Unit Two Exam

Pathogenic Fungus

Histoplasma Capsulatum

  • Acquisition: Found in most soils containing high nitrogen levels, such as those associated with bat and bird droppings.
  • Pathophysiology:
    • Spores are inhaled and reach the alveoli (sacs of the lungs).
    • Macrophages cannot digest Histoplasma; it begins to reproduce inside them through budding.
    • Macrophages carrying the yeast migrate from the lungs into blood and lymph vessels, leading to systemic effects.
  • Diseases Caused:
    • Systemic Histoplasmosis:
    • Spread through the blood and lymph to organs like the spleen and liver, causing inflammation and potential fatality.
    • Chronic Cutaneous Histoplasmosis:
    • Causes painful ulcer-like lesions on the skin.
    • Ocular Histoplasmosis:
    • Leads to redness and inflammation in the eyes.

Opportunistic Infections

  • Definition: Microorganisms that are normally part of the body’s flora but can cause disease if the immune system is weakened, if they overgrow, or if they gain access to unusual parts of the body.
  • Candida albicans:
    • Commonly found in the skin, gastrointestinal tract, mouth, and reproductive tract; can be transmitted between individuals.
    • Under certain conditions, it switches from yeast form to filamentous hyphae, damaging tissue and causing inflammation.
    • Types of Infections:
    • Thrush: Infection of the mouth, tongue, gums, and pharynx; common in infants and immunocompromised adults.
    • Cutaneous: Red rash in moist areas of the body, like groin.
    • Vulvovaginal: Symptoms include burning, redness, painful intercourse, and abnormal discharge, often occurring after taking antibiotics.
  • Treatment: Amphotericin B kills Candida by binding to ergosterol, forming pores that allow leakage of intracellular ions and macromolecules.

Animal Evolution

Characteristics Unique to the Animal Kingdom

  1. Chemoheterotrophs: Obtain energy from breaking chemical bonds in organic molecules.
  2. Multicellularity: Organisms composed of multiple cells.
  3. No Cell Walls: Composed of a flexible plasma membrane, allowing processes like phagocytosis; tissues are held together by extracellular components (e.g., collagen).
  4. Active Movement: Capable of faster and more complex movement.
  5. Diversity of Form: Includes both invertebrates and vertebrates.
  6. Diversity of Habitat: Occupy various ecosystems.
  7. Sexual Reproduction: Meiosis produces gametes; animals may have non-motile eggs and smaller motile sperm; some animals are capable of both sexual and asexual reproduction.
  8. Tissues: Collections of specialized cells that perform specific functions.
  9. Embryonic Development: Characterized by specific stages during development.

Types of Symmetry

  • Bilateral Symmetry:

    • Body has left and right halves that are mirror images, divided by the sagittal plane.
    • Importance: Facilitates the development of a central nervous system and facilitates cephalization (concentration of sense organs and neural tissues in the anterior end).

  • Radial Symmetry:

    • Body parts are arranged around a central axis, can be divided symmetrically along any plane through the center.

Animal Tissues

Structure, Function, and Location

  • Epithelial Tissue: Covers the outside of the body and lines organs and cavities.

    • Types:
    • Simple Squamous: Thin cells facilitating gas exchange; found in capillaries and alveoli.
    • Simple Cuboidal: Cube-shaped cells; involved in secretion; found in glands and kidney tubules.
    • Simple Columnar: Rectangular-shaped cells; functions include secretion and absorption; lines the gastrointestinal tract.
    • Stratified Squamous: Multiple layers providing protection; found in outer skin layers and openings like the mouth.
    • Pseudostratified Columnar: Varied cell heights; secretes and moves mucus; present in respiratory tracts.

  • Connective Tissue: Binds and supports other tissues, characterized by an extracellular matrix.

