Course review
Review each learning objective in this topic, then open its concept explanation or question set.
Learning objective
• Pathogens are disease-causing viruses, bacteria, fungi, protists, or parasites • Archaea are not currently known to cause human infectious diseases
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Learning objective
• Keratinized skin, shedding, lysozyme, mucus, and cilia are primary defences • Mucous membranes protect respiratory and digestive surfaces
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Learning objective
• Platelets and damaged tissue release clotting factors at wounds • Thrombin converts fibrinogen to fibrin, trapping blood cells and sealing entry points
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Learning objective
• Innate immunity is broad, rapid, and does not become more specific over life • Adaptive immunity is antigen-specific and produces memory cells
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Learning objective
• Phagocytes use amoeboid movement to reach infection sites • They recognize, engulf, and digest pathogens using lysosomal enzymes
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Learning objective
• B-cells produce antibodies after activation; T-cells assist or destroy infected cells • Lymphocytes originate in bone marrow and circulate through blood, lymph, and lymph nodes
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Learning objective
• Antigens are non-self molecules that trigger specific immune responses • They are often proteins or glycoproteins recognized by antibodies or lymphocyte receptors
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Learning objective
• B-cells bind antigen, internalize it, and present it with MHC proteins • Helper T-cells activated by the same antigen stimulate B-cell activation
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Learning objective
• Activated B-cells divide by mitosis through clonal selection • Plasma cells rich in rough ER secrete large amounts of one specific antibody
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Learning objective
• Memory B- and T-cells remain after the primary response declines • Re-exposure triggers faster, stronger secondary immunity
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Learning objective
• HIV is transmitted through infected blood, semen, vaginal fluids, or breast milk • Transmission risk depends on fluid exchange, barriers, and viral load
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Learning objective
• HIV infects helper T-cells using CD4 receptors and reverse transcriptase • AIDS results when helper T-cell loss weakens antibody production and immune coordination
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Learning objective
• Antibiotics block bacterial processes absent from eukaryotic cells • They do not treat viruses; antivirals target viral replication processes
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Learning objective
• Antibiotic use selects resistant variants that survive and reproduce • Multi-resistant strains arise through mutation, plasmids, and overuse of antibiotics
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Learning objective
• Zoonoses transfer from animal reservoirs to humans, sometimes through vectors • Examples include rabies, tuberculosis, Japanese encephalitis, and COVID-19
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Learning objective
• Vaccines contain weakened/inactivated pathogens, antigens, or genetic instructions • Immunization produces active artificial immunity and memory cells
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Learning objective
• Herd immunity indirectly protects susceptible people when many are immune • Thresholds depend on transmission route and pathogen contagiousness
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Learning objective
• Evaluate COVID-19 data using source reliability, trends, and controlled comparisons • Calculate percentage change, percentage difference, incidence, and vaccine efficacy
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