Chapter 05 Lecture Outline

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Chapter 05

Lecture Outline

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5.0 Tissue Organization

• Tissues

– Groups of similar cells and extracellular material

– Common function

– E.g., providing protection

– Study of tissues, histology

• Four types of tissues

– Epithelial, connective, muscle, nervous

– Varied structure and function

2

5.1a Characteristics of Epithelial Tissue

• Epithelium, also referred to as epithelial tissue

– Composed of one or more layers of closely packed

cells

– Contains little to no extracellular matrix

– Covers body surfaces

– Lines body cavities

– Forms majority of glands

3

• Cellularity

– Composed almost entirely of tightly packed cells

• Polarity

– Apical surface

oExposed to external environment or internal body space

oMicrovilli or cilia

– Lateral surface with intercellular junctions

– Basal surface

oEpithelium attached to connective tissue

o Lamina propia between


4

• Avascularity

– Nutrients obtained across apical surface or from basal

surface

• Extensive innervation

– Detect changes in environment in that region

• High regeneration capacity

– Undergoes frequent cell division

– Regenerates at high rate

– Necessary due to environmental exposure

– Continual replacement of lost cells

o Cell division of stem cells


5

Figure 5.1

6

Characteristics

of Epithelia

5.1b Functions of Epithelial Tissue• Physical protection

– Protects external and internal surfaces

– Protects from dehydration, abrasion, destruction

• Selective permeability

– Relatively non-permeable to some substances

– Promotes passage of other molecules

• Secretions

– Some cells are specialized to secrete

– May be scattered among other cell types

• Sensations

– Contain nerve endings

– Supply information to nervous system

o Info on touch, pressure, temperature, pain

– Specialized epithelium, neuroepithelium

o Houses cells responsible for sight, taste, smell, hearing, equilibrium

7

5.1c Classification of Epithelial Tissue

• Body has different types of epithelia

• Epithelia classification indicated by two-part

name

Number of epithelial cell layers

Shape of cells at apical surface

8

Classification by number of cell layers

• Simple epithelium

– One cell layer thick

– All cells in direct contact with basement membrane

– In areas where stress is minimal

– Filtration, absorption, or secretion is primary function

– E.g., lining of air sacs of lungs, intestines, blood vessels


9

Classification by number of cell layers (continued )

• Stratified epithelium

– Two or more layers of epithelial cells

– Only basal layer in contact with basement membrane

– In areas subjected to mechanical stress

o Better able to resist wear and tear

o E.g., skin, lining of the esophagus, lining of urinary bladder

– Cells in basal layer

o Continuously regenerate as apical layer cells lost


10

Classification by number of cell layers (continued )

• Pseudostratified epithelium

– Appears layered

o Due to cells’ nuclei distribution at different levels

– All cells attached to basement membrane

– Some do not reach the apical surface

– Simple epithelium


11

Classification by cell shape

• Squamous cells

– Flat, wide, irregular in shape

– Floor tile arrangement

– Nucleus flat

• Cuboidal cells

– About as tall as they are wide

– Edges somewhat rounded

– Nucleus spherical and in center of cell


12

Classification by cell shape (continued )

• Columnar cells

– Slender and taller than they are wide

– Nucleus oval; oriented lengthwise in basal region

• Transitional cells

– Change shape, depending on stretch of epithelium

– Located where epithelium stretches and relaxes

o E.g., lining of the bladder

– Polyhedral when epithelium relaxed

– More flat when epithelium stretched


13

Figure 5.2

Classification of Epithelia

14

Figure 5.3

Organization and Relationship of Epithelia Types

15

• Simple squamous epithelium

– Single layer of flat cells

– Spherical to oval nucleus

– Thinnest barrier

– Allows rapid movement of molecules across surface

– Lines air sacs of lungs (alveoli)

– Lines blood and lymph vessel walls (endothelium)

– Serous membrane of cavities (mesothelium)


