Lecture Exam 2 Required Terms to Know

Fundamental Tissues and Anatomical Terminology

  • Organ

    • A structural unit composed of two or more tissue types working together to perform a specific function.

  • Subcutaneous

    • Located or situated beneath the skin.

  • Subcutaneous Layer (Hypodermis)

    • The layer directly beneath the dermis composed of loose connective tissue rich in adipose tissue.
    • Functions in thermal insulation, energy storage, and anchoring the skin to underlying tissues.

  • Intramuscular

    • Located within the substance of a muscle.

  • Transdermal

    • A route of administration involving medication delivery across the skin to enter the systemic circulation.

Epithelial Tissue and Glands

  • Epithelial Tissue Roles and Cellular Structure

    • Roles: Protection, absorption, secretion, and filtration.
    • Cells: Categorized by cell shape into squamous, cuboidal, or columnar, and arranged as simple or stratified.

  • Epithelial Cell Shapes

    • Squamous: Flat epithelial cells specialized for rapid diffusion and filtration.
    • Cuboidal: Cube-shaped epithelial cells specialized for secretion and absorption (e.g., kidney tubules).
    • Columnar: Tall, rectangular epithelial cells specialized for secretion and absorption.

  • Epithelial Layering Classifications

    • Simple: Consists of a single layer of epithelial cells.
    • Stratified: Composed of multiple layers of epithelial cells designed for protection.
    • Pseudostratified: A single layer of cells of varying heights that gives the appearance of being multilayered.
    • Transitional: A specialized stratified epithelium that stretches; found lining the urinary bladder.
    • Keratinized: Epithelial cells filled with keratin that are dead at maturity, providing waterproof protection.

  • Basement Membrane

    • A thin extracellular layer situated beneath epithelial tissue.
    • Composed of the basal lamina and reticular lamina.
    • Anchors the epithelium to the underlying connective tissue and acts as a selective barrier.

  • Glandular Mechanisms and Types

    • Exocrine Glands: Glands that secrete substances through ducts onto epithelial surfaces.
    • Endocrine Glands: Ductless glands that secrete hormones directly into the bloodstream.
    • Merocrine Glands: Glands that release secretions via exocytosis without damaging the cell; this is the most common gland type in the body.
    • Holocrine Glands: Glands that release their secretions through complete cell rupture (e.g., sebaceous glands).

Connective Tissues and Matrix Components

  • Connective Tissue Overview

    • Role: Support, bind, protect, and transport.
    • Cells: Includes fibroblasts, adipocytes, macrophages, mast cells, and other specialized cell types.
    • Function: Forms the structural framework of the body, provides energy storage, and executes immune defense.

  • Ground Substance

    • The gel-like component of the extracellular matrix in connective tissue that surrounds cells and fibers.

  • Adipose Tissue

    • A specialized connective tissue composed primarily of adipocytes.
    • Functions to store energy as triglycerides, insulate the body, and cushion internal organs.

  • Cartilage

    • A firm, flexible connective tissue composed of chondrocytes residing within lacunae inside a gel-like matrix.
    • Provides structural support and reduces friction in joints.

  • Blood

    • A fluid connective tissue composed of liquid plasma and formed elements.
    • Formed Elements: Red blood cells (erythrocytes), white blood cells (leukocytes), and platelets.
    • Function: Responsible for nutrient/gas transport, physiological regulation, and biological protection.

  • Ligaments

    • Dense regular connective tissue structures that connect bone to bone.

Integumentary System Architecture and Layers

  • Integumentary System

    • Refers to the skin and its accessory structures, including hair, nails, and cutaneous glands.

  • Epidermis Overview

    • Functions: Protection, prevention of water loss, vitamin D synthesis, and immune defense.

  • Epidermal Layers (Strata)

    • Stratum Basale: The deepest layer of the epidermis containing mitotically active stem cells and melanocytes.
    • Stratum Spinosum: A layer of keratinocytes connected by desmosomes that provides structural strength.
    • Stratum Granulosum: The layer where keratinization intensifies and cells accumulate keratohyalin granules.
    • Stratum Corneum: The outermost epidermal layer consisting of dead, fully keratinized cells forming a protective barrier.

  • Thin vs. Thick Epidermis

    • Thin Epidermis: Covers most of the body; contains 44 layers; contains hair.
    • Thick Epidermis: Found on the palms and soles; contains 55 layers; lacks hair; features a thicker stratum corneum.

