Tissue = Groups of cells and cell products with similar structure and function.

There are four 1o tissues in the body:

1) Epithelium

2) Connective

3) Muscular

4) Nervous

Functions of Epithelial Tissue

1. Physical Protection

2. Regulate Exchange (permeability)

3. Provides Sensation

4. Produce Secretions

Characteristics of Epithelial Tissue

Characteristics of Epithelial Tissue

1. Cellularity – composed mostly of cells.

2. Polarity – sidenedness of tissue.

3. Attachments – physically connected to neighboring cells.

4. Avascular – has no blood supply of its own.

5. Highly Regenerative – replaces itself constantly.

Epithelial Tissue

Tight Junctions

Desmosomes

Specialized apical end

Classification of Epithelia

Cuboidal epithelium - Short cube-shaped hexagonal boxes.

1. Number of cell layers

2. Shape of Exposed (apical) cells

A) Single layer of cells = Simple Epithelium

B) Several layers of cells (more than one) = Stratified Epithelium

Squamous epithelium - Thin and flat.

Columnar epithelium - Taller than it is wide.

Transitional epithelium - Changes shapes (from squamous to cuboidal).

Simple (1 cell layer) Stratified (more than 1 cell layer)

1) Simple Squamous Epithelium

2) Simple Cuboidal Epithelium

3) Simple Columnar Epithelium

4) Pseudostratified Ciliated Columnar Epithelium

5) Stratified Squamous Epithelium

6) Stratified Cuboidal Epithelium

7) Stratified Columnar Epithelium

8) Transitional Epithelium

Classification of Epithelia

Glomerular capsule; Alveolus

Renal tubules; Thecal follicle (thyroid gland)

Stomach, Small and Large Intestines

Trachea, larynx, bronchi

Keratinized = EpidermisNon-keratinized = esophagus, cheek

Ducts of sweat glandsDucts of salivary glands

Male urethra

Urinary bladder, ureter

Simple Squamous Epithelium

Simple

Cuboidal

Epithelium

Simple Columnar Epithelium

Pseudostratified Ciliated Columnar Epithelium

Stratified Squamous Epithelium

Stratified Cuboidal Epithelium

Stratified Columnar Epithelium

Transitional Epithelium

Connective Tissue

Connective Tissue Proper

1) Blood 2) Lymph

Supporting Connective Tissue

Fluid Connective Tissue

1) Loose1) Areolar2) Adipose3) Reticular

2) Dense1) Regular2) Irregular3) Elastic

1) Bone1) Spongy2) Compact

1) Cartilage1) Hyaline2) Elastic3) Fibrocartilage

Areolar Tissue

Adipose Tissue

Reticular Tissue

Dense Regular Connective Tissue

Dense Irregular Connective Tissue

Elastic Tissue

Hyaline Cartilage

Elastic Cartilage

Fibrocartilage

Bone Tissue

Compact BoneSpongy Bone

Hematopoietic stem cells produce blood and lymph cells

Fluid Connective Tissue