Tissues

Epithelial Tissues

Connective Tissues

Muscle Tissues

Nervous Tissues

Objectives

Upon completion of this chapter, you should be able to:– Describe the general characteristics and functions

of epithelial tissue.– Name the types of epithelium and identify an organ

in which each is found.– Explain how glands are classified.– Describe the general characteristics of connective

tissue.– Describe the major cell types and fibers of

connective tissue.

Objectives

Upon completion of this chapter, you should be able to:– List the types of connective tissue that occur within

the body.– Describe the major functions of each type of

connective tissue.– Distinguish among the three types of muscle tissue.– Describe the general characteristics and functions

of nervous tissue.– Complete the review activities at the end of the

chapter.

Aids to Understanding Terms adip- fat chondr- cartilage -cyt cell epi- upon -glia glue (bind cells together) osseo- bone phago- to eat pseudo- false squam- scale strat- layer stria- groove (alternating)

Epithelial Tissues

Covering and lining; glandular Always has a free surface, while underside is

anchored to connective tissue by a thin, nonliving layer called the basement membrane (lamina)

Lack blood vessels (nourished by substances diffusing from connective tissue)

Reproduce readily. Protective barriers (skin, lining of mouth),

secretion, absorption, excretion, and sensory reception

Epithelial Tissues Classification

– ArrangementSimple ~ single layers of cellsStratified ~ many layers of cellsPseudostratified ~ one layer w/ cells of differing

heights

– ShapeSquamous ~ thin, flattened cellsCuboidal ~ cubelike cellsColumnar ~ elongated cellsTransitional ~ expandable

Simple Squamous Epithelium

Single layer of thin, flattened cells Occurs commonly where diffusion, osmosis, and

filtration are taking place– air sacs of lungs– walls of capillaries– insides of blood and lymph vessels– covers membranes that line body cavities

Simple Cuboidal Epithelium

Single layer of cube-shaped cells w/ centrally located nucleus

Secretion, Absorption– Kidney tubules – Glands -- secretion of glandular products

salivary glandspancreasliverovaries

Simple Columnar Epithelium

Single layer of elongated cells w/ nuclei located near basement membrane

Protection, secretion, absorption– Lining of uterus– Lining of various organs of digestive tract, e.g.,

stomach and intestines Microvilli often cover surface, increasing surface

area for more effective absorption Goblet cells scattered throughout, secreting

protective fluid (mucus) onto free surface

Pseudostratified Columnar Epithelium

Nuclei located at two or more levels within cells Cilia extend from free surface Goblet cells scattered throughout tissue Protection, secretion, movement of mucus and

cells– Lines passages of respiratory system– Lines tubes of reproductive system

Stratified Squamous Epithelium

Many layers of cells; thick Flattened near surface, cuboidal or columnar deeper Protection

– Skin (epidermis) As older cells are pushed outward, they accumulate the protein

keratin, harden, and die

– Lines mouth cavity, throat– Lines vagina, anal canal

Transitional Epithelium

Also called uroepithelium Specialized to undergo changes w/ tension Contracted, several layers of cuboidal cells; distended,

appears to contain only a few layers of cells Distensibility, protection, barrier from diffusion

– inner lining of urinary bladder – passageways of urinary system

Glandular Epithelium

Specialized to produce and secrete various substances into ducts or into body fluids

Found within columnar or cuboidal epithelium Exocrine glands

– glands that secrete products into ducts that open onto some internal or external surface

Endocrine glands– glands that secrete products into tissue fluid or

blood

Types of Exocrine Glands

Unicellular glands– Single secretory cell

mucus-secreting goblet cell

Multicellular glands– Simple glands

communicate with surface by means of unbranched ducts

– Compound glands communicate with surface by means of branched ducts

Simple Glands

Simple tubular gland – intestinal glands of small intestines

Simple coiled tubular gland– Eccrine (sweat) glands of skin

Simple branched tubular gland– Mucous glands in small intestine

Simple branched alveolar gland– Sebaceous gland of skin

Compound Glands

Compound tubular gland– Bulbourethral glands of male

Compound alveolar gland– Salivary glands

Glandular Secretions

Merocrine glands – fluid product that is released through the cell membrane

salivary glands, pancreatic glands, certain sweat glands of skin

Apocrine glands– cellular product and portions of the free ends of

glandular cells that are pinched off during secretion mammary glands, certain sweat glands of skin

Holocrine glands– entire cells that are laden with secretory products

sebaceous glands of skin

Connective Tissues

Most abundant tissue in body Many functions, esp. support, protection (against

infection), repair, storage (fat), packaging, production of blood cells

Wide range of vascularity (mostly, good supplies) Cells widely scattered in an intercellular matrix

