Chapter 4Tissues

4 Types of TissueHistology- study of tissues•1. Epithelial- covers exposed surfaces, lines internal

passageways and chambers, & forms glands

•2. Connective- fills internal spaces, provides structural support, transports materials within the body, & stores E reserves

•3. Muscle- contraction of (body, heart, hollow organs)

•4. Neural- carries information in the form of electrical impulses

1. Epithelial Tissue

• Cells bound closely together• Polarity- has an exposed (apical) surface & attached (basal)

surface• Has a basement membrane• nonliving layer because it is avascular lacks blood vessels• Gets nutrients from diffusion or absorption

• Readily regenerates using stem cell divisions• injury heals fast

Epithelial Tissue

F(x):• Used for protection, secretion (glands), absorption, excretion• Extremely sensitive- large sensory nerve supply

• Specialized:• Movement of fluids over layer- lubrication & protection• Movement through layer- control permeability• Produce secretions

• Microvilli- on epithelium that line internally• Cilia- escalator to move something (mucus), respiratory tract

Integrity

• Intercellular connections- attached to one another• Cell Adhesion Molecules (CAMs)-

transmembrane proteins that connect large areas of opposing plasma membranes

• Tight Junction- proteins lock plasma membrane tightly together• Adhesion belt- binds to neighbors• Keep things in a lumen/prevent diffusion-

digestive enzymes don’t reach basal layer

• Gap Junction- held together by transmembrane proteins called connexons• Allow small molecules & ions to pass (muscle

cells)• Communication b/w cells

• Desmosome- CAMS & proteoglycans• Resist stretching & twisting• Found in layers- why you peel instead of powder• 1. Spot- small discs connected to bands of

intermediate filaments• 2. Hemidesmosomes- ½ spot, anchor to

underlying tissue

Arrangement & Shape of Cells• A. Simple- single layer• B. Pseudostratified- appears

to have multiple layers but doesn’t• C. Stratified- 2 or more

layers

• A. Squamous- thin floor tiles• B. Cuboidal- cubes• C. Columnar- columns• D. Transitional- changes,

flat>cuboidal

Types of Simple Epithelium

Glandular Epithelium

• Gland- cell or group of cells that secrete• Endocrine- directly to blood (hormones)• Exocrine- onto surface of a covering or lining, into ducts• Ex: mucus, sweat, oil, saliva, earwax

• Types of Exocrine:•Modes of secretion:• 1. Merocrine- release fluids by exocytosis• *most are this• Ex: salivary & sweat

• 2. Apocrine- lose small portions by secretion• Ex: mammary glands

• 3. Holocrine- cell bursts & is destroyed• Ex: sebaceous- oil gland of skin (why your hair is greasy)

• Types of Secretions:• Serous glands- watery with enzymes• Ex: Parotid salivary glands

•Mucous glands > mucus (mucin & H2O)• Ex: sublingual salivary, submucosal of small intestine• Work to lubricate, protect, and trap foreign particles

•Mixed > both• Ex: submandibular salivary

< Note: spellings

Exocrine Gland Structure• Unicellular• Only are:

Mucous (Goblet) cells > mucins

Multicellular• Simple: 1 duct that does not divide• Compound: duct divides

2. Connective Tissue

• 3 basic components:• Specialized cells• Extracellular protein fibers• Ground substance-fluid

Last 2- Matrix

2. Connective Tissue

F(x):• Structural framework• Transports fluids• Protect organs• Supporting, surrounding, & interconnecting other types of tissue• Storing E- triglycerides• Defends body from invaders

Extra info:• Most abundant tissue in the body• Not found on the surface of the body• Very well vascularized (blood vessels) except tendons, ligaments, &

cartilage = harder to heal• Has a nerve supply except cartilage• Has extracellular matrix-nonliving substance

Cell types

• A. Fibroblast-most common, secrete proteins to make fibers• B. Mast- produce histamine, react to injury or infection• C. Macrophages- can move around in order to clear foreign particles• D. Plasma-secretes antibodies• E. Adipocytes-fat• F. White blood cells- immune system

