Chapter 4 Histology

Histology

The study of the normal structure of tissues.

Tissue

A group of structurally and functionally related cells and their external environment that together perform common functions.

Extracellular Matrix (ECM)

Surrounds the cell; ground substance and protein fibers.

Functions of Extracellular Matrix

Provides strength to resist forces, directs cells to their proper places, regulates cell development and survival, and holds cells in proper position.

Epithelial Tissue

A sheet of cells tightly packed together with little visible ECM, covering and lining body surfaces and cavities, and forming glands.

Five Functions of Epithelial Tissue

Protection, immune defenses, secretion, selective permeability, and sensation.

Connective Tissue

Cellular 'velcro' that connects all other tissues in the body; characterized by its extracellular matrix.

Muscle Tissue

Composed of cells that can contract and generate force.

Nervous Tissue

Generates, sends, and receives messages, containing additional supportive cells.

Ground Substance

The component of ECM that contains extracellular fluid.

Cell Junctions

Connections of neighboring cells in a tissue linked by integral proteins.

Tight Junctions

Connections similar to a zipper that prevent the passage of macromolecules.

Desmosomes

Junctions composed of integral linker proteins that provide mechanical stability.

Gap Junctions

Small pores made of protein channels allowing communication between adjacent cells.

Simple Epithelia

A single layer of cells.

Stratified Epithelia

More than one layer of cells.

Squamous Cells

Flattened cells.

Cuboidal Cells

Short, square-shaped cells.

Columnar Cells

Tall and elongated cells.

Exocrine Glands

Glands that secrete substances locally only.

Merocrine Secretion

Secretion method where product is released from intact cells.

Holocrine Secretion

Secretion method where the entire cell ruptures and spills its contents.

Apocrine Secretion

Secretion method where part of the cell pinches off.

Endocrine Glands

Glands that secrete hormones directly into the bloodstream.

Adipocytes

Fat cells with a single large lipid inclusion.

Fibroblasts

Cells in connective tissue that produce protein fibers.

Dense Regular Connective Tissue

Contains thick parallel bundles of collagen fibers; found in tendons and ligaments.

Cartilage

Avascular and tough flexible tissue that absorbs shock and resists tension and compression.

Chondrocytes

Mature cartilage cells located in lacunae.

Osteoblasts

Immature bone cells that produce bone matrix.

Erythrocytes (RBC)

Red blood cells that carry oxygen.

Leukocytes (WBC)

White blood cells involved in immune responses.

Cardiac Muscle

Involuntary muscle found in the heart with intercalated discs.

Striated Muscle Cells

Muscle cells with organized myofilaments, producing striations.

Neurons

Nerve cells that generate, conduct, and receive nerve impulses.

Neuroglial Cells

Supportive cells that assist in the function of neurons.

Serous Membranes

Membranes lining body cavities with mesothelium that produce serous fluid.

Mucous Membranes

Lines body passages that open to the outside and includes goblet cells.

Regeneration

Process by which damaged cells are replaced with the same cell type.

Fibrosis

Process of producing scar tissue from fibroblast proliferation.

Nutrition in Tissue Repair

Collagen synthesis requires protein intake and vitamin C.

Blood Supply in Tissue Repair

Adequate blood flow is essential for healing.