16

• Simple cuboidal epithelium

– Single layer

– Uniformly shaped cells

– About as tall as they are wide

– Centrally located spherical nucleus

– Designed for absorption and secretion

– Ideal for structural components of glands

o Thyroid gland

o Surface of ovary

o Walls of kidney tubules

o Secretory regions/ducts of most glands


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• Simple columnar epithelium

– Single layer of cells

– Taller than they are wide

– Oval nucleus, lengthwise in basal region

– Ideal for secretory and absorptive functions

– Two forms

o Nonciliated

o Ciliated


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Simple columnar epithelium (continued )

• Nonciliated

– Contains microvilli

oFuzzy structure—brush border

– Unicellular glands—goblet cells

oSecrete glycoprotein—mucin

oForms mucus when mixed with water

– Lines most of digestive tract from stomach to anal

canal


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Simple columnar epithelium (continued )

• Ciliated

– Cilia project from apical surface

oMove mucus along

– Goblet cells interspersed

– Lines

oBronchioles

oUterine tubes

˗ Helps move oocyte from ovary to uterus


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Pseudostratifed columnar epithelium

• Ciliated

– Contains cilia on apical surface

– Protective functions

– Goblet cells secrete mucin

o Traps foreign particles moved by cilia

– Located in large passageways of respiratory system

• Nonciliated

– Rare, lacks cilia, goblet cells

– Protective functions

– Occurs mainly in male urethra and epididymis


21

Stratified squamous epithelium

– Multiple cell layers

o Only deepest in direct contact with basement membrane

– Basal layers with cuboidal shape

– Apical cells with squamous shape

– Protects against abrasion and friction

– Stem cells in basal layer continuously divide

o Replace lost cells at surface

– Exists in keratinized and nonkeratinized forms


22

Stratified squamous epithelium (continued )

• Keratinized

– Superficial layers of dead cells

– Cells lack nuclei, filled with keratin

– Cells in basal region migrate toward apical surface

– Fill with keratin and die

– Found in epidermis


23

Stratified squamous epithelium (continued )

• Nonkeratinized

– All cells alive

– Kept moist with secretions (e.g., saliva, mucus)

– Lack keratin, protective protein

– Microscopically visible cell nuclei

– Lines

o Oral cavity, part of pharynx, esophagus, vagina, anus


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• Stratified cuboidal epithelium

– Two or more layers of cells

– Superficial cells cuboidal in shape

– Forms tubes and coverings

– Protection and secretion

– Forms walls of ducts in most exocrine glands

oSweat glands, parts of male urethra, periphery of

ovarian follicles


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• Stratified columnar epithelium

– Rare

– Two or more layers of cells

– Columnar cells at apical surface

– Protects and secretes

– Found ino Large ducts of salivary glands

o Some segments of male urethra


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• Transitional epithelium

– Limited to urinary tract

– In relaxed state

oBasal cells cuboidal or polyhedral; apical cells large and

rounded

– In stretched state

oApical cells flattened

– Binucleated cells (two nuclei)

– Allows for stretching as bladder fills


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5.1d Glands

• Glands

– Individual cells or multicellular organs

– Epithelial tissue

– Secrete substances used elsewhere or for

elimination

– May secrete

oMucin

oElectrolytes

oHormones

oEnzymes

oUrea (nitrogenous waste)

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• Endocrine glands

– Lack ducts

– Secrete hormones into blood

– Chemical messengers that influence cell activity elsewhere

• Exocrine glands

– Invaginated epithelium in connective tissue

– Connected with epithelial surface by duct

o Epithelium-lined tube for gland secretion

– E.g., sweat glands, mammary glands, salivary glands

5.1d Glands

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• Unicellular exocrine glands

