KIN 223 CHAPTER 5 LESSON OBJECTIVES

Cellularity

Composed of tightly packed cells.

Polarity

Epithelial tissue has an apical surface exposed to the environment and a basal surface attached to connective tissue.

Basement membrane

A barrier between epithelium and connective tissue.

Avascularity

Epithelial tissue lacks blood vessels.

Innervation

Epithelial tissue is richly innervated with nerves.

Regeneration capacity

Epithelial cells have a high ability to regenerate and heal.

Physical protection

Epithelial tissue protects against dehydration, abrasion, and destruction.

Selective permeability

Epithelial tissue allows selective passage of substances.

Secretions

Some epithelial cells are specialized for secretion.

Sensations

Epithelial tissue provides sensory information to the nervous system.

Simple epithelium

Composed of a single cell layer.

Stratified epithelium

Composed of two or more layers of cells.

Pseudostratified epithelium

Appears to have multiple layers but is a single layer of closely packed cells.

Squamous cells

Flat, wide, and irregularly shaped epithelial cells.

Cuboidal cells

Cube-shaped epithelial cells, about as tall as they are wide.

Columnar cells

Slender and taller than they are wide epithelial cells.

Simple Squamous

A single layer of flattened cells for rapid diffusion and filtration.

Simple Cuboidal

A single layer of cube-shaped cells for absorption and secretion.

Simple Columnar

A single layer of tall cells for absorption and secretion, with nonciliated and ciliated forms.

Pseudostratified Columnar

Appears stratified but is a single layer of tall cells, with ciliated and nonciliated forms.

Stratified Squamous

Multiple layers of flattened cells for protection, with keratinized and nonkeratinized forms.

Stratified Cuboidal

Two or more layers of cube-shaped cells for protection and secretion.

Stratified Columnar

Two or more layers of columnar cells for protection and secretion.

Transitional Epithelium

Multiple layers of cells that change shape when stretched, found in the urinary tract.

Glands

Individual or multicellular organs composed of epithelial tissue.

Endocrine glands

Secrete hormones into the bloodstream.

Exocrine glands

Secrete substances through ducts to epithelial surfaces.

Simple glands

Have a single, unbranched duct.

Compound glands

Have branched ducts.

Tubular glands

Have secretory portions and ducts of the same diameter.

Acinar glands

Have secretory portions that form expanded sacs.

Merocrine glands

Release secretions via exocytosis.

Apocrine glands

Release secretions by pinching off a portion of the cell.

Holocrine glands

Release secretions by rupturing the entire cell.

Connective tissue

Composed of cells, protein fibers, and ground substance.

Resident cells

Stationary cells housed in connective tissue.

Wandering cells

Move through connective tissue to protect the body.

Collagen fibers

Provide tensile strength and resist stretching.

Reticular fibers

Thin, branching fibers that form supportive networks.

Elastic fibers

Allow tissues to stretch and recoil.

Ground substance

Molecular material produced by connective tissue cells.

Extracellular matrix

Composed of ground substance and protein fibers.

Fibroblasts

Resident cells that produce fibers and ground substance.

Adipocytes

Fat cells that store energy.

Mesenchymal cells

Embryonic stem cells that replace damaged cells.

Fixed macrophages

Large, irregular-shaped resident cells that protect against harmful agents.

Glycosaminoglycans (GAGs)

Large molecules in ground substance that attract water.

Proteoglycans

Formed with GAG linked to a protein.

Glycoproteins

Proteins with carbohydrates attached.

Functions of connective tissues

Protection, support, binding structures, storage, transport, and immune protection.

Mesenchyme

Adult connective tissue with mesenchymal stem cells.

Mucous connective tissue

Found in the umbilical cord.

Loose connective tissue

Includes areolar, adipose, and reticular tissues.

Dense connective tissue

Includes dense regular, dense irregular, and elastic connective tissues.

Cartilage

A type of supporting connective tissue.

Blood

A type of fluid connective tissue.

Nervous tissue

Composed of neurons that transmit nerve impulses.

Organ

Composed of two or more tissue types working together.

Mucous