Anatomy & physiology for pg dentistry 01

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Anatomy & Physiology Anatomy & Physiology for PG Dentistryfor PG Dentistry

Prof. Prof. AshrafAshraf KamelKamelM.B.B.ChM.B.B.Ch., M.Sc., M.D. Histology, M.Sc. Cardiology., M.Sc., M.D. Histology, M.Sc. Cardiology

Diploma of Diploma of MdicalMdical EducationEducationProfessor at Professor at RCsDPRCsDP, KSA., KSA.

[email protected]@riyadh.edu.sa

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Anatomy & PhysiologyAnatomy & Physiologyfor PG Dentistryfor PG Dentistry

• Introduction; Human body organization / skin

• Skeletal System.

• Cardiovascular system

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• Blood & Lymphatic system

• Endocrine & Nervous tissue.

• Spinal cord and Spinal nerves.

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Introduction to ……..Introduction to ……..Introduction to ……..Introduction to ……..

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AnatomyAnatomy

• “tome” means to cut in Greek

• Describes the structures of the body:

– what they are made of– what they are made of

– where they are located

– associated structures

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PhysiologyPhysiology

• Is the study of:

– functions of anatomical structures, both

individual and cooperativeindividual and cooperative

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KEY CONCEPTKEY CONCEPT

• All physiological functions are performed by specific anatomical structures

• Principle of complementarity says that structureand function are complementary

– Function always reflects structure

– What a structure can do depends on its specific form

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IntroductionIntroduction

• Key to learning anatomy is understanding function

– For example:

Left side of heart is larger than right.Left side of heart is larger than right.

– Why is that?

Structure (anatomy) and function (physiology) are

intimately related

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Gross AnatomyGross Anatomy

• Structures large enough that one can see with the unaided eye

– Surface Anatomy - study of superficial markingsmarkings

– Regional Anatomy - The study of specific areas of the body (e.g. head, trunk)

– Systemic Anatomy - Study of the 11* specific organ systems

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Anatomical OrganizationAnatomical Organization

• We will start from the smallest and finish with the

largest

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Levels of OrganizationLevels of Organization

•• Chemical Level:Chemical Level: - atoms (e.g. carbon) combine to form molecules (e.g. glucose)

•• Cellular level:Cellular level:

– Smallest living units in organisms

– Cells contain organelles, each with a function

•• Tissue level Tissue level - different groups of cells that perform a function

•• Organ Level Organ Level - Different types of tissues that perform a common function

•• Organ system Organ system – consists of different organs that work closely together

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HomeostasisHomeostasis

• Homeostasis: ability to maintain a relatively stable internal environment in an ever-changing outside world

• All body systems working together to maintain a stable internal environment, respond to external and internal changes to function within a normal range internal changes to function within a normal range (body temperature, fluid balance)

• The internal environment of the body is in a dynamic state of equilibrium

• Failure to function within a normal range results in disease

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Homeostatic Control MechanismsHomeostatic Control Mechanisms

• Variables produce a change in the body

• The three interdependent components of control mechanisms:

– Receptor – monitors the environments and responds to changes (stimuli).

– Control center – determines the set point at which the variable is maintained.

– Effector – provides the means to respond to stimuli.

17Homeostatic Control MechanismsHomeostatic Control Mechanisms

Input:Informationsent along afferentpathway to

Receptor (sensor) Effector

Controlcenter Output:

Information sentalong efferentpathway to

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Change detected by receptor

Stimulus: Produces changein variable

Variable (in homeostasis)

Response ofeffector feedsback toinfluencemagnitude ofstimulus andreturns variableto homeostasis

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RegulationRegulation

• Most regulatory systems in the body use extrinsic regulation:

– responses controlled by nervousnervous and endocrineendocrine systems, e.g. brain regulates body temp.temp.

