Human AnatomyHuman Anatomy

Integumentary SystemIntegumentary System

Body MembranesBody Membranes

IntroductionIntroduction • Largest organ of the body Largest organ of the body • 21 square feet, 1.5-2 square meters 21 square feet, 1.5-2 square meters • 4 kilograms, 9 pounds, 7% - 15% of total body weight 4 kilograms, 9 pounds, 7% - 15% of total body weight • One square inch contains One square inch contains

– 20 blood vessels 20 blood vessels – 65 hairs and hair muscles 65 hairs and hair muscles – 78 nerves 78 nerves – 78 sensors for heat 78 sensors for heat – 13 sensors for cold 13 sensors for cold – 160 sensors for pressure 160 sensors for pressure – 100 sebaceous/oil glands 100 sebaceous/oil glands – 650 sudoriferous/sweat glands 650 sudoriferous/sweat glands – 1300 nerve endings 1300 nerve endings – 19,500,000 cells 19,500,000 cells – 0.5 million cells dying and being replaced 0.5 million cells dying and being replaced

Classification of Body Membranes Classification of Body Membranes

• Epithelial membranes – composed of Epithelial membranes – composed of epithelial tissue and underlying connective epithelial tissue and underlying connective tissuetissue

• Connective tissue membranes – Connective tissue membranes – composed of various types of connective composed of various types of connective tissue tissue

Classification of Body Membranes Classification of Body Membranes

Cutaneous membrane: The skin

Accounts for approximately 16% of body weight

The largest, most visible organ

Epithelial Membranes (cont’d.)Epithelial Membranes (cont’d.)

• Serous membrane: Two layers: simple squamous epithelium lies on basement membrane Types

Parietal: Lines walls of body cavities Visceral: Covers organs found in body

cavities

• Serous membrane Diseases

Pleurisy: inflammation of the serous membranes that line the chest cavity and cover the lungs

Peritonitis: inflammation of the serous membranes that line the walls of the abdominal cavity and cover the abdominal organs

Epithelial Membranes (cont’d.)Epithelial Membranes (cont’d.)

Epithelial Membranes (cont’d.)Epithelial Membranes (cont’d.)

• Mucous membranes Line body surfaces that open directly to

the exterior Produce mucus, a thick secretion that

keeps the membranes soft and moist

Connective Tissue Connective Tissue

• No epithelial componentsNo epithelial components

• Produce a lubricant called synovial fluidProduce a lubricant called synovial fluid– Synovial membranes between joints Synovial membranes between joints – Lining of the bursal sacsLining of the bursal sacs

FunctionFunction

• ProtectionProtection: barrier against microbes, dirt, chemicals; : barrier against microbes, dirt, chemicals; shock bsorber shock bsorber

• Water balanceWater balance: prevents loss of water and absorption : prevents loss of water and absorption

• Temperature regulationTemperature regulation: blood vessels near surface : blood vessels near surface vasoconstriction / vasodilation vasoconstriction / vasodilation

• Waste disposalWaste disposal: excretion of oil, water, Na+, CO2, etc. : excretion of oil, water, Na+, CO2, etc.

• Receptor organsReceptor organs: sensations of touch, pain, heat, : sensations of touch, pain, heat, cold, pressure cold, pressure

• Vitamin DVitamin D production production

• Epidermis Epidermis

• DermisDermis

• Subcutaneous (hypodermis) Subcutaneous (hypodermis)

Layers of the SkinLayers of the Skin

EpidermisEpidermis

• Outermost layer of skinOutermost layer of skin• Composed of 5 layers Composed of 5 layers • Avascular – no blood Avascular – no blood

supplysupply• Complete regeneration inComplete regeneration in

approximately 35 daysapproximately 35 days• Some regions are thicker Some regions are thicker

than others (thinner on than others (thinner on

scalp scalp andand armpit than on armpit than on

sole of foot) sole of foot)

DermisDermis • Called ‘corium’ or the true skinCalled ‘corium’ or the true skin• Framework of elastic connective tissue and Framework of elastic connective tissue and

blood vessels blood vessels • Contains Contains

• Blood vessels and capillaries Blood vessels and capillaries • Lymphatic vessels Lymphatic vessels • Nerves Nerves • Involuntary musclesInvoluntary muscles• Sweat and oil glandsSweat and oil glands• Hair shafts and hair follicles Hair shafts and hair follicles • Sensory receptors Sensory receptors

Subcutaneous – HypodermisSubcutaneous – Hypodermis

• Innermost layerInnermost layer• Composed of:Composed of:

– elastic and fibrous connective tissueelastic and fibrous connective tissue– Adipose (fatty) tissueAdipose (fatty) tissue

• Connects skin to underlying musclesConnects skin to underlying muscles

Microscopic View of the SkinMicroscopic View of the Skin

Accessory Organs of the SkinAccessory Organs of the Skin

• Hair Hair growth requires an epidermal tubelike

structure called a hair follicle Hair growth begins from hair papillae

located at the base of the follicle Hair root lies hidden in the follicle The visible part of the hair is called the shaft

Accessory Organs of the Skin (cont’d.)Accessory Organs of the Skin (cont’d.)

