TISSUE LE

VEL OF

ORGANIZATION

F A L L 20 1 2

• a – without• apo – front• cardium – heart• chondros –

cartilage• dendron – tree• desmos –

ligament• glia – glue• histos – tissue

• holos – entire• hyalos – glass• inter – between• krinein – to

separate• lacus – lake• meros – part• neuro – nerve• os – bone

VOCAB DEVELOPMENT

• peri – around• phagein – to eat• pleura – rib• pseudes – false• sistere – to set• soma – body• squama – plate

or scale• vas – vessel

VOCAB DEVELOPMENT

FOUR TISSUE TYPES • cells combine to form tissues• tissues are groups of specialized cells and cell

products that perform a limited number of functions • histology is the study of tissues • 4 basic types of tissues• epithelial• connective• muscle• neural

EPITHELIAL TISSUE• includes epithelia and glands• epithelia are layers of cells that cover internal or external surfaces • glands are composed of secreting cells derived from epithelia

EPITHELIAL TISSUE• Important Characteristics•cells that are bound closely together •a surface exposed to the environment or to some internal chamber or passageway•attachment to underlying connective tissue by a basement membrane•absence of blood vessels•continual replacement or regeneration of epithelial cells that are damaged or lost at the exposed surface

EPITHELIAL TISSUE • Functions of Epithelial Tissue• Provide physical protection•Control permeability• Provide sensation• Produce specialized secretions •Gland cells •Glandular epithelium• Exocrine- secretions are discharged to the surface of the epithelium• Endocrine- secretions are released into the surrounding tissue fluid and blood • These secretions are usually called hormones.

INTERCELLULAR CONNECTIONS • Undamaged epithelia form effective barriers.• The plasma membranes are held together by CAMs

and by a thin layer of intercellular cement. The CAMs bind to:

Cytoskeletal filaments Each other Extracellular materials

The CAMs form specialized attachment sites called cell junctions 3 types of junctions

Tight junctions Gap junctions Desmosomes

BASEMENT MEMBRANE • Lies between the epithelium and underlying

connective tissues • No cells, it is made up of a network of proteins • Provides strength and resists distortion

EPITHELIAL RENEWAL & REPAIR • Maintains its structures by the continuous

division of stem cells • Stem cells are unspecialized cells • Found in the deepest layer of the epithelium, near

the basement membrane

CLASSIFICATION OF EPITHELIA • Classified according to:• Number of cell layers• Shape of exposed cells

CLASSIFICATION OF EPITHELIA • Cell layers• Simple epithelium• Single layer of cells covering the basement

membrane • Thin• Found in protected areas inside the body • Line internal compartments & passageways • Common where absorption & secretion takes

place

CLASSIFICATION OF EPITHELIUM• Cell layers• Stratified Epithelium • Several layers thick above the basement membrane • Found in areas subject to mechanical or chemical

stresses

CLASSIFICATION OF EPITHELIUM• Cell shapes• Squamous • Cells are thin & flat• Nucleus occupies the thickest portion of each cell

• Cuboidal • Appear square in 2 dimensions• Appear hexagonal in 3 dimensions • Nucleus is near the center of each cell

CLASSIFICATION OF EPITHELIUM • Cell shapes• Columnar • Hexagonal, but taller & more slender than cuboidal • Nucleus is found near basement membrane

CLASSIFICATION OF EPITHELIA • Simple Squamous Epithelia• Found in protected regions where absorption takes

place or a slippery surface • Ex: exchange surfaces of lungs, lining of ventral body

cavities, lining of blood vessels• Simple Cuboidal Epithelia • Provides limited protection & occurs where absorption

& secretion take place • Secret enzymes & buffers in the pancreas & salivary

glands

CLASSIFICATION OF EPITHELIA • Simple Columnar Epithelia • Provide some protection & may occur in areas of

absorption or secretion• Ex: lines the stomach, the intestinal tract, and many

excretory ducts • Stratified Squamous Epithelia• Found where mechanical stresses are severe• Ex: surface of the skin, lining of the mouth, tongue,

esophagus

CLASSIFICATION OF EPITHELIA• Stratified Cuboidal Epithelia • Relatively rare• Ex: along the ducts of sweat glands and the ducts of

the mammary glands • Stratified Columnar Epithelia• Relatively rare• Ex: portions of the pharynx, epiglottis, urethra

