Chapter 15 - Immune System

Question 1

What are the two main branches of the immune system?

Answer 1

innate and adaptive immunity

Question 2

Which immune system are you born with?

Answer 2

innate immunity

Question 3

What is the function of a phagocyte?

Answer 3

to engulf and digest pathogens

Question 4

Name the three major types of phagocytes.

Answer 4

neutrophils, macrophages, dendritic cells

Question 5

What do B cells produce?

Answer 5

antibodies

Question 6

Which cells kill infected or abnormal body cells directly?

Answer 6

killer T cells (CD8)

Question 7

What type of immunity involves antibodies?

Answer 7

humoral immunity

Question 8

A(n) _____ is a molecule recognized as foreign that triggers an immune response?

Answer 8

antigen

Question 9

Which antibody is secreted first in a primary response?

Answer 9

IgM

Question 10

Which antibody is found in secretions like tears and breastmilk?

Answer 10

IgA

Question 11

What is the function of IgG?

Answer 11

long-term immunity; secondary response

Question 12

What is the function of IgA?

Answer 12

protects mucosal surfaces

Question 13

What is the function of IgE?

Answer 13

triggers allergies; fights parasites

Question 14

What is the function of IgM?

Answer 14

first antibody made; primary response

Question 15

What is the function of IgD?

Answer 15

B cell receptor

Question 16

What does a helper T cell do when activated?

Answer 16

releases cytokines to activate B and T cells

Question 17

What do natural killer (NK) cells do?

Answer 17

kill infected or abnormal cells without antigen

Question 18

What do interferons do?

Answer 18

block viral replication; alert nearby cells

Question 19

What do complement proteins do?

Answer 19

punch holes in pathogens; boost inflammation

Question 20

What is opsonization?

Answer 20

tagging pathogens for phagocytosis

Question 21

What activates helper T cells?

Answer 21

antigen on MHC II from APCs

Question 22

What do cytokines do?

Answer 22

signal and regulate immune cells

Question 23

A virus infects a cell. Which immune cell will destroy it and how?

Answer 23

killer T cell (CD8); by releasing perforins and granzymes to kill the infected cell

Question 24

A patient receives a flu shot. Which type of immunity is this? What will form?

Answer 24

active immunity; memory B and T cells will form

Question 25

A baby has high IgG but has never been sick. Why?

Answer 25

passive immunity from maternal IgG crossing the placenta

Question 26

Why is the secondary immune response faster than the primary?

Answer 26

memory cells recognize the antigen and respond rapidly

Question 27

What happens if APCs can't present antigens on MHC II?

Answer 27

helper T cells won't be activated → adaptive immunity will not be properly triggered

Question 28

Explain how innate and adaptive immunity work together in an infection?

Answer 28

innate cells (phagocytes) respond first and present antigen → APCs activate helper T cells → adaptive immunity launches B and T cell responses

Question 29

Why can you get an allergic reaction from peanuts but not from chicken?

Answer 29

peanut proteins act as allergens, triggering IgG-mediated hypersensitivity; chicken proteins do not

Question 30

What causes autoimmune disease?

Answer 30

the immune system mistakenly attacks the body's own tissues

Question 31

How is the complement system harmful if uncontrolled?

Answer 31

excessive activation can damage host tissues via inflammation and cell lysis

Question 32

How does HIV affect the immune system?

Answer 32

it destroys helper T cells (CD4), impairing both humoral and cell-mediated immunity

Question 33

Why can a person with no thymus not fight viral infections well?

Answer 33

they cannot produce mature T cells, which are required for killing infected cells

Question 34

A transplant recipient begins rejecting the new organ. What part of the immune system is involved?

Answer 34

killer T cells attacking the foreign tissue

Question 35

Why does a lack of pulmonary surfactant in premature infants lead to difficulty breathing?

Answer 35

without surfactant, surface tension in alveoli is too high, causing alveoli to collapse and making it hard the expand lungs

Question 36

Why does inhaling deeply increase the rate of gas exchange in the lungs?

Answer 36

it increases alveolar surface area exposure and airflow, maximizing the oxygen gradient into the blood

Question 37

How would low blood pH affect oxygen delivery to tissues?

Answer 37

low pH promotes O₂ unloading from hemoglobin (Bohr effect), enhancing delivery to tissues

Question 38

Why do people with emphysema exhale less effectively?

Answer 38

emphysema damages elastic fibers, reducing lung recoil, making exhalation difficult

Question 39

Why does someone with fibrosis have trouble inflating their lungs?

Answer 39

fibrosis decreases lung compliance, so more effort is needed to expand the lungs during inhalation

Question 40

How would damage to the diaphragm affect breathing?

Answer 40

the diaphragm is the primary muscle for inhalation; damage reduces lung expansion and airflow

Question 41

Why does breathing rate increase during exercise?

Answer 41

increased CO₂ production lowers blood pH, triggering chemoreceptors to increase ventilation

Question 42

Why does CO₂ build-up make blood more acidic?

Answer 42

Co₂ forms carbonic acid in the blood, which dissociates into H⁺ ions, lowering pH

Question 43

Why is hemoglobin necessary if oxygen dissolves in plasma?

Answer 43

plasma can only carry ~1.5% of O₂; hemoglobin carries 98.5%, enabling enough O₂ delivery for life

Question 44

What would happen if all residual volume were removed from the lungs?

Answer 44

alveoli would collapse, preventing gas exchange and making re-inflation extremely difficult

Question 45

Why does Henry's Law explain why scuba divers can get the bends?

Answer 45

at high pressure, more nitrogen dissolves in blood; rapid ascent reduces pressure, forming bubbles

Question 46

Why does oxygen diffuse from alveoli into capillaries but not the reverse?

Answer 46

there's a higher partial pressure of O₂ in alveoli than in deoxygenated blood, so O₂ diffuses into the blood

Question 47

Why is CO₂ more soluble in blood than O₂?

Answer 47

CO₂ is more soluble due to Henry's Law, allowing it to be transported more efficiently in plasma

Question 48

Why do people with asthma wheeze when they exhale, not when they inhale?

Answer 48

exhalation compresses airways more; inflammation and obstruction increase resistance during this phase

Question 49

What happens to partial pressure of O₂ (PO₂) at high altitudes, and how does the body respond?

Answer 49

PO₂ is lower, reducing O₂ diffusion into blood; the body increases ventilation and produces more red blood cells

Question 50

Why is a mismatch in ventilation and blood flow (V/Q mismatch) harmful for gas exchange?

Answer 50

it prevents optimal O₂ and and CO₂ exchange, either wasting airflow or blood flow in mismatched lung areas

Question 51

Why can a person with chronic bronchitis still have normal lung volumes but impaired gas exchange?

Answer 51

mucus and inflammation obstruct airflow, especially during exhalation, trapping stale air and limiting ventilation