• Usually occurs by negative feedback which can be modeled as a thermostat:

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Negative FeedbackNegative Feedback

• Most common way that homeostasis is

maintained in the body

• In negative feedback systems the response • In negative feedback systems the response

of the effector negates or opposes the

stimulus (shuts off the original stimulus)

• Example: Regulation of room temperature

20Signalwire turnsheater off

Response;temperaturedrops

Stimulus: rising roomtemperature

Balance

Effector(heater)

Setpoint

Control center(thermostat)

Heateroff

Receptor-sensor(thermometer inThermostat)

Signalwire turnsheater on

Response;temperaturerises

Stimulus: dropping roomtemperature

Effector(heater)

Setpoint

Receptor-sensor(thermometer inThermostat)

Control center(thermostat)

Heateron

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Negative Feedback:Negative Feedback:Maintaining Normal Limits Maintaining Normal Limits

Thermostat model

22Negative FeedbackNegative Feedback

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Positive FeedbackPositive Feedback

• NOT a way to maintain homeostasis

• Rare in nature because it is a “runaway train”is a “runaway train”

• The response of the effector output reinforces or exaggerates the stimulus (e.g. blood clotting, ovulation, child birth)

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Body TissuesBody TissuesBody TissuesBody Tissues

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Body TissuesBody Tissues

· Cells are specialized for particular functions

· Tissues

·Groups of cells with similar structure and function

·Four primary typesA. Epithelium

B. Connective tissue

C. Nervous tissue

D. Muscle

26System: A group of organs that interacts to carry out a major body function

Organ: Body structure that integrates different tissues and carries out a specific function

Stomach

Epithelial tissue: Protection, transport, secretion, and absorption

Connective tissue: Structural support

Muscle tissue: Movement

Nervous tissue: Communication, coordination, and control

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Epithelial TissuesEpithelial Tissues

· Found in different areasØBody coverings

ØBody linings

ØGlandular tissueØGlandular tissue

· Functions1. Protection

2. Absorption

3. Filtration

4. Secretion

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Epithelium CharacteristicsEpithelium Characteristics

· Cells fit closely together

· Tissue layer always has one free surface

· The lower surface is bound by a basement · The lower surface is bound by a basement membrane

·· AvascularAvascular (no blood supply)

· Regenerate easily if well nourished

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Classification of EpitheliumClassification of Epithelium

· Number of cell layers

·Simple – one layer·Simple – one layer

·Stratified – more than one layer

30Classification of Epithelia by Classification of Epithelia by Number of LayersNumber of Layers

Simple or stratified

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· Shape of cells

·Squamous – flattened·Squamous – flattened

·Cuboidal – cube-shaped

·Columnar – column-like

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Simple EpitheliumSimple Epithelium

·· Simple Simple squamoussquamous

·Single layer of flat cells

·Usually forms ·Usually forms membranes

·Lines body cavities

·Lines lungs and capillaries

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SquamousSquamous Epithelium Epithelium (surface view)(surface view)

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·· Simple Simple cuboidalcuboidal

·Single layer of cube-like cells

·Common in ·Common in glands and their ducts

·Forms walls of kidney tubules

·Covers the ovaries

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Simple Cuboidal & Squamous Simple Cuboidal & Squamous EpitheliumEpithelium

CuboidalCuboidal""

SquamousSquamous ""

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·· Simple columnarSimple columnar

·Single layer of tall cells

··Often includes goblet cells, which produce mucus

·Lines digestive tract

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Simple Columnar EpitheliumSimple Columnar Epithelium

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Simple Columnar EpitheliumSimple Columnar Epithelium

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·Single layer, but some cells are shorter than others

·Often looks like a

PseudostratifiedPseudostratified ColumnarColumnar

·Often looks like a double cell layer

·Sometimes ciliated, such as in the respiratory tract

·May function in absorption or secretion

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Pseudostratified Columnar Ciliated Pseudostratified Columnar Ciliated EpitheliumEpithelium

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Stratified EpitheliumStratified Epithelium

Stratified Stratified squamoussquamous

·Cells at the free edge are flattened

·Found as a protective covering where covering where friction is common

·Locations·Skin

·Mouth

·Esophagus

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·· Stratified Stratified cuboidalcuboidal

· Two layers of cuboidal cells

·· Stratified columnarStratified columnar

· Surface cells are columnar, cells · Surface cells are columnar, cells underneath vary in size and shape

·· Stratified Stratified cuboidalcuboidal and columnarand columnar

· Rare in human body

· Found mainly in ducts of large glands

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Transitional epitheliumTransitional epithelium