Hair Follicle

Accessory Organs of the Skin (cont’d.)Accessory Organs of the Skin (cont’d.)

• Receptors Specialized nerve endings that make it

possible for skin to act as a sense organ Relays messages to the brain of touch,

pain, temperature, and pressure

Skin Receptors

Accessory Organs of the Skin (cont’d.)Accessory Organs of the Skin (cont’d.)

• Nails Produced by epidermal cells over terminal

ends of fingers and toes Visible part is called nail body Root lies in a groove and is hidden by the

cuticle Crescent-shaped area nearest root is called

lunula Nail bed may change color with change in

blood flow

Accessory Organs of the Skin (cont’d.)Accessory Organs of the Skin (cont’d.)

Structure of Nails

Accessory Organs of the Skin (cont’d.)Accessory Organs of the Skin (cont’d.)

• Skin glands Sweat (sudoriferous) glands

Eccrineo Most numerous, important, and

widespread of the sweat glandso Produce perspiration (sweat), which

flows out through pores on skin surfaceo Function throughout life and assist in

body heat regulation

Accessory Organs of the Skin (cont’d.)Accessory Organs of the Skin (cont’d.)

• Skin glands Sweat (sudoriferous) glands

Apocrineo Found primarily in axilla (armpit) and

around genitaliao Larger than eccrine glandso Secrete a thicker secretion quite

different from eccrine perspiration

Accessory Organs of the Skin (cont’d.)Accessory Organs of the Skin (cont’d.)

• Skin glands Sebaceous glands

Secrete oil, or sebum, for hair and skin Level of secretion increases during

adolescence Amount of secretion is regulated by sex

hormones Sebum in sebaceous gland ducts may

darken to form a blackhead

Accessory Organs of the Skin (cont’d.)Accessory Organs of the Skin (cont’d.)

Functions of the SkinFunctions of the Skin

• Protection First line of defense against

Infection by microbes Ultraviolet rays from the sun Harmful chemicals Cuts and tears

Functions of the Skin (cont’d.)Functions of the Skin (cont’d.)

• Temperature regulation The skin can release almost 3,000

calories of body heat per day Mechanisms of temperature regulation

o Regulation of sweat secretiono Regulation of flow of blood close to

the body surface

Functions of the Skin (cont’d.)Functions of the Skin (cont’d.)

• Sense organ activity Skin functions as an enormous sense organ Receptors serve as receivers for the body,

keeping it informed of changes in its environment Meissner’s corpuscles detect light touch Pacinian corpuscles detect pressure Other receptors detect pain, heat, and

cold

Skin ColorSkin ColorMelanin Melanin • Only pigment made in the skin Only pigment made in the skin • Yellow to reddish-brown to black Yellow to reddish-brown to black • Racial differences due to kind and amount of melanin made Racial differences due to kind and amount of melanin made • Local accumulations .. freckles and pigmented moles Local accumulations .. freckles and pigmented moles • Exposure to sunlight increase manufacture of melanin .. Exposure to sunlight increase manufacture of melanin ..

protects DNA from UV damage and results in a tanprotects DNA from UV damage and results in a tan

Carotene Carotene • Yellow to orange Yellow to orange • Accumulates in the stratum corneum and fatty tissue of Accumulates in the stratum corneum and fatty tissue of

hypodermis hypodermis • Color obvious in palms and solesColor obvious in palms and soles

Skin CancerSkin Cancer

• Squamous CellSquamous Cell

• Basel CellBasel Cell

• Malignant MelanomaMalignant Melanoma

• Kaposi SarcomaKaposi Sarcoma

Causes of Skin CancerCauses of Skin Cancer

• Genetic predispositionGenetic predisposition

• Sun’s ultraviolet rays - causes mistakes in Sun’s ultraviolet rays - causes mistakes in mitosismitosis– More prone to blondes, red headsMore prone to blondes, red heads

• Most common skin cancer is squamous Most common skin cancer is squamous cellcell

BurnsBurns

• Burns are one of the most serious and frequent problems affecting the skin

• Treatment and recovery or survival depend on total area involved and severity or depth of burn

• Body surface area is estimated using the “rule of nines” in adults Body is divided into 11 areas of 9% each

Burns (cont’d.)Burns (cont’d.)

The Rule of Nines

Burns (cont’d.)Burns (cont’d.)

• Classification of burns First-degree (partial-thickness) burns: Only

the surface layers of epidermis are involved Second-degree (partial-thickness) burns:

Involve the deep epidermal layers Third-degree (full-thickness) burns:

Characterized by complete destruction of the epidermis and dermis