HISTOLOGY

THE STUDY OF TISSUES

GENERAL

Tissue = Cells with similar structure & function organized into groups or layers

Four major types:- Epithelial (Covers or lines surfaces, found

in glands)- Connective (Bind & support body parts)- Muscle (Movement)- Nervous (Detect changes & transmit info.)

CHARACTERISTICS OF EPITHELIAL TISSUE

Covers all body surfaces inside & outMany tightly packed cells, usually

arranged into layersFree surface & basement membraneFunctions: protection, absorption,

sensation, secretionHigh rate of cell division (healing)Avascular (rely on diffusion)

Epithelial Cell Surface

CLASSIFICATION OF EPITHELIAL TISSUE

Layers- Simple (one layer)- Stratified (>1 layer; Note: only cells at

surface have characteristic shape)Shapes

- Squamous- Cuboidal- Columnar- Transitional

CONNECTIVE TISSUE - GENERAL

Few cells widely spaced in non-living matrix

Matrix may be solid, semi-solid, fluidLargest % of tissue by weight; found in all

body partsBinds, protects, supportsMay be vascular

CONNECTIVE TISSUE - GENERAL

Fibroblast- Most common cell- Secretes fibers

* Collagen – strong, flexible, structural* Elastic – stretch & recoil* Reticular – highly branched, supportive

Differs in type & amount of fibers in matrix

Loose or dense; regular or irregular

MUSCLE TISSUE

Contract, provide movement3 types:

- Skeletal (attached to bones)

- Smooth (hollow organs)

- Cardiac (heart)

NERVOUS TISSUE

Regulate, coordinate, body functionsBrain, spinal cord, nerves2 types of cells:

- Neuron (nerve cell)* Most specialized cell in body* Conducts (Transmission of nerve

impulse)- Neuroglia (“nerve glue”)

* Assist neurons (bind, protect, supply)