·Shape of cells depends upon the amount of upon the amount of stretching

·Lines organs of the urinary system

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· Gland – one or more cells that secretes a particular product

· Two major gland types:

··Exocrine glandExocrine gland

Glandular EpitheliumGlandular Epithelium

··Exocrine glandExocrine gland

·Empty through ducts to the epithelial surface

· Include sweat and oil glands

··Endocrine Endocrine glandgland

·Ductless

·Secretions are hormones

Endocrine gland cell

Blood vessel

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II. Connective TissueII. Connective Tissue

· Found everywhere in the body

· Includes the most abundant and widely distributed tissuesdistributed tissues

· Functions

·Binds body tissues together

·Supports the body

·Provides protection

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Connective TissueConnective Tissue

• Widely spaced cellscells separated by fibersfibers and ground ground

substance (matrix). substance (matrix). [ three components ]

• Most abundant and variable tissue type

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• Functions

– connects organs

– gives support and protection (physical and immune)

– stores energy and produces heat

– movement and transport of materials

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Cells of Connective TissueCells of Connective Tissue

•• FibroblastsFibroblasts produce fibers and ground substance

•• MacrophagesMacrophages phagocytize foreign material and activate immune system– arise from monocytes (WBCs)

•• NeutrophilsNeutrophils wander in search of bacteria

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•• NeutrophilsNeutrophils wander in search of bacteria

•• Plasma cells Plasma cells synthesize antibodies– arise from WBCs

•• Mast cells Mast cells secrete – heparin inhibits clotting

– histamine that dilates blood vessels

•• AdipocytesAdipocytes store fat

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Fibers of Connective TissueFibers of Connective Tissue

A. Collagen A. Collagen fibers fibers (white fibers)

– tough, stretch resistant, yet flexible

– tendons, ligaments and deep layer of the skin

B. Elastic fibers B. Elastic fibers (yellow fibers)

– thin branching fibers of elastin protein

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– thin branching fibers of elastin protein

– stretch and recoil like rubberband (elasticity)

– skin, lungs and arteries stretch and recoil

C. Reticular C. Reticular fibersfibers

– thin, collagen fibers coated with glycoprotein

– framework in spleen and lymph nodes

66Connective Tissue Ground Connective Tissue Ground SubstanceSubstance

M A T R I XM A T R I X• Gelatinous material between cells

– absorbs compressive forces

• Consists of 3 classes of large molecules

1) 1) GlycosaminoglycansGlycosaminoglycans –– chondroitinchondroitin sulfatesulfate

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• disaccharides that attract sodium and hold water

• role in regulating water and electrolyte balance

2) 2) ProteoglycanProteoglycan (bottlebrush-shaped molecule)

• create bonds with cells or extracellular macromolecules

3) 3) Adhesive Adhesive glycoproteinsglycoproteins

• protein-carbohydrate complexes bind cell membrane to collagen outside the cells

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Connective Tissue CharacteristicsConnective Tissue Characteristics

· Variations in blood supply

·Some tissue types are well vascularized

·Some have poor blood supply or are avascular·Some have poor blood supply or are avascular

· Extracellular matrix

·Non-living material that surrounds living cells

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69MAJOR TYPES OF CONNECTIVE TISSUE

Cell

LOOSE CONNECTIVE TISSUE

Collagenfiber

Otherfibers

DENSE CONNECTIVE TISSUE

Cellnucleus

Collagenfibers

Matrix

PROPER AND SPECIALIZED

Fatdroplets

BLOOD

WBC

Plasma

CARTILAGE

BONE

Matrix

Cell

RBC

Matrix

Cell

ADIPOSE TISSUE

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Connective Tissue ProperConnective Tissue Proper

Connective tissue proper has two subclasses:

A.A. Loose connective tissuesLoose connective tissues::

1) Areolar CT

2) Adipose CT

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2) Adipose CT

3) Reticular CT

B.B. Dense connective tissuesDense connective tissues::

1) Dense regular CT

2) Dense irregular CT

3) Elastic CT

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Connective Tissue TypesConnective Tissue Types

