MUSCLE TISSUE & NERVOUS TISSUE Tissues - 3

Essential Question  How does form follow function in muscle and nervous tissue?

Muscle Tissue  Has cells that are contractile & excitable  Comes from mesoderm  Cells called muscle fibers

3 types of muscle 1. Skeletal 2. Cardiac 3. Smooth

Skeletal Muscle  Voluntary  Striated  multinucleated  Packaged by CT  Each muscle is an organ  Most connect to a bone & contraction causes bone to move

Cardiac Muscle  Involuntary  Striated  Found only in heart  Cell junctions: intercalated discs  Gap junctions that allows ions pass directly into neighboring cells for transmission of nerve impulse

Smooth Muscle  Involuntary  Nonstriated  Found in walls of organs  Found all thru GI tract  Contracts in waves called peristalsis Keeps food moving thru

Nervous Tissue  Irritable  Conductive  Comes from endoderm  Cells called neurons

Supporting Cells  Support neurons  In CNS  Astrocytes  Microglia  Oligodendocytes  Ependymal cells  In PNS  Schwann cells  Satellite cells