tissues: an overview. overview of tissue science tissues are groups of cells and extracellular...

Tissues: An OverviewTissues: An Overview

Overview of Tissue Overview of Tissue ScienceScience

Tissues are groups of cells and extracellular material that perform a specific group of functions. The four tissue types, in different combinations, form all of the structures of the human body.

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Overview of Tissue Overview of Tissue ScienceScienceHistology The study of tissuesFour Basic Tissue Types

◦Epithelial◦Connective◦Muscular◦NeuralWe use these to build organs*


Overview of Tissue Overview of Tissue ScienceScienceAn Orientation

to the Tissues of the Body

Epithelial TissueEpithelial TissueFunctions of

Epithelia◦Physical protection◦Permeability control◦Sensation trigger◦Specialized secretions


Epithelial TissueEpithelial TissueCharacteristics of Epithelia

◦Cells closely packed◦Has a “top and bottom”

Apical cells exposed to external or internal surface (“checkers”)

Cells attached to basement membrane

◦Lack blood vessels (avascular)◦Cells continually replaced


Epithelial TissueEpithelial TissueEpithelium An avascular layer of

cells that forms a barrier that covers internal or external surfaces

Glands Secretory structures

derived from epithelia


Epithelial TissueEpithelial TissueTwo Classes of Glandular Secretion

◦Exocrine secretion—Secretion onto a body surface

◦Endocrine secretion—Secretion (of hormones) into neighboring tissues and blood


Connective Tissues Connective Tissues Functions

◦Structural framework◦Fluid and solute transport◦Physical protection◦Tissue interconnection◦Fat storage◦Microorganism defense


Connective TissuesConnective TissuesMajor Types of Connective Tissue

Figure 4-7

Connective TissuesConnective TissuesConnective Tissue

Proper◦Protein fibers

Collagen fibers Provides toughness

Reticular fibers Supports cells

Elastic fibers Provides resilience


Connective TissuesConnective TissuesSupporting Connective Tissue

◦Cartilage Avascular Covered by a fibrous perichondrium Three types of cartilage

Hyaline cartilage Elastic cartilage Fibrocartilage


Connective TissuesConnective TissuesBone (Osseous Tissue)

◦Matrix provides unique properties Collagen fibers resist bending Calcium salts resist compression

◦Diffusion through canaliculi nourishes osteocytes

◦Covered by periosteum


MembranesMembranesProperties of Membranes

◦Barrier or interface◦Cover and protect◦An epithelium plus connective tissue

◦Four types of membranes


MembranesMembranesTypes of Membranes

◦Mucous Lines cavities that connect to exterior Mucus moistens surface Examples: oral cavity, airways

Serous Line internal cavities Watery fluid moistens surface Example: peritoneal membrane


MembranesMembranesTypes of Membranes

(continued)◦Cutaneous

Covers body surface Dry surface waterproofs the body Example: the skin

◦Synovial Lines joints Secretes slippery synovial fluid Lubricates joints Examples: knee, elbow


MembranesMembranesMembranes

Muscle TissueMuscle TissueProperties of Muscle

Tissue◦Capable of contraction◦Three types of muscle tissue

Skeletal muscle Cardiac muscle Smooth muscle


Muscle TissueMuscle TissueSkeletal Muscle Tissue

◦Contains elongated cells (fibers) Fibers tied together by loose

connective tissue Possesses microscopic striations Contains many nuclei Controlled by voluntary nervous

system Moves and stabilizes the skeleton


Muscle TissueMuscle TissueCardiac Muscle Tissue

◦Only in heart◦Short, branched fibers◦Single nucleus◦Striated◦Involuntary contraction◦Blood circulation◦Blood pressure


Muscle TissueMuscle TissueSmooth Muscle

Tissue◦Short, tapering cells◦No striations◦Involuntary contraction

Blood vessels Urinary bladder Digestive organs Uterus


Neural TissueNeural TissueProperties of Neural Tissue

◦Conduct electrical impulses◦Transfer, process, and store

information◦Comprises neurons and

neuroglia


Neural TissueNeural TissueNeurons- conduct nerve

impulsesNeuroglia-provides support,

protection and nutients.


Tissue Injuries and RepairTissue Injuries and Repair• An injury harms multiple tissues

simultaneously• Tissues make coordinated

response• Responses restore homeostasis• Two response types

◦Inflammation◦Restoration


Tissue Injuries and RepairTissue Injuries and RepairInflammation

◦Isolation of injured area◦Cleanup of damaged tissue◦Four signs of inflammation

Warmth Redness Swelling Pain


Tissue Injuries and RepairTissue Injuries and RepairRegeneration

◦Repair/replacement of damaged tissue

◦Restoration of tissue function◦Scar tissue from fibroblast activity◦Complete, partial, or no regeneration◦Tissue fibrosis common outcome

(scar tissue)


Tissues and AgingTissues and Aging

◦Healing slows◦Epithelia become thinner◦Connective tissues become more

fragile◦Bones weaken, become brittle◦Neuron and muscle fiber losses

accumulate◦Lifestyle interventions slow decline


Aging and TissuesAging and TissuesTissue heals faster in young adults Surgery of a fetus normally leaves

no scarsYoung tissues have a better

nutritional state, blood supply, and higher metabolic rate

Extracellular components also change with age

Changes in the body’s use of glucose, collagen, and elastic fibers contribute to the aging process

tissues: an overview. overview of tissue science tissues are groups of cells and extracellular...

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neighboring tissues

internal surface checkerscells

human body

groups of cells

bottomapical cells

avascular layer of cells

bendingcalcium salts