Anatomy Chapter 5&6

Protection

Body temperature regulation

Sensory Perceptions

Synthesis of vitamin D

Emotional expression

Reservoir of blood

process of replacing viable cells in the stratum basale with more and more of the waxy keratin protein as cells move from the deepest layer to the surface layer

Keratinocytes: makes up 90% of the cells. produce keratin (a tough fibrous protein that provides protection)

Melanocytes: produce the pigment melanin that protects against damage by UV radiation

Langerhans cells: macrophages that originated in the red bone marrow. They are involved in the immune responses

Merkel cells: function in the sensations of touch alone with the other adjacent tactile discs (receptors)

• stratum basale: bottom
• (deepest) layer. Continuous cell division occurs here and produces all the
• other layers.

• stratum spinosum:8–10
• keratinocytes

• The
• non-dividing cells of the 3rd
• layer (stratum granulosum) are
• filled with granules of keratin.

• stratum lucidum:4th
• layer but is only present in thick skin (the skin of the fingertips, palms, and
• soles).

• stratum corneum: always
• outermost, composed of approximately 20 layers of flat cell-remnants that are
• like “bags of turtle wax” (dead keratinocytes with no cellular organelles
• filled with only keratin protein.)

is composed of connective tissue containing collagen and elastic fibers.

• papillary region: lies
• just below the epidermis and consists of areolar connective tissue containing
• thin collagen and elastic fibers, dermal papillae (including capillary loops),
• corpuscles of touch and free nerve endings.

• reticular region: consists
• of dense
• irregular connective tissue containing collagen and elastic fibers,
• adipose cells, hair follicles, nerves, sebaceous (oil) glands, and sudoriferous
• (sweat) glands

• are “tension lines” in the
• skin that indicate the predominant direction of underlying collagen fibers.

• resists
• damage and offers protection to underlying tissues.

• provides
• temperature stability and prevents dehydration, and yet is capable of limited healing.

• •Merkel
• discs, free nerve endings (detect many stimuli), Meissner
• corpuscles, and hair root plexuses

• •Pacinian
• corpuscles

The shaft (above the skin surface)

The follicle (below the level of the skin)

A root that penetrates into

  the dermis includes:

•An epithelial root sheath

•A dermal root sheath

• Hair helps with touch sensations and protects the body against the harmful effects
• of the sun and against heat loss.

Sebaceous (oil) glands are connected to hair follicles.

They secrete an oily substance called sebum which does 2 important things:

•Prevents dehydration of hair and skin

•Inhibits growth of certain bacteria

• Eccrine sweat glands are the most numerous. They secrete a watery solution (600 ml per day) that helps
• to cool the body and eliminates small amounts of waste.

• Apocrine sweat glands are
• located mainly in the skin of the axilla, groin, areolae, and bearded facial
• regions of adult males. They secrete a slightly viscous sweat (Where body odor comes from)

Ceruminous glands are modified sweat glands located in the ear canal.

Epidermal wound healing occurs following superficial wounds that affect only the epidermis.

Return to normal function is the rule

Deep wound healing occurs when an injury extends to the dermis and subcutaneous layer.

Loss of some function and development of scar tissue is the rule.