Anatomy & Physiology, ch. 4

Tissues

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Question of the Day

What are the levels of organization found in the human body?

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Levels of Organization

Atoms, Molecules, Macromolecules, Organelles

Cells Tissues Organs Organ Systems Organisms

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Tissue

Groups of cells with specialized structure/function

4 major types Epithelial, Connective, Muscular, Nervous

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Epithelial

Epithelia and Glands Important characteristics

free surface exposed to environment or some internal chamber/passageway

basement membrane attaches it to connective tissue

Avascular

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Function of Epithelia

Physical protection Controls Permeability Provides Sensations Produces specialized Secretions

glandular epithelium (exocrine and endocrine)

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Cell Junctions between Epithelia

Gap Junction connection via channel proteins cardiac muscle and smooth muscle tissue

Tight Junction interlocking proteins on the outer lipid layer

of membranes prevents loss of water and solutes between

cells Desmosome

protein filaments and intercellular cement7

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General Structure

Contain microvilli or cilia on exposed surface specialize in active and passive transport increases surface area

Basement membrane connects epithelium to connective tissue

Stem cells responsible for cellular division and replacement/renewal of epithelia

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Classification of Epithelia Cell Layers

simple ephithelium• Thin, areas of secretion or absorption• line chambers/passageways

stratified ephithelium• Thicker, areas of mechanical/chemical stresses

Cell Shape Squamous Cuboidal Columnar 9

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Simple Epithelial Simple Squamous

lining of body cavities, blood vessels, heart, surface of lungs, kidney tubules

Simple Cubodial Secrets enzymes and buffers in pancreas/salivary

glands, lines kidney tububles Simple Columnar

Stomach, digestive tract, excretory ducts

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Pseudostratified Epithelia

Appears to be many layers Nuclei at different levels

Respiratory tract Ciliated pseudostratified epithelia line the

nasal cavity, trachea, bronchi and portions of male reproductive system

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Transitional Epithelium

Forms a barrier between waste Increase tension/pressure causes a

change in cell shape Lines Ureters and Urinary Bladder

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Stratified Epithelial Squamous

Epidermis, mouth, throat, vagina, anal canal Cubodial

Sweat, salivary, mammary glands, pancreas, (lumen)

Columnar Superfical layer is columnar; basal are cubodial Pharynx, male reproductive

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Glandular Epithelia Produce and secrete substances into ducts or bloodstream Exocrine Into a duct

Apocrine-lose parts of cell during secretion Merocrine- water, protein-rich secretion via exocytosis Holocrine- entire cell lyses during secretion

Secretions Serous:watery solution containing enzymes Mucous: thick, mucous Mixed: more than 1 type of gland cell, 2 different exocrine secretions

or 1 exo/endocrine secretions Endocrine Into bloodstream/tissue

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Connective Tissue Never exposed to the environment

outside the body Basic Structure

Specialized cells Protein fibers Ground Substance

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Functions of Connective Functions

Support and Protection Transport Materials Stores Energy Immunity

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Classification of Connective

Based on physical properties of ground substance Connective Tissue Proper

• many types of cells and fibers Fluid Connective Tissue

• distinctive cells in watery ground substance Supporting Connective Tissue

• Matrix is dense and closely packed fibers• Cartilage and bone

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Connective Tissue Proper Adipocytes Mast cells

Near blood vessels (heparin & histamine) Macrophages

Scavenger/defense cells Fibroblasts

Most common and most numerous Star shaped and release 3 types of fibers

• Collagen• Elastic• Reticular

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Fibroblast Fibers

Collagenous Elastic Reticular

Thick collagen fibers that are flexible but slightly elastic; great textile strength

Thin elastin fibers that stretch easily and resume shape

thin collagen fibers that are branched and form delicate supporting networks

Ligaments Tendons

Vocal cords various organs

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Loose Connective Tissue

Least specialized Binds skin to underlying tissues, fills

spaces between muscle, under most layers of epithelium

aka. Areolar Tissues

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Adipose Tissues

Formed when fat is deposited into cytoplasm of cells

Cushions joints and some organs, takes up space, insulator, energy storage Between muscles, beneath skin, around

organs and joints

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Dense Connective Tissue

Closely packed collagen and elastin fibers

Poor blood supply Extremely strong tissue

Binds body parts, tendons, ligaments, scalera of eye

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Blood & Lymph

Transports nutrients and other materials Maintains homeostasis Forms in the red bone marrow Comprised of red blood cells, white blood

cells, platelets, and blood plasma

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Cartilage Ridge form of connective tissue Matrix is comprised of collagenous fibers Chondrocytes are located within the matrix in

the lacunae Perichondrium surrounds cells and provides

nutrients Tissue repair is extremely slow Provides support/protection, framework,

structural models for bones 3 types

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Cartilage Types

Hyaline Elastic Fibrocartilage

Fine collagen fibers; most common

Dense elastin fibers; flexibility

Tough collagen fibers

End of bones, respiratory passage, nose

Ears, larynx Spine, knee, pelvic girdle

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Bone

Ridgedness due to CaCO3 and Ca3PO4

Matrix has many collagenous fibers Osteocyte is in the lacunae forming a

lamellae which when added to matrix forms the osteon

Healing happens faster than cartilage Protection/support/framework

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Muscle Tissue

Has the ability to contract 3 types

Skeletal Smooth Cardiac

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Muscle Tissue Types

Skeletal Smooth Cardiac

Voluntary; contains striations; stimulated by nerve impulse

Involuntary; lacks striations

Involuntary; striated; jointed cells via intercalated disc

Attached to bone

Walls of hallow organs

Heart only

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Nervous Tissue

Coordinates, regulates, and integrates body functions

Comprised of Neurons Neurological cells help to support

neurons

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