Integumentary- System

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Integumentary System : 

Integumentary System Covering the Body

Overview : 

Overview Integument refers to the skin that covers the body also called the cutaneous membrane or cutaneous layer Dermatology: Study of and treatment of the integumentary system

Components of the Integumentary System : 

Components of the Integumentary System Integument or skin Derivatives of the skin Nails Hair sweat glands sebaceous glands

Integument : 

Integument Skin

Tissues of the Integument : 

Tissues of the Integument epithelium- outer layer connective tissue- blood, CT proper smooth muscle- to control hair position and vessel diameter nervous tissue- sensation of touch, pain, temperature

Regions of the Integument : 

Regions of the Integument epidermis: upper region consisting of stratified squamous epithelium  dermis: lower region consisting of dense irregular connective tissue hypodermis (also called the subcutaneous layer) consist of areolar and adipose CT not considered part of the integument

Functions of the Integument : 

Functions of the Integument Protection from physical trauma selectively permeable- nicotine patch protection from UV rays which leads to tanning

Functions of the Integument : 

Functions of the Integument Prevention of water loss integument is water resistant but not waterproof TEWL: some interstitial fluid escapes to surface and then evaporates in a process called transepidermal water loss  Insensible perspiration- release of water vapor from sweat glands when we are not sweating

Functions of the Integument : 

Functions of the Integument Temperature regulation Vasoconstriction to prevent heat loss especially when it is cold Vasodilation to release heat on a hot day (skin become flush) Metabolic regulation Makes vitamin D3 in response to UV radiation Vitamin D3 regulates calcium and phosphate levels in the blood

Functions of the Integument : 

Functions of the Integument Immune challenge Contains Langherhan cells to trigger immune response  Sensory reception nerve endings for temperature, touch , texture, vibration sensation  Excretion by secretion Water, salts and urea secreted in sweat Secretes sebum to lubricate skin surface and hair

Epidermis : 

Epidermis

Epidermis : 

Epidermis Uppermost region of the integument Consist of 5 strata of epithelial cells: germinativum, spinosum, granulosum, lucidum, corneum

Stratum basale or germinativum : 

Stratum basale or germinativum Deepest layer Single layer of cuboidal to columnar cells Attached to the basement membrane

Stratum basale or germinativum : 

Stratum basale or germinativum Cells of the stratum basale  keratinocytes found in all strata keratinocyte stem cells reside in this layer make keratin tactile cells (Merkel cells) -scattered in the basale -sense touch

Stratum basale or germinativum : 

Stratum basale or germinativum Cells of the stratum basale Melanocytes scattered among keratinocytes of the basale layer makes melanin and transfers it to keratinocytes melanin accumulates in keratinocytes to protect nucleus from UV damage helps in skin color

Stratum spinosum : 

Stratum spinosum superficial to stratum basale Has spiny appearance in slide preparations several layers of keratinocytes attached together by desmosomes dendritic or langherhans cells are present here to fight infections and cancer cells

Stratum granulosum : 

Stratum granulosum superficial to stratum spinosum 3 to 5 layers of keratinocytes  keratinization begins here

Stratum lucidum : 

Stratum lucidum Superficial to granulosum Clear layer or thin translucent layer 2-3 cell layers thick found only in thick skin (soles and palms)

Stratum corneum : 

Stratum corneum most superficial layer Horny or hornlike layer this layer is visible consist of 20 -30 layers of dead, scaly, interlocking keratinized cells called corneocytes

Keratinization : 

Keratinization cells are filled with keratin cells nucleus and organelles disintegrate and cell begins to die what remains is keratin interlocked by phospholipid layer completed at upper layers where cells are dead but strong due to keratin

Life Span of Keratinocytes : 

Life Span of Keratinocytes first 2 weeks: migrate from stratum basale to stratum germinativum next 2 weeks: remain for 2 weeks in the stratum corneum before being shed or removed by abrasion

Thick Skin : 

Thick Skin has 5 strata including the stratum lucidum contains sweat glands but no hair follicles or sebaceous glands located in palms and soles

Thin Skin : 

Thin Skin covers most of the body has 4 strata contain hair follicles, sebaceous glands, sweat glands

Skin Color : 

Skin Color Hemoglobin component of red blood cells become red-colored when bound to oxygen dermal blood vessels have reddish tint that is observable through lightly pigmented epidermis in lighter complexioned individuals.

