flashcard 12:
Q: How does the acidic environment of the vagina provide defense?

Answer 12

A: It is inhospitable for many pathogens.

Question 13

Flashcard 13:
Q: What is lysozyme and what is its role in the body’s defense?

Answer 13

A: Lysozyme is an enzyme that breaks down the cell walls of bacteria, acting as an antibiotic.

Question 14

Flashcard 14:
Q: What are the cells of the immune system?

Answer 14

A: Lymphocytes and phagocytes (neutrophils) which originate from bone marrow.

Question 15

Flashcard 15:
Q: What is the role of B lymphocytes and T lymphocytes?

Answer 15

A: B lymphocytes mature in the bone marrow, and T lymphocytes mature in the thymus gland.

Question 16

Flashcard 16:
Q: How do B lymphocytes respond to pathogens?

Answer 16

A: They differentiate into plasma cells that produce antibodies.

Question 17

Flashcard 17:
Q: What are antigens?

Answer 17

A: Substances on pathogens that cause an immune response in the host organism.

Question 18

Flashcard 18:
Q: How do antibodies neutralize pathogens?

Answer 18

A: They bind to antigens forming an antigen-antibody complex, making the pathogen harmless.

Question 19

Flashcard 19:
Q: What are memory cells?

Answer 19

A: Lymphocytes that remain in the lymph nodes after an infection to quickly produce antibodies during a reinfection.

Question 20

Flashcard 20:
Q: How do antibodies work?

Answer 20

A: They are Y-shaped molecules that bind to specific antigens on pathogens.

Question 21

Flashcard 21:
Q: What is phagocytosis?

Answer 21

A: The process of engulfing and digesting pathogens.

Question 22

Flashcard 22:
Q: Which cells carry out phagocytosis?

Answer 22

A: Neutrophils (phagocytes) produced and matured in the bone marrow.

Question 23

Flashcard 23:
Q: How do neutrophils recognize pathogens?

Answer 23

A: Pathogens stick to receptor proteins on the neutrophil’s cell membrane.

Question 24

Flashcard 24:
Q: What happens after a neutrophil engulfs a pathogen?

Answer 24

A: It forms a vacuole (phagosome) inside the neutrophil, and lysosomes digest the pathogen.

Question 25

### Vaccination and Immunity **Flashcard 25:** Q: What is vaccination?

Answer 25

A: The treatment with a vaccine to stimulate an individual's immune system to develop acquired active immunity against a pathogen.

Question 26

**Flashcard 26:** Q: What does a vaccine contain?

Answer 26

A: Weakened or dead pathogens or harmless toxins produced by pathogens.

Question 27

**Flashcard 27:** Q: How does vaccination work?

Answer 27

A: It causes lymphocytes to produce antibodies and differentiate into memory cells, providing long-term immunity.

Question 28

### Passive Immunity **Flashcard 28:** Q: What is passive immunity?

Answer 28

A: A short-term defense against a pathogen by antibodies acquired from another individual.

Question 29

**Flashcard 29:** Q: How is passive immunity acquired during pregnancy?

Answer 29

A: Antibodies cross the placenta from the mother to the fetus.

Question 30

**Flashcard 30:** Q: How do newborns acquire passive immunity?

Answer 30

A: Through antibodies present in the mother's milk during breastfeeding.

Question 31

**Flashcard 31:** Q: Why is passive immunity temporary?

Answer 31

A: The borrowed antibodies eventually disappear, and the body does not produce memory cells.

Question 32

**Flashcard 32:** Q: How is passive immunity used for snakebite victims?

Answer 32

A: They are injected with antibodies (antiserum) produced in horses to provide temporary protection against venom.

Question 33

### Active Immunity **Flashcard 33:** Q: What is active immunity?

Answer 33

A: Long-term protection against some infectious diseases where the body produces its own antibodies.

Question 34

**Flashcard 34:** Q: How is active immunity acquired naturally?

Answer 34

A: By recovering from an infectious disease, which causes the body to produce memory cells.

Question 35

**Flashcard 35:** Q: How is active immunity acquired through vaccination?

Answer 35

A: By receiving a vaccine that stimulates the production of antibodies and memory cells.

Question 36

**Flashcard 36:** Q: Why are memory cells important in active immunity?

Answer 36

A: They allow the body to quickly produce the correct antibodies upon re-exposure to the same pathogen.

Question 37

### Importance of Passive Immunity for Infants **Flashcard 37:** Q: Why is passive immunity important for breast-fed infants?

Answer 37

A: It protects them against diseases the mother is immune to, as their immune system is not well-developed.

Question 38

**Flashcard 38:** Q: How do antibodies in breast milk protect infants?

Answer 38

A: They adhere to the gut wall and provide a defense against a range of pathogens.

Question 39

### Summary of Passive Immunity **Flashcard 39:** Q: How does passive immunity provide short-term defense?

Answer 39

A: By providing immediate but temporary protection antibodies acquired from another individual.

Question 40

**Flashcard 40:** Q: Why does passive immunity only last a short time?

Answer 40

A: The antibodies break down over time, and the body does not produce memory cells to clone them.