Tissues Although we have trillions of cells there are only about 200 different cell types Remember – cell types combine to form tissues

Overview of Tissue Science Histology (histos = tissue) The study of tissues Four Basic Tissue Types Epithelial Connective Muscular Neural (neuro = nerve) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Overview of Tissue Science Key Note Tissues are collections of cells and extracellular material that perform a specific but limited range of functions.The four tissue types, in varying combinations, form all of the structures of the human body. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Overview of Tissue Science An Orientation to the Tissues of the Body Figure 4-1

Epithelial Tissue Epithelium (singular form) An avascular (a = without + vas = vessel) layer of cells that forms a barrier that covers internal or external surfaces Glands Secretory structures derived from epithelia Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Epithelial Tissue Characteristics of Epithelia Cells closely packed other tissue types have cells often separated by extracellular materials Apical (free) cells exposed to external or internal surface Cells attached to basement membrane The basement membrane attaches the epithelial tissue to connective tissue Lack blood vessels (avascular) Cells continually replaced – remember how many pounds of skin cells you lose? Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Epithelial Tissue Functions of Epithelia Physical protection – protects against abrasion, dehydration, and destruction by physical or biological agents Permeability control – anything going into or out of the body must cross epithelium Sensation trigger – receptors can send information to the nervous system Specialized secretions – secretions produced by gland cells (glandular epithelium)

Epithelial Tissue Two Classes of Glandular Secretion Exocrine (krinein = to secrete) secretion—Secretion onto a body surface Endocrine —Secretion (of hormones) into neighboring tissues and blood Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Epithelial Tissue Intercellular Connections Cell adhesion molecules (CAMs): Special proteins that bind with a thin layer of intercellular cement. Their binding forms special attachment sites know as cell junctions Cell junctions Tight junctions – lipid layers of adjacent cell membranes bound together by interlocking cell proteins Gap junctions – two cells held together by embedded channel proteins which form a narrow passageway in which cells can communicate Desmosomes (desmos = ligament + soma = body) – durable interconnections that allow twisting, bending, stretching, or compression

Epithelial Tissue Intercellular Connections Figure 4-2

Epithelial Tissue The Epithelial Surface – apical surface often have specialized structures that distinguish them from other cell types Microvilli Abundant on transport cells Dramatically increase surface area (20x more than cells without) Found in intestinal lining, kidney tubules (where absorption and excretion take place) Cilia (a cell with cilia has about 250) Beat in coordinated fashion Move fluid along surface Found in airways, oviduct

The Surfaces of Epithelial Cells Epithelial Tissue The Surfaces of Epithelial Cells Figure 4-3

Epithelial Tissue The Basement Membrane – firmly connect epithelial cells to the rest of the body Noncellular meshwork anchors basal cells – made of protein fibers Underlies all epithelia Hemidesmosomes attach basal cells Resists passage of large molecules Strengthens against distortion Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Epithelial Tissue Epithelial Renewal and Repair Exposure shortens cell life Epithelium needs constant repair and replacement Epithelial stem cells undergo mitosis – unspecialized cells found in the deepest layer of the epithelium near the basement membrane Epithelium grows up from base Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Epithelial Tissue Classifying Epithelia – classified by number of layers and cell shape Number of layers Simple (one cell thick) – only found inside the body since the thickness is fragile and can not offer much protection (ventral body cavities, heart chambers and blood vessels) Stratified (multiple cells thick) – more protection since it has several layers above the basement membrane and found in areas subject to mechanical or chemical stress (surface linings of the skin, mouth and anus) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Epithelial Tissue Cell shape Squamous (flat) squama = plate or scale Nuclei occupies the thickest portion of the cell Looks like fried eggs laid side by side Cuboidal (cubic) Nuclei lie near the center of the cell Columnar (tall columns) Nuclei crowded into a narrow band close to the basement Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Epithelial Tissue Table 4-1

Name the cell shape

Name the cell shape

Name the cell shape

Simple Squamous Epithelium Epithelial Tissue Simple Squamous Epithelium Figure 4-4(a)

