Copyright © 2010 Pearson Education, Inc. TISSUES Ch. 3b.

Copyright © 2010 Pearson Education, Inc.

TISSUESCh. 3b


Tissues

• There are four types of tissue in the body

• Epithelial tissue

• Connective tissue

• Muscle tissue

• Nerve tissue


General Characteristics of Epithelial Tissue

1. Cells have: Polarity— apical (unattached/ free) and basal (attached) surfaces

• Apical surfaces: May bear microvilli /cilia

• Basal surface: Supported by a basement membrane


Characteristics of Epithelial Tissue

2. Composed of closely packed cells

3. Avascular

4. High rate of regeneration

Copyright © 2010 Pearson Education, Inc. Figure 4.2a

Stratified

Simple

Apical surface

Basal surface

Apical surface

Basal surface


Classification of Epithelia

• Ask two questions:

1. How many cell layers?

1 = simple epithelium

>1 = stratified epithelium


Classification of Epithelia

2. What type of cell?

• Squamous = flat

• Cuboidal

• Columnar

• # of cell layers followed by cell shape = epithelial classification

• If E.T. is stratified, name according to the top layers of cells

Copyright © 2010 Pearson Education, Inc. Figure 4.3a

(Simple squamous epithelium

Description: •Single layer of flat cells

Function: •Diffusion & Filtration

Location: •Air sacs of lungs•Lining of ventral body cavity


( Simple Cuboidal epithelium

Location: Glands and ducts

Function: Secretion andabsorption.

Description: Single layer of cubelike cells


(Simple Columnar epithelium

Description: Single layer of tall cells•May have goblet cells

Function: Absorption and secretion

Location: Lines most of digestive tract


Pseudostratified Ciliated Columnar epithelium

Trachea

Description: Single layer of cells of differing heights on same basement membrane; •May have goblet cells

Function: Secretion, propulsion of mucus byciliary action.

Location: upper respiratory tract.


Stratified squamous epithelium

Description: Thick, surface cells squamous

•Two types:• Non-Keratinized: alive • Keratinized: surface cells dead & full of keratin

Function: Protection in areas subjected to abrasion.

Location: Nonkeratinized: Lines cavities which open to exterior•Keratinized: forms epidermis

Copyright © 2010 Pearson Education, Inc. Figure 4.3f

Transitional epithelium

Description: Basal cells cuboidal/columnar •Surface cells dome shaped or squamous (depends on degree of stretch)

Function: Stretches readily

Location: Lines hollow urinary organs


Characteristics of Connective Tissue

• Connective Tissues are the most abundant and widely distributed tissue type

• C.T. has varying degrees of vascularity

• C.T. has cells separated by nonliving extracellular matrix (ground substance and fibers)


Components of Extracellular Matrix• Ground substance

• Interstitial fluid, Adhesion proteins (“glue”),

• Large polysaccharides

• Three Types of Fibers can be found within the ground substance:

• Collagen

• Strongest, most abundant type; Provides tensile strength; form thick cables

• Elastic

• Long, thin, fibers; allow for stretch

• Reticular

• Short, fine, branched fibers that form an internal network (mesh) that is supportive to other cells


Cells of Connective Tissue

• Cell Types

• “blasts” = Mitotically active and secretory cells

• “cytes” = Mature cells

• Fibroblasts in connective tissue proper

• Chondroblasts and chondrocytes in cartilage

• Osteoblasts and osteocytes in bone

• Hematopoietic stem cells in bone marrow

Copyright © 2010 Pearson Education, Inc. Figure 4.8j

Osseous tissue

Description: Hard, calcifiedmatrix; osteocytes in lacunae;

Function: Support, protection, attachment site for muscles.

Location: Bones

Lacunae

Lamella

Centralcanal


Connective Tissue: Cartilage

• Three types of cartilage:

• Hyaline cartilage

• Elastic cartilage

• Fibrocartilage


Cartilage: HyalineDescription: most abundant of cartilage types;less hard and more flexible than bone;Chondrocytes in lacunae.

Function: Supports,cushions, resists compressive stress.

Location: Forms most of embryonic skeleton; articular cartilage; cartilages of nose, trachea, larynx.

