Integument System BIO 211

What type of tissue is the epidermis made of?

Keratinized stratified squamous epithelium.

What are the five layers of the epidermis from deepest to most superficial?

Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum.

What are the three cell types found in the stratum basale?

Keratinocytes, melanocytes, and tactile cells (Merkel cells).

What do keratinocytes produce?

Keratin.

What does keratin do for the skin?

It strengthens the skin and makes it waterproof.

What do melanocytes produce?

Melanin.

What is the function of melanin?

It is a pigment that protects against UV light by absorbing radiation.

What are tactile cells (Merkel cells) sensitive to?

Touch.

What cells are found in the stratum spinosum?

Keratinocytes and dendritic cells (Langerhans cells).

What is the function of dendritic (Langerhans) cells?

They are phagocytes that engulf pathogenic microbes and cancer cells.

What happens to keratinocytes in the stratum spinosum?

They are pushed upward.

What happens in the stratum granulosum?

Keratinization begins.

What is the stratum lucidum?

A thin, translucent layer of dead keratinocytes found only in the palms and soles.

What is the function of the stratum lucidum?

It protects against UV light.

What is found in the stratum corneum?

20–30 layers of dead keratinocytes with no nucleus; the cell membrane contains keratin.

What is the importance of lipids in the stratum corneum cell membrane?

They help prevent disease.

What is thick skin?

Skin containing all five epidermal layers; it covers the palms of the hands and soles of the feet.

What is thin skin?

Skin covering most body surfaces and containing four epidermal layers; it lacks the stratum lucidum.

What is keratinization?

The process in which the cytoplasm of the outermost epidermal cells is replaced by the protein keratin.

What are the functions of keratinization?

Protection and waterproofing.

What are the two layers of the dermis?

The reticular layer and the papillary layer.

What type of tissue makes up the dermis?

Connective tissue, including areolar (loose), dense irregular, and blood tissue; it also contains smooth muscle and nervous tissue.

What is the reticular layer of the dermis?

The deepest dermal layer, made of dense irregular connective tissue and collagen.

What is found in the reticular layer?

Endings of hair follicles, tactile receptors, sweat glands, and sebaceous glands.

What is the papillary layer of the dermis?

The most superficial dermal layer, made of areolar (loose) connective tissue and elastic fibers.

What are dermal papillae?

Structures formed by the papillary layer that contain capillaries to feed the epidermis and sensory nerves.

What is the function of collagen in the dermis?

It provides tensile strength to the skin.

What is the function of elastic fibers (elastin) in the dermis?

They allow the skin to stretch and recoil.

What are the main functions of the dermis?

Temperature regulation through vasodilation/constriction, sensory reception, and secretion of sebum, sodium, water, and urea.

What is the process of hair growth called during the active cell division phase?

Anagen phase.

What is the catagen phase of hair growth?

A period of no cell division.

What is the telogen phase of hair growth?

The shedding phase.

What are nails made of?

Keratin; they are modified stratum corneum.

What are the functions of nails?

Protection and grasping.

Where is hair found?

Almost everywhere except thick skin and the lips.

What is hair made of?

Keratin growing from a papilla in the dermis.

What are the functions of hair?

Protection, heat retention, facial expression/recognition, sensory perception, and pheromone dispersion.

What is lanugo?

Hair found on the fetus and sometimes present at birth.

What is vellus hair?

Fine hair found all over the body.

What is terminal hair?

Coarse hair found on the scalp, brows, underarms, chest in men, and external genitalia.

What determines hair color?

Melanin in the hair matrix; genetics determines the structure of melanin.

What two types of melanin contribute to hair color?

Eumelanin and pheomelanin.

What are the two types of sweat glands?

Eccrine (merocrine) and apocrine.

Where is the secretory portion of a sweat gland located?

Embedded in the reticular layer of the dermis.

What does the duct of a sweat gland do?

It transports sweat to the skin surface through the epidermis.

What are eccrine (merocrine) sweat glands?

The most numerous sweat glands, found all over the body; there are about 3–4 million.

What do eccrine sweat glands secrete?

Sweat containing water, salt, and waste products.

What are the functions of eccrine sweat glands?

Thermoregulation, water balance, excretion of wastes, and maintaining normal flora to prevent growth of pathogenic microbes.

What are apocrine sweat glands associated with?

Hair follicles of the axilla and external genitalia.

What do apocrine sweat glands secrete?

A viscous fluid of proteins and lipids containing pheromones.

What type of glands are mammary glands?

Modified apocrine glands.

What type of glands are sebaceous glands?

Holocrine glands.

What does a holocrine gland do?

It ruptures to secrete its secretions.

What do sebaceous glands secrete?

An oily, waxy secretion called sebum.

What are the functions of sebum?

It lubricates the skin and kills pathogenic bacteria.

What tissues are found in the subcutaneous layer?

Loose areolar connective tissue and adipose tissue (subcutaneous fat).

Is the subcutaneous layer considered a true layer of the integument?

No. It is considered a supporting tissue.

What are the functions of the subcutaneous layer?

It pads and protects the body, stores fat for backup energy, provides thermal insulation, and binds skin to underlying structures such as muscle.

What is another name for the subcutaneous layer?

Hypodermis.

What happens to stem cell activity as skin ages?

Stem cells decrease in activity, causing less regeneration.

How does aging affect skin healing?

It causes slower healing.

How does aging affect collagen and elastin?

Collagen fibers decrease and elastin fibers lose elasticity, contributing to wrinkles.

How can sun exposure over a lifetime affect aging skin?

It can contribute to sunspots and skin cancer.

What is regeneration?

Replacement of lost cells with the same cell type.

What happens when normal skin cannot be regenerated?

Scar tissue forms.

What are the three types of skin cancer discussed in the slideshow?

Basal cell carcinoma, squamous cell carcinoma, and melanoma.

What causes basal cell carcinoma?

Exposure to UV light.

Where does basal cell carcinoma originate?

In stem cells in the stratum basale.

What does basal cell carcinoma usually look like when it first appears?

A small, shiny elevation that enlarges and develops a central depression with a pearly edge.

Where does basal cell carcinoma usually occur?

On the face.

How is basal cell carcinoma treated?

Surgical removal of the lesion.

What is notable about basal cell carcinoma?

It is the most common and least lethal skin cancer discussed in the slideshow.

Where does squamous cell carcinoma arise?

From keratinocytes of the stratum spinosum.

Where do squamous cell carcinoma lesions usually appear?

On the scalp, ears, lower lip, or dorsum of the hand.

What do early squamous cell carcinoma lesions look like?

Raised, reddened, and scaly.

What can later squamous cell carcinoma lesions form?

Concave ulcers with elevated edges.

How is squamous cell carcinoma treated?

Early detection and surgical removal.

Can squamous cell carcinoma spread to other parts of the body?

Yes. It may metastasize.

Where does melanoma arise?

From melanocytes, usually in a preexisting mole.

What is a risk factor for melanoma mentioned in the slideshow?

Severe sunburns, especially during childhood.

How is melanoma treated when detected early?

Surgical removal of the lesion.

What treatments may be used for advanced melanoma according to the slideshow?

Chemotherapy, interferon therapy, and radiation therapy.

Can melanoma metastasize?

Yes.

What does ABCDE relate to?

Features of skin lesions that are worrisome for cancer.

What does the slideshow recommend to help avoid skin cancer?

No tobacco and minimizing sun tanning.