Warm-Up

1. What is a tissue?2. The study of tissues is called ______.3. What are the 4 main types of

tissues? (See the intro to Chapter 4 in textbook)

Warm-UpWhat type of epithelial cell is shown below?

1. 2.

3.

4.

Simple Columnar Epithelium

Stratified Squamous Epithelium

Pseudostratified Columnar Epithelium

Simple Cuboidal Epithelium

Chapter 4

Tissue: group of cells that are similar in structure and function

Histology: study of tissues

Types of Tissues:1. Epithelium (covering)2. Connective (support)3. Muscle (movement)4. Nervous (control)

Preparing tissues for microscopy

Specimen is fixed (preserved) Cut into thin sections (slices) Stained with colored dyes

Part I: Epithelial Tissue

Epithelial Tissue

“epithe” = laid on, covering Structure:

1. Covering and lining epithelium2. Glandular epithelium

Function: Protection Absorption Filtration Secretion

Special Properties1. Polarity

Apical surface = exposed free surface or edge (some with microvilli, cilia)

Basal surface = lower, attached surface

2. Specialized contacts Fits close together to form continuous

sheets

Special Properties3. Supported by connective tissue

Rests on basement membrane 4. No blood supply (avascular)

Rely on diffusion and underlying connective tissue for food/O2

5. Regeneration – Replace lost cells

Classification Two names = (# cell layers) + (shape of cells) Cell Layers: simple or stratified Shapes: squamous, cuboidal, or columnar

Simple Epithelium

Absorption, secretion, filtration Very thin

Simple Epithelium

Simple Epithelium

Simple squamous Filtration, rapid diffusion Capillary walls, air sacs in lungs, kidney

filtration Serous membranes: slick layer lining

ventral body cavity and its organs

Simple Epithelium Simple cuboidal

Secretion & absorption Lines ducts of glands (salivary), kidney

tubules, ovary surface

Simple Epithelium

Simple columnar Absorption and

secretion Lines digestive tract Microvilli, cilia Mucous

membranes: lubricating mucus

Simple Epithelium

Pseudostratified columnar Rests on basement membrane – false

impression (pseudo) of being multi-layered

Secretes or absorbs Respiratory tract – cilia propels mucus

from lungs

Stratified Epithelium

2+ layers, more durable Main function = protect

Stratified Epithelium

Stratified squamous Withstand abuse, friction Esophagus, mouth, outer portion of skin

Stratified Epithelium

Stratified cuboidal Usually 2 layers Mainly in ducts of large glands (sweat,

mammary, salivary)

Sweat Gland Esophageal Gland

Stratified Epithelium

Stratified columnar Thick, waterproof layer Pharynx, male urethra, lining ducts

Transitional Epithelium

Able to change shape (cuboidal squamous)

Lining of hollow urinary organs (bladder, ureter, urethra)

Stretches when filled with urine

Glandular Epithelium

Gland: make and secrete a particular product

2 Types: Endocrine gland: produce hormones

secreted into tissue fluid or bloodstream

Exocrine gland: secrete products into ducts onto body surfaces or body cavities Eg. mucous, sweat, oil, saliva, bile

Exocrine Glands

Unicellular Multicellular Mucus cells or

goblet cells Duct structure