– Do not contain a duct

– Located close to epithelium surface

– Most common type is goblet cell

• Multicellular exocrine glands

– Numerous cells

– Acini—cells clusters that produce secretions

– Ducts transport secretions to epithelial surface

– Surrounded by fibrous capsule

o Extensions of capsule—septa, partition gland into lobes

5.1d Glands

30

Figure 5.5

General Structure

of Multicellular

Exocrine Glands

• Exocrine glands are classified by anatomic form or

method of secretion

• Anatomic form

– Simple glands—a single, unbranched duct

– Compound glands—branched ducts

– Tubular glands—secretory portion and duct same diameter

– Acinar glands—secretory portion forms expanded sac

– Tubuloacinar gland—both tubules and acini

5.1d Glands

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Figure 5.633

Structural Classification of Multicellular Exocrine Glands

• Method of secretion—merocrine, apocrine,

holocrine

– Merocrine glands

oPackage secretions into vesicles

oRelease secretions by exocytosis

oExamples include

– Lacrimal (tear) glands

– Salivary glands

– Some sweat glands (eccrine glands)

– Exocrine glands of the pancreas

–Gastric glands of the stomach

5.1d Glands

34

Apocrine glands

o Apical membrane pinches off and becomes

secretion

o Damage repaired by glandular cells

o Continue to produce new secretions in same

manner

o Examples include

˗ Mammary glands

˗ Ceruminous glands of ear

5.1d Glands

35

– Holocrine glands

o Formed from cells that accumulate product

o Cell disintegrates

o Viscous mixture of cell fragments and cell

product

o Ruptured cells replaced

o Examples include

˗ Oil-producing glands in the skin (sebaceous

glands)

5.1d Glands

36

Figure 5.7

37

Methods of Exocrine Gland Secretion

Copyright © 2016 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill EducationCopyright © 2016 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education

What did you learn?

• Why does an epithelium need

to be highly regenerative?

• How does simple epithelium

differ from stratified

epithelium?

• What epithelial tissue lines

the air sacs of the lungs?

• What mode of secretion is

employed by dandruff?

38

• Connective tissue

– Most diverse, abundant, and widely distributed of tissues

– Supports, protects, and binds organs

– Cells, protein fibers, and ground substance

– Examples

o Tendons

o Ligaments

o Adipose tissue

o Cartilage

o Bone

o Blood

5.2 Connective Tissue:

Cells in a Supportive Matrix

39

5.2a Characteristics of Connective Tissue

• All CT shares three basic components: cells,

protein fibers, ground substance

• Cells

– Classes of CT have specific cell types

– Most cells not in direct contact with each other

– Two classes of cells

o Resident cells: housed in the CT

o Wandering cells: continuously move through the CT

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• Resident cells

– Fibroblasts

o Most abundant resident cells in CT proper

o Produce fibers and ground substance of extracellular matrix

– Adipocytes

o Fat cells in small clusters in some types of CT proper

– Mesenchymal cells

o Embryonic stem cell that divides to replace damaged cells

– Fixed macrophages

o Derived from monocytes (white blood cells)

o Dispersed throughout matrix

o Phagocytize (engulf) damaged cells or pathogens

o Release chemicals that stimulate immune system/attract wandering cells


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• Wandering cells

– Mast cells

o Secrete heparin to inhibit blood clotting

o Secrete histamine to dilate blood vessels

– Plasma cells

o Form when B-lymphocytes are activated when exposed to foreign material

o Produce antibodies (proteins that immobilize foreign material)

– Free macrophages

o Mobile, phagocytic cells

o Function like fixed macrophages, yet able to move

– Other leukocytes

o Neutrophils

˗ Phagocytizes bacteria

o T-lymphocytes

˗ Leukocyte that attacks foreign materials


42

• Protein fibers

– Strengthen and support tissue

– Three types: collagen fibers, reticular fibers, elastic

fibers

– Collagen fibers

oUnbranched, “cable-like” long fibers

oStrong, flexible, and resistant to stretching

oAppear white in fresh tissue

oNumerous in tendons and ligaments


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– Reticular fibers

o Similar to collagen fibers but thinner

o Form branching, interwoven framework

o Tough but flexible

o Abundant in stroma (CT framework) of

˗ Lymph nodes, Spleen, Liver

– Elastic fibers

o Contain protein elastin

o Branching wavy fibers

o Stretch and recoil easily

o Yellow in color when fresh

o Help structures return to normal shape after stretching

o Found in skin, arteries, lungs


44

• Ground substance

– Noncellular material produced by CT cells

– Residence of CT cells and protein fibers

– Consistency:

oViscous (e.g., blood)

o semisolid (e.g., cartilage)

oSolid (e.g., bone)

