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Question 1

Innate Immunity

Answer 1

Defenses present at birth, offering immediate protection against pathogens.

Non-specific: Acts against a wide range of microbes without specificity.

No memory component: Cannot recall previous encounters with pathogens.

Always present: Active before an infection occurs, providing rapid response

Question 2

First Line Defenses: Physical Barriers

Answer 2

Skin: Outer layer consists of dead cells and keratin, which are difficult for microbes to penetrate.

Mucous Membranes: Line tracts like the digestive tract, secrete mucus that traps microbes, and has a mucociliary escalator to remove trapped microbes.

Fluids: moves microbes away from the body

Question 3

First Line Defenses: Chemical Barriers

Answer 3

Stomach acid: Destroys many bacteria and toxins

Skin (fatty acids and lactic acid):
Prevents growth of microbes

Lysozyme:
An enzyme that degrades peptidoglycan
Found in sweat, tears, saliva, and nasal secretions

Lactoferrin:
Iron binding proteins in milk
Makes iron unavailable to slow growth of microbes

Defensins:
Short polypeptides
Poke holes in microbial membrane
Produced by epithelial cells

Normal Microbiota:
Prevents growth of pathogens

Question 4

Second Line Defenses: Cellular Defenses (read more)

Answer 4

Granulocytes: Basophils, eosinophils, and neutrophils are involved in phagocytosis.

Mononuclear Phagocytes: Monocytes become macrophages in tissues, engulfing pathogens.

Dendritic Cells: Phagocytize pathogens and present antigens to adaptive immune cells.

Lymphocytes: Natural killer cells destroy infected or tumor cells; T and B cells are part of adaptive immunity.

Question 5

Second Line Defenses: Molecular Defenses (read more)

Answer 5

Complement System:

Series of proteins circulating in blood, activated in cascade fashion upon detection of microbes.

Functions include opsonization, enhancing inflammation, and directly lysing foreign cells.

Question 6

Inflammatory Response

Answer 6

Triggered by tissue damage, leading to increased blood vessel permeability, migration of leukocytes, and localized swelling and heat.

Signs include pain, redness, and swelling, aiding in pathogen elimination and tissue repair

Question 7

Fever

Answer 7

Triggered by toxins, LPS or chemicals produced by immune system; Elevation in body temperature triggered by pathogens or immune system chemicals.

Benefits include enhanced phagocytosis, slowed microbial growth, and increased metabolism.

Question 8

Antiviral Interferons (IFNs)

Answer 8

Produced when cells detect viral RNA

Proteins released by infected cells to warn neighboring cells of viral infection

Induce neighboring cells to enter an antiviral state, inhibiting viral replication

Neighboring cells undergo apoptosis if infected