Download Notes on Integumentary System (Dermis)

Skin Continued
Region 1
Region 2
Region 3
Dermis (Region 2)
Structure
– Collagen and elastic fibers located throughout the
dermis
• Collagen fibers give skin its toughness
• Elastic fibers give skin elasticity
– Blood vessels
– Differs in thickness
(ex. thick on feet and hands/thinner on eyelids)
2 Layers of the dermis
1. Papillary layer (upper) made of
areolar connective tissue
– Upper region (papillary) –
Dermal papillae – projections
that increase surface area.
– Cause ridges in epidermis:
make our fingerprints
– Meissner’s corpuscles –
touch receptors
– Pain receptors
– Capillaries (must nourish
the epidermis)
– Hold epidermis to the
dermis
2. Reticular Layer (Deep tissue) Dense irregular connective
tissue and Adipose CT
– Contains:
• Blood vessels
• Hair
• Pacinian corpuscles: pressure receptors
• Oil glands (sebaceous)
• Sweat glands and ducts (eccrine and apocrine)
• Heat and cold receptors
• Phagocytes (phago- eater) immune cells
Hypodermis or Subcutaneous layer
(Region 3)
• Function
• Attaches dermis to underlying bone and muscle
• Stores body fat (approx. ½ of the body’s fat)
What type of tissue must this be?
Appendages of the Skin
Exocrine Glands
1. Sebaceous glands
– Located by hair root
– Produce oil (sebum)
• Lubricant for skin (keeps it soft)
• Prevents brittle hair
• Stops excess evaportion
– Cause blackheads and pimples
• Gland becomes enlarged
because a build up of waste
products from the bacteria on
the surface of the skin
2. Sweat glands (AKA: Sudoriferous)
– Produce sweat
1. Eccrine
– Found everywhere but in margin of lips, nail beds,
and eardums
– Open via duct to pore on skin surface
2. Apocrine
– found in armpit, pubic and areola
– Ducts empty into hair follicles
Sweat Composition
– Mostly water, Salts and Urea (nitrogen
waste also found in urine)
• Function
– Helps dissipate excess heat (cools the body)
– Excretes waste products
– Acidic nature inhibits bacteria growth
3. Hair
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Produced by hair follicle: sheath surround hair root
Consists of hard keratinized epithelial cells (dead)
Melanocytes provide pigment for hair color
Arrector pili muscle
• Smooth muscle (involuntary)
• Pulls hairs upright when cold or frightened
Accessory Organs - Wax
• Wax (ceruminous) – located in outer ear canal
– Produces cerumen
– Secretions provide defense against foreign bodies
Accessory Organs - Nails
• Nails
– Scale-like modifications of the epidermis
• Heavily keratinized
– Stratum basale extends beneath the nail bed
• Responsible for growth
– Lack of pigment makes them colorless
• Function
– Grasp and manipulate objects