TISSUES & MEMBRANES

Marieb: Chaps. 4 - 5

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Introduction 1. Tissue - group of cells with related or

common structure and function 2. Types of Tissues

Epithelial (covering) Connective (support) Muscle (movement) Nervous (control)

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I. Epithelial Tissue (cover, line, transport) A. Cell Types

1. Squamous - Flat or scalelike 2. Cuboidal - Cube or hexagonical 3. Columnar - Rectangular 4. Transitional - several layers with appearance of

cells varying from layer to layer 5. Simple - single layer, little wear and tear,

transport functions (semi-permeable) 6. Stratified - multilayer, wear & tear with

replacement of surface layers 7. Pseudostratified - one lay but all cells do not

reach the top

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Fig. 4.2

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B. Classification SIMPLE 1. Simple Squamous Epithelial -

a) single layer, thin cells closely packed together b) little intercellular/extracellular space or matrix c) non-vascular - no blood vessels d) basement membrane - epithelial layer attached

to underlying connective tissue e) diffusion of gases (lungs, capillaries) f) filtration - kidney capsule g) mesothelium - squamous that lines cavities &

organs

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Fig. 4.3

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2. Simple Cuboidal a) boxy-like appearance b) function - secretion or absorption c) kidney tubules or glandular ducts or

tubes

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3. Simple Columnar Right angle view with basal nuclei Function - protection, absorption, secretion Line digestive tract with microvilli Goblet cells - mucous secretion (slide 9) Cilia (microtubular structure) for movement along

surface of cells Found in Respiratory tract, Oviducts

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Figure 4.4 Goblet cell (unicellular exocrine gland).

(b)(a)

Microvilli

Secretoryvesiclescontainingmucin

Golgiapparatus

Rough ER

Nucleus

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4. Pseudostratified a) variations in levels of nuclei of cells b) all touching basement membrane, but all do not

reach the top of the tissue c) ducts of glands d) can be ciliated with mucus goblet cells e) Respiratory tract & Female reproductive system

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STRATIFIED 4. Stratified Squamous Epithelium

a) multilayered - basal cells dividing appear as cuboidal or columnar cells

b) Nonkeratinized Stratified Squamous - Wet surface and wear and tear Mouth - Esophagous - Vagina

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4. Stratified Squamous Epith - continued c) Keratinized Stratified Squamous

Outermost cells die and contain keratin Keratin - waterproofing Barrier and protection from bacteria

SKIN

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5. Stratified - Transitional Epithelium a) similar to Nonkeratinized Stratified Squamous b) outer cells relaxed/nonstretched = NOT FLAT c) outer cells stretched = flat/squamous d) urinary bladder and urethra and ureters

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6. Stratified Cuboidal Epithelium

a) rare - usually 2 layers b) lines ducts of larger glands - sweat

glands and mammary glands

7. Stratified Columnar Epithelium a) rare - basal cells compressed b) line parts of male urethra

line parts of glandular ducts

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C. Glandular Classification

1. Gland - group of cells that release a chemical into a duct or the blood a) Exocrine - gland with a duct / tube

Salivary - water and chemicals Sweat - water and salts Pancreas - enzymes and buffers

b) Endocrine - ductless glands Hormones released into the blood Pituitary / Thyroid

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2. Exocrine - release/secretion a) Holocrine - chemical in

cytoplasm - cell dies & its contents are discharged - cell replaced - SEBACEOUS

b) Merocrine - secretion occurs with no other cellular contents - exocytosis - PANCREAS & SALIVARY

c) Apocrine - apical portion with chemical is pinched off - MAMMARY GLANDS

Fig. 4.6

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3. EXOCRINE STRUCTURE a) Unicellular - goblet cells (Fig. 4.4) b) Multicellular glands and various ducts

Different shapes to gland and/or duct

Fig.4.5

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Figure 4.5 Types of multicellular exocrine glands.

Compound duct structure(duct branches)

Simple tubular

ExampleIntestinal glands

Simple branchedtubular

ExampleStomach (gastric)glands

Compound tubular

ExampleDuodenal glands of small intestine

Compound alveolarExampleMammary glands

SimplealveolarExampleNo importantexample in humans

Simple branchedalveolarExampleSebaceous (oil)glands

CompoundtubuloalveolarExampleSalivary glands

Tubularsecretorystructure

Alveolarsecretorystructure

Surface epithelium Duct Secretory epithelium

Simple duct structure(duct does not branch)

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II. Connective Tissue

A. Introduction 1.loose or dense 2.diverse class 3.Fig. 4.7

Cells Fibers Matrix

extracellular

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4. Classes of connective tissue

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B. Areolar Tissue1. Loose CT - supports & binds organs, role in

inflammation & infections, body fluids

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2. Cells a) Fibroblasts - immature cells

