Integumentary System, CH 6

What is the Integumentary System?

Skin, Hair, Nails, Sudoriferous & Sebaceous glands, sensory receptors

Three layers of the skin

Epidermis, Dermis, Hypodermis

What is the top layer of the skin?

Epidermis

What is the middle layer of the skin?

Dermis

What is the lower level of the skin?

Hypodermis

Describe Keratinized stratified squamous epithelium

Keratinized means its dead and waterproof

Stratified squamous means its many layers of thin flat cells

What’s the function of Keratinized stratified squamous epithelium?

Protects underlying tissues from abrasion, germs(pathogens), and water loss.

Where is the Keratinized stratified squamous epithelium?

Its mainly on the Epidermis, the top layer of the skin

Sequence the layers of the Epidermis, from bottom to top

1. Stratum Basale

2. Stratum Spinosum

3. Stratum Granulosum

4. Stratum Lucidum

5. Stratum Corneum

What type of cells are the Stratum Corneum made up of? And where is the Stratum Corneum located specifically?

Corneocytes. It is the outermost layer of the epidermis.

What type of cells are the Stratum Lucidum made up of? And where is the Stratum Lucidum located specifically?

Keratinocytes filled with eleidin (a clear protein), located only in thick skin, such as the palms of the hands and soles of the feet, just beneath the stratum corneum.

What type of cells are the Stratum Granulosum made up of? And where is the Stratum Granulosum located specifically?

Keratinocytes containing keratohyalin granules. It is located just below the stratum corneum (or lucidum in thick skin) and above the stratum spinosum in the epidermis.

What type of cells are the Stratum Spinosum made up of? And where is the Stratum Spinosum located specifically?

Keratinocytes connected by desmosomes, It is located below the stratum granulosum and above the stratum basale in the epidermis.

What type of cells are the Stratum Basale made up of? And where is the Stratum Basale located specifically?

Basal keratinocytes, melanocytes, and Merkel cells. It is the deepest layer of the epidermis, sitting directly on the basement membrane above the dermis

Are Keratinocytes in all of the cell layers of the Epidermis? T or F

True

What do Keratinocytes do?

They synthesize keratin

Where can we find Keratinocyte stem cells and what do they do?

Only in the basal layer, and their function is cell divison.

Where are melanocytes?

Only in the Stratum Basale layer.

What do melanocytes do, and whats the color range?

They synthesize melanin, yellow → brown → black

Describe Melanin

Melanin packaged into melanosomes

Melanosomes transferred to keratinocytes

Melanin shields DNA from UV

What do Tactile/Merkel Cells do?

They’re responsible for sensory

What are Epidermal Dendritic Cells?

Langerhan cells

Macrophages

What do Epidermal Dendritic Cells do?

they activate the immune response

Stratum Basale (basal layer)

Deepest layer

Singe layer of cells

Keratinocyte stem cells

Melanocytes

Tactile (Merkel) cells

Stratum spinosum

Several layers of keratinocytes

No cell division

Tight junctions

Desmosomes

Glycolipid produced

Epidermal dendritic cells

Stratum Granulosum

3 – 5 layers of keratinocytes

Keratinization begins

Keratin accumulates

Nucleus and organelles disintegrate

Cells start to die

Stratum Lucidum

2-3 cell layers

Translucent

Only in thick skin

• Palmar surfaces of hands

• Plantar surfaces of feet

Stratum Corneum

Superficial Layer

20 – 30 layers

Dead, flat cells: Keratinized

Thick plasma membrane

Lipid coating

Functions:

• Protection

• Waterproofs

Humans can shed ~50,000 cells

every minute
T or F

True

Whick takes up most of the body? Thick or Thin skin

Thin Skin

The main function of melanin is to______

shield the nucleus from damage by ultraviolet radiation

properties of thick skin

Palms & soles

5 layers

Sweat glands

No hair follicles

No sebaceous glands

properties of thin skin

Most of body

4 layers

No stratum lucidum

Sweat glands, hair follicles &

sebaceous glands

Florio is taking a drug that inhibits cell division. Which layer of the epidermis would be affected by this drug?

Stratum Basale

What are the 3 pigments that contribute to skin color

Melanin, Carotene, Hemoglobin

Describe Carotene

Yellow to Orange, acquired from some fruits and veggies

Describe Hemoglobin

Red pigment, pinkish hue of skin

What 2 layers make up the Dermis

Papillary Layer, Reticular Layer

What type of tissue is the Papillary Layer made up of?

Areolar CT

What type of tissue is the Reticular Layer made up of?

Dense Irregular CT

What are Dermal papillae, and where are they?

Capillary loops, tactile(Meissner’s) corpuscles, Free nerve endings, and in the Papillary layer.

What are tactile corpuscles?

they’re light touch receptors

What are free nerve endings and where

They’re for pain, and in the dermal papillae in the papillary layer

What are friction ridges?

Large folds and valleys of epidermis and dermis

What type of fibers are in the Reticular Layer?

Collagen and Elastic Fibers

What is in the Reticular Layer?

Lamellar (Pacinian) Corpuscles, and Pain Receptors

What are Lamellar Corpuscles, and where are they

They’re deep in the dermis, and detect deep pressure. They’re in the Reticular Layer

What are cleavage(tension) lines?

