Anatomy and Physiology Ch. 4 Objectives

Tissue

Groups of cells similar in structure and performing a common function.

Histology

The study of tissues.

Primary Human Tissue Types

Epithelial (covering), connective (support), muscle (movement), nervous (control).

Epithelial Cellularity

Mostly close-packed cells with little extracellular material.

Epithelial Specialized Contacts

Cells bound closely together by desmosomes and tight junctions.

Epithelial Polarity

Cells have a free apical surface and an attached basal surface.

Basement Membrane

Basal and reticular lamina that reinforces epithelial sheets and defines boundaries.

Epithelial Vascularity

Avascular (no blood vessels) but innervated; nourished by underlying connective tissue.

Epithelial Regeneration

High capacity; lost cells are rapidly replaced by cell division.

Epithelial Cell Shapes

Squamous (fried egg), cuboidal (cube), and columnar (sphere).

Epithelial Layers

Simple (single layer) and stratified (several layers).

Exocrine Glands

Externally secreting glands with an epithelial-walled duct.

Endocrine Glands

Internally secreting, ductless glands that produce hormones.

Unicellular Glands

Isolated secretory cells releasing substances without a duct.

Multicellular Glands

Exocrine secretory substances made of many cells connected via a duct.

Simple vs. Compound Glands

Simple has a single unbranched duct; compound has a branched duct.

Tubular vs. Alveolar Glands

Tubular cells form tubes; alveolar/acinar form flasklike sacs.

Merocrine Glands

Secrete products by exocytosis (e.g., pancreas, sweat glands).

Holocrine Glands

Accumulate product, rupture, and release dead cell fragments.

Osteocytes

Bone cells.

Lacunae

Small fluid-filled cavities within the bone matrix where cells live.

Fibroblasts

Primary cells found in general connective tissues.

Central Canal

Structural channels found within compact bone tissue.

Osteon

Large cylindrical structural unit of compact bone.

Canaliculi

Tiny microscopic canals allowing nutrients, wastes, or fluids to move.

Intercalating Disc

Specialized dark junctions connecting adjacent cardiac muscle cells end-to-end.