Large, branching processes Formation of new tissue and repairs Produce fibers

b) Fibrocyctes -mature cells Maintain tissue

c) Macrophages - phagocytosis for defense d) Plasma cells - origin in wbc production of

antibodies e) Mast cells - near blood vessels to initiate local

inflammation Heparin - anticoaggulant Histamine - increase vessel permeability

f) Pigment cells and Fat Cells (store nutrients)

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3. Fibers - proteins from fibroblasts a) Collagen (white fibers) - tough, bundle

arrangement, some degree flexibility b) Elastic fibers (yellow) - also protein = elastin,

flexible and branching (skin, lungs, etc.) c) Reticular fibers - shorter, finer collagen fibers,

more give than traditional collagen

4. Matrix - Fluid nature - nutrients and wastes Hyaluronic acid - viscous Hyaluronidase - liquefy ground substance

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C. Adipose Tissue - Fat 1. Fibroblast - modified

to store fats 2. Large vacuole 3. Functions

Store energy raw

materials Insulation

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D. Dense / Collagenous CT 1. Collagen fibers

predominate matrix (regular) 2. Fibroblasts line up 3. Tendons

Muscle to bone 4. Ligaments

Bone to Bone More elastic

5. Dense irregular Fig. 4.9e) Fibrous covering of organs

Fig. 4.8d

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•E. Elastic CT

1. Elastic fibers produced by fibroblasts2. Stretch & return to original shape3. Walls blood vessels, vocal cords, respiratory tract between cartilage rings

F. Reticular CT 1. Reticular fibers

from fibroblasts 2. Internal framework

for organs - Spleen / Liver

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III. Cartilage

1. Functions - tough but flexible, supportive structure, large amounts of tissue fluid

2. Chondrocyctes - cartilage cells from mesenchyme tissue

Produce collagen & elastic fibers in a different matrix 3. Matrix - collagen & elastic fibers and

Chondroitin sulfate (gel like matrix) (Fig.4.7) 4. Lacunae - space in matrix around cell 5. Perichondrium - outer surface of cartilage tissue

associated with fibrous CT

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A. Hyaline Cartilage 1. Location

a) surface of bone - joint articulating cartilage b) ribs attached to sternum c) nose cartilage d) fetal skeleton e) respiratory tract

2. Chondrocytes - Produce collage fibers

that are NOT visible 3. Lacunae 4. Perichondium

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B. Elastic Cartilage

1. Support and maintain shape 2. Larynx / Outer ear /

Eustachian tube 3. Chondrocytes with

visible elastic

(& collagen) fibers Lacunae Matrix - fibers and

chondroitin sulfate

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C. Fibrocartilage 1. Strength / Support / rigidity 2. Vertebral discs and Pubic

symphysis 3. Chondrocytes with

visible collagen fibers Lacunae Matrix - fibers and

chondroitin sulfate

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IV. Bone (connective tissue)Chap. 6

A. Functions 1. Support 2. Protection 3. Movement 4. Mineral storage - calcium 5. Blood cell formation

Blood also CT

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B. Anatomy of Long Bone (Fig. 6.3)

1. Epiphysis 2. Articulating

cartilage 3. Periosteum

With inner layer

Osteoblasts 4. Diaphysis 5. Bone Marrow

Red/Yellow 6. Osteoclasts 7. Bone

Spongy Compact

1.7.

4.

3.

2.

5.

6

7.

3.

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Fig. 6.3

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8. Haversian System of compact bone

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Figure 6.7 Microscopic anatomy of compact bone.

Endosteum lining bony canalsand covering trabeculae

Perforating (Volkmann’s) canal

Perforating (Sharpey’s) fibers

Periosteal blood vesselPeriosteum

Lacuna (withosteocyte)

(a)

(b) (c)

Lacunae

Lamellae

NerveVeinArtery

CanaliculiOsteocytein a lacuna

Circumferentiallamellae

Osteon(Haversian system)

Central(Haversian) canal

Centralcanal

Interstitial lamellae

Lamellae

Compactbone

Spongy bone

Fig. 6.6

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C. Intramembranous Bone formationembryonic cranial skeleton = fibrous

membranes (Fig. 6.7)

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Figure 6.8 Intramembranous ossification.

Mesenchymalcell

CollagenfiberOssificationcenter

Osteoid

Osteoblast

Osteoid

Osteocyte

Newly calcifiedbone matrix

Osteoblast

Mesenchymecondensingto form theperiosteum

Blood vessel

Trabeculae ofwoven bone

Fibrousperiosteum

Osteoblast

Plate ofcompact bone

Diploë (spongybone) cavitiescontain redmarrow

1 2

3 4

Ossification centers appear in the fibrousconnective tissue membrane.

• Selected centrally located mesenchymal cells cluster and differentiate into osteoblasts, forming an ossification center.

Bone matrix ( osteoid ) is secreted within the

fibrous membrane and calcifies. • Osteoblasts begin to secrete osteoid, which is calcified within a few days.• Trapped osteoblasts become osteocytes.

