Chapter 5 Integumentary Marie b

8/10/2019 Chapter 5 Integumentary Marie b

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You gotta have skin;All you really need is skin. Skin's the thing, that if you've got itoutside, It helps keep your insides in.

Alan Sherman (1924-1973 )

Ch 5: Integumentary System

Developed by John Gallagher, MS, DVM


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Two Major Subdivisions

! Cutaneous Membrane, i.e.skin ! Epidermis ! Dermis ! Hypodermis

! Accessory Structures! Excretory glands (?) ! Hair ! Nails


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Function of skin! Protection

! Mechanical! Immune

! Heat regulation

! As a membrane! Absorption! Excretion

! Vitamin D metabolism! Sensation


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Made up of all 4 tissue types


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Epidermis

! Type of Epithelium? ! Avascular

! Different layers(= strata) ! 4 layers in thin skin ! 5 layers in thick skin


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Epithelial tissues

Squamous

Simple Stratified

Keratinized

Nonkeratinized

Columnar

Simple

Pseudostratified

Transitional

Cuboidal

Simple

Stratified

A Concept Map (from Histo, Part 1)


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Stratumgerminativum

= stratum basale

Innermost,single layer

Stratum Germinativum! Cell types:

! Stem cells (basal cells)! Melanocytes ! Merkel cells (touch receptors in hairless skin only)


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Stratum Spinosum! Stem cell daughter cells (some can still divide) ! Establishment of Desmosomes

! The desmosomes create the spines as artifact pulls the cellsapart

Several cellsthick


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Stratumgranulosum

Stratum Granulosum! Cells displaced from stratum spinosum ! Keratinocytes ! Production of keratohyalin and keratin fibers ! Cells start to die. Dehydration leaves interlocked layers of keratin

and keratohyalin

Small granulesof keratin


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Stratumlucidum

Stratum Lucidum

! In thick skin only, i.e., palms of hands and soles of feet! Cells do not stain well ! clear (lucid) looking

Mostlykeratin


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Stratum Corneum

! Many layers of flattened, dead cells, filled with keratin ! Continually sloughed ! Water-resistant but not water proof ( " insensible perspiration) ! Relatively dry - advantage? ! Keratinization occurs everywhere except for anterior surface of eye

S t r a t u m

c o r n e u m

15-30 layers(much thickerin thick skin)


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Thin vs. Thick Skin

! Up to 1.5 mm! Where??

" Average 0.08 mm" Most of body

Refers to epidermis


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Skin Color

! Hemoglobin (dermal blood supply)! Reddish tones ! Pale, due to? ! Bluish (=?), due to?

! Melanin! Produced by melanocytes of stratum basale

! Carotene! Obtained from plant foods

Depends on 3 pigments:


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Number ofmelanocytes samein all people,production levelsdiffer !

Melanocytes

Function ? UVprotection?


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Albinism

Vitiligo


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Dermis

! 1. Papillary layer Areolar (loose)c.t.

! 2. Reticular layer dense irregularc.t.


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Review of Connective Tissue

This is similar to Table 4.2

Loose (areolar) Reticular Adipose

Hyaline Elastic

Fibrocartilage

Irregular Regular Elastic

Compact Spongy


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1. Papillary Layer

! Dermal papillaeproject betweenepidermal ridges

! Aerolar c.t.! Capillaries! Tactile receptors

M#


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2. Reticular Layer! Consists of! Dense irregular c.t.! Accessory Structures

! Hair! Glands! Nerves

! Blood Supply


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Hypodermis! 2 other names

! Subcutaneous Layer (subcutis)! Superficial fascia

! Indistinct boundary (c.t. fibersinterwoven)! Loose c.t.

! Function ! Stabilization of skin while

allowing for independentmovement


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Accessory Structures:! Hair follicles and hair! Glands

! 1. Sebaceous Glands ! 2. Apocrine glands ! 3. Eccrine sweat glands

! Nails


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Hair Follicles & Hair

! 5 million hairs/humanbody. (98% not on topof head)

! Three hair types (vellus intermediate terminal)

! Function ?

! Hair color! Growth cycle


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Skin Glands


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2) Apocrine Sweat Glands!

Empty into hair follicle! Location: armpits, groin, nipples! Viscous, cloudy secretion ! good nutrient source for

bacteria (odor !!)

! Secretion may contain Pheromones! Secretion begins at puberty and is stimulated during

emotional distress (cold sweat)


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Apocrine Sweat Glands


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3) Merocrine (Eccrine) Sweat Glands

! Merocrine secretion ! Empty directly onto skin surface ! Location: most all over body (esp.

abundant on palms & soles: ~ 500/cm 2) ! Clear, watery secretion (99% H 2O; rest

NaCl + some waste products)

! Sensible perspiration; Function: ?


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For purpose of completion:! Other integumentary Glands:

! Mammary glands : Modified apocrine sweatglands

! Ceruminous glands : Modified sweatglands in ears


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Skin Pathology

Sunburn


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Skin Cancers

1. Basal Cell Carcinoma (Epithelioma) 2. Most common, not malignant Squamous Cell CA Stratum spinosum

Melanoma

BCC

SCC

Iris Melanoma DermalMelanoma


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Skin and Aging Process


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Chapter 5 Integumentary Marie b