Mid Term Exam #2 Study Guide Bio 11

Midterm Exam #2 Study Guide Bio 11

Overview of Topics

  • Review the following systems:
    • The Lymphatic and Immune Systems
    • Digestive System and Nutrition
    • Respiratory System
    • Urinary System
    • Skeletal System
    • Muscular System
    • Nervous System
    • Senses
    • Endocrine System

Lymphatic and Immune Systems

Microbes, Pathogens, and You

Microorganisms
  • Microorganisms are widely distributed in the environment and perform many beneficial functions.
  • Human infectious diseases are usually caused by pathogens, mainly bacteria and viruses.
Three Lines of Defense
  • The body has three defenses against invasion:
    1. Barriers to entry
    2. First responders
    3. Acquired defenses

Bacteria

  • Bacteria are single-celled prokaryotes.
    • Contain a cell wall made of a unique amino-disaccharide.
    • Some have a protective capsule outside the cell wall.
    • May harbor plasmids that confer antibiotic resistance.
    • Reproduce by binary fission.
    • Can release toxins damaging to humans.

Viruses

  • Viruses are acellular and obligate parasites.
    • Composed of:
    • An outer capsid of protein
    • An inner core of nucleic acid (either DNA or RNA)
    • Rely on host cell's enzymes and ribosomes for replication.

Prions

  • Prions are infectious protein particles that cause degenerative nervous system diseases.
  • Disease results when normal prion proteins misfold into a rogue form, converting normal proteins into the abnormal configuration.

The Lymphatic System

  • Composed of lymphatic vessels and organs, with four main functions:
    1. Absorb excess tissue fluid and return it to the bloodstream.
    2. Absorb fats from intestines and transport them to the bloodstream.
    3. Produce, maintain, and distribute lymphocytes.
    4. Defend the body against pathogens.

Lymphatic Vessels

  • Form a one-way system for lymph to travel to cardiovascular veins in the shoulders.
Functions of Lymphatic Vessels
  • Take up excess tissue fluid, called lymph, and transport it.

Lymphatic Organs

  • Primary Organs:
    • Red bone marrow (site of stem cell production)
    • Thymus gland (site of T cell maturation, located in the thoracic cavity)
  • Secondary Organs:
    • Spleen: Contains white and red pulp; white pulp has high lymphocyte concentration, while red pulp filters blood.
    • Lymph Nodes: Packaged with B lymphocytes; filter lymph and initiate immune responses.

Innate Defenses of the Body

  • Innate defenses protect against a broad range of pathogens; acquired defenses respond specifically to particular pathogens.

Barriers to Entry

  • Physical Barriers:
    • Intact skin and mucous membranes, which are effective at infection prevention.
    • Ciliated cells in the upper respiratory tract clear mucus and particles.
  • Chemical Barriers:
    • Sebaceous gland secretions, lysozyme in sweat/saliva/tears, and acidic pH of stomach/vagina.
    • Normal flora bacteria prevent colonization by potential pathogens.

Inflammatory Response

  • Characterized by: redness, heat, swelling, pain, due to histamine release causing smooth muscle dilation and increased blood flow.
    • Increased temperature enhances phagocyte activity.

Protective Proteins

  • The complement system (plasma proteins) enhances inflammatory response, attracts phagocytes, and can lyse bacteria.
  • Interferons are proteins produced by infected cells, providing resistance against viral attacks.

Acquired Defenses of the Body

  • Activated when innate systems fail; dependent on specific antigens.

B Cells and Antibody-Mediated Immunity

  • B Cells: Have B-cell receptors that bind to specific antigens, leading to clonal selection and proliferation.
    • Types of B Cells:
    • Plasma cells produce antibodies and undergo apoptosis after their role.
    • Memory B cells persist to produce antibodies on subsequent exposures.
  • Antibodies (Immunoglobulins): Y-shaped molecules composed of heavy and light chains with variable regions that bind specific antigens.
  • Classes of Antibodies: IgG, IgM, IgA, IgD, IgE, each with unique functions.

T Cells and Cell-Mediated Immunity

  • Attack infected or cancerous cells and stimulate immune responses.
  • Types of T Cells:
    • Cytotoxic T cells: directly kill infected cells.
    • Helper T cells: stimulate B cells and other immune cells, produce cytokines.

Acquired Immunity

  • Active Immunity: Developed through infection or vaccination; long-lasting due to memory B and T cells.
  • Passive Immunity: Received antibodies from another source (e.g., maternal antibodies).
  • Monoclonal Antibodies: Hybridomas producing specific antibodies for diagnostics.

Cytokines and Immunity

  • Various cytokines, including interferon, enhance recovery from diseases such as cancer.

Hypersensitivity Reactions

  • Allergies result from overreactions to harmless substances.
    • Immediate Allergic Reactions: Triggered by IgE antibodies; symptoms range from mild to anaphylaxis.
    • Delayed Allergic Reactions: Associated with T cells (e.g., contact dermatitis).

Autoimmune and Immune Problems

  • Autoimmune diseases arise from immune reactions against body tissues (e.g., rheumatoid arthritis, lupus).
  • Transplant Rejection: Occurs as immune cells attack foreign tissue; managed by immunosuppressive drugs.
  • Genetic engineering can aid in reducing organ rejection.
  • SCID: Severe combined immunodeficiency involves deficiencies in both antibody and cell-mediated immunity.
  • AIDS: Acquired immune deficiency syndrome example.

Digestive System & Nutrition

Purpose of Digestion

  • To ingest, digest, absorb nutrients, and eliminate wastes.

Structure of the Digestive Tract

  • Composed of four layers:
    1. Mucosa
    2. Submucosa
    3. Muscularis
    4. Serosa

Anatomy of the Digestive Tract

  • First Part:
    • Mouth, pharynx, esophagus
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