C H A P T E R

© 2013 Pearson Education, Inc.© Annie Leibovitz/Contact Press Images

Tissue: The Living Fabric:

4

Types of Primary Tissues

• Epithelial tissue– Covers

• Connective tissue– Supports

• Muscle tissue– Produces movement

• Nerve tissue– Controls

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• Brain• Spinal cord• Nerves

Nervous tissue: Internal communication

• Muscles attached to bones (skeletal)• Muscles of heart (cardiac)• Muscles of walls of hollow organs (smooth)

Muscle tissue: Contracts to cause movement

Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters• Lining of digestive tract organs and other hollow

organs• Skin surface (epidermis)

• Bones• Tendons• Fat and other soft padding tissue

Connective tissue: Supports, protects, binds other tissues together

Figure 4.1 Overview of four basic tissue types: epithelial, connective, muscle, and nervous tissues.

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Epithelial Tissue (Epithelium)

• Form boundaries

• Two main types (by location)– Covering and lining epithelia

• On external and internal surfaces

– Glandular epithelia• Secretory tissue in glands

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Characteristics of Epithelial Tissue

1. Cells have polarity—apical (upper, free) and basal (lower, attached) surfaces

2. Are composed of closely packed cells

3. Supported by a connective tissue reticular lamina (under the basal lamina)

4. Avascular but innervated

5. High rate of regeneration

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Classification of Epithelia

• Ask two questions:1. How many layers?

1 = simple epithelium

>1 = stratified epithelium

2. What is the shape of the cell• Squamous• Cuboidal• Columnar

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Figure 4.2a Classification of epithelia.

Basal surfaceStratified

Classification based on number of cell layers.

Basal surfaceSimple

Apical surface

Apical surface

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Cells of Epithelial Tissues

• Squamous cells

• Cuboidal cells

• Columnar cells

(If stratified, name according to apical layer of cells)

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Cuboidal

Squamous

ColumnarClassification based on cell shape.

Figure 4.2b Classification of epithelia.

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Overview of Epithelial Tissues

• For each of the following types of epithelia, note:– Description– Function– Location

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Air sacs of lung tissue

Nuclei of squamous epithelial cells

Function: Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae.

Location: Kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity (serosae).

Description: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia.

Photomicrograph: Simple squamous epithelium forming part of the alveolar (air sac) walls (140x).

Simple squamous epithelium

Figure 4.3a Epithelial tissues.

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Simple Squamous Epithelium

• Two other locations– Endothelium

• The lining of lymphatic vessels, blood vessels, and heart

– Mesothelium• The epithelium of serous membranes in the ventral

body cavity

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Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action.

Location: Nonciliated type lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus.

Description: Single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells).

Simple columnar epithelium

Basement membrane

Photomicrograph: Simple columnarepithelium of the small intestine mucosa (660x).

Mucus of goblet cell

Simple columnar epithelial cell

Microvilli

Figure 4.3c Epithelial tissues.

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Pseudostratified columnar epithelium

Function: Secrete substances, particularly mucus; propulsion of mucus by ciliary action.

Description: Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting cells and bear cilia.

Photomicrograph: Pseudostratified ciliated columnar epithelium lining the human trachea (800x).

Cilia

Basement membrane

Pseudo-stratified epithelial layer

Location: Nonciliated type in male’s sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract.

Trachea

Figure 4.3d Epithelial tissues.

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Stratified squamous epithelium

Function: Protects underlying tissues in areas subjected to abrasion.

Description: Thick membrane composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers.

Basement membrane

Location: Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane.

Nuclei

Connective tissue

Stratified squamous epithelium

Photomicrograph: Stratified squamous epithelium lining the esophagus (285x).

Figure 4.3e Epithelial tissues.

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Connective Tissue

• Most abundant and widely distributed of primary tissues

• Four main classes– Connective tissue proper– Cartilage– Bone – Blood

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Table 4.1 Comparison of Classes of Connective Tissues (1 of 2)

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Table 4.1 Comparison of Classes of Connective Tissues (2 of 2)

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Major Functions of Connective Tissue

• Binding and support

• Protecting

• Insulating

• Storing reserve fuel

• Transporting substances (blood)

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Characteristics of Connective Tissue

• Three characteristics make connective tissues different from other primary tissues– Have mesenchyme (an embryonic tissue) as

their common tissue of origin– Have varying degrees of vascularity (blood

vessels)– Have extracellular matrix

• Connective tissue not composed mainly of cells• Largely nonliving extracellular matrix separates

cells– So can bear weight, withstand tension, endure abuse

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Connective Tissue Fibers

• Three types of fibers provide support– Collagen

– Elastic fibers

– Reticular

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Cells

• "Blasts" cells– Immature forum; mitotically active; secrete ground

substance and fibers – Fibroblasts in connective tissue proper– Chondroblasts in cartilage– Osteoblasts in bone– Hematopoietic stem cells in bone marrow

• "Cyte" cells– Mature form; maintain matrix– Chondrocytes in cartilage – Osteocytes in bone

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Other Cell Types in Connective Tissues

• Fat cells– Store nutrients

• White blood cells– Neutrophils, eosinophils, lymphocytes– Tissue response to injury

• Mast cells– Initiate local inflammatory response against foreign

microorganisms they detect

• Macrophages– Phagocytic cells that "eat" dead cells,

microorganisms; function in immune system

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Extracellular matrixGround substanceFibers• Collagen fiber• Elastic fiber• Reticular fiber

Capillary

Neutrophil

Mast cell

Fat cell

Lymphocyte

Fibroblast

Macrophage

Cell typesFigure 4.7 Areolar connective tissue: A prototype (model) connective tissue.