  • Epidermal Cells and Pigments

    • Keratinocytes: The primary cells of the epidermis that produce the protective protein keratin.
    • Melanocytes: Specialized cells located in the stratum basale that produce melanin.
    • Melanin: Pigment produced by melanocytes that protects cell nuclei against ultraviolet (UV) radiation.
    • Carotene: A plant pigment (provitamin A) that accumulates in the stratum corneum and subcutaneous fat, giving skin a yellow-orange tint.
    • Dendritic Cells: Immune cells in the epidermis (Langerhans cells) that present antigens to activate the body's immune response.

  • Dermis

    • The connective tissue layer located directly beneath the epidermis.
    • Contains blood vessels, nerves, cutaneous glands, and hair follicles.
    • Cleavage Lines: Lines of natural tension in the dermis determined by collagen fiber orientation; surgical incisions made parallel to these lines heal more easily.

Accessory Structures and Cutaneous Secretions

  • Sweat Glands and Functions

    • Eccrine (Merocrine) Sweat Glands: Widely distributed sweat glands that produce watery sweat primary for thermoregulation.
    • Apocrine Sweat Glands: Located mainly in the axillary and groin regions; secrete a thicker, protein-rich sweat into hair follicles; become active at puberty and are associated with body odor.
    • Function of Sweat: Cools the body through heat loss, excretes small amounts of waste, and contributes to acid mantle protection.

  • Sebaceous Glands and Sebum

    • Sebaceous Glands: Oil glands associated with hair follicles that secrete sebum.
    • Sebum: An oily secretion that lubricates and softens skin and hair.

  • Hair Follicles and Hair Types

    • Hair Follicle: An epidermal tube structure that produces hair.
    • Lanugo Hair: Fine, unpigmented fetal hair.
    • Vellus Hair: Fine, pale body hair present over most of the body.
    • Terminal Hair: Coarse, long, pigmented hair.

  • Nails

    • Hard keratin plates covering the dorsal surfaces of distal phalanges.
    • Functions: Protect distal digits, enhance fine motor function, and assist in grasping.

Thermoregulation, Burns, and Bone Homeostasis

  • Thermoregulation Principles

    • Evaporation: Heat loss mechanism where liquid sweat converts to vapor, absorbing and removing body heat.
    • Body Response to Cold: Vasoconstriction, shivering, decreased sweating, and increased metabolic rate.

  • Burn Classification

    • First-Degree Burn: Affects the epidermis only; causes redness and pain.
    • Second-Degree Burn: Affects the epidermis and partial dermis; characterized by blister formation.
    • Third-Degree Burn: Full-thickness burn that destroys the epidermis and dermis, possibly extending into deeper tissues; destroys nerves, making the damaged area often painless initially.

  • Osteoporosis

    • A condition occurring when bone resorption exceeds bone formation.
    • Causes: Aging, hormonal changes (such as decreased estrogen\text{decreased estrogen}), physical inactivity, and poor calcium or vitamin D intake.

Muscular, Nervous, and Serous Membrane Systems

  • Muscular Tissue Types and Functions

    • General Function: Produces movement, maintains body posture, and generates heat.
    • Skeletal Muscle: Voluntary, striated muscle attached to bones, composed of long multinucleated muscle fibers.
    • Cardiac Muscle: Involuntary, striated muscle found exclusively in the heart; composed of branching cells connected by intercalated discs for synchronized contraction.
    • Smooth Muscle: Involuntary, non-striated muscle located in the structural walls of hollow organs.

  • Nervous Tissue and Neuronal Structure

    • Nervous Tissue: Composed of neurons and neuroglia; coordinates bodily activities through electrical signaling.
    • Neurons: Specialized cells that transmit electrical impulses.
    • Glial Cells: Non-neuronal cells that support, insulate, nourish, and protect neurons.
    • Dendrites: Branching neuronal processes that receive incoming signals.
    • Cell Body: Integrates incoming signal input.
    • Axon: Conducts electrical impulses away from the cell body.
    • Axon Terminals: Transmit signals to the next target cell.

  • Serous Membranes of the Lungs

    • Pleura: A double-layered serous membrane surrounding the lungs.
    • Parietal Pleura: The outer pleural layer lining the interior of the thoracic cavity walls.
    • Visceral Pleura: The inner pleural layer covering the outer surface of the lungs.
    • Intrapleural Fluid: Serous fluid located between the parietal and visceral pleural layers that reduces friction during breathing.