– Ground substance + protein fibers = extracellular

matrix


45

• Ground substance (continued )

Glycosaminoglycans (GAGs)

o Large molecule in ground substance

o Carbohydrate building blocks, some with attached

amines

o Negatively charged and hydrophilic

o Charge attracts cations, water follows

o Types include

˗ Chondroitin sulfate

˗ Heparin sulfate

˗ Hyaluronic acid


46

• Ground substance (continued )

Proteoglycanso Formed with GAG linked to a protein

o 90% carbohydrate in the form of GAGs

o Large structure due to negative repelling charges

o Perform numerous important functions

Adherent glycoproteinso Proteins with carbohydrates attached

o Bond CT cells and fibers to ground substance

o Includes: fibronectin, fibrillin, laminin


47

48

Connective Tissue Components and Organzation

Figure 5.8

• Collagen is an important protein

• Strengthens and supports almost all body tissues

• Vitamin C essential for healthy collagen fibers

• Scurvy caused by vitamin C deficiency

• Symptoms: weakness, gum ulceration, hemorrhages,

abnormal bone growth

• Caused by nutritional deficiencies

• Treated by consuming foods high in vitamin C or

supplements

Clinical View: Scurvy

49

5.2b Functions of Connective Tissue

• Functions of CT

– Physical protection

o Bones of skull and thoracic cage protect delicate organs

o Adipose tissue protects kidneys and eyes

– Support and structural framework

o Bones, body framework

o Place for muscle attachment

o Cartilage keeps trachea and bronchi open

o Supportive capsules around kidney and spleen

– Binding of structures

o Ligaments bind bone to bone

o Tendons bind muscle to bone

o Dense irregular tissue anchors skin to muscle and bone

50

• Functions of CT (continued )

– Storage

o Adipose CT is the major energy reserve

o Bone, primary reservoir for calcium and phosphorus

– Transport

o Blood carries nutrients, gases, wastes between regions of body

– Immune protection

o Leukocytes protects body against disease

o Immune response when necessary

o Extracellular matrix restricts movement of disease-causing

organisms

5.2b Functions of Connective Tissue

51

Marfan Syndrome• Hereditary defect in

elastin fibers

– Symptoms:• Hyperextensible joints,

hernias of the groin, visual problems from elongated eyes and deformed lenses

• Tall stature, long limbs, spidery fingers, abnormal spinal curvature, weakened heart valves and arterial walls

– Most die by age 50 due to aortic rupture

5-52

5.2c Embryonic Connective Tissue

• Two types of embryonic CT: mesenchyme, mucous CT

• Mesenchyme

– First type of CT in developing embryo

– Source of all other CT cells

• CT Proper

• Supporting CT

• Fluid CT

– Adult CT often has mesenchymal stem cells

o Provide support in repair of tissue

• Mucous connective tissue

– Second type of embryonic CT

– Found in umbilical cord only

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CT proper – Loose and Dense

• Loose CT

– Fewer cells and protein fibers than dense CT

– Protein fibers are sparse and irregularly arranged

– Abundant ground substance

– Body’s “packing material”, supports structures

– Three types

1. Areolar

2. Adipose

3. Reticular

5.2d Classification of Connective Tissue

55

• Loose CT (continued )

Areolar CT

o Loose organization of collagen and elastic fibers

o Highly vasularized

o Contains all fixed and wandering cells of CT proper

o Ground substance is abundant and viscous

o Found in the papillary layer of dermis

o Major component of subcutaneous layer

o Surrounds organs, nerve and muscle cells, and blood

vessels


56


Adipose CT (fat)o Composed mostly of adipocytes

o Two types

˗ White (stores energy, acts as insulator, cushions)

