Ch. 5 - Integumentary System (HSF)

Integumentary System consists of…

skin, hair, nails, sweat glands, oil glands

2 Distinct Regions of Skin

Epidermis & Dermis

Epidermis (basic location & makeup)

superficial region

epithelial tissue (keratinized stratified squamous)

avascular

Dermis (basic location & makeup)

underlies epidermis

fibrous connective tissue

vascular

Hypodermis (not part of skin)

Subcutaneous layer deep to skin

Shares similar function to skin

Mostly adipose tissue

Absorbs shock and insulates

Anchors skin to underlying structures

4 Cell Types found in the Epidermis

Keratinocytes, Melanocytes, Dendritic Cells, Tactile Cells

Keratinocytes

Produces fibrous keratin

MAJOR cell of epidermis

Tightly connected by desmosomes

Millions slough off everyday

Keratin

protein that gives skin its protective properties

Desmosomes

specialized adhesive protein complexes that anchor neighboring animal cells together.

prevent cells from being pulled apart under physical pressure.

Melanocytes

Spider-shaped cells

Located in deepest epidermis

Produce pigment MELANIN

Dendritic Cells

Star-shaped macrophages

In deep epidermis

Activators of immune system

Macrophages

eat bacteria, like a vacuum

Tactile Cells

Sensory receptors that sense touch

5 Layers of Epidermis

Stratum…

1. Basale

2. Spinosum

3. Granulosum

4. Lucidum

5. Corneum

Thick Skin (Epidermis)

5 Layers of Strata

Found in high-abrasion areas (palms and sols)

ONLY ONE in Epidermis (Stratum Lucidum)

Thin Skin (Epidermis)

Contains ONLY 4 layers/strata

4 Types

ex. stratum … basale, spinosum, granulosum, corneum

Stratum Basale (think of the basal layer)

deepest of all epidermal layers (base)

firmly attached to the dermis

preforms active mitosis

small amounts of melanocytes in this layer

Stratum Spinosum (think of as prickly layer)

Several cells thick

Weblike system of intermediate pre-keratin filaments attached to desmosomes.

Keratinocytes appear spikey

Keratinocytes, melanosomes, and dendritic cells within.

Stratum Granulosum (think of as granular layer)

4-6 cells thick, but cells are flattened

this layer is THIN

nuclei and organelles disintegrate and keratinization begins

Keratinization

cells accumulate keratohyalin granules that help form keratin fibers in upper layers.

Stratum Lucidum (think of it as clear layer)

ONLY THICK LAYER OF EPIDERMIS

thin, translucent band of 2-3 rows of clear, flat, DEAD keratinocytes

superficial to stratum granulosum (on top of)

Stratum Corneum (think of it as the horn-e layer)

20-30 rows of flat, keratinized, dead cells

accounts for ¾ of the epidermal thickness

functions as a BARRIER to protect deeper cells from environment, prevents water loss, protect from abrasion and penetration.

Apoptosis

controlled cell death

dandruff and dander

dead cells sloughing off, shedding 50,00 cells every min

Dermis (makeup)

LARGE

mostly dense irregular CT (strong, flexible)

cells include fibroblasts, macrophages (mainly)

fibers bind body together

Dermis contains …

nerves, blood vessels, lymphatic vessels, epidermal hair follicles, oil and sweat glands.

2 Layers of Dermis

Papillary (closer to epidermis) & Reticular (below papillary)

Papillary Layer (makeup)

Superficial layer of areolar CT - loose, interlacing collagen, elastic fibers, and blood vessels.

Loose fibers allow phagocytes to patrol for microorganisms.

Dermal Papillae

superficial region of dermis that sends fingerlike projections up into epidermis - contain capillary loops, free nerve endings, and touch receptors.

Dermal Papillae lies on top of …, giving rise to …

dermal ridges, epidermal ridges

Friction Ridges

enhance gripping ability, sense of touch, gives us our fingerprint patterns

Reticular Layer

80% of dermal thickness

makeup of coarse, dense fibrous CT

Cutaneous Plexus (Reticular)

Network of blood vessels between reticular layer and hypodermis.

Cleavage Lines (Reticular)

in reticular layer

caused by many collagen fibers running parallel to skin surface

invisible to external

Flexure Lines (Reticular)

dermal fold at or near joints

dermis is tightly secured to deeper structures

visible on hands, wrist, fingers, soles, toes

Striae (Stretch Marks)

extreme stretching of skin causing dermal tears, leaving silvery white scars.

Blisters

fluid filled pockets that separate epidermal and dermal layers from acute short-term traumas.

3 pigments contributing to skin color

Melanin, Carotene, Hemoglobin

Carotene

Yellow to Orange Pigment

Obvious in palms and soles

Accumulates in stratum corneum and hypodermis

Hemoglobin

Pinkish hue of fair skin due to lower levels of melanin.

Cells/Layers Die and are Dead because…

they are farther away from blood supply.