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Connective tissue proper: loose connective tissue, adipose

Description: Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet.

Photomicrograph: Adipose tissue fromthe subcutaneous layer under the skin (350x).

Nucleus of adipose(fat) cell

Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs.

Location: Under skin in subcutaneous tissue; around kidneys and eyeballs; within abdomen; in breasts. Fat droplet

Adipose tissue

Mammary glands

Figure 4.8b Connective tissues.

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Cartilage: hyaline

Description: Amorphous but firmmatrix; collagen fibers form animperceptible network;chondroblasts produce the matrixand when mature (chondrocytes)lie in lacunae.

Function: Supports and reinforces;serves as resilient cushion; resistscompressive stress.

Location: Forms most of theembryonic skeleton; covers theends of long bones in joint cavities;forms costal cartilages of the ribs;cartilages of the nose, trachea, andlarynx.

Costalcartilages Photomicrograph: Hyaline cartilage from

a costal cartilage of a rib (470x).

Matrix

Chondrocytein lacuna

Figure 4.8g Connective tissues.

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Cartilage: elastic

Description: Similar to hyalinecartilage, but more elastic fibersin matrix.

Function: Maintains the shape ofa structure while allowing greatflexibility.

Location: Supports the externalear (pinna); epiglottis.

Photomicrograph: Elastic cartilage fromthe human ear pinna; forms the flexibleskeleton of the ear (800x).

Chondrocytein lacuna

Matrix

Figure 4.8h Connective tissues.

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Cartilage: fibrocartilage

Description: Matrix similar to butless firm than that in hyalinecartilage; thick collagen fiberspredominate.

Function: Tensile strength allowsit to absorb compressive shock.

Location: Intervertebral discs;pubic symphysis; discs of kneejoint.

Photomicrograph: Fibrocartilage of anintervertebral disc (125x). Special stainingproduced the blue color seen.

Collagenfiber

Chondrocytesin lacunae

Intervertebraldiscs

Figure 4.8i Connective tissues.

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Others: bone (osseous tissue)

Description: Hard, calcifiedmatrix containing many collagenfibers; osteocytes lie in lacunae.Very well vascularized.

Function: Supports and protects(by enclosing); provides levers forthe muscles to act on; storescalcium and other minerals andfat; marrow inside bones is thesite for blood cell formation(hematopoiesis).

Location: Bones

Photomicrograph: Cross-sectional viewof bone (125x).

Lamella

Centralcanal

Lacunae

Figure 4.8j Connective tissues.

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Connective tissue: blood

Description: Red and white bloodcells in a fluid matrix (plasma).

Function: Transport respiratorygases, nutrients, wastes, and othersubstances.

Location: Contained within bloodvessels.

Photomicrograph: Smear of human blood(1670x); shows two white blood cellssurrounded by red blood cells.

Plasma

White bloodcells:• Lymphocyte• Neutrophil

Red bloodcells(erythrocytes)

Figure 4.8k Connective tissues.

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Skeletal muscle

Description: Long, cylindrical,multinucleate cells; obviousstriations.

Function: Voluntary movement;locomotion; manipulation of theenvironment; facial expression;voluntary control.

Location: In skeletal musclesattached to bones or occasionallyto skin.

Photomicrograph: Skeletal muscle(approx. 440x). Notice the obvious bandingpattern and the fact that these large cells aremultinucleate.

Striations

Nuclei

Part of musclefiber (cell)

Figure 4.9a Muscle tissues.

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Cardiac muscle

Description: Branching, striated,generally uninucleate cells thatinterdigitate at specializedjunctions (intercalated discs).

Function: As it contracts, itpropels blood into the circulation;involuntary control.

Location: The walls of the heart.

Photomicrograph: Cardiac muscle (900x);notice the striations, branching of cells, andthe intercalated discs.

Striations

Nucleus

Intercalateddiscs

Figure 4.9b Muscle tissues.

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Smooth muscle

Description: Spindle-shapedcells with central nuclei; nostriations; cells arranged closelyto form sheets.

Function: Propels substances orobjects (foodstuffs, urine, a baby)along internal passageways;involuntary control.

Location: Mostly in the walls ofhollow organs.

Photomicrograph: Sheet of smoothmuscle (720x).

Smoothmusclecell

Nuclei

Figure 4.9c Muscle tissues.

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Nervous Tissue

• Main component of nervous system– Brain, spinal cord, nerves– Regulates and controls body functions

• Neurons– Specialized nerve cells that generate and conduct

nerve impulses

• Neuroglia– Supporting cells that support, insulate, and protect

neurons

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Nervous tissue

Description: Neurons arebranching cells; cell processesthat may be quite long extend fromthe nucleus-containing cell body;also contributing to nervous tissueare nonexcitable supporting cells.

Function: Neurons transmitelectrical signals from sensoryreceptors and to effectors (musclesand glands) which control theiractivity; supporting cells supportand protect neurons.

Location: Brain, spinalcord, and nerves.

Photomicrograph: Neurons (350x).

Neuronprocesses

Nuclei ofsupportingcells

Cell bodyof a neuron

Neuron processes Cell body

Axon Dendrites

Figure 4.10 Nervous tissues.

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