Chapter 5: the Integumentary System

Functions of the skin (PTSDE)

1. Protection
2. Temperature regulation
3. Sensation
4. Vitamin D production
5. Excretion

Which of these is NOT a primary function of the integumentary system?

A. protection.
B. sensation.
C. absorption.
D. temperature regulation.

C. absorption.

Is the hypodermis part of the skin?

No, it's loose connective tissue that connects skin to underlying structures.

3 characteristics of epidermis

1. Avascular (nourished by diffusion from capillaries in papillary layer)
2. Cells are arranged into layers (strata)
3. Basement membrane separates it from the dermis

Keratinocytes

The most abundant epidermal cells that produce keratin for strength

T or F: There are the same number of melanocytes in all people.

true

Langerhans' cells

part of the immune system

Merkel's cells

detect light touch and superficial pressure

Desquamate

when cells of deeper layers undergo mitosis, move towards the surface, then slough off

Keratinization

when cells move outward through layers, fill with keratin, die, then form a hardened superficial layer

Epidermal strata (Come Let's Get Sun Burnt)

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

Stratum corneum

most superficial layer that contains cornified cells

Stratum lucidum

thin clear zone located in the palms and soles only

stratum granulosum

contains keratohyalin granules, and in the superficial layers the nucleus and other organelles degenerate, and the cell dies

Stratum spinosum

there is limited cell division in this layer, and it contains desmosomes, lamellar bodies, and additional keratin fibers

Stratum basale

this is the deepest portion of the epidermis and is high in mitotic activity

How thick is your skin?

1/2mm to 5mm (epidermis+dermis)

What is the main difference between thick skin and thin skin?

Thin skin lacks the stratum lucidum, while thick skin has all 5 epithelial strata.

Where is thick skin located?

Areas subject to pressure or friction (like palms, fingertips, and soles)

When is a callus called a corn?

when it's over a bony prominence

What is a callus?

an increase in the number of layers of stratum corneum

What are the three things that give skin its color?

1. Pigments
2. Blood circulation
3. Thickness of stratum corneum

Melanin

protects against UV light, comes from AA tyrosine, and can be brown, black, yellow, or red

Melanocytes

processes that extend between keratinocytes and determine skin color (melanin produced by these is transferred to keratinocytes)

What is the production of melanocytes determined by?

genetics, hormones, and exposure to light

Carotene

a yellow pigment from vegetables that accumulates in the stratum corneum, adipose cells (dermis), and hypodermis

Cyanosis

a bluish discoloration of the skin resulting from a decrease in blood oxygen content

What all does the dermis contain?

connective tissue with many fibers, fibroblasts, macrophages, some adipocytes and blood vessels, nerves, hair follicles, smooth muscles, glands, and lymphatic vessels

Sensory functions of the dermis

pain, itch, tickle, temperature, touch, pressure, two-point discrimination

Papillary layer of dermis

1/5 of the overall layer & contains areolar/loose connective tissue with lots of elastic fibers, dermal papillae, capillary beds, Meissner's receptors to sense touch, and free nerve endings to sense pain

Which layer of the dermis is responsible for fingerprints?

Papillary layer

Reticular layer of dermis

4/5 of the overall layer & contains dense irregular connective tissue and collagen/elastic fibers

Cleavage (tension) lines

formed by the elastin and collagen fibers that are oriented in the same direction in the reticular layer

Striae

stretch marks

If desquamation of the epidermis takes place, why doesn't a tattoo fade?

The macrophages in the reticular layer hold the pigment where it is so it doesn't spread to the rest of the body.

Hypodermis

the deepest layer beneath the skin that consists of loose connective tissue (collagen and elastic fibers)

3 types of cells in the hypodermis

1. Fibroblasts
2. Adipose cells (most)
3. Macrophages

What are 2 other names for the hypodermis?

subcutaneous tissue or superficial fascia

How much of the body's fat does the hypodermis contain?

about 1/2

What are the 3 functions of the hypodermis?

1. Energy source
2. Insulation
3. Padding

Where is hair not found?

palms, soles, lips, portions of external genitalia, and distal fingers/toes

What are the 3 layers of hair?

medulla, cortex, cuticle

Medulla

the central core of a hair (C)

Cortex

the bulk of a hair (B)

Cuticle

the hair surface (A)

Dermal root sheath

part of dermis that surrounds the epithelial root sheath

Matrix of hair bulb

source of hair

External epithelial root sheath

This is the stratum basale and remains after injury to supply a source of new epidermis.

