tissue histology four primary types epithelial connective muscular nervous tissues

•Tissue

•Histology

•Four Primary TypesEpithelialConnectiveMuscularNervous

Tissues

Epithelial TissueFunctions

*Covering or lining

Protection

Permeability controlSecretion

Absorption

Excretion

Sensory

Function is determined by cell type & number of cell layers.

Basement Membrane

apical

basal

Structural Characteristics of Epithelia

Cellularity

Polarity

Avascular

Innervated

Regeneration

Polarity of Epithelial Cells

Classification of EpitheliaThe function of the epithelium determines which type.

Classified according to1. Number of cell layers

Simple vs. Stratified 2. Shape of apical cell

Squamous, cuboidal, columnar 3. Special features

Cilia, villi

End with epithelium to complete the naming

Arrangements

• Simple

• Stratified

• Pseudostratified

• Transitional

Shapes

• Squamous

• Cuboidal

• Columnar

Special Features

• Cilia

• Goblet Cells

• Villi

• Microvilli

Simple Squamous Epithelium

Diffusion, filtration, secretion, absorption

Location:

• Lining of blood vessels (endothelium)

• Peritoneum

• Alveoli

Simple Cuboidal Epithelium

Functions

Secretion

Absorption

Locations

Lining of ducts

Glands (salivary, pancreas, thyroid)

Kidney tubules

Thyroid Follicle

Simple Columnar Epithelium

• FunctionsSecretionAbsorption

• LocationsGI tractExcretory ductsReproductive tract

• Special Features

Pseudostratified Ciliated Columnar Epithelium

Mixture of cell heights nuclei located at various distances from surface.

All cells touch basement membrane

•FunctionsExcretionMovement

•LocationsRespiratory tract except for lungs Male reproductive ducts

Stratified Squamous Epithelium• Function

Protection (multiple layers = better protection)

• Keratinized vs. non-keratinized

• Location? Where we need protection!Skin surfaceEntrances/exits of body, e.g. mouth, vagina

Stratified cuboidal and columnar: quite rare, found in glands and ducts

Transitional Epithelium

• Layered appearance due to overcrowding.

• Function

Extreme expansion

Recoil

• Location

Bladder

Ureters

stretched

Locations in the Body

Oh…and this tissue type!

Connective Tissue: Supports, protects, binds tissues

Structural characteristics:

• Specialized cells

• Extracellular matrix– Protein fibers – Ground substance (fluid-like)

• Mostly highly vascular

Extracellular matrix – all non-living components

Functions Functions

• Structural framework

• Transport

• Support and protection

• Energy storage

Classification of Connective Tissues

Connective Tissue ProperConnective Tissue ProperTypes:

Areolar Dense regular ReticularAdipose Dense irregular

Types of Fibers:

CollagenElasticReticular

Defense:

MacrophagesPlasma CellsMast CellsOther WBC

Stop

Fluid C. T.

• Blood• Lymph

Supporting C.T.

• Cartilages– Hyaline

– Elastic

– Fibrocartilage

• Bone – Mineral matrix

Study individual types of c.t. in labStudy individual types of c.t. in lab

Membranes = Combination of Membranes = Combination of Epithelia & C.T. Epithelia & C.T.

• Mucous membranes– Lining of cavities that communicate with exterior

• Serous membranes– Lining of sealed, internal cavities

• Cutaneous membranes– Skin

• Need to know membranes

• Parietal vs. visceral

Muscle Tissue

Skeletal

Cardiac

Smooth (not striated)

Skeletal Muscle

•Voluntary

•Heavily striated

•Multinucleated

Cardiac Muscle

•Heart (Only)

•Involuntary

•Striated

•Intercalated disks

•Heavily branched

•Single central nucleus

Smooth Muscle• Involuntary

• No striations

• Single central nucleus

Nervous Tissue

• Neurons– Transmit electrical

impulses

• Neuroglia– Supportive cells of the

nervous system

Neural Tissue