Download - Ch 4 dermis -class
Chapter 4Skin and Body Membranes
“The Dermis”
F. DermisF. Dermis1.Papillary layer
Projections called dermal papillae Pain receptors Capillary loops
2. Reticular layer Blood vessels Glands Nerve receptors
Nerve ReceptorsNerve Receptors
Free nerve endings
• detect temp, mechanical stimuli (such as pressure), pain, & touch
Meissner’s corpuscles
• Tactile, light touch, found in abundance in fingertips, palms, soles, lips, tongue, face, genitals. In dermal papillae.
Pacinian corpuscles
• Deep, pressure, adaptive
G. Normal Skin Color DeterminantsG. Normal Skin Color Determinants1. Melanin
a. Yellow, brown or black pigment
b. Pigment produced by melanocytes
c. Melanocytes are mostly in the stratum germinativum
d. Amount of melanin produced depends upon genetics and exposure to sunlight
2. Carotene
a. Orange-yellow pigment from some vegetables
3. Hemoglobin
a. Red coloring from blood cells in dermis capillaries
b. Oxygen content determines the extent of red coloring
G. MelaninG. Melanin
H. Appendages of the SkinH. Appendages of the Skin
1.Sebaceous glands
a. Produce oil
- Lubricant for skin
- Kills bacteria
b. Most with ducts that empty into hair follicles
c. Glands are activated at puberty
H. Appendages of the SkinH. Appendages of the Skin
2. Sweat glands
a. Widely distributed in skin
b. Two types
Eccrine
Open via duct to pore on skin surface
Apocrine
Ducts empty into hair follicles
c. Sweat and Its Functionc. Sweat and Its Function
i. Composition Mostly water Some metabolic waste Fatty acids and proteins (apocrine only)
ii. Function
• Helps dissipate excess heat
• Excretes waste products
• Acidic nature inhibits bacteria growth
iii. Odor is from associated bacteria
H. Appendages of the SkinH. Appendages of the Skin
3. Hair
a. Produced by hair bulb
b. Consists of hard keratinized epithelial cells
c. Melanocytes provide pigment for hair color Figure 4.7c
d. Hair Anatomyd. Hair Anatomy
i. Central medulla
ii. Cortex surrounds medulla
iii. Cuticle on outside of cortex
-Most heavily keratinized
e. Associated Hair Structurese. Associated Hair Structures
i. Hair follicle
Dermal and epidermal sheath surround hair root
ii. Arrector pilli
Smooth muscle
Goose bumps
iii. Sebaceous gland
iv. Sweat gland
Appendages of the SkinAppendages of the Skin
4. Nails
a. Scale-like modifications of the epidermis
Heavily keratinized
b. Stratum basale extends beneath the nail bed
Responsible for growth
c. Lack of pigment makes them colorless