Integumentary System

What is the largest organ of the body?

The skin

What is skin vital for?

Temperature regulation, protection against water loss, and invasion from microorganisms

What are the two major regions of the integument?

The epidermis and dermis

Most of the epidermis is made of…?

Keratinocytes

Keratinocytes

Cells that produce the protective protein keratin

What is the most superficial layer?

The epidermis

What does the dermis primarily consist of?

Collagenous fibers

What is not a layer of the integument but anchors the integument to underlying bone or muscle?

The hypodermis

How can you determine the epidermis layer?

By the epithelial cells

How can you distinguish the hypodermis?

By the abundant adipose tissue

What are the keratinocytes of the epidermis composed of?

Keratinized stratified squamous epithelium

What is keratins purpose?

It protects the lower layers of the epidermis from wear and tear

Strata

The number of layers of the epidermis

Does the epidermis have blood vessels between the cells?

No

The epidermis is…

Nourished by the vessels in the dermis

What is the deepest layer of the epidermis?

The stratum basale

Basement membrane

The way the single layer of cells are attached to the dermis

Melanocytes

The specialized cells in the stratum basale

Melanin

Brown pigment produced by melanocytes

Melanin purpose

Protects the stratum basale from the damaging effects of ultraviolet radiation

The layer of numerous cells superficial to the stratum basale is?

The stratum spinosum

What are the stratum basale and stratum spinosum classified as?

The stratum germinativum

What layer of granular cells is superior to the stratum spinosum?

The stratum granulosum

What layer is superficial to the stratum granulosum?

The stratum lucidum

Where is the stratum lucidum located?

The palms of the hand and soles of the feet

What is the most superficial layer of the integument?

The stratum corneum

What is the epidermis made of?

Keratinized stratified squamous epithelium

What is the first phase that occurs in the stratum basale?

The cells are involved in rapid cell division

What is the second phase that occurs in the stratum spinosum?

Cells undergo a process of producing precursor molecules that leads to the general waterproofing of the cells by keratinization

What is the final phase that occurs?

Completion of the waterproofing process

How often does the epidermis renew itself?

Every 5-6 weeks

What is the dermis responsible for?

The structural integrity of the integumentary system

What are the two major regions of the dermis?

The papillary and reticular layer

What is the largest layer of the dermis?

The reticular layer

What are the majority fibers of the dermis?

Irregularly arranged collagenous along with lesser numbers of elastic and reticular fibers

What do collagenous fibers do?

Provide strength and flexibility

What do elastic fibers do?

Provide elasticity to the skin

Where do blood vessels occur?

In the dermis

What do the blood vessels do?

Bring nutrients to the dermis and epidermis

Why are dermal blood vessels important?

They release heat to the external environment

What do nerves in the dermis do?

Receive sensory inputs and transmit impulses to the central nervous system

What is sensory information received by?

Light touch receptors of the dermis

Where are tactile (meissner) corpuscles located?

In the upper portion of the dermis

Where are tactile (merkel) discs located?

In the upper and lower dermis

What do the two receptors do?

Allow for the perception of very slight touch stimuli

Where are deep touch or pressure receptors found?

In the dermis

What do lamellar (pacinian) corpuscles do?

Sense pressure

What are naked nerve endings in the dermis that respond to numerous environmental stimuli?

Pain receptors

What is another name for the hypodermis?

Subcutaneous tissue

How does the hypodermis attach to the dermis?

By collagenous and elastic fibers

What are two broadly distributed glands?

Sweat glands and sebaceous (oil) glands

What are the secretory parts of sweat glands composed of?

Simple cuboidal epithelium and connective tissue

What are the two different types of sweat glands?

Eccrine and apocrine

Eccrine glands

Sensitive to temperature and produce normal body perspiration

Perspiration reduces the temperature of the body by?

Evaporative cooling

Apocrine sweat glands

Secrete water and a higher concentration of organic acids than eccrine glands

What are two more localized glands?

Mammary and ceruminous glands

What do sebaceous glands secrete?

An oily material called sebum

What does sebum do?

Lubricates the hair and decreases the wetting action of water on the skin

Hair consists of keratinized cells produced in what?

Hair follicles

Shaft

The portion that erupts from the skin surface

Root

A deeper portion that is enclosed by the follicle

Hair bulb

The actively growing portion of the hair

What hair has a short growth phase and long rest phase?

Axilla, groin, eyelashes and eyebrows

What hair has a longer growth phase?

Scalp hair and beard hair

Dermal papilla

A region with blood vessels and nerves that reach the hair bulb

Root sheath

Formed by the outer dermal layer of connective tissue and an inner epithelial layer

Hair “standing on end” is caused by what?

The contraction of arrector muscles

Arrector muscle

A cluster or parallel smooth muscle fibers that connect the hair follicle to the upper regions of the dermis

What are arrector muscles controlled by?

The autonomic nervous system

Medulla

The central portion of the hair enclosed by an outer cortex

What is the layer superficial to the cortex?

The cuticle of the hair

What does most of the nail consist of?

The nail body

What part of the nail do you clip?

The free edge

Eponychium

The cuticle of the nail

Nail root

The area that generates the rest of the nail body

The nail bed is?

The layer deep to the nail body

Lunule

The small white crescent that occurs at the base of the nail

Hyponychium

The region under the free edge of the nail

On each side of the nail is?

The nail groove

Nail groove

A depression between the nail body and the skin of the fingers

Nail fold

The ridge above the groove