Chapter 5: The Integumentary System

What are the three major regions of the integumentary system?

1) Epidermis

2) Dermis

3) Hypodermis

Describe the epidermis

Outermost superficial region, made of stratified squamous

Describe the dermis

Middle region, made of connective areolar/dense irregular

Describe the hypodermis. What is its function?

Deepest region, made of adipose tissue, provides protection

Is the epidermis keratinized or non-keratinized?

Keratinized (stratified squamous)

How many layers is the epidermis made of?

4-5 layers

What 4 cell types make up the epidermis?

1) Keratinocytes

2) Melanocytes

3) Merkel cells

4) Langerhans’ cells

Describe the function of keratinocytes

Produce the fibrous protein keratin

Describe the function of melanocytes

Produce the brown pigment melanin

Describe the function of Langerhans’ cells

Macrophages that help activate the immune system, can travel along the skin

Describe the function of Merkel cells

Act as touch receptors in association with sensory nerve endings

List the layers of the epidermis from bottom to top.

1. Stratum germinativum (stratum basale)
2. Stratum spinosum
3. Stratum granulosum
4. Stratum corneum

Describe the stratum germinativum

Deepest level of the epidermis, attached to the dermis, single row of keratinocytes that undergoes rapid division

Describe the stratum granulosum

Second highest level of the epidermis, produce keratin, drastic changes in the keratinocytes occur

Describe the stratum spinosum

Second lowest level of the epidermis, where the nucleus of the disintegrates, and a chain forms, webs begin to attach to desmosomes

Describe the stratum corneum

Top layer of the epidermis, comprised of dead cells joined by tight junctions, and desmosomes; waterproof, protect, insensitive

Describe the stratum lucidum

Thick layer of skin apart of the epidermis only found in the palms and soles

What are the two layers of the dermis?

Top: papillary

Bottom: reticular

What is the papillary layer comprised of?

Areolar connective tissue (elastic and collagen)

What are dermal papillae?

Peg-like projections on its superior surface

What can the dermal papillae contain?

1) Capillary loops

2) Meissner’s corpuscles

3) Free nerve endings

What are Meissner’s corpuscles responsible for?

Sensing gentle touch

What is the reticular layer comprised of?

Dense irregular, adds stretchiness, strength and resiliency to skin

What layer makes up 80% of the skin?

The reticular layer

What is the hypodermis also known as?

The subcutaneous layer

What is the hypodermis composed of?

Adipose and areolar connective tissue

What are the three types of pigments that contribute to skin color?

1) Melanin

2) Carotene

3) Hemoglobin

Describe melanin

Yellow to reddish-black pigment, freckles and moles result from local accumulations of melanin

Describe carotene

Yellow to orange pigment, most obvious in the palms and soles of feet

Describe hemoglobin

Reddish pigment responsible for the pinkish hue of the skin

What are merocrine glands?

Gland responsible for electrolyte secretion (sweat), cools body to maintain a certain temperature

What are eccrine glands?

Sweat glands found in palms, soles of feet, and forehead

What are apocrine glands?

Sweat glands found in the armpits and groin responsible for release of sexual hormones

What are ceruminous glands?

Modified apocrine glands in the external ear canal and secrete cerumen

What are mammary glands?

Specialized sweat glands that secrete milk

What is a nociceptor?

A sensory nerve the detects pain

What are Pacinian corpuscles?

A sensory nerve responsible for sensing deep pressure

What are sebaceous glands?

Oil producing glands typically attached to hair follicles, secrete sebum, also known as holocrine glands

What is a hair follicle?

The lumen where hair strands grows out of

What is the hair bulb?

The base of the hair strand where cells divide, has a blood supply to provide oxygen

What kind of skin layers make up a hair follicle?

Stratum corneum transitions into stratum germinativum as it enters the lumen

What is the hair strand made of?

Near the bulb it is made of non-keratinized squamous and transitions to keratinized squamous into dead cells