Simple Cuboidal Epithelium Epithelial Tissue Simple Cuboidal Epithelium Figure 4-4(b)

Simple Columnar Epithelium Epithelial Tissue Simple Columnar Epithelium Figure 4-4(c)

Pseudostratified Ciliated Columnar Epithelial Tissue Pseudostratified Ciliated Columnar Figure 4-5(a)

Transitional Epithelium Epithelial Tissue Transitional Epithelium Figure 4-5(b)

Stratified Squamous Epithelium Epithelial Tissue Stratified Squamous Epithelium Figure 4-5(c)

Epithelial Tissue Glandular Epithelia Three secretion mechanisms Merocrine (meros = part) Exocytosis of vesicles – most common Mucus – effective lubricant, protective barrier, and sticky trap for foreign particles Apocrine (apro = off) Release of apical cytoplasm (outermost part) because they become packed with secretory vesicles Milk production from mammary glands Holocrine (holos = entire) Burst of entire contents Hair follicle glands produce an oily hair coating Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Mechanisms of Glandular Secretion Epithelial Tissue Mechanisms of Glandular Secretion PLAY Glandular Secretions Figure 4-6

Connective Tissues Connective Tissues Components Specialized cells Extracellular matrix Protein fibers Fluid phase (the ground substance) Both the protein fibers and ground substance form the matrix The extracellular matrix accounts for most of the volume of the connective tissue Most diverse tissue in the body! Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Connective Tissues Functions Structural framework - establish a bony structural framework Fluid and solute transport – moves dissolved materials from one part of the body to another Physical protection - protects delicate organs Tissue interconnection- surrounds and interconnects other tissue types Fat storage – fats stored in fat (adipose) cells Microorganism defense – specialized cell that respond to invasions through cell-to-cell interaction Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

What are the functions of epithelia? Science Starter What are the functions of epithelia?

Connective Tissues Classifying Connective Tissues Connective tissue proper Many types of cell with a syrupy ground substance Examples: tissues under the skin, fatty tissues, ligament, and tendons Fluid connective tissues Cells in a watery ground substance Examples: blood and lymph Supporting connective tissues Less diverse cells and a matrix of dense ground substance and closely packed fibers Examples: cartilage and bone Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Major Types of Connective Tissue Connective Tissues Major Types of Connective Tissue Figure 4-7

Connective Tissues Connective tissue proper Contains varied cell populations and fiber types surrounded by a syrupy ground substance Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Connective Tissues Connective Tissue Proper Resident and migrating cells Fibroblasts – the most abundant cells and are responsible for producing and maintaining connective tissues and ground substance Macrophages – engulf (phagocytize) damaged cells or pathogens They can also release chemicals that mobilize the immune system Fat cells (adipose) – permanent residents Has such a large droplet of lipid that the nucleus is squeezed to one side of the cell Mast cells – small, mobile connective tissue cells often found near blood vessels Filled with chemical that are released to start the body’s defense system Other white cells – please read pg 100

Connective Tissues Connective Tissue Fibers (three types) Protein fibers Collagen fibers – most common Long, straight and unbranched Provides toughness Reticular fibers – (reticulum = network) least common Thinner than collagen Commonly form a branching interwoven framework Supports cells – various organs Elastic fibers – contain protein elastin Provides resilience – stretched and wavy and will return to original length Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Cells and Fibers of Connective Tissue Proper Connective Tissues Cells and Fibers of Connective Tissue Proper Figure 4-8

Connective Tissues Connective Tissue Proper - Three types Loose connective tissue – least specialize connective tissue Forms the layer that separates the skin from the underlying muscle Example: beneath dermis of skin Adipose tissue (fat) is a loose connective tissue that has become dominated by fat cells Provides padding, shock absorption and insulation Also provides energy storage Example: “love handles” 3. Dense connective tissue – mostly collagen fibers Examples: dermis, tendons, ligaments Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Loose Connective Tissue Connective Tissues Loose Connective Tissue Figure 4-9(a)

Connective Tissues Adipose Tissue Figure 4-9(b)

