Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Biology of Human Aging Chapter 4 The Integumentary System

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Outline 1.Review of structure and Function Epidermis / Dermis 2. Age-related Changes Epidermal Changes Dermal Changes Hypodermal Changes 3. Age-Related Dysfunctions Lentigo, Senile Purpura, Senile Angioma, Acrochordon, Senile Pruritus, Senile keratosis, Seborrheic Keratosis, Herpes Zoster, Decubitus Ulcers 4. Skin Cancers Basal Cell Carcinoma Squamous Cell Carcinoma Malignant Melanoma Secondary Skin Cancer

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Introduction/Background  Integumentary system comprises the skin, hair, nails & various glands located in the skin.  Age  change in general appearance of skin  wrinkles & sags  Coupled w/ gradual graying of hair  reminder of aging changes  creams & hair dyes  won’t actually delay aging process  Plastic surgery  removes some of the aging changes  still not helpful!  Factors affecting rate and degree of changes in integumentary system:  Intrinsic factors  Heredity  Dietary habits  Levels of various hormones  extrinsic factors  Sun and wind (increase potential for skin cancer)  use of protective sun- shield lotions

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Other factors contributing to aging of skin: 1.Occupation: Extended sun exposure (photoaging) 2.Recreational preference: Boating or sunbathing Exposure to sun is the major cause of aging changes in the skin

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Review of Structure and Function Single most important function: help to maintain a stable internal environment (homeostasis)  normal functioning of various cells  Protective covering  prevents water loss  Partial barrier  blocks the entrance of microorganisms  Pigment cells  protect against UV radiation; (Vitamin D)  Sweat glands and network of blood vessels  regulate temperature Temperature rise: 1.blood vessel dilation  higher volume of blood to surface  heat is lost by radiation from blood to environment 2.Increase in sweat gland activity  skin surface becomes wet  body heat loss by evaporation  Provides information on external environment to nervous system (through receptors sensitive to pain, temperature, touch)

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Process drugs and compounds (smoking patches, seasickness) this function is similar to the function of liver  Part of the immune system (hormone that enhances the growth and development of T cells residing in skin) Review of Structure and Function

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The Integumentary System Skin: major component of the integumentary system, separates body from external environment via an interrupted covering over entire body Consists of three major regions: 1.Epidermis – outermost superficial region 2.Dermis – middle region 3.Hypodermis (superficial fascia) – deepest region (a layer of loose connective tissue; attaches dermis to underlying muscles, also fat deposition provides padding & also fat storage)

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skin (Integument) Figure 5.1

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Epidermis Consists of several layers of thin, flat cells (squamous cells)  form stratified squamous epithelium Under constant pressure or friction thickens  soles of the feet & palms of the hand  calluses and corns No blood vessels or nerve fibers; nutrient and waste  diffusion Inadequate supply (gas & nutrients) to outer cells  dead cells  gradual replacement of cytoplasm with Keratin, Outer-most layer of epidermis composed of thin, dead cells All of the cells of epidermis are replaced every 28 days Skin color: determined by amount & distribution of melanin Dark skinned: contain more melanin Light-skinned people: reddish hue due to blood vessels Oriental people: variation of melanin that causes their epidermis to have yellowish hue

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Cells of the Epidermis 1.Keratinocytes – produce the fibrous protein keratin 2.Melanocytes – produce the brown pigment melanin 3.Langerhans’ cells – epidermal macrophages that help activate the immune system 4.Merkel cells – function as touch receptors in association with sensory nerve endings

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Waterproofing  Protection from abrasion and penetration  Rendering the body relatively insensitive to biological, chemical, and physical assaults Functions

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Dermis Located immediately beneath the epidermis, thicker than epidermis Second major skin region containing strong, flexible connective tissue (collagenous & elastic fibers) Well-supplied with blood vessels, nerves, sweat glands, oil-secreting sebaceous glands Specialized receptors provide information concerning touch, pain, pressure, temperature changes to nervous system Cell types include fibroblasts, macrophages, and occasionally white blood cells Composed of two layers – papillary and reticular

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Dermis: Papillary Layer  Papillary layer  Areolar connective tissue with collagen and elastic fibers  Dermal papillae contain capillary loops, Meissner’s corpuscles, and free nerve endings