CLASSIFICATION OF EPITHELIA • Psuedostratified Epithelia • Called this because it looks stratified but it is not • Found in portions of the respiratory tract

• Transitional Epithelia• Stratified epithelium that tolerates repeated

stretching • Lines the urinary bladder

GLANDULAR EPITHELIA • Exocrine secretions are produced by exocrine

glands and are discharged through a duct to the outside.

• Endocrine secretions are produced by ductless glands and are released into blood or tissue fluids

GLANDULAR EPITHELIA • Mechanisms of Secretion • Merocrine secretion• Most common form of secretion• Leaves the cell intact and able to function • Product is released from secretory vesicles by

exocytosis • Ex: mucus

GLANDULAR EPITHELIA • Mechanisms of Secretion• Apocrine secretion• Involves the loss of cytoplasm and the secretory

product• Leaves the cell intact and able to function

GLANDULAR EPITHELIA • Mechanisms of Secretion• Holocrine secretions • Entire cell becomes packed with secretions and

bursts and dies • Ex: sebaceous glands

GLANDULAR EPITHELIA • Types of secretions • Serous • Watery solution contains enzymes (saliva)

• Mucous• Thick, slippery mucus (snot)

• Mixed • Contains more than one type of secretion

CONNECTIVE TISSUES • 3 basic components• Specialized cells• Protein fibers• Ground substance• Fluid

• Matrix- extracellular protein fibers & ground substance that surround the cells of connective tissue

CONNECTIVE TISSUES • Never exposed to the outside• Highly vascularized • Contain receptors that provide pain, pressure,

temperature, & other sensations

CONNECTIVE TISSUES • Functions • Support & Protection• Transportation of materials• Storage of energy reserves • Defense of the body

CONNECTIVE TISSUES • Three major types • Connective tissue proper• Fluid connective tissues • Blood • lymph

• Supporting connective tissues • Cartilage • Bone

CONNECTIVE TISSUE PROPER • Cells found in connective tissue proper• Fibroblasts • Fibrocytes• Macrophages• Fat cells (adipocytes) • Mast cells

CONNECTIVE TISSUE PROPER• 3 types of connective tissue fibers • Collagen fibers• Most common fibers in connective tissue proper

• Elastic fibers • Return to their original shape after stretching

• Reticular fibers• Least common • Form the framework of various organs

CONNECTIVE TISSUE PROPER • Types of connective tissue proper• Classified into types based on their relative

proportions or cells, fibers, & ground substance • Loose• Dense

CONNECTIVE TISSUE PROPER • Loose Connective Tissues • Locations• Beneath the dermis of the skin • Digestive tract• Respiratory and urinary tracts • Between muscles• Around blood vessels, nerves, & joints

CONNECTIVE TISSUE PROPER • Loose connective tissue functions. • Cushions organs• Provides support, but allows independent movement• Phagocytic cells defend against pathogens

CONNECTIVE TISSUE PROPER• Loose Connective Tissue• Adipose tissue (composed mainly of triglycerides) • Locations:• Underneath the deep skin (sides, buttocks,

breasts)• Padding around eyes and kidneys

• Functions: • Provides padding & cushions shocks • Insulates• Stores energy reserves

CONNECTIVE TISSUE PROPER• Dense Connective Tissue• Locations: • Between skeletal muscles & skeleton• Tendons- connect muscle to bone

• Between bones • Ligaments – connect bone to bone

• Covering skeletal muscles• Capsules of internal organs

CONNECTIVE TISSUE PROPER• Dense connective tissue • Functions:• Provides firm attachment• Conducts pull of muscles• Reduces friction between muscles• Stabilizes relative position of bones• Helps prevent over expansion of organs (bladder)

