ANS 331: Tissues

I.	Four basic tissues

	1.	Epithelial
		--Covers and lines
	2.	Connective
		--Provides support
	3.	Muscle
		--Enables movement
	4.	Nervous
		--Controls work

II.	Epithelial Tissue

	1.	Functions

		A.	Protect, cover, and Line
		B.	Filter biochemical substances
		C.	Absorb Nutrients
		D.	Provide sensory input
		E.	Manufacture secretions
		F.	Manufacture excretions

	2.	Features

		A.	General Characteristics
		
			a.	Polar
				i.	Basement Membrane
				ii.	Apical Surface
			b.	Lateral Surfaces connected
				i.	Junctional Complexes
			c.	Avascular
				i.	Rely on underlying C.T. 
					to provide oxygen and nutrients
			d.	Innervated
				i.	Stomach, intestines, and cervix 
					are exceptions
				ii.	Provide valuable sensory input
				
		B.	Cellular Attachments
		
			a.	Tight Junctions
				i.	Plasma Membranes Fuse
				ii.	Limit extracellular passage between cells

			b.	Desmosomes
				i.	Plasma Membranes attached by filaments
				ii.	Narrow extracellular space (25-35 nm)

			c.	Gap Junctions
				i.	Very narrow extracellular space (2-4 nm)
				ii.	Channels (connexons) extend across space (2 nm)  
					1.	Link cytoplasms to transfer materials cell to cell
					2.	Important in electrical transmission
					
		C.	Basement Membrane
		
			a.	Also called basal lamina
			b.	Foundation of epithelial cell
			c.	Meshwork of fibers that connects C.T.
			d.	Acts as partial barrier
			
		D.	Surface Specializations
		
			a.	Microvilli
				i. Finger-like projections on apical surface
				ii.Brush border
				iii. Increase surface area for absorption and secretion
				
			b.	Ciliation
				i.	Involved in movement
				
			c.	Keratinization
				i.	Provide protection and waterproofing
				

	3.	Three Criteria for Classification of Epithelium

		A.	According to Cell Layers

			a.	Simple
			b.	Stratified
			c.	Pseudostratified

		B.	According to Cell Shape

			a.	Squamous (Flat & Thin)
			b.	Cuboidal
			c.	Columnar
			
		C.	Surface Specialization
			
			a.	Ciliated
			b.	Keratinized

	4.	Types of Epithelial Tissue

		A.	Simple Squamous

			a.	Diffusion 
			b.	Filtration
			c.	Examples
				--Capillaries
				--Alveoli in Lungs
				--Bowman's Capsule in Kidney

		B.	Stratified Squamous

			a.	Protection
			b.	Examples
				--Epidermis of Skin
				--Lining of mouth, esophagus, anus, & vagina

		C.	Transitional

			a.	Cells that can flatten under physical force
			b.	Examples
				--Urinary Bladder
				--Gall Bladder

		D.	Simple Cuboidal

			a.	Secretion
			b.	Examples
	    		              --Endocrine Glands (Thyroid, Ovary)
				--Exocrine Glands (Salivary, Sweat, Mammary)

		E.	Simple Columnar

			a.	Secretion 
			b.	Absorption
			c.	Cellular Metabolism
			d.	Often Ciliated, movement
			e.	Examples
				--Line Digestive System
				--Line Bronchi in Lungs
				--Line Oviducts			

		F.	Stratified Columnar

			a.	Protection
			b.	Some Absorption and Secretion
			c.	Examples
				--Epiglottis
				--Anal Canal
				--Male Urethra

		G.	Pseudostratified Columnar

			a.	Secretion
			b.	Protection
			c.	Often ciliated--Movement
		        d.	Examples
				--Large Glandular Ducts
				--Parotid Gland
				--Respiratory Passageways
				--Eustachian (Auditory) Tubes

	5.	Epithelial Tissue named by Location or Function

		A.	Mucous Membranes

			a.	Moist Epithelial tissues
			b.	Secrete Mucus
			c.	Form linings of digestive, respiratory, 
				urinary, and reproductive tract
			d.	Usually stratified or simple 
				cuboidal

		B.	Serous Membranes

			a.	Moist Epithelial tissues
			b.	Secrete Serous Fluid
			c.	Form layers of ventral body cavities 
				--Pleura, Pericardium, and Peritoneum
			d.	Simple Squamous Epithelium (Mesothelium)