˗ Brown (found in newborns, generates heat, lost as we

age)

o Adipocyte number remains stable

o Weight gain/loss due to adipocytes enlarging or shrinking


57


Reticular CT

o Meshwork of reticular fibers, fibroblasts, leukocytes

o Structural framework of many lymphatic organs

˗ Spleen

˗ Thymus

˗ Lymph nodes

˗ Bone marrow


58

CT proper

• Dense CT

– Mostly protein fibers

– Less ground substance than loose CT

– Collagen fibers predominate

– Three categories

1. Dense regular

2. Dense irregular

3. Elastic


59

• Dense CT(continued )

– Dense regular CT

o Tightly packed, parallel collagen fibers

o Resemble stacked lasagna noodles

o In tendons and ligaments

˗ Stress typically applied in a single direction

o Few blood vessels

o Takes a long time to heal


60

• Dense CT(continued )

– Dense irregular CTo Clumps of collagen fibers extend in all directions

o Provides support and resistance to stress in multiple directions

o Extensive blood supply

o Found in:

˗ Most of the skin dermis

˗ Periosteum of bone

˗ Perichondrium of cartilage

o Forms capsules around some internal organs


61

• Dense CT(continued)

–Elastic CT

o Branching, densely packed elastic fibers

o Able to stretch and recoil

o Found in

˗ Walls of large arteries

˗ Trachea

˗ Vocal cords


62

• Supporting CT

– Two types: cartilage, bone

• Cartilage

– Collagen and elastic protein fibers

– Stronger and more resilient than other CT

– More flexible than bone

– In areas of body that need support and must withstand deformation (e.g., tip of

nose)

– Avascular in mature state

– Chondrocytes—mature cells

o Occupy small spaces called lacunae

– Three types

1. Hyaline cartilage

2. Fibrocartilage

3. Elastic cartilage


64

• Hyaline cartilage

– Most common type

– Clear, glassy appearance under microscope

– Chondrocytes irregularly scattered

– Surrounded by perichondrium

– Located in

o Nose, trachea, and larynx

o Costal cartilage

o Articular ends of long bones

o Most of fetal skeleton


65

• Fibrocartilage

– Weight-bearing cartilage, resists compression

– Protein fibers in irregular bundles between

chondrocytes

– Sparse ground substance

– No perichondrium

– Located in

o Intervertebral discs

oPubic symphysis

oMenisci of knee joint


66

• Elastic cartilage

– Flexible, springy cartilage

– Numerous densely packed elastic fibers

oEnsure tissue is resilient and flexible

– Resists deformational pressure

– Chondrocytes closely packed

– Surrounded by a perichondrium

– Located in external ear and epiglottis


67

• Bone

– More solid than cartilage

– Greater support, but less flexible

– Organic components (collagen and glycoproteins)

– Inorganic components (calcium salts)

– Bone cells—osteocytes

o Housed within spaces in extracellular matrix called lacunae

– Two types

o Compact bone

o Spongy bone


69

• Bone types

– Compact bone

oPerforated by neurovascular canals

oCylindrical structures—osteons

˗ Display concentric rings of bone CT called lamellae

˗ Lamellae encircle central canal, location of blood

vessels and nerves

– Spongy bone

oLocated in interior of bone

oLatticework structure, strong and lightweight


70

• Bone functions

– Levers for movement

– Supports tissues

– Protects vital organs

– Stores minerals, e.g., calcium and phosphorus

– Houses hemopoietic cells, which make blood cells


71

• Fluid CT

Two types: blood, lymph

• Blood

– Fluid connective tissue with formed elements

o Cells

o Erythrocytes transport respiratory gases

o Leukocytes protect against infectious agents

o Cellular fragments, called platelets, help clot blood

– Liquid ground substance is called plasma

o Dissolved proteins

o Transports nutrients, wastes, hormones


73

Fluid CT (continued )

• Lymph

– Derived from blood plasma

– No cellular components or fragments

– Ultimately returned to bloodstream


74


What did you learn?