·· AreolarAreolar connective connective tissuetissue

·Most widely distributed connective tissueconnective tissue

·Soft, pliable tissue

·Contains all fiber types

·Can soak up excess fluid

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·· Adipose tissueAdipose tissue

·Matrix is an areolar tissue in which fat globules predominate

·Many cells contain large lipid depositslarge lipid deposits

·Functions

· Insulates the body

· Protects some organs

· Serves as a site of fuel storage

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·· Reticular Reticular connective tissueconnective tissue·Delicate network of

interwoven fibers

· Forms stroma· Forms stroma(internal supporting network) of lymphoid organs

· Lymph nodes

·Spleen

·Bone marrow

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·· Dense Dense regular regular connective connective tissuetissue

·Main matrix element is collagen fibers

·Cells are fibroblasts

Slide 3.59Slide 3.59Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

·Cells are fibroblasts

·Examples

· Tendon – attach muscle to bone

· Ligaments – attach bone to bone Figure 3.18d

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Connective Tissue TypesConnective Tissue TypesCARTILAGE· Rubbery matrix. 3 types:

·· Hyaline cartilage:Hyaline cartilage: Most widespread with lots of collagen fibers, glassy, blue-white appearance

· Sites: larynx, costal cartilage,

(a) Hyaline cartilage

· Sites: larynx, costal cartilage, articular cartilage; fetal skeleton.

·· Elastic Cartilage: Elastic Cartilage: found where elasticity is desired; external ear

·· FibrocartilageFibrocartilage: : highly compressible, forms disks between the vertebrae of spinal column

(b) Elastic cartilage

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· BONE (osseous tissue)

·Composed of:

·Bone cells in lacunae (cavities)

·Hard matrix of calcium salts

·Large numbers of collagen fibers

·Used to protect and support the body

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· Blood·Blood cells

surrounded by fluid matrixmatrix

·Fibers are visible during clotting

·Functions as the transport vehicle for materials

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III. Muscle TissueIII. Muscle Tissue

· Function is to produce movement

· Three types

·Skeletal muscle

·Cardiac muscle·Cardiac muscle

·Smooth muscle

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Muscle Tissue TypesMuscle Tissue Types

·· Skeletal muscleSkeletal muscle

·Can be controlled voluntarily

·Cells attach to ·Cells attach to connective tissue

·Cells are striated

·Cells have more than one nucleus

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·· Cardiac muscleCardiac muscle· Found only in the

heart

· Function is to pump blood (involuntary)blood (involuntary)

·Cells attached to other cardiac muscle cells at intercalated disks

·Cells are striated

·One nucleus per cell

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·· Smooth muscleSmooth muscle

· Involuntary muscle

·Surrounds hollow ·Surrounds hollow organs

·Attached to other smooth muscle cells

·No visible striations

·One nucleus per cell

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IV. Nervous TissueIV. Nervous Tissue

· Neurons and nerve support cells

· Function is to send impulses to other impulses to other areas of the body

· Irritability

·Conductivity

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Tissue RepairTissue Repair

·· RegenerationRegeneration

·Replacement of destroyed tissue by the same kind of cells

·· FibrosisFibrosis

·Repair by dense fibrous connective tissue (scar tissue)

· Determination of method

·Type of tissue damaged

·Severity of the injury

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Events in Tissue RepairEvents in Tissue Repair

· Capillaries become very permeable

· Introduce clotting proteins

·Wall off injured area·Wall off injured area

· Formation of granulation tissue

· Regeneration of surface epithelium

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Regeneration of TissuesRegeneration of Tissues

· Tissues that regenerate easily

·Epithelial tissue

· Fibrous connective tissue and bone

· Tissues that regenerate poorly· Tissues that regenerate poorly

·Skeletal muscle

· Tissues that are replaced with scar tissue

·Cardiac muscle

·Nervous tissue within the brain and spinal cord

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Developmental Aspects of TissueDevelopmental Aspects of Tissue

· Epithelial tissue arises from all three primary germ layers

· Muscle and connective tissue arise from the mesodermthe mesoderm

· Nervous tissue arises from the ectoderm

· With old age there is a decrease in mass and viabililty in most tissues

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KEY CONCEPTKEY CONCEPT

• The body is divided into 11 organ systems

• All organ systems work together

àIntegrationàIntegration

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Nervous System

Endocrine System

Muscular System

Skeletal System

IntegumentarySystem

Circulatory System

Lymphatic System

Main organs: Brain, spinal cord, peripheral nerves, sensory organs

Main organs: Pituitary, thyroid, adrenal, pancreas, and other hormone-secreting glands

Main organs: Skeletal, cardiac, and smooth muscle

Main organs: Bones, tendons, ligaments, cartilage

Main organs: Skin, sweat glands, hair, nails

Main organs: Heart, blood vessels, blood

Main organs: Lymph nodes, lymph ducts, spleen, thymus

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Respiratory System

Digestive System

Excretory System

Reproductive System

Main organs: Lungs, diaphragm, trachea, and other airways

Main organs: Pharynx, esophagus, stomach, intestines, liver, pancreas, rectum, anus

Main organs: Kidneys, bladder, ureter, urethra

Main organs: Female : ovaries, oviducts, uterus, vagina, mammary glands Male : testes, sperm ducts, accessory glands, penis

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Anatomy & PhysiologyAnatomy & Physiology

SKINSKINIntegumentaryIntegumentary SystemSystem

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• Integumentary system is the skin and the organs

derived from it (hair, glands, nails).

• One of the largest organs:

IntegumentaryIntegumentary System System

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– 2 square meters.

– Largest sense organ in the body

• The study of the skin is Dermatology.

110Function(s)Function(s)

1. Physical protection

2. Thermoregulation

3. Excretion

4. Synthesis of vitamin D

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4. Synthesis of vitamin D

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Skin is formed of Skin is formed of 22 layers:layers:A – EpidermisEpidermisB – DermisDermis

N.B.N.B. S.C. layer (hypodermis) is S.C. layer (hypodermis) is NOT NOT a part of the skina part of the skin

Structure of SkinStructure of Skin

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112Structure of SkinStructure of Skin22 layers – EpidermisEpidermis and DermisDermis

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Figure 5.1 The Components of the Figure 5.1 The Components of the IntegumentaryIntegumentary SystemSystem

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AnatomyAnatomy

Skin• Epidermis

• Dermis

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NOT NOT a part of the skina part of the skin

• Subcutaneous layer or hypodermis

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116The Epidermis The Epidermis

• Stratified squamous epithelium

–mechanical protection

–Keeps microorganisms outside the body.

• Avascular: depends on diffusion of nutrients and

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• Avascular: depends on diffusion of nutrients and

oxygen from dermis. As a result, superficial cells,

far from the source of nutrients, are dead.

• Epidermal cells are called KeratinocytesKeratinocytes.

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Types of SkinTypes of Skin117

According to number of layers of epidermis, we have

Two Types of skin :

1. Thick skin: → Epidermis: 5 layers.

– only on the palms of the hands and soles of the feet.

2. Thin skin: → Epidermis: 4 layers.

−covers the rest of the body.

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Layers of the Epidermis: Layers of the Epidermis:

In order, from the basal lamina toward the free surface, are:

1. Stratum germinativum

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2. Stratum spinosum

3. Stratum granulosum

4.4. Stratum Stratum lucidumlucidum (only in thick skin)

5. Stratum corneum

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Figure 5 – 4The Structure of the Epidermis. A portion of the epidermis in thick skin, showing the major stratified layers of epidermal cells. Langerhans cells cannot be distinguished in standard histological preparations.

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germinativumgerminativum

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germinativumgerminativum

121EpidermisEpidermis isis fixedfixed toto thethe dermisdermis byby::

1.1. HemidesmosomesHemidesmosomes attach basal cells to basal

lamina.

2.2. EpidermalEpidermal ridgesridges, extend down into the dermis,

3.3. DermalDermal papillaepapillae (singular = papilla) extend up

between the epidermal ridges. This interlocking

arrangement increases the strength of the bond

EpidermisEpidermis isis fixedfixed toto thethe dermisdermis byby::

1.1. HemidesmosomesHemidesmosomes attach basal cells to basal

lamina.

2.2. EpidermalEpidermal ridgesridges, extend down into the dermis,

3.3. DermalDermal papillaepapillae (singular = papilla) extend up

between the epidermal ridges. This interlocking


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between the epidermis and dermis.


between the epidermis and dermis.

Epidermal ridges and dermal papillae are

responsible for the finger prints that are

genitically determined, unique to the

individual, and do not change during

lifetime.

Epidermal ridges and dermal papillae are

responsible for the finger prints that are

genitically determined, unique to the

individual, and do not change during

lifetime.

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Thin Skin and Thick SkinThin Skin and Thick Skin

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(a) The basic organization of the epidermis. The proportions of the

various layers vary with the location sampled.

(b) Thin skin covers most of the exposed body surface.

(c) Thick skin covers the surfaces of the palms and soles.

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• Innermost layer.

• Basal cells are stem cells whose divisions replace

the more superficial keratinocytes that are lost or

shed at the epithelial surface.

11-- Stratum Stratum GerminativumGerminativum

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• skin color results from the synthetic activities of

pigment cells called melanocytes, which are

distributed between cells of the stratum

germinativum.

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MelanocytesMelanocytes

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MelanocytesMelanocytes

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2. Stratum Spinosum2. Stratum Spinosum

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22-- Stratum Spinosum Stratum Spinosum

• 8 to 10 layers of cells. (Figure 5-4).

• Bound together by desmosomes → spiny layer.

• Some cells continue to divide.

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• Contains Langerhans cells, that participate in

the immune response and defense against:

(1) microorganisms … and

(2) skin cancers.

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• High magnification of cells from the stratum spinosum.

• This section shows the

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• This section shows the spines (intercellular bridges).

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DesmosomesDesmosomes

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Melanin pigments

1313. Stratum Granulosum3. Stratum Granulosum

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33-- Stratum GranulosumStratum Granulosum

•• 33--55 layerslayers ofof keratinocyteskeratinocytes.

• The cells stopstop dividingdividing.

• Synthesize large amounts of proteins keratinkeratin and keratohyalinkeratohyalin.

–– KeratinKeratin, is a tough, fibrous protein, constitutes the basic

structural component of hair and nails.

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structural component of hair and nails.

–– KeratohyalinKeratohyalin forms dense granules in the cytoplasm.

• As keratin fibers develop, the cells grow thinner and flatter and their

nuclei and other organelles then disintegrate, and the cells die.

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44-- Stratum Stratum LucidumLucidum

• In the thickthick skinskin of the palms and soles, a glassyglassy stratum lucidum (clear layer)

covers the stratum granulosum (Figure 5-4).

• The cells are flat,flat, denselydensely packed,packed, andand filledfilled withwith keratinkeratin..

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55-- Stratum Stratum CorneumCorneum (cornu = horn)

• Contains 15 to 30 layers15 to 30 layers of keratinized dead cells.

• The dead cells in each layer of the stratum corneum remain tightly

interconnected by desmosomesdesmosomes.

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1. A protectiveprotective barrierbarrier ofof dead,dead, durable,durable, && expendableexpendable cellscells..

2.2. DryDry, so it is unsuitable for the growth of microorganisms.

3. The stratum corneum is waterwater resistantresistant, but notnot waterproof.

Each day 500500 mlml of water from interstitial fluid slowly penetrate

Important Notes about S. Important Notes about S. CorneumCorneum

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the surface, to be evaporated into the surrounding air. The process

is called insensibleinsensible perspirationperspiration , to distinguish it from the

sensiblesensible perspirationperspiration produced by active sweatsweat glands.

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• Layers of the skin

• Layers of the Epidermis

• Layers of the Dermis

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• Layers of the Dermis

137Skin Color Skin Color

TheThe colorcolor ofof thethe skinskin isis aa resultresult ofof::

(1) Epidermal pigmentation (Carotene and Melanin) and

(2) Dermal circulation.

EpidermalEpidermal PigmentationPigmentation::

A.A. CaroteneCarotene:: orange-yellow pigment apparent in light-skinnedindividuals in the stratum corneum, and fatty tissues under dermis.Carotene is found in a variety of orange vegetables, such as carrots.

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Carotene is found in a variety of orange vegetables, such as carrots.

B.B. MelaninMelanin:: brown or black pigment produced by melanocytes.

• The melanin protects from ultraviolet (UV) radiation ofof sunlightsunlight,

which cancan damagedamage DNADNA, causing mutations and cancercancer.

The differences in skin color among individuals and even The differences in skin color among individuals and even

among races do among races do notnot reflect different numbers of melanocytes, reflect different numbers of melanocytes,

but merely different levels of but merely different levels of synthetic activitysynthetic activity..

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Figure 5-5ab

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Melanocytes.

(a) The location and orientation ofmelanocytes in the stratumgerminativum of a dark-skinnedperson.

(b) Comparable micrograph of the skinof a pale-skinned person.

139Dermal Circulation Dermal Circulation

A. The pigmentpigment hemoglobinhemoglobin, in the red blood cells which binds and

transports oxygen in the bloodstream gives the skin a reddishreddish tinttint..

B. In inflammationinflammation blood vessels are dilated so skin looks firy - red.

C. In AnemiaAnemia :: (↓ Hb) → PallorPallor

D.D. CyanosisCyanosis (the skin takes on a bluish coloration):

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D.D. CyanosisCyanosis (the skin takes on a bluish coloration):

When the circulation or gas exchange are slower than normal most of

hemoglobin in blood remains deoxygenated leading to cyanosis as in:

– extreme cold.

– circulatory or respiratory disorders, such as heart failure or severe

asthma.

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141The Epidermis and Vitamin DThe Epidermis and Vitamin D

When exposed to ultraviolet radiation:

1. Skin: epidermal cells convert a cholesterol-related steroid intocholecalciferolcholecalciferol.

2. Liver then converts cholecalciferol into an intermediaryintermediary productproduct..

3. Kidneys use the intermediary product to synthesize the hormonecalcitriolcalcitriol.. (active(active vitvit D)D)..

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calcitriolcalcitriol.. (active(active vitvit D)D)..

• Cholecalciferol can also be absorbed by the digestive tract.

• Calcitriol is essential for the intestinal absorption of calcium andphosphorus.

• Inadequate calcitriol leads to impaired bone maintenance andgrowth.

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The dermis lies between epidermis and subcutaneous layer.

Two layers:

(1)(1) Papillary layerPapillary layer: : (Superficial) areolarareolar tissuetissue that fills the dermal papillae projecting between the epidermal ridges.

T h e D e r m i sT h e D e r m i s

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(2)(2) Reticular layerReticular layer: : (Deep) consists of 2 types of interwoven fibres:

–– Collagen fibersCollagen fibers strong and resist stretching, but are easily bent or twisted.

–– Elastic fibersElastic fibers permit stretching and recoil to original length.

In addition to CT it contains 2 other tissue types: Muscle & Nervous.

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DermisDermis

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144DermisDermis

CT adds collagen and elastic fibers which give

strength and stretch properties.

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DermisDermis

2. Muscle – arrector pili smooth muscle which is attached to shaft of hair follicle.

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The arrector pili muscle originates in the connective tissue sheath ofthe hair follicle and inserts into the papillary layer of the dermis.

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DermisDermis

3. Nervous – detects light touch, stretch, deep pressure,vibration and temperature.

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The Subcutaneous LayerThe Subcutaneous LayerN O T A P A R T O F S K I NN O T A P A R T O F S K I N

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ConsistsConsists ofof areolar and adipose tissues.

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Accessory Structures Accessory Structures

The accessory structures of the integument include:

1.1. hairhair follicles,follicles,

2.2. sebaceoussebaceous glands,glands,

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3.3. sweatsweat glands,glands, andand

4.4. NailsNails..

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• Figure shows the

relationships

between the skin,

hair follicle, arrector

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hair follicle, arrector

pili muscle, and

sebaceous and sweat

glands.

150Nails:Nails:

• Plates of highly packed, keratinized cells.

• Protection, scratching, & manipulation.

• Formed by cells in nail bed called the matrix (in area of lunula).

• Growth = 1 mm / week.

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Hair Follicles and Hair Hair Follicles and Hair HairsHairs areare presentpresent everywhere,everywhere, exceptexcept::

– Palms and soles.

– Lips.

– Nipples.

– Portions of the external genitalia.

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– Portions of the external genitalia.

Hairs are produced in hairhair folliclesfollicles..

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Glands in the Skin Glands in the Skin

Skin contains two types of exocrine glands:

1.1. Sebaceous glands:Sebaceous glands:

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2.2. Sweat glands:Sweat glands:

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Figure 5-11

Sebaceous Glands and Follicles

The structure of sebaceous glands and sebaceous

follicles in the skin

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Sebaceous (Oil) Glands Sebaceous (Oil) Glands

•• DischargeDischarge aa waxy,waxy, oilyoily secretionsecretion calledcalledsebumsebum into hair follicles (Figure 5-11).

•• SebumSebum isis aa mixturemixture ofof triglycerides,cholesterol, proteins, and electrolytes.

•• SebumSebum isis releasedreleased throughthrough holocrineholocrine

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•• SebumSebum isis releasedreleased throughthrough holocrineholocrinesecretionsecretion, a process that involves the rupture ofthe secretory cells.

•• FuntionsFuntions ofof SebumSebum;; inhibits the growth ofbacteria, lubricates and protects the keratin of thehair shaft, and conditions the surrounding skin.

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Sweat GlandsSweat Glands

The skin contains two types of sweat glands:The skin contains two types of sweat glands:

(1) Apocrine sweat glands and

(2) Merocrine sweat glands (Figure 5-12).

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(2) Merocrine sweat glands (Figure 5-12).

These names refer to the mechanism of

secretion, introduced in Chapter 4.

157Mechanisms of Glandular Secretion:

(a) (a) MerocrineMerocrine secretion:secretion: secretory vesicles are discharged at the apical surface of the gland cell by exocytosis.

(b)(b) ApocrineApocrine secretionsecretion:: involves the loss ofapical cytoplasm.

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(c)(c) HolocrineHolocrine secretionsecretion:: occurs as superficialgland cells burst. Continued secretion involvesthe replacement of these cells through themitotic division of underlying stem cells.

apical cytoplasm.

The gland cell then undergoes growth andrepair before it releases additional secretions.

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Figure 5-12ab

Sweat Glands

(a) Apocrine sweat glands, located in the axillae, groin, and nipples, produce a thick, odorous fluid

(b) Merocrine sweat glands produce a watery fluid

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(A) Apocrine Sweat Glands (A) Apocrine Sweat Glands

1.1. Found Found in armpits (axillae), around nipples, and in groin.

2.2.begin secreting at pubertybegin secreting at puberty.

3.3.SecreteSecrete their products into hair follicles.

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3.3.SecreteSecrete their products into hair follicles.

4.4.Produce Produce a sticky, cloudy, and potentially odorous secretion. The sweat produced is a nutrient source for bacteria, which intensify its odor.

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1.1. Smaller,Smaller, moremore numerousnumerous && moremore widelywidelydistributeddistributed than apocrine glands.

2. The palmspalms andand solessoles have the highest numbers.

3.3. DischargeDischarge theirtheir secretionssecretions by ductsducts onto the surfaceof the skin.

(B) Merocrine Sweat Glands (B) Merocrine Sweat Glands

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of the skin.

4. The sweat produced is called sensiblesensible perspirationperspiration.

5.5. SweatSweat isis 99 percent water, & contans electrolytes; esp.sodium chloride (gives sweat a saltysalty tastetaste), a number oforganic nutrients, an antibiotic, and various wasteproducts.

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Functions of Functions of MerocrineMerocrine sweat glands: sweat glands:

1.1. Cooling of Cooling of the skinthe skin to reduce body temperature.

2.2. Excreting water, electrolytes & some drugs.Excreting water, electrolytes & some drugs.

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3.3. Protection:Protection: Sweat dilutes harmful chemicals and

discourages the growth of microorganisms in two ways

through the action of dermicidindermicidin that has powerful

antibiotic properties.

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Prof. Ashraf Kamel, Prof. Ashraf Kamel,

Email: [email protected]@riyadh.edu.sa

Healthcare

Anatomy & physiology for pg dentistry 01