		C.	Endothelium

			a.	Lines heart, and blood and lymph vessels
			b.	Simple Squamous Epithelium

		D.	Glandular Epithelium

			a.	Produce a secretion
				--Sweat, milk, hormones, enzymes
			b.	Excrete a waste product
				--bile, urea
			c.	Exocrine Glands
				--Have a duct
			d.	Endocrine Glands
				--Empty secretions directly into blood
			e.	Other Classifications by secretion
				i.	Merocrine
					--No secretion accumulation
					--Secretion by exocytosis
				ii.	Holocrine
					--Accumulates secretions
					--Secretion by cell rupture (death)
				iii.	Apocrine
					--Accumulates secretions
					--Some cell damage and loss of 
						cytoplasm at secretion

III.	Connective Tissue

	1.	Functions

		A.	Internal Framework of Organs
		B.	Bind Tissues and Organs together for Support
		C.	Serve as Food Storage Sites
		D.	Form Rigid Framework of Body

	2.	Form: Intercellular Matrix

		A.	Cell types

			a.	Fibroblasts
			b.	Macrophages
				--Phagocytes
				--Remove foreign matter and dead cells

  		A.	Ground Substance

			a.	Fluid to gel to solid

		B.	Fibers

			a. 	Collagenous (white) fibers
				--Bundles of fibrils
				--Strong and inelastic
				--Composed of Collagen

			b.	Elastic (yellow) fibers

				--long, threadlike branching fibers
				--can return to original size after 
					stretching
				--Composed of Elastin

			c.	Reticular fibers
				--short, thin fibers--inelastic
				--form internal framework (stroma)
				--Composed of Reticulin

	3.	Types of Connective Tissues

		A.	Loose (Areolar) C.T.

			a.	Most widespread C.T.
			b.	Made up of mostly collagenous, 
				but some elastic and reticular fibers
			c.	Examples
				--attaches skin to underlying tissue
				--fills space between organs--support
				--surrounds and supports blood vessels

			d.	Contains large amounts of intercellular 
					fluid
				--if excessive edema

 		B.	Dense Irregular C.T.

			a.	A denser version of areolar C.T.
			b.	More Collagenous fiber, studier
			c.	Examples
				--Forms Dermis of skin

		C.	Dense Regular C.T.

			a.	Collagenous fibers, tightly packed in 
				parallel bundles
			b.	Very Strong
			c.	Examples
				--Tendons
				--Ligaments (contains some elastic fibers)

		D.	Elastic C.T.

			a.	Elastic fibers, tightly packed
			b.	Strong and Stretchy
			c.	Examples:
				--Walls of arteries
				--Walls of trachea
				--Vocal Chords

		E.	Adipose Tissue

			a.	Composed of Fat Cells in loose C.T.

		F.	Cartilage

	                a.	Collagenous fibers in chondrin matrix 
				(ground substance)
			b.	Produced by chondroblasts & chondrocytes
				--Reside in lacunae
			c.	Little blood supply
			d.	Types

				i.	Hyaline
					--tightly packed
					--embryonic skeleton, trachea rings, 
						costal cartilage, 
						articular (joint) cartilage

				ii.	Elastic
					--less packed, more elastic fibers
					--ear, epiglottis, auditory tubes

				iii.	Fibrocartilage
					--more fibrous than hyaline
					--slightly compressible
					--intravertebral disks, articular 
						disks, pubic symphysis

	        G.	Bone

		        a.	Mineralized (inorganic salts) collagenous 
				fibers
			b.	Very strong and rigid
			c.	Produced by osteoblasts
			d.	Good Blood Supply
				--Lacunae and canaliculi
			e.	Makes up skeleton

		H.    	Special Connective Tissue

			a.	Blood
				--Fluid matrix that surround blood cells 
					(Plasma)
			b.	Reticuloendothelial System
				--Macrophages

					i.  	Kupffer cells (liver)
					ii.	Dust cells (lung)
					iii.	Microglia (CNS)


IV.	Muscle Tissue

	1.	Functions

		A.	Movement
      		B.	Support

	2.	Form

		A.	Fibers

			a.	Muscle cell

		b.	Highly Contractile

	3.	Types of Muscle Tissue

		A.	Skeletal

			a.	Long Bundles of muscle cells, striated by 
				myofibrils
			b.	Multinucleated, form at periphery of cells
			c.	Form Skeletal Muscle

		B.	Cardiac

			a.	More branching, divided by intercalated 
				disks, striated

			b.	Multinucleated, Nuclei centrally located

			c.	Form Heart Muscle

		C.	Smooth

			a.	Not Striated, spindle-shaped cells
			b.	Uninuclear, centrally located nuclei
			c.	Found in ducts, blood vessels, digestive 
				and reproductive tracts



	

V.	Nervous Tissue

        1.	Function 

		A.  	Signal (impulse) receiving and transmission

	2.	Form and Type

		A.	Neurons 

			a.	Nerve cells
				--cell body
				--cytoplasmic extensions 
					(dendrites and axons)

		B.	Supportive Cells

			a.	Neuroglia
			b.	Schwann Cells