BODY TISSUES

Four Main Types of Body Tissues• Sometimes I refer to them as

basic tissue types• Epithelium• Connective• Muscular • Nervous

Epithelium Lining, covering, and glandular tissue

of the body.

Functions:ProtectionAbsorptionFiltrationSecretion

Special Characteristics of Epithelium Fits closely together to form continuous

sheets. Membranes always have one free, unattached

surface.Apical surface

Lower surface of the epithelium rests on the basement membrane.

No blood supply of their own. (depend on diffusion)

Can regenerate easily if well nourished.

Types of Epithelium Simple- one layer of cells

Stratified- more than one layer of cells.

Pseudostratified- single layer, but appears stratified because some cells are shorter than others.

Simple Squamous Single layer of thin squamous cells

On a basement membrane

Fit closely together

Usually found where filtration or exchange of substances occurs.

Stratified Squamous Most common stratified epithelium in the body

Several layers of squamous cells

Cells closest to free edge are squamous shaped, but those closest to the basement membrane appear cuboidal.

Found in cites that receive a lot of abuse or frictionEsophagus, mouth, outer portion of the skin

Simple Cuboidal One layer of cuboidal cells

On a basement membrane

Common in glands and ducts

Walls of kidneys, surface of ovaries

Stratified Cuboidal At least two layers of cuboidal cells

Rare in the body

Found mainly in the ducts of large glands

Simple Columnar Single layer of tall cells that fit closely together.

Lines entire length of digestive tract

Goblet cells-produce lubricating mucus are often seen here.

Mucosae (mucous membranes)- epithelial membranes that line body cavities open to the body exterior

Stratified Columnar Surface cells are columnar

Basal cells vary in size and shape.

Fairly rare in the body

Found mainly in the ducts of large glands.

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Pseudostratified Columnar

Single layer of cells

Some cells are shorter than others, making nuclei appear at different heights.

Functions in absorption and secretion.

Ciliated pseudostratified are found in the respiratory tract. Cilia propel mucus upward and away from the lungs

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Transitional Highly modified

Stratified squamous epithelium

Basal layer cells are cuboidal or columnar

In urinary system

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Connective Tissue Connects body parts

Found everywhere in the body

Most abundant and widely spread tissue type

Well vascularized, has its own blood supply.

Extracellular matrix- nonliving substance found outside the cells.

Matrix Matrix is what makes connective tissues different

from other tissues.

Produced by connective tissue cells and secreted outside of the cell.

Composed of water and proteins

Because of its matrix, connective tissue is able to form soft packing tissue around other organs to bear weight and withstand abuse.

Bone Osseous tissue

Composed of bone cells (osteocytes) sitting in cavities called lacunae

Surrounded by layers of a hard matrix

Protect and support other body organs

Hyaline Cartilage Most widespread cartilage

Less hard and more flexible than bone.

Has abundant collagen fibers

Glassy matrix

Found in larynx, attaches ribs to breastbone, covers the end of bones where joints form.

Elastic Cartilage Less hard and more flexible than bone.

Found where elasticity is desired.

Supports external ear

Fibrocartilage Forms the cushion-like disks between

the vertebrae of the spinal column

Areolar Tissue Most widely distributed connective

tissue in the body.

Soft, pliable, cobwebby tissue

Cushions and protects body organs

Helps hold internal organs together

Adipose Tissue Fat tissue

Oil occupies most of a fat cell’s volume and pushes the nucleus to the side

Forms subcutaneous tissue beneath the skin.

Insulates the body and protects it from heat and cold.

Blood Vascular tissue

Consists of blood cells surrounded by a nonliving matrix called plasma

Transport vehicle for the cardiovascular system.

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Muscular Tissue Highly specialized to contract or shorten

to produce movement

Muscle cells are ellongated and therefore called fibers

Skeletal Muscle Packaged by connective tissue sheets attached to the

skeleton.

Can be controlled- voluntary

Form the flesh of the body

The result of their action is gross body movements or changes in facial expressions.

Cells are long, cylindrical, multinucleate, and have striations (stripes)

Smooth Muscle Visceral muscle

No striations are visible

Single nucleus and are spindle shaped (pointed at each end)

Found in the walls of hallow organs

When smooth muscle contracts the cavity of the organ becomes smaller(constricts) or enlarges(dilates)

Peristalsis- food moving through the small intestine – muscle contracting in a wavelike motion

Cardiac Muscle Found only in the heart

Has striations

Uninucleate

Branching

Fit tightly together at gap junctions called intercalated disks.

Involuntary

Nervous Tissue All neurons receive and transmit

electrochemical impulses from one part of the body to another.