T I S S U E S , G L A N D S A N D M E M B RA N E S

CHAPTER 4

TISSUES

• Histology is the study of tissues

Four main groups of tissues• Epithelial • Connective • Muscle • Nervous tissue

EPITHELIAL TISSUE

• Forms a protective covering for the body• Is the main tissue of outer layer of skin• Forms membranes, ducts, and the lining of body

cavities and hollow organs

CLASSIFICATION EPITHELIAL TISSUEClassification by shape• Squamous• Cuboidal• Columnar

Classification by arrangement• Simple• Stratified• Pseudostratified

SPECIAL FUNCTIONS OF EPITHELIAL TISSUE

• Traps foreign particles• Mucus-secreting (goblet) cells• Cilia

• Self-repairs quickly

GLANDS

• Specialized to produce a substance sent out of a body or tissue.

•Exocrine glands• Single cell• Multiple cells

•Endocrine glands

EXOCRINE GLANDS

• Have tubes or ducts to secrete substances.• oil glands• Lacrimal glands• Sweat glands

ENDOCRINE GLANDS

• Not secreted through ducts, secreted directly into surrounding fluid• hormones

CONNECTIVE TISSUE

Categorized by physical properties• Circulating connective tissue• Generalized connective tissue• Structural connective tissue

GENERALIZED CONNECTIVE TISSUE

Two forms• Loose• Areolar tissue• Adipose tissue

• Dense• Irregular• Regular• Elastic

LOOSE CT

• Areolar- surrounds organs and vessels• Adipose- stores fat

DENSE CT

Types of dense connective tissue• Irregular; mostly collagenous fibers in random

arrangement. Examples: membranes, capsules• Regular; mostly collagenous fibers in parallel

alignment. Examples: tendons, ligaments• Elastic; elastic fibers. Examples: vocal cords,

blood vessel walls

STRUCTURAL CT

• Cartilage• Hyaline cartilage• Fibrocartilage• Elastic cartilage

• Bone• Osseous tissue• Bone marrow

STRUCTURAL CT

MUSCLE TISSUETypes of muscle tissueSmooth-

- involuntary muscle- non striated-lines hollow organs (small intestine etc)• Skeletal muscle• Voluntary muscle• Striated muscle

• Cardiac muscle (myocardium)• Involuntary muscle• Intercalated disks• Smooth muscle (visceral muscle)

MUSCLE TISSUE

NERVOUS TISSUE

Body’s communication system is made of nervous tissue• Brain• Nerves• Spinal cord

NERVOUS TISSUE

NEURON

Basic unit of nervous tissue • Nerve cell body• Fibers• Dendrite• Axon• Nerve

NEUROGLIA

• Protect neurons• Form myelin sheath around neurons to speed up

impulses

MEMBRANES

Thin sheets of tissue• Cover a surface• Serve as a divider• Line a hollow organ or body cavity• Anchor an organ• Contain cells that secrete lubricants

EPITHELIAL MEMBRANES

Several types• Serous• Mucous• Cutaneous

SEROUS MEMBRANESThree types of serous membranes• Pleurae• Serous pericardium• Peritoneum

Organization of the serous membrane• Parietal layer• Visceral layer

MUCOUS MEMBRANES

Vary in structure and function• Trap and remove foreign particles• Protect deeper tissue• Absorb food materials

CONNECTIVE TISSUE MEMBRANESConnective tissue without epithelium• Synovial membranes• MeningesFibrous bands or sheets that support and hold organs• Superficial (subcutaneous) fascia• Deep fasciaMembranes that support organs• Fibrous pericardium• Periosteum• Perichondrium

TISSUES AND AGING

Tissues lose elasticity as they age• Skin• Blood vessels• Tendons and ligaments• Bones• Muscles