• What are the three basic

components of connective tissue?

• What CT fibers are deficient in

Marfan’s Syndrome?

• What is mesenchyme?

• Compare loose connective tissue to

dense connective tissue.

• Describe the composition and

location of fibrocartilage.

• List the 10 different types of CT.

76

• Muscle tissue

– Cells contract when stimulated

– Contraction causes movement

o Voluntary motion of body parts

o Contraction of heart

o Propulsion of material through digestive and urinary tracts

– Three types

1. Skeletal

2. Cardiac

3. Smooth

5.3 Muscle Tissue: Movement

77


• Skeletal muscle tissue

– Striated or voluntary muscle tissue

– Moves skeleton

– Long cylindrical cells

o Skeletal muscle fibers

– Arranged in parallel bundles that run length of entire

muscle

– Multinucleated

– Alternating light and dark bands, striations

– Does not contract unless stimulated by somatic nervous

system

o Voluntary

78


• Cardiac muscle tissue

– Confined to middle layer of heart wall, myocardium

– Responsible for heart contraction to pump blood

– Visible striations

– Cells short and often bifurcating

– One or two nuclei

– Cells connected by intercalated discs

• Strengthen connection between cells

• Promote rapid conduction of electrical activity

– Involuntary

• Cannot be controlled by voluntary nervous system

• Pacemaker cells initiate contraction

79


• Smooth muscle tissue

– Visceral or involuntary muscle tissue

– Lacks striations; appears smooth

– Cells are spindle-shaped

– Cells short with one central oval nucleus

– Found in walls of intestines, stomach, airways, bladder,

uterus, blood vessels

– Helps propel movement through these organs

– No voluntary control over the muscle

80

• Nervous tissue

– Located in the brain, spinal cord, and nerves

– Cells called neurons

oReceive, transmit, and process nerve impulses

– Larger number of glial cells

oDo not transmit nerve impulses

o Instead, are responsible for protection, nourishment, and

support of neurons

5.4 Nervous Tissue:

Information Transfer and Integration

82

• Parts of a neuron

– Cell body

o Houses nucleus and other organelles

– Nerve cell processes extend from cell body

– Shorter and more numerous processes are called dendrites

o Receive incoming signals and transmit information

– Axon is the single long process extending from the cell

body

o Carries outgoing signals to other cells

– Neurons are longest cells in the body

5.4 Nervous Tissue:

Information Transfer and Integration

83

5.5a Organs

• Organs

– Two or more tissue types

– Work together to perform specific complex

functions

– Different structures must work in concert

– E.g., stomach, contains all four tissue types

85

5.5a Organs

• The stomach

– Lined by epithelium

o Secretes substances for chemical digestion of nutrients

– Areolar and dense CT in walls

o Blood vessels and nerves

o Provides shape and support

– Three layers of smooth muscle in walls

o Contract and relax to mix stomach contents

– Abundant nervous tissue

o Responsible for regulating muscle contraction and gland

secretion

86

Figure 5.1187

Roles of Tissue in an Organ

5.5b Body Membranes

• Body membranes

– Formed from epithelial layer bound to underlying CT

– Line body cavities

– Cover viscera

– Cover body’s external surface

– Four types

1. Mucous

2. Serous

3. Cutaneous

4. Synovial

88

Figure 5.12

89

Body

Membranes

• Mucous membrane

– Mucosa

– Lines compartments that open to external environment

– Includes: digestive, respiratory, urinary, and reproductive

tracts

– Performs absorptive, protective, and secretory functions

– Formed from epithelium and underlying CT

o CT component, lamina propria

o Covered with a layer of mucus derived from goblet cells,

multicellular glands, or both

5.5b Body Membranes

90

• Serous membrane

– Lines body cavities that do not open to external

environment

– Simple squamous epithelium (mesothelium)

