Chapter 4
Tissues
4 Types of Tissue
Histology- 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 diffusiondigestive 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)
< Note: spellings
• Ex: sublingual salivary, submucosal of small intestine
• Work to lubricate, protect, and trap foreign particles
• Mixed > both
• Ex: submandibular salivary
Exocrine Gland Structure
• Unicellular
Multicellular
• Only are:
• Simple: 1 duct that does not divide
• Compound: duct divides
Mucous (Goblet) cells > mucins
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 types
Chondrocytes-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