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Dermis: Reticular Layer  Reticular layer  Accounts for approximately 80% of the thickness of the skin  Collagen fibers in this layer add strength and resiliency to the skin  Elastin fibers provide stretch-recoil properties

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Hypodermis  Subcutaneous layer deep to the skin  Composed of adipose and areolar connective tissue

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skin Color  Three pigments contribute to skin color  Melanin – yellow to reddish-brown to black pigment, responsible for dark skin colors  Freckles and pigmented moles – result from local accumulations of melanin

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Sweat Glands and Sebaceous Glands Sweat Glands Different types prevent overheating of the body Sebaceous Glands Soften skin when stimulated by hormones Secrete an oily secretion called sebum

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Sebaceous Glands  Simple alveolar glands found all over the body  Soften skin when stimulated by hormones  Secrete an oily secretion called sebum

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Functions of the Integumentary System Protection – chemical, physical, and mechanical barrier Body temperature regulation is accomplished by: 1.Dilation (cooling) and constriction (warming) of dermal vessels 2.Increasing sweat gland secretions to cool the body Cutaneous sensation – exo-receptors sense touch & pain

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Functions of the Integumentary System 1.Metabolic Functions – synthesis of vitamin D in dermal blood vessels 2.Blood Reservoir – skin blood vessels store up to 5% of the body’s blood volume 3.Excretion – limited amounts of nitrogenous wastes are eliminated from the body in sweat

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects of the Integument: Old Age Epidermal replacement of cells slows and skin becomes thinner Skin becomes dry and itchy Subcutaneous fat layer diminishes, leading to intolerance of cold Decreased elasticity and loss of subcutaneous tissue leads to wrinkles Decreased numbers of melanocytes and Langerhans’ cells increase the risk of skin cancer

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Age-related changes Epidermal changes Thinner Permeability of the surface cells increased Larger melanocytes and grouped together; dark pigment plaques (age spots) Decrease in the number of immune cells in skin with aging

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Age-related changes Dermal Changes Number of fibroblast and fibers is reduced Thin and somewhat translucent Elastic fibers become less resilient Slight calcification & formation of cross-links Reduce in numbers and gradual atrophy of sweat & sebaceous gland temp. regulation problem  slow in growth of fingernails General loss of body hair Reduction of pigment in the hair with aging (heredity factors) Changes in dermal sensory receptor (pain, temp, touch, etc)

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Age-related changes Hypodermal changes (subcutaneous tissue) General loss of fat (most obvious in face and limbs) Cause of wrinkles Loss of padding  reduction in blood supply to the skin  pressure sores when bedridden Temperature regulation (older individuals feel chilly most of the time) Modern Maturity Magazine “old age is when, upon getting out of the bathtub, you notice that the full-length mirror is steamed up – and you are glad of it”

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Age-related Dysfunctions Lentigo: after 50, dark-brown irregular areas, increased melanin, no tendency to malignancy Senile Purpura: irregularly shaped purple patches, forearm and back of hands, minimal Senile Angiomas: 75% over 70, elevated clusters of dilated capillaries, red spot, (cutaneous tags), Acrochordon: small pendulous skin growth (cutaneous tags), chest, neck, eyelids (itching) Senile pruritus: loss of water, oil-secreting sebaceous glands, sweat glands, cracks (itching) actinic keratosis) precancerous Senile keratosis: (actinic keratosis) localized red areas of skin, soft-thicken-scaly-yellow brown precancerous Seborrheic keratosis: formation of benign epidermal tumors, no precancerous, face, chest, back Herpes Zoster: viral disease, shingles, same virus that causes small-pox, attacks sensory nerve Decubitus Ulcers: pressure sores cavities of dead tissue form in skin, bedridden or immobilized Skin cancer: malignant vs. benign, metastasize, early detection, melanoma vs. non-melanoma most common Basal cell carcinoma: most common, from cells in deepest or basal layer of epidermis Squamous cell carcinoma: develops from squamous EP, less common than basal, malignant melanins Malignant melanoma: highly malignant, potentially dangerous, usually develops in melanins Secondary skin cancer: originate in other areas of the body