Skin Continued Region 1 Region 2 Region 3
- Slides: 13
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 – Contain Meissner’s corpuscles – touch receptors – Pain receptors – Capillaries (must nourish the epidermis)
2. Reticular Layer (Deep tissue) Dense irregular connective tissue and Adipose CT – Contains: • Blood vessels • Hair • Pacinian corpuscles: pressure receptors • Oil glands • Sweat glands and ducts • 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 – Produce sweat – Two types 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 Produced by hair follicle: sheath surround hair root Consists of hard keratinized epithelial cells (dead) Melanocytes provide pigment for hair color Structure – • Follicle – produces hair, surrounds root • Shaft – superficial portion above the surface • Root – portion below the surface • Bulb – onion shaped structure that surrounds the follicle. – Arrector pili muscle • Smooth muscle (involuntary) • Pulls hairs upright when cold or frightened – –
Appendages of the Skin Figure 4. 7 a
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
Appendages of the Skin Figure 4. 9
- Milady facial steps
- Stratum lucidum
- Thin skin vs thick skin
- 2-4 completing the square
- Continued division method
- Continued abbreviation
- 8-8 practice completing the square
- Newton's second law
- Chapter 8 section 3 cellular respiration
- Continued adjective
- Continued slide
- Demonstrative adjectives continued answers
- Continued
- Continued proofs transversals and special angles