Internal epithelial root sheath

This is the white bulb you see when hairs are pulled out

Hair papilla

part of the dermis that projects into the hair bulb and supplies blood

Growth stage of hair growth

matrix adds cells at base of hair root and hair elongates at an average rate of 0.3mm/day

Rest stage of hair growth

follicle shortens and holds hair in place until the hair falls out of the follicle

Arrector pili

a smooth muscle attached to hair follicles that causes "goose bumps" to appear on the skin and the hair to "stand on end" when contracted

The outermost layer of the hair shaft is the
A. cortex.
B. medulla.
C. cuticle.
D. corn

C. cuticle.

Hair is formed from epithelial cells in the
A. matrix.
B. dermal root sheath.
C. hypodermis.
D. cuticle.

A. matrix.

What does the sebaceous gland do?

secretes sebum that prevents drying and may inhibit bacteria

What type of secretion do sweat glands display?

merocrine/eccrine usually (especially on palms and soles), but apocrine in the axillae and genitalia areas

Merocrine (eccrine) secretion

open directly onto surface, and produce isotonic fluid (water + NaCl)

Apocrine secretion

open into hair follicles (like sebaceous glands) and produce odorless organic compounds - bacteria make it smell

Ceruminous glands

modified merocrine sweat glands in external auditory meatus that produce earwax (sebaceous and ceruminous secretions)

What does earwax do?

prevents dirt and insects (along with hair) from getting in your ear and it keeps eardrum supple

Mammary glands

modified apocrine sweat glands

Which of these parts of the body have the most merocrine sweat glands?
A. margin of the lips.
B. soles of the feet.
C. forearm.
D. back of the neck.

B. soles of the feet.

free edge of nail

nail body

eponychium of nail

nail root

nail matrix

What is the nail body made of?

stratum corneum

What is the eponychium of the nail?

the corneum superficial to the nail body (the cuticle)

Where is the nail root located?

under the skin

What two things produce the nail body?

the matrix and nail bed

T or F: Nails grow continuously.

true, at a rate of 0.5-1.2mm/day

What makes up the integumentary system?

skin, hair, glands, nails

Which of these qualities must a medication possess to be readily absorbed from a skin patch?
A. lipid soluble.
B. water-soluble.
C. must contain keratin.
D. must be acidic

A. lipid soluble.

In what layer of the skin does vasodilation/constriction take place?

the papillary layer of the dermis

Sweating usually happens after exercise. What specific glands and in what layer of the skin are they found?

Vitamin D (calcitriol), a hormone, aids in the absorption of what ion?

Calcium (Ca++), by stimulating uptake of Ca++ from intestines

What is calcium used for?

bone growth/repair, clotting, & nerve and muscle function

What are sources of calcitriol (Vitamin D)?

dairy, liver, egg yolks, supplements

First-degree burn

epidermis

Second-degree burn

part of dermis

Third-degree burn

dermis and epidermis are destroyed

Partial thickness burn

includes 1st and 2nd degree burns (epidermis and part of dermis destroyed)

Full thickness burn

3rd degree burn (dermis and epidermis destroyed)

What is the rule of nines?

Adult:
each upper limb = 9%
each lower limb = 18%
trunk = 18%
head and neck = 9%
perineum and genitalia = 1%

Child:
each upper limb = 9%
each lower limb = 17%
trunk = 16%
head and neck = 15%
perineum and genitalia = 1%

7 effects of aging

1. Skin is more easily damaged because the epidermis thins and amount of collagen decreases
2. Skin infections will be more likely
3. Wrinkling occurs because of a decrease in elastic fibers
4. Skin becomes drier
5. Blood supply decreases because of a poor ability to regulate temperature
6. Melanocytes decrease (vitiligo) or increase (age spots)
7. Risk of skin cancer increases because sunlight ages skin

Actinic keratosis

rough scaly patches on the skin on areas that are sun exposed

What are the ABCDEs of melanoma?

asymmetry, border, color, diameter, evolving