Tissues

Chapter 5

Tissue

• Definition – an aggregation of cells in which each cooperates with all others in the performance of a given function

• Examples of general functions– Movement– Protection– Support– Production of chemicals

Principal Tissue Types

• Epithelial

• Connective

• Muscular

• Nervous

Human Anatomy, 3rd editionPrentice Hall, © 2001

Epithelial Tissue• Functions

– Coverings and linings– Forms glands

• Characteristics– Closely packed cells – Continuous sheets– Basement membrane– Avascular

• Classification– Simple– Stratified

Epithelia of Coverings and Linings

Squamous Epithelium

• Simple Squamous Epithelium– Highly adapted to

diffusion, osmosis, & filtration

www.stegen.k12.mo.us/.../TissueSlides.htm

Squamous Epithelium

• Stratified Squamous Epithelium– Surface layer is flat– Function -

protection

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Cuboidal Epithelium

• Simple cuboidal epithelium– Function – secretion

and absorption

– Lines glands and their ducts

• Stratified Cuboidal epithelium– Surface layer cube-

shaped

– Function – protectionwww.stegen.k12.mo.us/.../TissueSlides.htm

Glandular Epithelium

• Gland – 1 or more cells

• Function – secretion

• Types– Exocrine – to surface or ducts – Endocrine – to blood

Transitional Epithelium

• Can be stretched

• Lines hollow structures that expand

• Function – prevents rupture of organ

http://www.mhhe.com/biosci/ap/histology_mh/stratepi.html

Columnar Epithelia

• Simple columnar epithelium– Functions

• Protection,• Absorption or

secretion

• Stratified columnar epithelium– More than one layer– Function

• Protectionwww.stegen.k12.mo.us/.../TissueSlides.htm

Pseudostratified Columnar Epithelium

• Appear stratified but all cells connect to the basement membrane

• Functions– Protection– Secretion

http://bioweb.uwlax.edu/zoolab/Table_of_Contents/Lab-1b/Pseudostratified_Model_1/pseudostratified_model_1.htm

Connective Tissue

• Most abundant tissue

• Functions are varied

• Characteristics– Specialized cells, widely scattered– Rich blood supply– Much matrix

• Extracellular fibers

• Ground substance

Cell Types Found in Connective Tissue

• Fibroblasts– Secrete the molecules that form the matrix– Fixed cells

• Fibrocytes

• Macrophages– “Big eaters”– May be fixed or wandering

Connective Tissue Fibers• Collagen fibers

– Most common type– White– Strong, ropelike– Form ligaments, tendons

• Reticular fibers– Thin– Woven into rough, flexible network

• Elastic fibers– Yellow– Thin– Stretch

• Contain elastin

Ground Substance

• Extracellular fluid in connective tissue– Water– Glycoproteins

Types of Connective Tissue

Human Anatomy, 3rd editionPrentice Hall, © 2001

Loose (Areolar) Connective Tissue• Fibers not abundant• Contains all 3 types of fibers• Examples of locations

– Between skin and muscles

– Around digestive tract

– Around blood vessels

Human Anatomy, 3rd editionPrentice Hall, © 2001

Adipose Tissue

• Most of the volume is adipocytes• Provides padding, slows heat loss, food reserve• Locations

– Wherever there is loose connective tissue

Dense Connective Tissue

• Types– Dense Regular Connective Tissue– Dense Irregular Connective Tissue– Elastic Connective Tissue

Human Anatomy, 3rd editionPrentice Hall, © 2001

Dense Regular Connective Tissue• Lots of collagen fibers in bundles• Cells – fibroblasts in rows between bundles• Examples

– Tendons, ligaments

Human Anatomy, 3rd editionPrentice Hall, © 2001

Dense Irregular Connective Tissue

• Tensions in various directions

• Occurs in sheets• Locations

– Periosteum

– Perichondrium

– Fibrous capsules of some organs

– Fasciae

– Dermis

Human Anatomy, 3rd editionPrentice Hall, © 2001

Elastic Tissue• Lots of elastic fibers• Fibroblasts in spaces between fibers• Provides stretch and strength

Cartilage

• Dense network of collagenous fibers & elastic fibers in a gel-like substance

• Cells – chondrocytes in lacunae– Chondroblasts

• Perichondrium – surrounds surface of cartilage

Types of Cartilage

• Hyaline cartilage

• Fibrocartilage

• Elastic cartilage

Human Anatomy, 3rd editionPrentice Hall, © 2001

Hyaline Cartilage

• Most common• Provides

flexibility and support

• Locations– Ends of bones

– Trachea

– Larynx

– Embryonic skeleton

Human Anatomy, 3rd editionPrentice Hall, © 2001

Fibrocartilage• Visible collagenous fibers with scattered chondrocytes• Provides strength and rigidity• Locations

– Intervertebral discs

– Symphysis pubis

Human Anatomy, 3rd editionPrentice Hall, © 2001

Elastic Cartilage• Threadlike network of elastic fibers with chondrocytes• Provides strength and maintains shape• Locations

– Pinna

– Eustacian tube

Human Anatomy, 3rd editionPrentice Hall, © 2001

Bone

• Solid matrix • Cells

– Osteocytes in lacunae

– Osteoblasts

– Osteoclasts

• Periosteum surrounds surface of bone

Human Anatomy, 3rd editionPrentice Hall, © 2001

Blood• Functions

– Transport medium

– Regulation

– Protection

• Composition– Plasma – fluid

– Formed elements – cells & cell fragments

• Erythrocyte

• Leukocyte

• Thrombocyte

Human Anatomy, 3rd editionPrentice Hall, © 2001

A Red Blood Cell

Human Anatomy, 3rd editionPrentice Hall, © 2001

SEM of RBCs

Muscular Tissue

• Specialized cells

• Function - contraction

• 3 types– Skeletal muscle– Cardiac muscle– Smooth muscle

Human Anatomy, 3rd editionPrentice Hall, © 2001

Skeletal Muscle• Connected to bones• Striated• Multinucleated• Voluntary

Human Anatomy, 3rd editionPrentice Hall, © 2001

Cardiac Muscle• Found in the heart• Striations• Intercalated discs• Involuntary

Human Anatomy, 3rd editionPrentice Hall, © 2001

Smooth Muscle• Found in walls of internal organs• Nonstriated• Involuntary

Human Anatomy, 3rd editionPrentice Hall, © 2001

Nervous Tissue• Specialized cells• Function – conduction of electrical impulses• Cells

– Neurons– Neuroglia