exam 2 a&p

Chapter 3: The Cell

  • Basic Cellular Processes:

    • Metabolism: The set of life-sustaining chemical reactions in organisms.

    • Transport: The movement of nutrients and waste products across cell membranes.

    • Communication: Interaction between cells through signaling molecules.

    • Reproduction: The process by which cells divide and give rise to new cells.

  • Structure and Function of the Phospholipid Bilayer:

    • Composed of phospholipids with a hydrophilic (water-attracting) "head" and two hydrophobic (water-repelling) "tails".

    • Provides a semi-permeable barrier allowing selective entry and exit of substances.

  • Membrane Protein Types:

    • Integral Proteins: Embedded within the membrane and can span across it.

    • Peripheral Proteins: Attached to the exterior or interior surfaces of the membrane.

  • Role of Cholesterol in Membranes:

    • Cholesterol molecules are interspersed within the phospholipid bilayer.

    • They help stabilize membrane fluidity and maintain structural integrity at various temperatures.

  • Selectively Permeable Definition:

    • A characteristic of cellular membranes that allows certain molecules to pass while restricting others.

  • Difference between Passive and Active Transport:

    • Passive Transport: Movement of molecules without energy input, down their concentration gradient.

      • Examples include:

        • Diffusion — Movement of small molecules directly through the membrane.

        • Facilitated Diffusion — Movement through membrane proteins (e.g., glucose transport).

        • Osmosis — Diffusion of water across a semipermeable membrane.

    • Active Transport: Requires energy expenditure (ATP) to move substances against their concentration gradient.

      • Na+/K+ Pump: Exports 3 Na+ ions out of the cell and imports 2 K+ ions into the cell, crucial for maintaining cellular function.

  • Understanding Tonicity and Water Response:

    • Tonicity refers to the ability of an extracellular fluid to change the shape or tone of cells by altering their internal water volume.

      • Isotonic: No net movement of water; cells maintain their shape.

      • Hypotonic: Water moves into the cell, it swells and may burst.

      • Hypertonic: Water moves out of the cell, it shrinks.

  • Cell Organelles — Structure and Function:

    • Nucleus: Contains genetic material (DNA) and controls cellular functions.

    • Mitochondria: Produces ATP through cellular respiration.

    • Endoplasmic Reticulum:

      • Rough ER: Studded with ribosomes; synthesizes proteins.

      • Smooth ER: Lacks ribosomes; synthesizes lipids and detoxifies.

    • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion.

    • Lysosomes: Contains digestive enzymes to break down waste.

    • Ribosomes: Synthesizes proteins.

    • Cytoskeleton: Provides structural support and aids in intracellular transport.

  • Protein Synthesis Phases:

    • Transcription: The process by which DNA is transcribed to mRNA.

    • Translation: The process in which mRNA is translated into an amino acid sequence to form proteins.

  • Cell Cycle Phases and Major Events:

    • G1 Phase: Cell growth and preparation for DNA replication.

    • S Phase: DNA replication occurs, resulting in two sister chromatids for each chromosome.

    • G2 Phase: Further growth occurs, and the cell prepares for mitosis.

    • M Phase (Mitosis): The cell divides into two daughter cells.

  • Definition of Cytokinesis:

    • The process during cell division where the cytoplasm of a parental cell is divided into two daughter cells.

Chapter 4: Histology

  • Tissue Components:

    • Cells: The basic structural units of life that perform various functions.

    • Extracellular Matrix (ECM): A complex network of proteins and carbohydrates outside cells that provides structural and biochemical support to surrounding cells.

  • Functions of Each Tissue Type:

    • Epithelial Tissue: Covers body surfaces, lines cavities and organs, forms glands.

    • Connective Tissue: Supports, binds together, and protects tissues and organs.

    • Muscle Tissue: Responsible for body movement.

    • Nervous Tissue: Transmits signals for communication between body parts.

  • Components of Ground Substance and Protein Fibers:

    • Ground Substance: Composed of glycoproteins, proteoglycans, and fluid; serves as the medium through which cells exchange nutrients and waste.

    • Protein Fibers: Collagen (provides strength), Elastic fibers (provides elasticity), Reticular fibers (supportive framework for organs).

  • Types of Cell Junctions:

    • Tight Junctions: Prevent leakage of materials between cells.

    • Desmosomes: Provide mechanical stability by anchoring adjacent cells together.

    • Gap Junctions: Allow communication between adjacent cells through small channels.

  • Epithelial Tissue Characteristics:

    • Avascular: Lacks blood vessels and relies on diffusion for nutrient uptake.

    • Basement Membrane: A thin layer that supports the epithelium and anchors it to the underlying connective tissue.

    • Classification: Based on cell shape (squamous, cuboidal, columnar) and the number of layers (simple, stratified).