    • Types:
    • Blood: Composed of plasma and cellular components (e.g., erythrocytes, leukocytes, platelets).
    • Loose Connective: Provides structural support and nutrients; contains collagen and elastic fibers.
    • Adipose Tissue: Stores energy, insulates, and protects; populated with adipocytes.
    • Hyaline Cartilage: Tough, flexible tissue found in joints and respiratory tracts.
    • Dense Regular: Strong, stretching ability due to parallel collagen fibers; forms ligaments and tendons.
    • Bone (Osseous): Contains osteocytes and provides support; characterized by a central canal for blood vessels and lacunae housing osteocytes.

  • Muscle Tissue: Specialized for movement.

    • Types:
    • Skeletal Muscle: Attached to bones; multi-nucleated; striated.
    • Smooth Muscle: Non-striated; found in organs; involuntary control.
    • Cardiac Muscle: Striated; found in the heart; connected by intercalated discs allowing synchronized contraction.

  • Nervous Tissue: Composed of neurons (conduct impulses) and neuroglia (support cells).

    • Neuron Structure:
    • Cell Body: Contains the nucleus.
    • Dendrites: Receive signals.
    • Axon: Transmits signals away from the cell body.

Animal Diversity

Taxa

  • Porifera:

    • Anatomy: No symmetry, three functional layers, outer epithelium, mesohyl, spicules, spongin, flagellated choanocytes.
    • Characteristics: Free-swimming larvae that metamorphose into sessile adults; capable of cellular redifferentiation.
    • Modes of Reproduction: Asexual fragmentation and sexual reproduction.

  • Cnidaria:

    • Anatomy: Two body forms (polyp and medusa), containing nematocytes for prey capture.
    • Characteristics: Radial symmetry, specialized nerve cells; reproduce asexually through budding or sexually through gametes.

  • Platyhelminths:

    • Anatomy: Includes flame cells for waste removal and is mainly hermaphroditic.
    • Characteristics: Bilateral symmetry, predatory/exclusive nature; reproduce sexually or asexually.

  • Infection Pathologies:

    • Schistosoma infection: Acquired through contaminated water; larvae penetrate skin, leading to systemic symptoms. Treated with praziquantel.
    • Tapeworm anatomy: Segmented flatworms lacking digestive tracts; attachment via scolex. Symptoms include nausea, weight loss, and intestinal blockage. Cysticercosis results from larvae in muscle tissue.

Animal Evolution Continued

Developmental Processes

  • Protosome vs. Deuterostome:
    • Protosome: Mouth develops first from the blastopore; undergoes determinate development.
    • Deuterostome: Anus develops first; undergones indeterminate development.

Segmentation Benefits

  • Independent segment function and protection against injury.
  • Each segment contains a complete set of adult organs.

Respiratory System

Role of Oxygen (O₂) and Carbon Dioxide (CO₂)

  • Oxygen: Required for ATP production.
  • Carbon Dioxide: Waste product of cellular respiration.
  • Diffusion Factors:
    • Concentration: Gradient affects diffusion rates.
    • Solubility: CO₂ is more soluble in blood, allowing for quicker membrane passage.
  • Respiratory Membrane Properties:
    1. Living cell composition.
    2. Thinness enhances diffusion.
    3. Large surface area enhances gas exchange.
    4. Moisture is essential for gas dissolution.
    5. Ventilation mechanisms bring fresh gas to the membrane.

Fick's Law of Diffusion

  • R = rac{DA riangle P}{d}
    • Where A = surface area, ( riangle P ) = pressure difference, d = distance.

Modes of Respiration

  • Cutaneous Respiration: Through the skin, typical in certain amphibians.
  • Gills: Include both external and internal forms; involve movement for proper gas exchange.

Human Respiratory System

  • Alveoli: The gas exchange site with extensive surface area; consists of simple squamous epithelium.
  • Mechanism:
    • Inhaled air pathway: Larynx → Glottis → Trachea → Bronchi → Bronchioles.
    • Cleansing mechanism: Mucus traps debris during passage.