Lab 6: Integumentary System

Describe the papillary region of the dermis

*(1/5) *Superficial *Thin collagen and elastic fibers *Dermal papillae

Describe the reticular layer of the dermis

*(4/5) *Attached to subcutaneous layer *80% of dermal thickness *Dense irregular connective tissue containing collagen and elastic fibers *Blood vessels, hair follicles, nerves, sebaceous (oil) and sudoriferous (sweat) glands *Provides strength, extensibility and elasticity

Describe Melanocytes

*8% of cells *Produce the pigment melanin that protects against damage by UV radiation

Describe keratinocytes

*90% of the cells *Produce keratin: a tough fibrous protein that provide protection

Describe eccrine

*99% water *Thermoregulation *Elimination of waste *Stimulated by emotional stress *Cold sweat *Excreted into pore on epidermal surface *Most common *Regulates body temp through evaporation

What is cellulitis

*A bacterial infection of the dermis and subcutaneous layer *Causes cracks between toes *Skin has a lot of bacteria living on its surface

Describe acne

*An inflammation of the sebaceous glands *Sebaceous ducts blocked by accumulated sebum give rise to whiteheads *If the material oxidizes and dries, it darkens to form blackheads (Chocolate and fried foods do not cause acne)

Describe hair

*Composed of dead, keratinized epidermal cells *Helps with touch, protections from sun damage, reduces heat loss *Located on most of all skin surfaces *Genetics and hormones determined hair thickness and distribution patterns *Straight hair is stronger *Curly hair is flat

Describe the dermis

*Connective tissue *Vascular *Ink injected into dermis for tattoos *Dense, irregular connective tissue containing collagen and elastic fibers *Embedded with blood vessels, nerves, glands, and hair follicles -essential for epidermis survival

Describe the stratum corneum

*Dead keratinocytes *Thickness can vary *Continually shedding and replacing *Callus formation *Greatest contributor to epidermal thickness

Describe merkel cells

*Detect touch and sensations *Least abundant *Found deepest layer of epidermis (basale) *Associated with sensory neurons

What is a hair follicle

*Epithelial layer that surrounds the hair root *Hair matrix forms new hair cells

Describe the thick skin of the epidermis

*Hairless *5 layers -Stratum basale -Stratum spinosum -Stratum granulosum -STRATUM LUCIDUM -Thick stratum corneum

Describe the thin skin of the epidermis

*Hairy *4 layers -Stratum basale -Stratum spinosum -Stratum granulosum - Thin stratum corneum

Describe nails

*Hard, keratin zed epidermal cells *Nail root insets into a fold of the skin *consists of a body, free edge, and nail root

Describe the stratum basale

*Highly mitotic *Stem cells in this layer undergo cell division to continually produce new keratinocytes that move up and differentiate *has melanocytes *has merkel cells *Clinical application: new skin cannot regenerate if injury destroys a larger area of the stratum basale and its stem cells (burn victims)

Describe the subcutaneous layer of the skin

*Hypodermis *Beneath dermis but not part of the skin *Storage depot for fat *Contains blood vessels hat supply the skin *Loose areolar/adipose connective tissue that attached the skin to the underlying tissues and organs *NOT part of the integumentary system

Describe langerhans cells

*Immune system cells *Macrophages that originated in the red bone marrow *Involved in the immune response e

Describe dermal papillae

*Increases surface area *Consists of: 1. capillary loops (papillary plexus) 2. messiner corpuscle (sensitive to touch) 3. free nerve endings (dendrites that lack structural specialization) *Finger-like projections that extend into the epidermis *Increase the surface area of the dermis *different free nerve ending give rise to general sensation (warmth, pain, tickling, itching)

Describe the hair matrix

*Inside the bulb and part of the medulla *responsible for the growth of existing hairs *If removed or destroyed hair will not grow back

Describe Psoriasis

*Kim Kardashian *Keratinocytes divide and move more quickly than normal from the stratum basale to the stratum corneum and shed prematurely *Immature keratinocytes --> abnormal keratin --> flaky, silvery, white or red scaled on skin *Treatment is to suppress cell devision, decrease rate of cell growth, inhibit keratinization

Describe the stratum granulosum

*Middle of the epidermis *3-5 layers of flattened keratinocytes undergoing apoptosis (programmed cell death; cell degenerate) *Release a lipid-rich secretion that acts as a water repellant sealant (prevents loss and entry of water and foreign materials)

Describe ceruminous

*Modified to secrete cerumen (ear wax)

Describe the epidermis

*Most important layer *Avascular (no bleeding when cut) *Epithelial tissue *Composed of keratinized epithelium which contains four major types of cells