Costalcartilages

Chondrocytein lacuna

Matrix


Cartilage: Elastic

Function: Also allowsgreat flexibility.

Location: Ear, epiglottis.

Chondrocytein lacuna

Matrix


Cartilage: Fibrocartilage

Location: Intervertebral discs

Intervertebraldiscs

Chondrocytesin lacunae

Collagenfiber


Connective tissue proper: Dense regular connective tissue

Description: Parallel collagen fibers

Function: Withstands tensilestress when pulling force is applied in one direction.

Location: Tendons, mostligaments

Shoulderjoint

Ligament

Tendon

Collagenfibers

Nuclei offibroblasts


Connective tissue proper: Dense irregular connective tissueDescription: Irregularly arranged collagen fibers

Function: Withstandstension exerted in manydirections

Location: Fibrous capsules of organs ,joints; dermis ofskin Collagen

fibers

Nuclei offibroblasts

Fibrousjointcapsule


Connective tissue proper: Areolar connective tissue Description: Most widely distributed variety of CT•Soft, pliable, like cobwebs

Function: Wraps and cushionsorgans

Location: Under epithelia of body, universal packaging material

Epithelium

Laminapropria

Fibroblastnuclei

Elasticfibers

Collagenfibers


Connective tissue proper: Adipose connective tissue

Description: Closely packed adipocytes

Function: Reserve fuel insulation; supports & protects organs.

Location: Hypodermis; around kidneys and eyeballs; in abdomen; breasts.

Nucleus offat cell

Vacuolecontainingfat droplet

Adiposetissue

Mammaryglands


Connective tissue proper: Reticular connective tissue

Description: Network of reticular fibers

Function: Fibers form a soft internal skeleton that supports other cells

Location: Lymphoid organs (lymph nodes, bone marrow, and spleen).

Spleen

White bloodcell(lymphocyte)

Reticularfibers


Others: bloodDescription: Red and whiteblood cells in a fluid matrix(plasma).

Function: Transport ofrespiratory gases, nutrients,wastes, and other substances.

Location: Contained withinblood vessels.

Neutrophil

Red bloodcells

Lymphocyte

Plasma


MUSCLE TISSUE


(a) Skeletal muscleDescription: Long, cylindrical,multinucleate cells; obviousstriations.

Function: Voluntary movement

Location: Skeletal musclesattached to bones oroccasionally to skin.

Photomicrograph: (approx. 460x).

Nuclei

Striations

Part ofmuscle fiber (cell)


(b) Cardiac muscleDescription: Branching, striated, Have intercalated discs.

Function: Propel blood into circulation; involuntary control.

Location: Walls of the heart.

Photomicrograph: (500X);

Intercalateddiscs

Striations

Nucleus


(c) Smooth muscleDescription: Spindle-shapedCells; no striations; cells form sheets.

Function: Propels substancesor objects; involuntary control.

Location: Mostly in wallsof hollow organs.

Photomicrograph: Sheet of smooth muscle (200x).

Smoothmusclecell

Nuclei


NERVOUS TISSUE


Function: Transmit electricalsignals from sensory receptorsto effectors.

Location: Brain, spinalcord, and nerves.

Description: Neurons w/ cell processes that extend from the cell body; Contains supporting cells

Dendrites

Neuron processes Cell body

Axon

Nuclei ofsupportingcells

Cell bodyof a neuron

Neuronprocesses

Nervous tissue


Steps in Wound Repair• Inflammation

• Increased blood flow with healing components & clotting factors to damaged area (redness, swelling, pain, heat) due to the release of inflammatory chemicals

• Clot forms and exposed portion forms scab

• Organization and restored blood supply

• Granulation tissue forms=new capillaries and phagocytes and fibroblasts

• Regeneration and fibrosis

• Surface ET regenerates, scab detaches, underlying scar tissue


Scab

Blood clot inincised wound

Epidermis

Inflammatorychemicals

Migrating whiteblood cell

Artery


Regeneratingepithelium

Area ofgranulationtissueingrowth

FibroblastMacrophage


Regeneratedepithelium

Fibrosedarea

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