Lecture Human anatomy and physiology - Chapter 5: The integumentary system

Would you be enticed by an ad for a coat that is waterproof, stretchable, washable, and permanent-press, that automatically repairs small cuts, rips, and burns? How about one that’s guaranteed to last a lifetime? Sounds too good to be true, but you already have such a coat-your skin. The skin and its derivatives (sweat and oil glands, hairs, and nails) make up a complex set of organs that serves several functions, mostly protective. Together, these organs form the integumentary system.

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PowerPoint ® Lecture Slides

prepared by Janice Meeking, Mount Royal College

C H A P T E R

5

The Integumentary System

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technically part of skin)

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• Hair follicle receptor

(root hair plexus)

Cutaneous vascular plexus

Adipose tissue

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that help activate immune system Tactile (Merkel) cells—touch receptors

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Dermis

Stratum corneum

Most superficial layer; 20–30 layers of dead cells represented only by flat membranous sacs filled with keratin Glycolipids in

extracellular space.

Stratum granulosum

Three to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated granules (release lipids) and keratohyaline granules.

Stratum spinosum

Several layers of keratinocytes unified by desmosomes Cells contain thick bundles of intermediate filaments made of pre-keratin.

Stratum basale

Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers.

See occasional melanocytes and epidermal dendritic cells.

(a)

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Layers of the Epidermis: Stratum Basale

(Basal Layer)

• Deepest epidermal layer firmly attached to the dermis

• Single row of stem cells

• Also called stratum germinativum: cells

undergo rapid division

• Journey from basal layer to surface

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Layers of the Epidermis: Stratum Spinosum (Prickly Layer)

• Cells contain a weblike system of

intermediate prekeratin filaments attached to desmosomes

• Abundant melanin granules and dendritic cells

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Layers of the Epidermis: Stratum

Granulosum (Granular Layer)

• Thin; three to five cell layers in which the cells flatten

• Keratohyaline and lamellated granules

accumulate

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Layers of the Epidermis: Stratum Lucidum (Clear Layer)

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Layers of the Epidermis: Stratum Corneum (Horny Layer)

• 20–30 rows of dead, flat, keratinized

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Melanocyte

Melanin granule

Tactile (Merkel) cell

Sensory nerve ending Epidermal

dendritic cell Dermis

Keratinocytes

Stratum corneum

Most superficial layer; 20–30 layers of dead

cells represented only by flat membranous

sacs filled with keratin Glycolipids in

extracellular space.

Stratum granulosum

Three to five layers of flattened cells,

organelles deteriorating; cytoplasm full of

lamellated granules (release lipids) and

keratohyaline granules.

Stratum spinosum

Several layers of keratinocytes unified by

desmosomes Cells contain thick bundles of

intermediate filaments made of pre-keratin.

Stratum basale

Deepest epidermal layer; one row of actively

mitotic stem cells; some newly formed cells

become part of the more superficial layers See

occasional melanocytes and epidermal

dendritic cells Desmosomes

(b)

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• Strong, flexible connective tissue

• Cells include fibroblasts, macrophages, and occasionally mast cells and white blood cells

• Two layers:

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• Hair follicle receptor

(root hair plexus)

Cutaneous vascular plexus

Adipose tissue

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Layers of the Dermis: Papillary Layer

• Papillary layer

elastic fibers and blood vessels

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Layers of the Dermis: Reticular Layer

• Reticular layer

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Skin Markings: Friction Ridges

• Epidermal ridges lie atop deeper dermal papillary ridges to form friction ridges of fingerprints

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Skin Markings: Cleavage Lines

• Collagen fibers arranged in bundles form

cleavage (tension) lines

• Incisions made parallel to cleavage lines heal more readily

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(b)

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Skin Color

• Three pigments contribute to skin color:

responsible for dark skin colors

keratinocytes where it forms “pigment shields” for nuclei

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Skin Color

palms and soles

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Appendages of the Skin

• Derivatives of the epidermis

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Sweat Glands

• Two main types of sweat (sudoriferous)

glands

on palms, soles, and forehead

antibodies, dermcidin, metabolic wastes

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(b) Photomicrograph of a

Secretory cells

Dermal connective tissue

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Sweat Glands

anogenital areas

glands?)

