dr. b ch 04_lecture_presentation

© 2012 Pearson Education, Inc.

4The Integumentary System

PowerPoint® Lecture Presentations prepared bySteven BassettSoutheast Community College Lincoln, Nebraska


Introduction

• The integumentary system is composed of:• Skin• Hair• Nails• Sweat glands• Oil glands• Mammary glands


Introduction

• The skin is the most visible organ of the body

• Clinicians can tell a lot about the overall health of the body by examining the skin

• Skin is capable of repair even after serious damage because of containing stem cells persist both in epidermis and dermis.


Integumentary Structure and Function

• Cutaneous membrane• Epidermis• Dermis

• Accessory structures• Hair follicles• Exocrine glands• Nails


Figure 4.1 Functional Organization of the Integumentary System

IntegumentarySystem

CutaneousMembrane

AccessoryStructures

Epidermis

Dermis

Hair Follicles

Exocrine Glands

Nails

• Physical protection from environmental hazards

• Synthesis and storage of lipid reserves

• Coordination of immune response to pathogens and cancers in skin

• Thermoregulation

• Excretion

• Synthesis of vitamin D3

• Sensory information

• Protects dermis from trauma,chemicals

• Controls skin permeability, prevents water loss

• Prevents entry of pathogens

• Synthesizes vitamin D3

• Sensory receptors detect touch, pressure, pain, and temperature

• Coordinates immune response to pathogens and skin cancers

• Nourishes and supports epidermis

• Restricts spread of pathogens penetrating epidermis

Papillary Layer Reticular Layer

• Stores lipid reserves

• Attaches skin to deeper tissues

• Sensory receptors detect touch, pressure, pain, vibration, and temperature

• Blood vessels assist in thermoregulation

• Produce hairs that protect skull

• Produce hairs that provide delicate touch sensations on general body surface

• Assist in thermoregulation

• Excrete wastes

• Lubricate epidermis

• Protect and support tips of fingers and toes


Figure 4.1 Functional Organization of the Integumentary System (Part 1 of 2)

CutaneousMembrane

Epidermis

Dermis

• Protects dermis from trauma,chemicals

• Controls skin permeability, prevents water loss

• Prevents entry of pathogens

• Synthesizes vitamin D3

• Sensory receptors detect touch, pressure, pain, and temperature

• Coordinates immune response to pathogens and skin cancers

• Nourishes and supports epidermis

• Restricts spread of pathogens penetrating epidermis

Papillary Layer Reticular Layer

• Stores lipid reserves

• Attaches skin to deeper tissues

• Sensory receptors detect touch, pressure, paid, vibration, and temperature

• Blood vessels assist in thermoregulation


Figure 4.1 Functional Organization of the Integumentary System (Part 2 of 2)

AccessoryStructures

Hair Follicles

Exocrine Glands

Nails

• Produce hairs that protect skull

• Produce hairs that provide delicate touch sensations on general body surface


• Excrete wastes


• Protect and support tips of fingers and toes



• Functions include:• Physical protection• Regulation of body temperature• Excretion of products (secretion)• Synthesis of products (nutrition)• Sensation• Immune defense



• Skin (cutaneous membrane) is made of two divisions

• Epidermis• Dermis

• Hypodermis (subcutaneous layer) is deep to the dermis. This layer separates the skin from deep fasciae

• Accessory structures• Hair, nails, exocrine glands


Figure 4.2 Components of the Integumentary System

Cutaneous MembraneAccessory Structures

Dermis

Papillary layer

Epidermis

Reticular layer

Subcutaneous layer(hypodermis)

Hair shaft

Pore of sweatgland duct

Tactile corpuscle

Sebaceous gland

Arrector pili muscle

Sweat gland duct

Hair follicle

Lamellated corpuscle

Nerve fibers

Sweat gland

Fat

Artery

VeinCutaneousplexus


The Epidermis

• There are four cell types found in the epidermis• Keratinocytes

• Produces a tough protein called keratin• the most abundant cells in the epidermis.

• Melanocytes• Pigment cells located deep in the epidermis• Produce melanin (skin color)

• Merkel cells• Sensory cells• They send their free nerve endings into the epidermis, which are

very sensitive to gentle touch.

• Langerhans cells• Fixed macrophages


The Epidermis

• Layers of the Epidermis• Stratum basale (stratum germinativum)

• Deepest layer

• Stratum spinosum• Stratum granulosum• Stratum lucidum• Stratum corneum

• Most superficial layer


Surface

Stratum corneum

Stratum lucidumStratum granulosumStratum spinosum

Stratum basaleBasal lamina

Dermis

Epidermis of thick skin LM × 225

Figure 4.3 The Structure of the Epidermis


Table 4.1 Epidermal Layers


The Epidermis

• Epidermal ridges• Stratum germinativum forms epidermal

ridges• Ridges (dermal papillae) extend into the

dermis• Creates ridges we call fingerprints


Figure 4.4ab Thin and Thick Skin

Epidermis

Epidermalridge

Dermalpapilla

Dermis

Stratumcorneum

Basallamina

Dermis

Thin skin covers most ofthe exposed body surface.(During sectioning thestratum corneum haspulled away from the restof the epidermis.)

The basic organization of theepidermis. The thickness of theepidermis, especially the thicknessof the stratum corneum, changesradically depending on thelocation sampled.

LM × 240


Figure 4.5 The Epidermal Ridges of Thick Skin

Pores of sweatgland ducts

Epidermal ridge

SEM × 25


The Epidermis

• Skin color• Due to:

• Dermal blood supply• Thickness of stratum corneum• Various concentrations of carotene and melanin


Figure 4.6 Melanocytes

Thin skin LM × 600

Melanocytesin stratumbasale

Melaninpigment

Basal lamina

Melanosome

Keratinocyte

Melaninpigment

Melanocyte

Basallamina

Melanocytes produce and store melanin.

This micrograph indicates thelocation and orientation ofmelanocytes in the stratumbasale of a dark-skinned person.


The Dermis

• The dermis consists of two layers• Papillary layer

• Superficial dermis

• Reticular layer• Deep dermis


The Dermis

• Papillary layer (details)• Consists of:

• Dermal papillae• Capillaries• Nerve axons


The Dermis

• Reticular layer (details)• Consists of:

• Interwoven network of dense irregular connective tissue

• Hair follicles• Sweat glands• Sebaceous glands


Figure 4.2 Components of the Integumentary System

Cutaneous MembraneAccessory Structures

Dermis

Papillary layer

Epidermis

Reticular layer

Subcutaneous layer(hypodermis)

Hair shaft

Pore of sweatgland duct

Tactile corpuscle

Sebaceous gland


Sweat gland duct

Hair follicle

Lamellated corpuscle

Nerve fibers

Sweat gland

Fat

Artery

VeinCutaneousplexus


Figure 4.7a The Structure of the Dermis and the Subcutaneous Layer

Dermal papillae

Papillary layer

Reticular layer

Cutaneous plexus

Adipocytes

Papillaryplexus

Epidermalridges

Papillary layer of dermis SEM × 649

The papillary layer of the dermis consistsof loose connective tissue that containsnumerous blood vessels (not visible),fibers (Fi), and macrophages (not visible).Open spaces, such as those marked byasterisks, would be filled with fluidground substance

Fi


Figure 4.7b The Structure of the Dermis and the Subcutaneous Layer

Dermal papillae

Papillary layer

Reticular layer

Cutaneous plexus

Adipocytes

Papillaryplexus

Epidermalridges

SEM × 1340Reticular layer of dermis

The reticular layer of the dermis containsdense, irregular connective tissue.


Accessory Structures

• Hair• Made of keratin 98% of the 5 million hairs on the body are not

on the head. The fine hairs grown on the fetus body is

called Lanugo.

• Hair follicles Hair follicles are the organs that form the

hairs.


Figure 4.9a Accessory Structures of the Skin

A diagrammatic view of asingle hair follicle

Hair papilla

Hair bulb

Connectivetissuesheath

Arrectorpili muscle

Sebaceousgland

Hair shaft

Boundarybetween hair

shaft andhair root

Hairroot

Exposed shaftof hair


Figure 4.9b Accessory Structures of the Skin

A light micrograph showing the sectional appearanceof the skin of the scalp. Note the abundance of hairfollicles and the way they extend into the dermis.

Subcutaneousadipose tissue

Epidermis

Dermis

MedullaPapilla

Scalp, sectional view LM × 66

Hair bulb

Cortex

Connective tissue sheathof hair follicle

External root sheath

Glassy membrane

Hair

Hair follicle, cross section

Hair shaft

Sebaceous gland




• Glands in the skin

• Eccrine glands or Merocrine glands:• The most abundant and widely distributed

sweat glands that regulate body temperature.

• Sebaceous glands:• Often associated with hair follicles. This is

true also with Apocrine sweat glands that connect to the hair follicle to access to the surface of the skin.


Figure 4.12 A Classification of Exocrine Glands in the Skin

Exocrine Glands

Sebaceous Glands Sweat Glands

Typical Sebaceous Glands Sebaceous Follicles Apocrine Sweat Glands Merocrine Sweat Glands

Ceruminous Glands Mammary Glands


• Excrete wastes


• Secrete oily lipid (sebum) that coats hair shaft and epidermis

• Provide lubrication and antibacterial action

types

consist of

Secrete into hair follicles Secrete onto skin surface

• Produce watery solution by merocrine secretion

• Flush epidermal surface

• Perform other special functions

types

• Limited distribution (axillae, groin, nipples)

• Produce a viscous secretion of complex composition

• Possible function in communication

• Strongly influenced by hormones

• Widespread• Produce thin secretions, mostly water

• Merocrine secretion mechanism

• Controlled primarily by nervous system

• Important in thermoregulation and excretion

• Some antibacterial action

special apocrine glands

Secrete waxy cerumeninto external ear canal

Apocrine glandsspecialized for milkproduction


Figure 4.13 Sebaceous Glands and Follicles

Epidermis

Dermis

Subcutaneouslayer

Sebaceousfollicle

Sebaceousgland

Lumen (hairremoved)

Wall ofhair follicle

Basal lamina

Discharge ofsebum

Lumen

Breakdown ofcell walls

Mitosis andgrowth

GerminativecellsSebaceous gland LM × 150



• Sweat glands• Mammary glands

• A special type of apocrine gland• Produce milk under the control of hormones from

the pituitary gland

• Ceruminous glands• A special type of apocrine gland• Found only in the ear canal• Produce cerumen (ear wax)• Provide minimal protection associated with the ear


Figure 4.15c Structure of a Nail

Phalanx

Proximal nail fold

Nail root LunulaNailbody Hyponychium

DermisEpidermis

Longitudinal section

Eponychium


Aging and the Integumentary System

• Epidermis becomes thinner• Dermis becomes thinner• Number of Langerhans’ cells decreases• Vitamin D production declines• Melanocyte activity declines• Glandular activity declines• Hair follicles stop functioning• Skin repair slows down Mechanical stress can trigger stem cell divisions resulting in calluses. Regeneration occurs after damage. The inability to completely heal after severe damage may result in acellular

scar tissue.


Figure 4.16 The Skin during the Aging Process

Fewer Melanocytes Fewer ActiveFollicles

Thinner, sparsehairs

• Pale skin• Reduced tolerance for sun exposure

Skin repairs proceedmore slowly.

Reduced Skin Repair Decreased Immunity

Thin Epidermis

Reduced SweatGland Activity

The number of dendritic cellsdecreases to about 50 percent of levelsseen at maturity (roughly age 21).

• Decreased vitamin D production• Reduced number of Langerhans cells

• Slow repairs

Tendency tooverheat

Thin DermisReduced Blood SupplyDry EpidermisChanges in Distribution ofFat and HairDue to reductions insex hormone levels

Reduction insebaceous andsweat gland activity

• Slow healing• Reduced ability to lose heat

Sagging andwrinkling due tofiber loss

dr. b ch 04_lecture_presentation

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