Integumentary System

What structures make up the integument?

The epidermis and dermis, along with skin derivatives such as hair and nails.

What are the two main layers of the skin?

The epidermis and dermis.

Which layer of the skin is superficial?

The epidermis.

Which layer of the skin is deep?

The dermis.

What are the main functions of the integumentary system?

Protection, regulation of body temperature, secretion, and vitamin D synthesis.

How does the integument provide protection?

It acts as a physical, chemical, and biological barrier.

What type of epithelium makes up the epidermis?

Stratified squamous epithelium.

Is the epidermis vascularized?

No, the epidermis is avascular.

How often does the epidermis regenerate?

Every 35–45 days.

How many layers can the epidermis have?

Four or five layers, depending on whether the skin is thin or thick.

Where are new skin cells generated?

In the stratum basale.

What happens to epidermal cells as they move upward?

They are pushed through the layers and undergo keratinization.

What is keratinization?

The process by which cell contents are replaced with keratin, a protein.

What happens to cells after they become keratinized?

They are dead but physically strong.

What happens to the stratum corneum?

Its top layers are sloughed off and replaced by layers from below.

What are the layers of the epidermis from superficial to deep?

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

Which epidermal layer is absent in thin skin?

Stratum lucidum.

What types of connective tissue make up the dermis?

Strong, flexible dense irregular and areolar connective tissue.

Is the dermis vascularized?

Yes, it is highly vascularized.

Is the dermis innervated?

Yes, it is innervated for sensation.

What are the two layers of the dermis?

The papillary layer and reticular layer.

What percentage of the dermis is the papillary layer?

About 20%.

What type of connective tissue makes up the papillary layer?

Areolar connective tissue.

What is the function of the papillary layer?

It provides nutrients to the epidermis.

What are dermal papillae?

Structures that increase surface area for transport of materials into the epidermis.

What percentage of the dermis is the reticular layer?

About 80%.

What type of connective tissue makes up most of the reticular layer?

Dense irregular connective tissue.

What do the collagen and elastic fibers in the reticular layer provide?

Stretch and strength.

What is the hair shaft made of?

Dead keratinized epithelial cells.

What is the function of the hair follicle?

It generates the cells that form the hair.

Where is the hair follicle located?

In the dermis.

What is the arrector pili muscle?

Smooth muscle that raises hair and causes goosebumps.

Where is the arrector pili muscle located?

In the dermis.

What are merocrine (eccrine) sweat glands?

Sweat glands that produce sweat in response to heat or stress and open onto the skin surface.

What is the product of merocrine sweat glands?

99% water and 1% salts/wastes.

Where are merocrine sweat glands found?

All over the body.

What do apocrine sweat glands secrete?

A substance responsible for characteristic body odor.

Where do apocrine sweat glands open?

Onto hair follicles.

What is the product of apocrine sweat glands?

Proteins and lipids that are odorous.

Where are apocrine sweat glands found?

In the axilla and groin.

What do sebaceous glands secrete?

An oily substance called sebum.

What is the function of sebum?

It waterproofs the hair and skin and moisturizes the skin.

Where are sebaceous glands found?

All over the body in association with hair follicles.

What is the hypodermis?

Superficial fascia that supports the skin.

What tissues make up the hypodermis?

Areolar and adipose connective tissues.

What is one function of the hypodermis?

It allows movement of the skin over deeper muscles and bones.

What separates the hypodermis from deeper muscle and bones?

Deep fascia.

What is the order of the integumentary layers from superficial to deep?

Epidermis → dermis → hypodermis.