Dense Connective Tissues Figure 4-9(c)

Connective Tissues Fluid Connective Tissues Cells + a liquid ground substance Blood RBCs, WBCs, platelets + plasma Lymph Lymphocytes + lymph fluid Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Connective Tissues Supporting Connective Tissue Support the body Bone (osseous tissue) Osteocytes + collagen + calcium salts Cartilage Chondrocytes + firm gel Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Connective Tissues Bone (Osseous Tissue) Matrix provides unique properties Collagen fibers resist bending Calcium salts resist compression Diffusion through canaliculi nourishes osteocytes Covered by periosteum Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Connective Tissues Bone Figure 4-11

Connective Tissues Supporting Connective Tissue Cartilage Avascular Covered by a fibrous perichondrium Three types of cartilage Hyaline cartilage Elastic cartilage Fibrocartilage Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Connective Tissues Hyaline Cartilage Figure 4-10(a)

Connective Tissues Elastic Cartilage Figure 4-10(b)

Connective Tissues Fibrocartilage Figure 4-10(c)

Membranes Properties of Membranes Barrier or interface Cover and protect An epithelium plus connective tissue Four types of membranes Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Membranes Types of Membranes Mucous Serous Lines cavities that connect to exterior Mucus moistens surface Examples: oral cavity, airways Serous Line internal cavities Watery fluid moistens surface Example: peritoneal membrane Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Membranes Types of Membranes (continued) Cutaneous Synovial Covers body surface Dry surface waterproofs the body Example: the skin Synovial Lines joints Secretes slippery synovial fluid Lubricates joints Examples: knee, elbow Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Membranes Membranes Figure 4-12

Muscle Tissue

Muscle Tissue Properties of Muscle Tissue Capable of contraction Actin filaments Myosin filaments Three types of muscle tissue Skeletal muscle Cardiac muscle Smooth muscle Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Muscle Tissue Skeletal Muscle Tissue Contains elongated cells (fibers) Fibers tied together by loose connective tissue Possesses microscopic striations Contains many nuclei Controlled by voluntary nervous system Moves and stabilizes the skeleton Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Skeletal Muscle Tissue Figure 4-13(a)

Muscle Tissue Cardiac Muscle Tissue Only in heart Short, branched fibers Single nucleus Striated Involuntary contraction Blood circulation Blood pressure Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Muscle Tissue Cardiac Muscle Tissue Figure 4-13(b)

Muscle Tissue Smooth Muscle Tissue Short, tapering cells No striations Involuntary contraction Blood vessels Urinary bladder Digestive organs Uterus Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Muscle Tissue Smooth Muscle Tissue Figure 4-13(c)

Neural Tissue

Neural Tissue Properties of Neural Tissue Conduct electrical impulses Transfer, process, and store information Comprises neurons and neuroglia Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Tissue Neurons Dendrites Cell body Axon (nerve fibers) Information entry Cell body Information integration Axon (nerve fibers) Information transmission Synaptic terminals Information transfer Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Tissue Neuroglia Several types of neuroglia Provide physical support Maintain extracellular chemistry Supply nutrients Defend against infection Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Tissue Neural Tissue Figure 4-14

Tissue Injuries and Repair An injury harms multiple tissues simultaneously Tissues make coordinated response Responses restore homeostasis Two response types Inflammation Regeneration Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Tissue Injuries and Repair Inflammation Isolation of injured area Cleanup of damaged tissue Four signs of inflammation Warmth Redness Swelling Pain Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Tissue Injuries and Repair Regeneration Repair/replacement of damaged tissue Restoration of tissue function Scar tissue from fibroblast activity Complete, partial, or no regeneration Tissue fibrosis common outcome Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Tissues and Aging Tissues Change with Age Healing slows Epithelia become thinner Connective tissues become more fragile Bones weaken, become brittle Neuron and muscle fiber losses accumulate Lifestyle interventions slow decline Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Tissues and Aging Aging and Cancer Incidence 25% develop cancer Cancer risk rises with age After heart disease, cancer second leading cause of death Smoking linked to 40% of cancers 75% caused by environment Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings