The Tissue Level of The Tissue Level of OrganizationOrganization

What are the body tissues?What are the body tissues?

Epithelial tissueEpithelial tissue Connective tissue Connective tissue Nervous tissueNervous tissue Muscle tissue Muscle tissue

HistologyThe study of tissues

Tissue OverviewTissue OverviewEpithelialEpithelialCover exposed surfacesCover exposed surfacesForms inner lining of body cavitiesForms inner lining of body cavitiesLines hollow organsLines hollow organsProduces glandular secretionsProduces glandular secretionsLacks blood vesselsLacks blood vesselsCells tightly packed and continuously Cells tightly packed and continuously replaced.replaced.

Major Functions: protection, secretion, Major Functions: protection, secretion, absorption and excretion.absorption and excretion.

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Connective•Fill internal spaces and provides frameworks•Extracellular matrix consisting of fibers and fluid•Stores fat•Produces blood cells•Protects against infection•Helps repair damaged tissues.

Major Functions: connects, supports, protects

Muscle Tissue•Contracts to produce movements

Neural (Nervous Tissue)•Conducts electrical impulses•Carries information•Coordinates function

Key NoteKey Note

Tissues are collections of cells Tissues are collections of cells and extracellular material that and extracellular material that perform a specific but limited perform a specific but limited range of functions.The four range of functions.The four tissue types, in varying tissue types, in varying combinations, form all of the combinations, form all of the structures of the human body.structures of the human body.

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An Orientation An Orientation to the Tissues to the Tissues

of the Bodyof the Body

Figure 4-1

What are the different types of What are the different types of epithelial tissue?epithelial tissue?

1.1. Simple epithelium (one layer of cells)Simple epithelium (one layer of cells)A. Simple A. Simple squamoussquamous epithelium – Thin, epithelium – Thin, flattenedflattenedExchange of gases. Location: lungs, blood Exchange of gases. Location: lungs, blood vessel lining, lymph vessels, thoracic and vessel lining, lymph vessels, thoracic and abdominal membranes.abdominal membranes.

B. Simple B. Simple cuboidalcuboidal epithelium – cube-shaped epithelium – cube-shapedSecretion and absorption. Location: kidneys Secretion and absorption. Location: kidneys and various glands.and various glands.

What are the different types What are the different types of epithelial tissue?of epithelial tissue?

C. Simple C. Simple columnarcolumnar epithelium – elongated epithelium – elongated cells with nuclei near basement membrane.cells with nuclei near basement membrane.Protection, secretion, absorption, Protection, secretion, absorption, secretion of mucus, possess microvilli. secretion of mucus, possess microvilli. Location: uterus lining and digestive tract.Location: uterus lining and digestive tract.

D. Pseudostratified columnar epithelium – D. Pseudostratified columnar epithelium – false stratification. Nuclei are at two or false stratification. Nuclei are at two or more levels.more levels.Moves mucus over surface of tissue. Moves mucus over surface of tissue. Location: Respiratory system.Location: Respiratory system.

What are the different types of What are the different types of epithelial tissue?epithelial tissue?

2.2. Stratified epithelium (two or more Stratified epithelium (two or more cell layers)cell layers)

A. Stratified squamous epithelium – made of A. Stratified squamous epithelium – made of different types of cells found in mouth and different types of cells found in mouth and esophagusesophagusa)a)Stratified cuboidal epithelium – found in Stratified cuboidal epithelium – found in glandsglandsb)b)Stratified columnar epithelium – found in Stratified columnar epithelium – found in glandsglandsc)c)transitional epithelium – modified stratified transitional epithelium – modified stratified squamous epithelium found in the urinary squamous epithelium found in the urinary bladder, the ureters and urethrabladder, the ureters and urethra

Epithelial Tissue DrawingsEpithelial Tissue Drawings

What are the Functions of What are the Functions of Connective Tissues? Connective Tissues?

Structural frameworkStructural framework Fluid and solute Fluid and solute

transporttransport Physical protectionPhysical protection Tissue interconnectionTissue interconnection Fat storageFat storage Microorganism defenseMicroorganism defense

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What are the different types of connective tissue?

1. Connective Tissue (Proper)

A.Areolar – forms delicate, thin membranes throughout the body. Location: Binds the skin to the underlying organs. Fills spaces between muscles.

B.Adipose – also known as fat. Stores fat, cushions and insulates. Location: beneath the skin, in some abdominal membranes, around kidneys, heart and various joints.

C. Reticular – Thin, branched collagenous fibers. Supports walls of the liver, spleen and lymphatic organs.

2.Dense Connective Tissue

A. Regular – Strong, collagenous fibers. Bind structures as parts of tendons and ligaments.

B. Irregular – Thicker, randomly distributed collagenous fibers. Location: Dermis

C. Elastic – Made of elastic fibers and is flexible. Location: Lungs and blood vessels.

Loose connective tissue – soft and few fibersAreolar tissue – soft, flexible tissue that protects the body

organs

3. Specialized3. Specialized

A. Bone (osseous tissue) – made of calcium A. Bone (osseous tissue) – made of calcium and collagen that form circles around central and collagen that form circles around central canalscanalsRapidly healing. Location: BoneRapidly healing. Location: Bone

B. Cartilage – very soft and flexibleB. Cartilage – very soft and flexibleDense connective tissue– very strong fibers Dense connective tissue– very strong fibers that lack blood supply. Slow to heal.that lack blood supply. Slow to heal.Provides supportive framework. Location: Provides supportive framework. Location: ends of various bones, ear, larynx, between ends of various bones, ear, larynx, between vertebrae, knee, and pelvic girdle.vertebrae, knee, and pelvic girdle.

C. Blood – made of cells suspended in fluid. C. Blood – made of cells suspended in fluid. Formed in the hollow parts of certain bones.Formed in the hollow parts of certain bones.

Types of muscle tissueTypes of muscle tissue1. Skeletal muscle – Long, threadlike cells 1. Skeletal muscle – Long, threadlike cells containing several nuclei. Have striations containing several nuclei. Have striations (alternating dark and light cross-markings).(alternating dark and light cross-markings). controlled voluntarily by pulling on bones or controlled voluntarily by pulling on bones or skinskinContract when stimulated by nerve impulses Contract when stimulated by nerve impulses and relax when impulse is gone.and relax when impulse is gone.

2. Cardiac muscle (heart muscle) – Striated with 2. Cardiac muscle (heart muscle) – Striated with single nuclei. single nuclei. controlled involuntarilycontrolled involuntarily

3. Smooth muscle (visceral muscle) – Spindle-3. Smooth muscle (visceral muscle) – Spindle-shaped cells with single nuclei. Involuntarily shaped cells with single nuclei. Involuntarily controlled.controlled.found in the walls of hollow organs such as found in the walls of hollow organs such as stomach, bladder, uterus, and blood vesselsstomach, bladder, uterus, and blood vessels

What are the Four Types of What are the Four Types of Membranes?Membranes?

MucousMucous Lines cavities and tubes opening to the Lines cavities and tubes opening to the

outside of the body.outside of the body. Made of epithelium and loose Made of epithelium and loose

connective tissue.connective tissue. Secrete mucousSecrete mucous Mucous moistens surfaceMucous moistens surface ExamplesExamples: oral cavity, airways: oral cavity, airways

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SerousSerous Line internal body cavities that do not open Line internal body cavities that do not open

to the outsideto the outside Made of epithelial and loose connective Made of epithelial and loose connective

tissuetissue Cells secrete watery fluid that lubricates Cells secrete watery fluid that lubricates

surfaces.surfaces.

CutaneousCutaneous Covers body surfaceCovers body surface Example: the skinExample: the skin

SynovialSynovial Lubricates and lines jointsLubricates and lines joints Examples: knee, elbowExamples: knee, elbow