Skin Color : 

Skin Color Melanin produced by melanocytes transferred to keratinocytes in stratum basale which colors the entire epidermis shades of yellow, reddish tan, brown, black

Skin color : 

Skin color Melanocyte activity: everyone may have the same amount of melanocytes but may have different activity levels of melanocytes may have different shades of melanin granules darker skinned individuals have more active melanocytes UV exposure darkens melanin that is already present and triggers production of more--process of tanning

Fig. 5.5 : 

Fig. 5.5

Skin color : 

Skin color Carotene yellow orange pigment acquired through diet of carrots, corn, squash accumulates in keratinocytes of stratum corneum and within hypodermal fat

Skin Markings : 

Skin Markings nevus ( a mole) localized overgrowth of melanocytes freckles: localized areas of excessive melanocyte activity

Skin Markings : 

Skin Markings hemangioma: skin discoloration due to blood vessels that overgrow to form benign tumors

Skin Markings : 

Skin Markings friction ridges found of fingers, palms, soles and toes folds of dermis and epidermis Form our fingerprints increase friction or grip

Dermis : 

Dermis Connective tissue of the skin

Dermis : 

Dermis lower layer of integument lies deep to epidermis thicker layer of the integument Regions of the dermis Papillary layer Reticular layer

Papillary Layer : 

Papillary Layer superficial region of dermis adjacent to epidermis consist of areolar CT

Papillary Layer : 

Papillary Layer dermal papillae projection of dermis towards epidermis interlock with inferior projection of epidermis called epidermal ridges house sensory receptors and blood vessels

Reticular Layer : 

Reticular Layer deep portion of dermis extends to hypodermis made up of dense irregular CT structures include hair follicles Sebaceous and sweat glands nerves blood vessels

Features of the Dermis : 

Features of the Dermis Fibers Collagen fibers for strength elastic fibers for stretch and recoil stretch marks (striae) caused by excessive stretching of skin that tears the collagen fibers Wrinkles flexibility and thickness of skin is lessened which leads to sagging of skin

Features of the Dermis : 

Features of the Dermis Tension lines (lines of cleavage) parallel orientation of collagen and elastic fibers throughout the skin surgical incision are made parallel to line to promote healing

Features of the Dermis : 

Features of the Dermis Extensive innervation to monitor sensation Extensive vascularization supply nutrients to both the dermis and epidermis vasodilation and vasoconstriction for thermoregulation

Hypodermis : 

Hypodermis Insulation and cushion

Hypodermis : 

Hypodermis Referred to as the subcutaneous layer or superficial fascia consist of areolar CT or adipose CT If adipose tissue dominates, then it is called subcutaneous fat

Hypodermis : 

Hypodermis CT fibers of reticular layer are interwoven with CT fibers of hypodermis to bind both regions Distribution men: neck, upper arms, abdomen, lower back, buttocks women: breasts, hips, thighs, buttocks

Accessory Organs : 

Accessory Organs Nails, hairs, glands

Nails : 

Nails consist of dead keratinized cells from the stratum corneum nail body: main area of nail; pink due to underlying BV of CT free edge: distal white area--no BV lunula: at proximal end; white due to thickened stratum basale which obscure BV nail folds: folds of skin a lateral borders

Nail : 

Nail nail bed: covered by nail body; contains deeper living layers of epidermis nail root: proximal portion of nail beneath skin nail matrix: proximal thickening of nail bed from which nail grows hyponychium: distal region thickened stratum corneum beneath free edge

Nail : 

Nail nail plate: formed by nail root + nail body + free edge nail groove: bound nail fold to nail eponychium: cuticle- band of epidermis that extends onto nail body

Hair : 

Hair

Hair : 

Hair Pilus: single strand of hair consist of keratinized cells Types of hair lanugo: fine unpigmented hair on fetus vellus: fine hair that replace lanugo by birth primary human hair found on upper and lower limbs terminal hair: coarse pigmented hair on scalp, eyebrows, eyelashes replaces vellus hair in axillary and pubic regions at puberty forms beard, hair on arms, legs, and trunk of males

Structure of Hair : 

Structure of Hair hair bulb swelling at base of hair where it originates in the dermis Contains live keratinocytes hair papilla Connective tissue region contains blood vessels and nerves projects into hair bulb root: portion of hair below skin Consist of dead keratinocytes

Structure of Hair : 

