TISSUE LE

VEL OF

ORGANIZAT

ION

F AL L 2

01

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