    • Types of Exocrine Glands: Secrete substances through ducts to an epithelial surface or into the lumen.

  • Connective Tissue Types:

    • Two Basic Groups:

      • Loose Connective Tissue: Includes areolar and adipose tissues.

      • Dense Connective Tissue: Includes tendons and ligaments.

    • Cell Types in Connective Tissue: Fibroblasts, adipocytes, macrophages, leukocytes.

    • Special ECM for Each Connective Tissue: Specialized composition depending on the tissue type; collagenous matrix in dense connective tissue, gelatinous matrix in loose connective tissue.

  • Functions of Each Type of Connective Tissue:

    • Provide structural support, store energy, defend against pathogens, transport nutrients (in blood).

  • Muscle Tissue Types:

    • Striated Muscle: Skeletal muscle and cardiac muscle characterized by a striped appearance.

    • Smooth Muscle: Lacks striations, found in walls of hollow organs.

    • Differences in Cell Structure: Striated muscles have multiple nuclei, while smooth muscle has a single nucleus.

  • Nervous Tissue Cells:

    • Neurons: Specialized cells that transmit nerve impulses.

    • Glial Cells: Support and protect neurons; can be differentiated into several types (e.g., astrocytes, oligodendrocytes).

  • True Membranes vs. Membrane-like Structures:

    • True Membranes: Include serous membranes that cover organs; consist of a layer of epithelial cells and a layer of connective tissue.

    • Membrane-like Structures: Have similar properties but do not meet strict definitions of true membranes.

  • Structure and Layers of a True Membrane:

    • Typically consists of two layers: a parietal layer that lines the cavity and a visceral layer that covers the organs within the cavity.

Chapter 5: Integumentary System

  • Structure and Function of the Cutaneous Membrane (Skin):

    • Consists of two major layers: the epidermis (outer layer) and dermis (inner layer).

    • Provides a protective barrier against environmental hazards, regulates temperature, and allows sensory perception.

  • Avascular Nature of Skin:

    • The skin is avascular; it lacks blood vessels, which is important to prevent bleeding and provides a barrier to pathogens.

    • Nutrients are delivered through diffusion from underlying blood vessels in the dermis.

  • Feedback Loops and Homeostasis in Skin:

    • Skin plays a critical role in maintaining homeostasis by regulating body temperature (thermoregulation), preventing excessive water loss, and sensing the environment.

    • Feedback loops involving thermoregulation help maintain internal temperature despite external fluctuations.

  • Cell Types in the Epidermis:

    • Keratinocytes: The predominant cell type; responsible for producing keratin, a protective protein.

    • Melanocytes: Produce melanin, the pigment responsible for skin color.

    • Langerhans Cells: Immune cells that help in protecting against pathogens.

    • Merkel Cells: Sensory cells that initiate the sensation of touch.

  • Layers of the Epidermis:

    • Stratum Corneum: Outermost layer; consists of dead keratinized cells.

    • Stratum Lucidum: Present in thick skin; provides an extra layer of protection.

    • Stratum Granulosum: Keratinocytes begin to lose their nuclei and become more keratinized.

    • Stratum Spinosum: Provides strength and flexibility to the skin.

    • Stratum Basale: Deepest layer; actively dividing cells and where melanocytes are located.

  • Keratinocyte Life Cycle:

    • Starts in the stratum basale; cells divide and migrate upward through the epidermis, becoming more keratinized until they die and are shed from the skin surface.

  • Differences between Thick and Thin Skin:

    • Thick Skin: Found in areas prone to abrasion (e.g., palms, soles); has an additional layer (stratum lucidum) and a thicker stratum corneum.

    • Thin Skin: Covers most of the body; thinner epidermis and lacks stratum lucidum.

  • Cell Types in the Dermis:

    • Composed of various cell types including fibroblasts (which produce collagen), macrophages, and fat cells.

  • Functions of Dermis:

    • Provides structural support, nourishment to the epidermis, houses blood vessels, nerves, and glands.

  • Skin Markings:

    • Includes features such as fingerprints (due to dermal papillae) and stretch marks, which arise from the stretching of skin and rupture of collagen fibers.

  • Melanocyte Structure and Function:

    • Neuron-like cells located in the basal layer of the epidermis; produce melanin which contributes to skin color and protects against UV radiation.

  • Melanocyte and Keratinocyte Interaction:

    • Melanocytes transfer melanin to keratinocytes, leading to pigmentation in the skin and protection from UV damage.

  • Accessory Structures of Skin and Functions:

    • Hair Follicles: Contribute to hair growth and sensory function.

    • Sebaceous Glands: Secrete sebum for lubrication and waterproofing of skin and hair.

    • Sweat Glands: Aid in temperature regulation and waste excretion.