Bundles of collagen and elastic fibers

They’re oriented in parallel bundles

Affects tissue healing

Bundles resist stress during routine movement

What is a Blister?

Separation of dermis and epidermis by a fluid filled

pocket

What are stretch marks (straie)?

Tearing of dermis

Where is the Subcutaneous Layer?

In the Hypodermis, superficial fascia

deep to the skinW

What type of CT is the Subcutaneous Layer made up of

Adipose and Areolar CT

What are the functions of the Subcutaneous Layer

Protection, Energy Storage, Insulation

The subcutaneous layer is not well vascularized. T or F

False, it is very well vascularized.

The principal tissue found in the reticular layer of the dermis is

___________.

dense irregular connective tissue

What cells produce vitamin D3 when exposed to UV radiation?

KeratinocytesW

What ways can you get Vitamin D3 intake?

From the Sun (UV radiation), from food or supplements

What do we need Vitamin D for?

Vitamin D is needed to absorb calcium from small intestine.

What are some Epidermal derivatives?

Nails, Hair, Hair follicles, sweat glands, oil glands

Hair (Pili) consists of what cells?

dead, keratinized cells

Three structures of hair

Hair bulb, root, shaft

What are the three layers to hair, name them from outer to inner

Cuticle, cortex, medulla

What does a hair follicle do?

surrounds the root of the hair

What is the hair matrix made up of?

stem cells

What is hair papilla made up of?

Dermal tissue, capillaries

Root hair plexus

Nerve fibers

Sensitive touch receptors

Arrector pili muscle

Smooth muscle attached to follicle

Make hair stand up

Forces sebum out of follicle

• Lubricates skin

Functions of Hair

maintains warmth (protects against heat loss)

alerts body of insects or other things on the skin

guards the scalp from physical trauma

shields skin from sunlight

Hair and nails are derivatives of the _________.

Epidermis

Apocrine Gland

Apical membrane pinches off and cytoplasmic contents becomes secretion

Merocrine Gland

Secretions are packaged into vesicles and released by exocytosis

Holocrine Gland

Cell accumulates a product and then ruptures, secretion is made up of product and cell fragments

what are the three types of exocrine glands

Eccrine (Merocrine), Apocrine sweat, Sebaceous

Merocrine (Eccrine) glands

Entire body

Merocrine glands

Secrete sweat

99% water

1% NaCl, vitamin C, antibodies, dermicidin, metabolic wastes

Functions

• Thermoregulation

• Antibacterial properties

• Release metabolic wastes

Apocrine sweat glands

Only in axillae, around nipples, anogenital

areas

Merocrine glands

• Secrete viscous, cloudy sweat

• Lipids and proteins

• Produces odor when broken down by bacteria

• Ducts empty into hair follicles

• Begin functioning at puberty

• Function: Pheromone signaling and emotional sweating

Mammary glands

• Breast

• Secrete milk

What are specialized apocrine sweat glands

Ceruminous, they’re in the external ear canal and secrete cerumen.

Are Sebaceous glands in thick skin? Y or No

NO

Where do Sebaceous glands secrete, and what type of secretion?

They secrete into hair follicles and its holocrine secretion

What is Sebum?

Bactericidal

Softens hair and skin

Relatively inactive until puberty

Whitehead

Blocked sebaceous duct

Closed

Blackhead

Blocked sebaceous gland

Open - sebum oxidize

Pustule

Red elevation

Contains pus

• WBC, dead skin cells, bacteria

Cyst

Severely inflamed

What are the two types of tissue repair?

Regeneration, and Fibrosis

What is regeneration

complete replacement of damaged cells, function restored

What is fibrosis

gap filled by scar tissue w/ collagen fibers, function not fully restored

What are the steps of tissue repair?

Wound → blood clot, WBC clean wound → blood vessels grow, granulation tissue forms → regeneration and fibrosis.

What are Burns?

Tissue damage from heat, electricity, radiation, or certain chemicals

What are the dangers of severe burns?

Water loss and electrolyte imbalance

Infection

Describe 1st degree burns

Only the epidermis is damaged

Localized redness, swelling, and pain

Most important role of eccrine sweat glands

Body temperature regulation

Describe 2nd degree burns

Epidermis and upper regions of dermis are damaged

Blisters, swelling, painful

Describe 3rd degree burns

Epidermis, dermis and subcutaneous layer damaged

• Skin color turns gray-white, cherry red, or black

• No initial edema or pain (nerve endings destroyed)

• Dehydration & electrolyte imbalance is major concern

• Skin grafting usually necessary

What causes skin cancer?

Overexposure to UV radiation

Frequent irritation of the skin

Most skin tumors are malignant and metastasize. T or F

False, most skin tumors are benign and do not metastasize

Describe Cell Carcinoma

Keratinocyte stem cells

• Stratum basale

• Slow growing and do not often metastasize

Skin Cancer

Describe Squamous Cell Carcinoma

• Keratinocytes of stratum spinosum

• Most often on scalp, ears, lower lip or hands

• Early detection and removal = good prognosis

• Can metastasize

Describe Melanoma

Melanocytes

Increased risk if severe sunburns (especially in

childhood)

Aggressive growth and highly metastatic

• Survival rate improved with early detection and

removal

• Advanced cases difficult to cure

Which is most dangerous type of skin cancer?

Melanoma

What forms of therapy for Melanoma

Chemo,interferon, and radiation