– Produces thin, watery serous fluid

o Derived from blood plasma

o Reduces friction between opposing surfaces

– Forms parietal and visceral layers

– Serous cavity is in between

5.5b Body Membranes

91

• Cutaneous membrane

– Skin

– Covers external surface of body

– Composed of

o Keratinized stratified squamous epithelium

o Underlying CT

– Protects internal organs and prevents water loss

5.5b Body Membranes

92

• Synovial membrane

– Lines some joints in body

– Composed of

o Areolar CT

o Covered by squamous epithelial cells lacking basement

membrane

– Synovial fluid secreted by epithelial cells

o Reduces friction among moving bone parts

o Distributes nutrients to cartilage

5.5b Body Membranes

93


What did you learn?

• What are the four types of

membranes? Where are these

located in the body?

• What are the differences

between the parietal and

visceral layers of the serous

membrane?

94

5.6a Tissue Development

• Stages of tissue development

– Oocyte fertilized by a sperm

– Forms diploid cell, zygote

– After multiple cell divisions, becomes blastocyst

– Cells forming embryo, embryoblast

– Three primary germ layers formed by 3rd week

o Ectoderm, mesoderm, endoderm

– Growing structure now an embryo

95

96Figure 5.13

Primary

Germ Layers

and Their

Derivatives

• Hypertrophy

– Increase in size of existing cells of a tissue

• Hyperplasia

– Increase in number of cells of a tissue

• Atrophy

– Shrinkage of tissue by decrease in cell number or size

– Due to normal aging or disuse

– E.g., bedridden individual

o Skeletal muscle fibers become smaller

o Reversible by physical therapy

5.6b Tissue Modification

97

Clinical View: Stem cells

98


• Metaplasia

– Change of mature epithelium to a different form

– May occur as epithelium adapts to environment

– E.g., smokers

o Experience metaplastic changes in trachea epithelium

o Normal pseudostratified ciliated columnar epithelium

changed

o Becomes nonkeratinized stratified squamous epithelium

o Will revert back quickly if person quits smoking

99

• Dysplasia

– Abnormal tissue development

– May be precancerous, or revert back to normal

– Must be closely monitored by professionals

– E.g., cervical dysplasia due to exposure to human

papillomavirus


100

• Neoplasia

– Tissue growth is out of control

– Tumor of abnormal tissue develops

o Benign

˗ Localized growth

˗ Does not spread

o Malignant

˗ Metastasizes, spreads and invades other tissues

˗ Cancer

˗ Can interfere with normal functioning, leading to death


101

• Necrosis

– Tissue death

– Due to irreversible tissue damage

– Inflammatory response to tissue damage

– E.g., gangrene

• Necrosis of soft tissues of a body part

• Due to diminished arterial blood supply

• Most common in limbs, fingers, toes

• Major complications of diabetes


102

• Intestinal gangrene

Follows obstruction of blood supply to intestines

If untreated, leads to death

• Dry gangrene

Involved part is desiccated and shriveled

Usually due to extreme cold

• Wet gangrene

Caused by bacterial infection of tissues with lost blood

supply

Ruptured dying cells release fluid, allows bacteria to flourish

• Gas gangrene

Bacteria invade necrotic tissue (often muscle)

Bacteria produce gas bubbles

Clinical View: Gangrene

103

5.6c Aging of Tissues

• All tissues change with aging

– Proper nutrition, good health, normal circulation,

infrequent wounds—all promote normal functioning

– Support, maintenance, replacement of cells and

extracellular matrix

o Less efficient after middle age

– Structure and chemical composition of many tissues altered

o Epithelia thins

o CT loses pliability and resiliency

o Collagen declines

o Bones become brittle

o Muscles atrophy

104


What did you learn?

• What are the three primary germ layers?

• What is the difference between hypertrophy and hyperplasia?

• What is the difference between metaplasia, dysplasia, and neoplasia?

• Which is a more severe form of cancer, benign or malignant?

105

Chapter 05 Lecture Outline

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