secrete cerumen

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Sebaceous (Oil) Glands

• Widely distributed

• Most develop from hair follicles

• Become active at puberty

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(a) Photomicrograph of a sectioned sebaceous gland (220x)

Sebaceous gland duct Hair in

hair follicle Secretory cells

Dermal

connective

tissue

Sebaceous gland

Sweat pore

Eccrine gland

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Hair

• Functions

skin

heat loss, and sunlight

• Distribution

nipples, and portions of external genitalia

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Hair

• Consists of dead keratinized cells

• Contains hard keratin; more durable than soft keratin of skin

• Hair pigments: melanins (yellow, rust brown, black)

production, increased air bubbles in shaft

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(a) Diagram of a cross section of

a hair within its follicle

• Connective tissue root sheath

• Glassy membrane

• External epithelial root sheath

• Internal epithelial root sheath

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(b) Photomicrograph of a cross section of a hair and hair follicle (250x)

• Connective tissue root sheath

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Hair Follicle

• Hair follicle receptor (root hair plexus)

• Arrector pili

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• Internal epithelial root sheath

• Connective tissue root sheathFollicle wall

Hair matrix Melanocyte Hair papilla

Subcutaneous adipose tissue

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(d) Photomicrograph of longitudinal view

of the hair bulb in the follicle (160x)

Sebaceous gland

Hair root Hair bulb

Figure 5.6d

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Types of Hair

• Hair Growth

regressive stage and resting phase (1–3 months)

months in eyebrows)

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Hair Thinning and Baldness

• Alopecia—hair thinning in both sexes after age 40

• True (frank) baldness

condition

response to DHT

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Structure of a Nail

• Scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes

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Lateral nail fold

Lunule

Nail matrix Root of nail

Proximal nail fold Nail bed

Eponychium (cuticle)

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Functions of the Integumentary System

1 Protection—three types of barriers

defensins retard bacterial activity

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water- soluble substances

substances, plant oleoresins (e.g., poison ivy), organic solvents, salts of heavy metals, some drugs

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2 Body temperature regulation

(at normal body temperature)

vessels and increased sweat gland activity (sensible perspirations) cool the body

3 Cutaneous sensations

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• Some skin lotions contain enzymes in liposomes that can fix damaged DNA

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Skin Cancer

• Three major types:

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Basal Cell Carcinoma

• Stratum basale cells proliferate and slowly invade dermis and hypodermis

• Cured by surgical excision in 99% of cases

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Squamous Cell Carcinoma

• Involves keratinocytes of stratum spinosum

• Most common on scalp, ears, lower lip, and hands

• Good prognosis if treated by radiation therapy

or removed surgically

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• Characteristics (ABCD rule)

A: Asymmetry; the two sides of the pigmented

area do not match B: Border exhibits indentations

C: Color is black, brown, tan, and sometimes red

or blueD: Diameter is larger than 6 mm (size of a pencil

eraser)

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• Heat, electricity, radiation, certain chemicals

Burn (tissue damage, denatured protein, cell death)

• Immediate threat:

to renal shutdown and circulatory shock

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Rule of Nines

• Used to estimate the volume of fluid loss from burns

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Anterior and posterior head and neck, 9%

9% 9%

(Perineum, 1%)

4 1/2%

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Partial-Thickness Burns

• First degree

pain

• Second degree

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(a) Skin bearing partial

thickness burn (1st and 2nd degree burns)

1st degree burn

2nd degree burn

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Full-Thickness Burns

• Third degree

destroyed)

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(b) Skin bearing full

thickness burn (3rd degree burn)

3rd degree burn

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Severity of Burns

• Critical if:

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Developmental Aspects: Fetal

• Ectoderm epidermis

• Mesoderm dermis and hypodermis

• Lanugo coat: covering of delicate hairs in 5th and 6th month

• Vernix caseosa: sebaceous gland secretion; protects skin of fetus

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Developmental Aspects: Adolescent to

Adult

• Sebaceous gland activity increases

• Effects of cumulative environmental assaults show after age 30

• Scaling and dermatitis become more common

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Developmental Aspects: Old Age

• Epidermal replacement slows, skin becomes thin, dry, and itchy

• Subcutaneous fat and elasticity decrease,

leading to cold intolerance and wrinkles

• Increased risk of cancer due to decreased numbers of melanocytes and dendritic cells

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Skin-Burns: Study Guide

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Skin-Healing of Wounds: Study Guide

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