FLUID CONNECTIVE TISSUES • 2 types• Blood• Plasma- watery matrix• Red blood cells• Account for half the volume of blood• Transport oxygen through the blood

• White blood cells- immune response • Platelets- clotting

• Lymph • Forms as interstitial fluid enter lymphatic vessels • Circulated throughout the entire body• Supports your immune system

SUPPORTING CONNECTIVE TISSUES • 2 types • Cartilage • Bone

SUPPORTING CONNECTIVE TISSUES • Cartilage• Heals poorly because it is avascular• 3 types of cartilage• Hyaline cartilage• Elastic cartilage• Fibrous cartilage

SUPPORTING CONNECTIVE TISSUES• Elastic Cartilage • Locations: • Auricle of external ear• Epiglottis • Auditory tube• Part of larynx

• Functions:• Provides support• tolerates distortion without damage and returns to

original shape

SUPPORTING CONNECTIVE TISSUES • Hyaline Cartilage• Locations: • Between tips of ribs & bones of the sternum • Cover bone surfaces at synovial joints• Supporting larynx, trachea, & bronchii• Forms part of the nasal septum

• Functions:• Provides stiff but somewhat flexible support• Reduces friction between bony surfaces

SUPPORTING CONNECTIVE TISSUES• Fibrous Cartilage• Locations:• Pads within knee joint• Between the pubic bones of the pelvis &

intervertebral discs• Functions:• Resists compression• Prevents bone on bone contact • Limits relative movement

SUPPORTING CONNECTIVE TISSUES • Bone• Osteocytes- cells that make up bones (hard outer part

of the bone)• Periosteum- covering around the bone

MEMBRANES • Membranes are physical barriers• 4 types • Mucous• Serous• Cutaneous• Synovial

MEMBRANES • Mucous Membranes • Line cavities• Communicate with the exterior

MEMBRANES • Serous Membranes • Line sealed, internal sub divisions of the ventral cavity • 3 serous membranes • Pleura- line the pleural cavities and covers the lungs• Peritoneum- line the abdominal cavity & covers the surface of the

enclosed organs • Pericardium- lines the pericardial cavity & covers the heart

• Parietal & visceral portions • Parietal portion- lines the inner surface of the cavity• Visceral portion- covers the outer surface of organs within the

body cavity• Primary function: Minimize friction between the parietal and

visceral surfaces when an organ moves or changes shape

MEMBRANES • Cutaneous Membrane• Covers the surface of the body (skin) • Thick • Waterproof• Usually dry • Consists of: stratified squamous epithelium &

underlying dense connective tissues

MEMBRANES • Synovial Membranes• Consist primarily of loose connective tissue & an

incomplete layer of epithelial tissue• Found in joints that are allowed to move free • Lubricates joints

MUSCLE TISSUE• Specialized from contraction• 3 types:• Skeletal• Cardiac• Smooth

MUSCLE TISSUE • Skeletal Muscle Tissue• Cells- long, cylindrical, striated, multinucleate • Locations: • Combined with connective tissues & neural tissue in

skeletal muscles• Functions:• Moves or stabilized the position of the skeleton• Guards entrances and exits to the digestive,

respiratory, and urinary tracts• Generates heat• Protects internal organs

MUSCLE TISSUE• Cardiac Muscle Tissue• Cells: short, branched, and striated; usually have a

single nucleus• Location:• Heart

• Functions:• Circulates blood• Maintains blood pressure

MUSCLE TISSUE • Smooth Muscle Tissue • Cells: short, spindle shaped, and non striated; single

central nucleus • Location: • Walls of blood vessels• Digestive, respiratory, urinary, & reproductive organs

• Functions:• Moves food, urine, and reproductive tract secretions• Controls diameter of respiratory passageways• Regulates diameter of blood vessels

NEURAL TISSUE • Specialized for the conduction of electrical

impulses from one region of the body to another. • Most is found in the brain and spinal cord • 2 basic types of cells• Neurons• 3 main parts • Cellbody• Dendrites• Axon

• neuroglia