Woven bone and periosteum form.• Accumulating osteoid is laid down between embryonic blood vessels in a random manner. The result is a network (instead of lamellae) of trabeculae called woven bone.• Vascularized mesenchyme condenses on the external face of the woven bone and becomes the periosteum.

Lamellar bone replaces woven bone, just deep to

the periosteum . Red marrow appears. • Trabeculae just deep to the periosteum thicken, and are later replaced with mature lamellar bone, forming compact bone plates.• Spongy bone (diploë), consisting of distinct trabeculae, per- sists internally and its vascular tissue becomes red marrow.

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Fig. 6.9 - Endochondrial Ossification - other bones of skeleton formed this way and pages 183-184.

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Figure 6.9 Endochondral ossification in a long bone.

1 2 3 4 5 Bone collarforms aroundhyaline cartilagemodel.

Cartilage in thecenter of thediaphysis calcifiesand then developscavities.

The periostealbud invades theinternal cavitiesand spongy bonebegins to form.

The diaphysis elongatesand a medullary cavityforms as ossificationcontinues. Secondaryossification centers appearin the epiphyses inpreparation for stage 5.

The epiphysesossify. Whencompleted, hyalinecartilage remains onlyin the epiphysealplates and articularcartilages.

Hyalinecartilage

Area ofdeterioratingcartilage matrix

Epiphysealblood vessel

Spongyboneformation

Epiphysealplatecartilage

Secondaryossificationcenter

Bloodvessel ofperiostealbud

Medullarycavity

Articularcartilage

Childhood toadolescence

BirthWeek 9 Month 3

Spongybone

Bonecollar Primaryossificationcenter

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Bone Growth (Figs. 6.10 & 6.11)

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Figure 6.10 Growth in length of a long bone occurs at the epiphyseal plate.

Calcified cartilagespicule

Osseous tissue(bone) coveringcartilage spicules

Resting zone

Osteoblast depositingbone matrix

Proliferation zoneCartilage cells undergo mitosis.

Hypertrophic zoneOlder cartilage cells enlarge.

Ossification zoneNew bone formation is occurring.

Calcification zoneMatrix becomes calcified; cartilage cells die; matrix begins deteriorating.

1

2

3

4

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V. Muscle Tissue - Next Unit- motion due to filament contraction- classification - location / nerve innervation / appearance

-skeletal -voluntary / striated

-cardiac - involuntary / striated

-smooth/visceral - involuntary / nonstriated

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VI. Nervous Tissue- Neuron = Nerve Cell- Generate & Conduct Electrical signals- Cell Processes

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VII. Membranes (epithelial & underlying CT) Fig. 4.11

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Figure 4.11 Classes of membranes.

Cutaneous membrane(skin

Mucosa of nasalcavity

Mucosa of lungbronchi

Mucosa of mouth

Esophagus lining

Parietal pericardium

Visceral pericardium

(a) Cutaneous membrane (the skin) covers the body surface.

(b) Mucous membranes line body cavities open to the exterior.

(c) Serous membranes line body cavities closed to the exterior.

Parietalperitoneum

Visceralperitoneum

Parietal pleuraVisceral pleura

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VII. Membranes1. Mucous Membranes

a) line body area open to the outside Digestive, respiratory, urogenital

b) moist due to mucus secretion (urine) and cilia to move materials

c) secretion of mucus and absorption of materials

d) underlying CT binds plus flexible

(lamina propria)

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VII. Membranes2. Serous Membranes

a) lines areas not open to outside & their organs

b) mesothelium & loose CT c) visceral portion = around organ parietal portion = around cavity d) pleural = lungs peritoneum = abdominopelvic cavity/organs

3. Synovial Membrane a) lines joint cavity b) no epithelial component

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Synovial Joint

(loose CT)

Fig8.3 -.4

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VIII. Skin / Cutaneous Membrane A. Epidermis - stratified keratinized sq.

1. Stratum basale - dividing columnar shape 2. Stratum spinosum - multilayers of newly

formed cells 3. Stratum granulosum - flatten cells/pigment

formation, 1st step in Keratin formation 4. Stratum lucidum - Dead cells, flat, keratin Formation (palm/sole) 5. Stratum corneum- 2 dozen layers dead, keratinized squamous

cells that are shed

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B. Dermis1. Loose CT (dense, collagen, elastic) Blood vessels, Nerves (sensory) Hair follicles and Glands = Epidermal in origin

2. Dermal Ridges / Papilla 3. Subcutaneous layer - with

Adipose / Areolar CT

C. Accessory Organs 1. Hair - epidermal origin plus

arrector pili muscle

2. Sebaceous Glands Holocrine Keeps hair/skim pliable,

water-proof 3. Sweat Glands(merocrine)

Open to surface via duct

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Fig. 5.5

Fig. 5.6