Describe the bulb

*Onion-shaped and at the end of the follicle *The bulb houses the papilla of the hair which contain blood vessels that nourish the growing follicle

Describe the stratum lucidum

*Only present in thick skin *Translucent in fresh skin *fingertips, palms, soles *Contained layer of dead keratinocytes *Contain a large amount of keratin and thickened plasma membranes *Additional layer of toughness

What are epidermal ridges

*Reflect that contours of the underlying dermal papillae *On palms and soles the dermal papillae lie on top of larger mounds called dermal ridges which in turn case the overlying epidermis to form epidermal ridges *Increase friction and gripping ability *Form the basis for fingerprints and footprints *Sweat pores open along their crests leaving identifying films on everything we touch *Pattern is genetically determined and unique *Present on thick skin

What are the accessory structures of the integumentary system

*Sebaceous gland (oil) *Sudoriferous gland (sweat) *hair *nails *sensory receptors (SKIN is main)

What are arrector pili

*Smooth muscle attached to the hair follicle *Contraction makes hair perpendicular with skin surface

How does physiological or emotional stress affect hair

*Stimulated arrector pili contration which pulls hair perpendicular to the skin surface *Causes goosebumps because skin around the shaft forms slight elevations

Describe hair root plexus

*Touch receptors *Surround each follicle and are sensitive to touch *Generates nerve impulses when hair is removed or moved

Describe the stratum spinosum

*above the stratum basale *thorn-like projections on slides *has langerhan cells *some melanocytes

Describe dermal tearing

*can occur when the dermis is stretched too much resulting in silvery white scar called striae or stretch marks

Describe the nail matrix

*cells divide mitotically to produce new cells *Growth rate determined by age, health, nutritional status *Avg. nail growth is 1mm/week but is somewhat slower in toes

Describe the sebaceous (oil) glands

*connected to hair follicles' secreting portion lies in the dermis and open up into the neck of the hair follicle *secretes sebum (lipid-rich substance) -prevents hair from becoming brittle (makes it shiny and hydrophobic) -inhibits growth of some bacteria -prevents dehydration of hair and skin -typically empty into a hair shaft

Describe lanugo hairs

*fine, non pigmented, downy hairs that cover the body of the fetus

Describe the medulla of the root

*has melanocytes for hair color *white hair has no pigment granules but rather air bubbles *Gray hair has few melanocytes

Describe apocrine

*located mostly in subcutaneous layer of axilla and genitals and bearded facial regions in males *sweat contains proteins that support bacterial colonization *stimulated by emotion stress and sexual excitement *Excreted into hair follicles *Basis for body odor *no role in thermoregulation

Describe terminal hairs

*long, coarse, heavily pigmented hairs

Describe vellus hairs

*peach fuzz *short, fine, pale hairs barely visible to the naked eye *at puberty vellus hairs are replaced with terminal hairs due to androgen stimulation (chest, armpit, face)

Describe the difference between thin and thick skin

*vary based on thickness, strength degree of keratinization, distribution and type of hair, glands, pigmentation, vascularity, and innervation

What are the 3 components of the sudoiferous (sweat) gland

1. Apocrine 2. Eccrine 3. Ceruminous

What are the 2 layers of the skin

1. Epidermis (superficial) 2. Dermis (deep)

What are the 4 major cells of the Epidermis

1. Keratinocytes 2. Melanocytes 3. Langerhans cells 4. Merkel cells

What are the 3 types of hair

1. Lanugo hair 2. Terminal hair 3. Vellus hair

What are the 3 layers of the root

1. Medulla 2. Cortex 3. Cuticle

What are the 2 layers of the dermis

1. Papillary region 2. Reticular

What are the functions of the integumentary system

1. Protection 2. Body temp. 3. Vitamin D production 4. Sensory info about surrounding environment 5. Excretion and absorption

What are the 2 main sections of hair

1. Shaft: projections above the skin 2. Root: penetrates into dermis

Why is the dermis important for the survival of the epidermis?

Because the epidermis is avascular it relies on the dermis nutrients to diffuse

What is the most superficial layer of the epidermis

Corneum

What is albinism

Inherited inability to produce melanin

What determines hair color

Melanocytes in the medulla of the root

What is vitilago

Partial or complete loss of melanocytes from patches of skin that produce irregular white spots

What is elasticity

ability to return to original shape after being stretched

What is extensibility

ability to stretch- think about the stretching that takes place during pregnancy

How does hair grow

at an angle

Why is skin considered an organ

because it has many types of tissues that work together to form specific functions

Where is thick skin found

in areas where exposure to friction is the greatest (fingertips, palms, toes)

What is dermatoglyphics

the study of the pattern of epidermal ridges