Structure of Hair shaft: portion of hair above skin surface (dead keratinocytes) matrix: portion of hair bulb from which new basal hair cells are formed

Structure of Hair : 

Structure of Hair medulla: center portion of hair  cortex: several layers of flattened cells that surround the medulla  cuticle: multiple layers of cells surrounding the cortex

Slide 52: 

Figure 5.7a

Hair Follicle : 

Hair Follicle oblique tube that surrounds the hair root extends into dermis and maybe hypodermis

Hair Follicle : 

Hair Follicle wall of hair follicle connective tissue root sheath outer layer that is derived from connective tissue  epithelial root sheath inner layer that is derived from epidermis

Hair Follicle : 

Hair Follicle arrector pili muscle extend inferiorly form dermal papilla to anchor hair follicle contracts to pull follicle upright causing goose bumps

Hair Color : 

Hair Color caused by production of melanin in hair matrix color variation caused by different shades of melanin gray hair: gradual reduction of melanin production white hair: no pigment produced

Hair Growth and Replacement : 

Hair Growth and Replacement hair grows at 1/3 mm/day for 2-5 years to about 1 m afterwhich, hair in the follicle stops growing for 3-4 months then new growth starts that pushes out old hair from follicle Follicles are active at different times All hair follicles will not stop at the same time

Sweat Glands : 

Sweat Glands Merocrine (eccrine) sweat glands release secretions directly onto surface of skin palms, sole, and forehead have the highest number secretion is primarily water with trace of NaCl, urea, ammonia Controlled by nervous system

Sweat Glands : 

Sweat Glands Apocrine sweat glands release secretions directly into hair follicles located in arm pits, areola, pubic region, anal region secretions: viscous and cloudy due to proteins and lipids react with bacteria on skin to cause odor  active after puberty Influenced by hormones

Sebaceous glands : 

Sebaceous glands release sebum (waxy, oily secretion) usually directly into hair follicle activated during puberty keep skin and hair moist blocked glands may lead to boils

Ceruminous Glands : 

Ceruminous Glands located in ear canal make waxy secretion lubricate eardrum and ear canal

Mammary Glands : 

Mammary Glands modified apocrine sweat glands functional only in pregnant females produce milk

Clinical Disease and Terminology : 

Clinical Disease and Terminology

Acne : 

Acne Acne: term to describe plugged sebaceous glands Types of acne Comedo: sebaceous gland’s ducts is plugged with sebum Blackhead: open comedo Whitehead: closed comedo

Acne : 

Acne Types of acne Papule: dome-shaped lesions filled with blood cells, skin cells and bacteria Nodule: similar to papule but extends into deeper skin layers Cyst: fluid filled nodule

Burns : 

Burns 1st degree burn: localized to epidermis

Burns : 

Burns 2nd degree burn: localized to epidermis and dermis

Burns : 

Burns 3rd degree burn: penetrates epidermis, dermis and hypodermis

Skin Cancer : 

Skin Cancer Chronic exposure to UV rays can damage DNA in epidermal cells UV exposure is dominant causal factor in skin cancer Most prevalent on head and neck Most common in fair-skinned individuals but everyone is susceptible

Basal Cell Carcinoma : 

Basal Cell Carcinoma Most common type of skin cancer Least dangerous because seldom metastasizes Originates in stratum basale Usually on face Treated by surgical removal

Squamous Cell Carcinoma : 

Squamous Cell Carcinoma Originates from keratinocytes of stratum spinosum Appears on scalp, ears, lower lip, back of hand May metastasize Treated by early detection and surgical removal

Malignant Melanoma : 

Malignant Melanoma Most deadly form of skin cancer Has aggressive growth and metastasis Arises from melanocytes in pre-existing mole Early detection and surgical removal is critical for survival Chemotherapy, radiation and interferon therapy are used after metastasis

Terms : 

Terms Athletes foot: fungal infection of skin especially between toes Blister: thin-walled fluid-filled sac usually deep to or within epidermis Caused by burn or excessive friction Cold sore or fever blister small fluid filled blister on lips (mouth) Caused by herpes virus which infects nerve cells that supply the skin

Terms : 

Terms Dandruff: flaking of the epidermis of the scalp Eczema: skin inflammation Hives: eruption of raised areas on skin due to foods, drugs or stress Keloid: excess scar tissue due collagen accumulation during healing Wart: growth of epidermal cells to form roughened projection from skin; caused by human papilloma virus (HPV)

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