Cyanosis

Blue or Gray Skin Color

Low Oxygenation

Erythema

Redness

Fever, High Blood Pressure, Inflammation, Allergy

Pallor

Pale Color

Anemia, Low Blood Pressure, Fear, Anger

Jaundice

Yellow Color

Liver Disorders

Newborns have it

Bronzing

Inadequate steroid hormones

Bruises

Black-and-blue marks

Clotted blood beneath skin

Hair (definition)

Flexible Strands of Dead Keratinized Cells

Produced by hair follicles

Contains hard keratin (tough and more durable)

Hair (function)

Warn of insects on skin

Hair on Head against physical trauma

Protects from heat loss

Shield skin from sunlight

Shaft (hair regions)

extends above scalp, where keratinization is complete.

Root (hair regions)

with scalp, where keratinization is still going on.

3 Parts of Hair Shaft

Medulla, Cortex, Cuticle

Medulla (hair shaft parts)

central core of large cells and air spaces

Cortex (hair shaft parts)

several layers of flattened cells surrounding medulla

Cuticle (hair shaft parts)

outer layer consisting of overlapping layers of single cells

Hair pigments are made by … in what?

Melanocytes in Hair Follicles

Different melanin creates …

all hair colors

Gray hair results when …

melanin production decreases and air bubbles replace melanin in shaft.

Structure of Hair Follicle (2 Parts)

Hair Bulb, Hair Follicle Receptor, Hair Matrix, Arrector Pili, Hair Papilla

Extends Epidermal Surface to Dermis

Hair Bulb

expanded area at deep end of follicle.

Hair Follicle Receptor

Sensory nerve ending that wrap around bulb

Hair Matrix

Actively dividing area of bulb that produces hair cell. As the matrix makes new cells, it pushes older ones upward.

Arrector Pili

Small band of smooth muscles attached to follicle.

Responsible for “goose bumps”

Goosebumps

When cold - hairs stand up to keep heat.

When scared - puffs up to look bigger.

Hair Papilla

dermal tissue containing a knot of capillaries that supplies nutrients to growing hair.

Types of Hair (2)

Vellus & Terminal

Vellus Hair

Pale, fine body hair of children and adult females

Terminal Hair

Found on scalp and eyebrows

Appears in axillary and pubic areas (at puberty for both sexes)

On face and neck (at puberty for men)

2 things that affect hair growth

Nutrition and Hormones

Nails

Scale-like modifications of epidermis, contain hard keratin.

Protective cover for surfaces of fingers and toes.

Nail Bed

Epidermis underneath the nail plate

Nail Matrix

thickened portion of bed that is responsible for nail growth.

Nail Folds

Skin folds that overlap border of nail

Eponychium or Cuticle

Nail fold that projects onto the surface of nail body

Hyponychium

area under free edge of plate, accumulates dirt

Lunule

half-moon shaped, thickened nail matrix, appears white

2 types of sweat glands

Eccrine & Apocrine

Cells in Sweat Glands are called…

Myoepithelial Cells

Myoepithelial Cells

think muscle

contract upon nervous system stimulation to force sweat into ducts.

Eccrine Sweat Glands

SECRETION IS SWEAT EXTERNALLY

does NOT smell

most numerous types

located on palms, soles, and forehead

ducts connect to pores

FUNCTION IS … thermoregulation by sympathetic nervous system

Apocrine Sweat Glands

SECRETION IS MILKY OR YELLOWISH SWEAT

(containing fatty substance and protein)

SMELLS

bigger than eccrine sweat glands

located in axillary and anogenital areas

ducts emptying into hair follicles

start functioning at puberty

Modified Apocrine Glands (2)

Ceruminous - secrete cerumen (earwax)

Mammary - secrete milk

Sebaceous (oil) Glands

Widely distributed (not on thick skin of soles and palms)

Secrete sebum (oil) and INTO hair follicles.

Inactive until puberty and stimulated by hormones.

Functions of Skin

BARRIER (protection, body temp regulation, cutaneous sensations, metabolic functions, blood reservoir, excretion of wastes)

Most Common Skin Disorders are…

Infections

Less Common, but more damaging skin disorders are… (2)

Skin Cancer and Burns

How to access for Skin Cancer?

A (asymmetry)

B (border) - bad if uneven

C (color) - bad if 2 or more colors

D (diameter) - bad if larger than ¼ inch

E (evolution) - bad if change in shape, size, color

3 Major Types of Skin Cancer

Basal Cell Carcinoma, Squamous Cell Carcinoma, Melanoma

Risk Factors for Skin Cancer

Overexposure too UV radiation, frequent irritation, things with carcinogens.

Burns

Tissue damage caused by heat, electricity, radiation, or chemicals.

Burns are classified by…

Severity

First Degree Burn

Epidermal Damage Only

redness, swelling, pain

Second Degree Burns

Epidermal and Upper Dermal damage

Blister Appear

Third Degree Burn

Entire Thickness of Skin

skin color turns gray, white, cherry red, or black

area is NOT painful because nerve ending are destroyed

skin grafting is necessary.

Critical Burns are

25% of body has 2nd burns

10% of body has 3rd burns

Treatment of Burns

Removal of Burned Skin

Antibiotics

Covering

Skin Grafts