TissuesTissuesDr. Gerald Brasington

TissuesTissuesHistology: The study of

microscopic structure of tissues.Integumentary System: The skin

and its appendages.Every tissue of the body falls into

one of 4 main categories:◦Epithelial◦Connective◦Muscle◦Nervous

Epithelial TissueEpithelial TissueDistinguished by its close

association of cells epithelial cells are packed close together with little material between them.

Epithelium is avascular.Epithelial tissue covers body

surfaces, lines inside of body cavities and organs, and forms glands.

Epithelial tissue Epithelial tissue (continued)(continued)3 main functions:

◦1. Protection◦2. Control of permeability◦3. Secretion of needed substances

from glands

Epithelial tissue Epithelial tissue (continued)(continued)Arrangement of cells results in

clumps or sheets◦Sheet- like: covering or lining epithelium- Covers the body and organ surfaces.

◦Lines all hollow structures. Often protective form a barrier

regulates movement of substances

Epithelial tissue Epithelial tissue (continued)(continued)Clump- like Glandular

epithelium◦Form glands

Glands- 2 types◦Exocrine: Secrete products into body

cavities and surfaces by way of tubular ducts.

◦Endocrine: Secretions diffuse into bloodstream for transport throughout body. Hormones

Epithelial tissue Epithelial tissue (continued)(continued)Epithelial tissue usually has

connection tissue under it.Often borders a hollow space

(cavity or lumen)The side exposed to a body space

apical (free) surface.The side exposed to connective

tissue is the basal surface.Basement membrane- layer of

protein fibers anchor epithelial sheet to connective tissue.

Classification of epithelial Classification of epithelial tissuetissueCell shape

◦Squamous- Flat with a thin nucleus◦Cuboidal- Cube-shaped with round

nucleus near the center of the cell◦Columnar- Tall with an oval nucleus

near the basal surface◦Transitional- Shape changing from

round when tissue is relaxed to flat when tissue is stretched.

organization (layers)◦Simple- One layer◦Stratified- Multiple layered.

Connective TissueConnective TissueArises from MesenchymeEmbryological Mesenchyme5 types of connective tissue:

◦Loose Connective Tissue◦Dense Connective Tissue◦Cartilage◦Bone◦Blood

Connective Tissue Connective Tissue (Continued)(Continued)General function is to connect

and support the tissues and organs of the body.

Muscle TissueMuscle TissueSpecialized cells containing

molecular filaments of protein (Myosin and Actin) arranged in parallel bundles.

The filaments enable the cells to shorten in length (contract).

Contraction of many cells in a coordinated manner cause body movements.

Also aids in temperature regulation.

Muscle Tissue (Continued)Muscle Tissue (Continued)3 types of muscle

◦Skeletal: attached to bones; Main type; Voluntary; cells and very long & cylindrical. Striped appearance striations.

◦Smooth: Sheets that contribute to the walls of hollow organs blood vessels, Stomach, Small intestines. Cells are spindle shaped, lack striations, involuntary control.

◦Cardiac: Forms the wall of the heart. Branched, contain striations. Intercalated Discs.

Nervous TissueNervous TissueNeural tissue is specialized cells that

“communicate” with each other through electrochemical signals (conductivity).

The cells are called Neurons. Found in brain, spinal cord, and nerves.

Contain a large axon conducts signal to other cells.

Numerous, smaller dendrites receive signals from other cells.

Neuroglia: small non-conductive support cells.

The EndThe End