Ch5 Tissues INK

Concept Definitions

  • Terminology: Key terms that will help in discussions:

    • Tissue: A group of cells that work together to perform a specific function.

    • Histology: The study of tissues at the microscopic level.

    • Organ: A structure composed of two or more tissue types working together.

    • Extracellular Matrix: A non-cellular component in all tissues that provides structural and biochemical support.

    • Stem Cells: Undifferentiated cells capable of giving rise to various cell types.

    • Epithelial Tissue: A tissue that covers body surfaces and lines cavities.

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

    • Muscle Tissue: A tissue that contracts to produce movement.

    • Nervous Tissue: Comprises neurons and glial cells for signal transmission and processing.

Tissues and Histology

  • Tissue Types:

    • Epithelial

    • Connective

    • Muscle

    • Nervous

  • Histology: Focuses on the microscopic study of tissues. The "4 Cs": Cover, Connect, Contract, Communicate.

Epithelial Tissue, Characteristics

  • Basement Membrane: A thin layer that anchors epithelial tissue.

  • Composition: Primarily composed of cells with minimal extracellular matrix.

  • Function: Covers body surfaces and forms glands. Has distinct free (apical) and basal surfaces.

  • Specialized Contacts: Cells are tightly bound to each other.

  • Nonvascular: Nutrients diffuse from underlying blood vessels.

Functions of Epithelial Tissue

  • Classification:

    • Based on physical characteristics such as cell shape and number of layers.

  • Functions include protection, absorption, secretion, and filtration.

Test Yourself: Form Fits Function

  • Concept: The functional role of tissues relates closely to their structure.

  • Examples:

    • Simple Squamous: Specialized for diffusion and filtration (found in alveoli).

    • Stratified Squamous: Provides protection (found in skin).

Glands

  • Secretory Organs: Derived from epithelial tissue.

  • Types of Glands:

    • Merocrine: Secretes without loss of cytoplasm.

    • Apocrine: Releases glandular cell fragments.

    • Holocrine: Entire cell becomes part of secretion.

Connective Tissue

  • Overview: Abundant tissue found throughout the body; diverse types fulfilling various functions.

Cells of Connective Tissue

  • Specialized cells produce the extracellular matrix with different roles:

    • Blasts: Build the matrix (e.g., osteoblasts).

    • Cytes: Maintain the matrix (e.g., osteocytes).

    • Clasts: Break down the matrix (e.g., osteoclasts).

Extracellular Matrix

  • Components: Includes collagen, elastin, and reticular fibers.

  • Ground Substance: Fills space between cells and fibers, playing a key role in tissue hydration and nutrient transport.

Functions of Connective Tissue

  • Roles include:

    • Enclosing and separating organs (e.g., fibrous tissue).

    • Connecting tissues (e.g., tendons and ligaments).

    • Supporting movement (e.g., bone and cartilage).

    • Storage (e.g., adipose tissue).

    • Cushioning and insulating (e.g., fat).

    • Transportation (e.g., blood).

    • Protection (e.g., immune cells).

Embryonic Connective Tissues

  • Mesenchyme: Source for all connective tissue cells.

  • Mucous Connective Tissue: Found in umbilical cord.

Adult Connective Tissues

  • Types:

    • Connective Tissue Proper: Loose and dense types.

    • Supporting Connective Tissue: Cartilage and bone.

    • Fluid Connective Tissue: Blood.

Muscle Tissue

  • Characteristics: Capable of contraction to produce movement.

  • Types:

    • Skeletal Muscle: Voluntary, striated, attached to skeleton.

    • Cardiac Muscle: Involuntary, striated, found in heart.

    • Smooth Muscle: Involuntary, non-striated, found in hollow organs.

Nervous Tissue: Neurons

  • Key Locations: Brain, spinal cord, and nerves.

  • Neuron Structure:

    • Cell Body: Contains the nucleus.

    • Axon: Transmits impulses away from the cell body.

    • Dendrites: Receive signals from other neurons.

Nervous Tissue: Neuroglia

  • Supportive cells that nourish, protect, and insulate neurons.

Internal Membranes

  • Types:

    • Mucous: Line cavities open to outside; secrete mucus.

    • Serous: Line closed cavities; secrete serous fluid.

    • Synovial: Line joints; secrete synovial fluid for lubrication.

Tissue Types and their Functions

  • Simple Squamous: Allows diffusion (e.g., lung alveoli).

  • Simple Cuboidal: Secretion and absorption (e.g., kidney tubules).

  • Simple Columnar: Secretion/absorption and movement of substances (e.g., intestines).

  • Stratified Squamous: Protection against abrasion (e.g., skin).

  • Transitional Epithelium: Accommodates changes in volume (e.g., urinary bladder).

Embryonic Connective Tissue

  • Mesenchyme: Origin of all adult connective tissues. Has delicate collagen fibers in a semifluid matrix.

  • Mucous Connective Tissue: Present in the umbilical cord, rich in stem cells.