• Matrix- between cells, supports cells, binds cells together

Fibers

• A. Collagen- strong, resists pulling• Ex: bone, cartilage, tendons, ligaments

• B. Elastic- can stretch & return• Ex: skin, blood vessels, lungs

• C. Reticular- support & strength• Ex: soft organs

•Mesenchyme- embryonic connective tissue• Stem cells give rise to all other connective tissue•Mucous connective tissue (Wharton’s Jelly)- found in

many parts of embryo

Types of connective tissue

• 1. Areolar/Loose- strength, elasticity• Ex: makes up basement membrane, blood vessels, packages organs

• 2. Adipose-(fat) • insulation, energy reserve• Deep to skin & around heart & organs

• 3. Reticular• Supporting framework of spleen & lymph nodes, filters & removes old

blood cells• Liver, spleen, red bone marrow

• 4. Dense Regular• Strong attachment• Tendons, ligaments

• 5. Dense Irregular• Strength• Dermis of skin, fibrous capsules in joints

Cartilage-3 typesChondrocytes-cartilage cells

• 6. Hyaline• Smooth surface for movement at joints, flexibility• ends of long bones, ribs, trachea, nose

• 7. Elastic• Support & shape• External ear, larynx

• 8. Fibrocartilage• Support (very tough)• Intervertebral discs, knee, pubic

• 9. Bone/Osseous- protection of other organs, structure, stores minerals & fat, makes new blood in red marrow• Bone cells sit in cavities called lacunae and are

surrounded by layers of matrix made of calcium• Haversian System• Canal-blood vessels & nerves• Lacuna-space with a bone cell (osteocyte)• Lamellae- layers• Canaliculi- canals for nutrients & wastes

• 10. Blood• Transports gases, nutrients, & wastes• Red & white cells in plasma

3. Muscular tissue

• Contracts & shortens to produce movements

• 1. Skeletal• Motion, posture, heat• Attached to bones by tendons• Voluntary, striated (bands), multinucleate, fibers don’t branch

• 2. Smooth• Motion (constriction & contraction)• Blood vessels, airways, stomach, intestines, bladder, uterus• involuntary, single nucleus, spindle-shaped cells

• 3. Cardiac• Pumps blood in heart• Involuntary, striated (bands), single nucleus, cylinder shaped cells• Intercalated discs- junctions that allow ions to pass from cell to cell=

electrical impulse

4. Nervous Tissue• Regulates & controls body functions

Membranes• 1. Mucous (mucosae)- lines a cavity that opens to the outside• Kept moist to reduce friction- releases mucus or uses

urine/semen

• 2. Serous- lines a cavity that doesn’t open to the outside• Parietal- inner surface of cavity• Visceral/Serosa- outer surfaces of organs• A. pleura-lungs• B. pericardium- heart• C. peritoneum- abdominal organs

• 3. Synovial- where bones come together (Articulations)• Synovial fluid-lubricant in joints

4. Cutaneous- skin (ch5)

Inflammation- • impact, abrasion, distortion, chemicals, infection, extreme temps kills cells,

damages tissue > Lysosomal enzymes > Necrosis- tissue destruction• Pus- accumulation of debris, fluid, dead cells• Abscess- accumulation of pus in an enclosed space• Causes redness, swelling, warmth, pain

• If bacteria = infection

Tissue repair:• Mast cells > release chemicals (histamine, heparin, prostaglandins) to

stimulate inflammation (stimulate nerves=pain)• Blood vessels dilate to increase blood flow (warmth & redness), capillaries

infuse plasma (swelling) > increases O2 & carries away waste • Phagocytes > eat debris & pathogens• Regeneration- repair by fibroblasts make scar tissue until tissue is returned

to normal

• Epithelia, connective (except cartilage), & smooth muscle heal well• Inflammatory Response Video #1 , Inflammatory Response Video #2,

Inflammatory Response Video #3