– Fibers and ground substance Types of connective tissue vary in their

proportions of cells, fibers, and ground substance

Connective Tissues

Major Cell Types– Fibroblasts

widely distributed, large, star-shaped cells secrete proteins that become fibers

– Macrophages Motile cells that are sometimes attached to fibers clear foreign particles from tissues by phagocytosis

– Mast cells large, usually located near blood vessels release substances that may help prevent blood clotting

(heparin) and promote inflammation (histamine)

Connective Tissues

Connective Tissue Fibers– Collagenous fibers (white fibers)

thick, threadlike fibers of collagen with great tensile strength

hold structures together

– Elastic fibers (yellow fibers) bundles of microfibrils composed of elastin; elastic provide elastic quality to parts that stretch

– Reticular fibers thin fibers of collagen (major structural protein of body) form supportive networks within tissues

Loose (Areolar) Connective Tissue

Binds organs together Holds tissue fluids Located beneath the skin, between muscles, and

beneath epithelial tissues Cells are mainly fibroblasts, located some

distance apart and separated by gel-like ground substance that contains many collagenous and elastic fibers

Adipose Tissue

Protection, insulation, and storage of fat Located beneath the skin, around the kidneys,

behind the eyeballs, and on the surface of the heart

Contain large fat droplets that cause nuclei to be pushed close to cell membrane

Fibrous Connective Tissue

Binds organs together Located in tendons (connect muscles to bones),

ligaments (connect bones to bones at joints), protective white layer of eyeball, and deep layer of skin

Contains many closely packed, thick, collagenous fibers and a fine network of elastic fibers; few cells -- fibroblasts

Blood supply relatively poor -- slow repair

Elastic Connective Tissue

Provides elastic quality Located between adjacent vertebrae, in walls of

arteries and airways Consists mainly of yellow, elastic fibers in

parallel strands or branching networks

Reticular Connective Tissue

Support Located in walls of liver, spleen, and lymphatic

organs Composed of thin, collagenous fibers arranged in

a three-dimensional network

Cartilage

Supports parts, provides frameworks and attachments, protects underlying tissues, and forms structural models for many developing bones

Chondrocytes occupy small chambers called lacunae and are completely surrounded by matrix

Enclosed in a covering of fibrous connective tissue called the perichondrium (location of blood supply)

Lacks direct blood supply Three types: hyaline, elastic, and fibrocartilage

Hyaline Cartilage

Support, protection, provides framework Located in ends of bones, nose, and rings in walls of

respiratory passages Most common type of cartilage Role in the growth of most bones and repair of bone

fractures

Elastic Cartilage Support, protection, provides flexible framework Located in framework of external ear and part of larynx Matrix contains many elastic fibers

Fibrocartilage Support, protection, shock absorption Located between bony parts of backbone, pelvic girdle,

and knee Very tough; many collagenous fibers

Bone (Osseous Tissue) Support, protection, provides framework Located in bones of skeleton Most rigid connective tissue, due largely to calcium

phosphate and calcium carbonate in matrix Protects vital parts in the cranial and thoracic cavities,

and serves as attachment for muscles Contains red marrow -- forms blood cells Matrix deposited in thin layers called lamellae Osteocytes clustered in concentric circles around

osteonic (Haversian) canals

Blood

Cells (red, white, platelets) are suspended in a fluid intercellular matrix called plasma

Most blood cells form in hematopoietic tissues in red marrow within the hollow parts of certain bones

Muscle Tissues Contractile; elongated cells (muscle fibers) Three types: skeletal, smooth muscle, cardiac muscle Skeletal muscle tissue

– found in muscles attached to bones– controlled by conscious effort (voluntary muscle tissue)– cells have many nuclei, plus alternating light and dark

cross-markings called striations– Responsible for moving head, trunk, and limbs, as well as

movements involved with facial expressions, writing, talking, singing, chewing, swallowing, and breathing

Muscle Tissues Smooth Muscle Tissue

– Lacks striations; single, centrally located nucleus– Found in walls of hollow internal organs (stomach,

intestines, urinary bladder, uterus, blood vessels)– Involuntary muscle tissue– Responsible for moving food through GI tract, constricting

blood vessels, and emptying bladder Cardiac Muscle Tissue

– Only in the heart; involuntary muscle tissue– striated cells joined end to end by intercalated disk– single nucleus

Nervous Tissue Found in the brain, spinal cord, and peripheral nerves Basic cells -- nerve cells or neurons plus neuroglial cells

(support and bind components of nervous tissue together, carry on phagocytosis, supply nutrients to neurons by connecting them to blood vessels)

Coordinate, regulate, and integrate many body functions