Chapter 5: The Integumentary System

Chapter 5 · The integumentary system is your body's first line of defense The Integumentary System has 2 parts: 1. Cutaneous Membrane 2. Accessory structures Cutaneous Membrane composed of the epidermis and the dermis · Epidermis ↳ stratified squamous epithelium ↳ avascular ↳ 4 specialized cell types -Keratinocytes: skin thickness and strength -Melanocytes: melanin (pigment) -Merkel cells: help with sensation -Langerhans cells: function in the immune response ↳ the epidermis has 4 layers (5 in thick skin) 5 layers of the Epidermis: ① Stratum Corneum ② Stratum Lucidum (not in thin skin) ③ Stratum Granulosum ④ Stratum Spinosum ⑤ Stratum Basale (underneath Stratum Basale is the dermis) Acronym for the layers in order: Cows Lick Grass and Sometimes “Basal” Cutaneous Membrane Cont'd Sensible perspiration: water loss that you can feel (like sweat) Insensible perspiration: water loss that you cannot sense or feel (diffusion of water from interstitial fluids) ↳ perspiration like this occurs on the top layer of the epidermis: Stratum Corneum · Dermis ↳ lies below the epidermis and is attached to underlying subcutaneous tissue ↳ made of 2 layers of connective tissue: ① Papillary layer (superficial dermis) ↳ contains network of blood vessels and nerve fibers ② Reticular layer (deep dermis) ↳ contains collagen and elastic fibers (for strength and flexibility) · Subcutaneous Layer ↳ also called hypodermis or superficial fascia ↳ consists mainly of adipose tissue (fat) ↳ blood vessels on the superficial region of the subcutaneous fascia (good place for needles) Pigmentation · MELANIN: a pigment produced by melanocytes in the stratum basale ↳ darker skintones are a result of larger melanosomes that carry the pigment · Albinism: a disorder where the melanocytes are unable to make melanin · Freckles: caused by having some larger melanosomes in certain spots of the face · UV radiation increases melanin production, and having naturally darker skin (more melanin) only slightly helps protect against UV rays · CAROTENE: a yellow-orange pigment in your skin, which is also in orange vegetables Accessory Structures · includes hair follicles, exocrine glands, and nails 1. Hair: non-living structures produced by hair follicles ↳ Cushion, protection, insulation and sensation ↳ arrector pill muscles are what causes hair to stand up ↳ hair grows from bulb to shaft ↳ Vellus hair: peach fuzz ↳ Terminal hair: thick hair (eyebrows, armpit) 2. Exocrine Glands · Sebaceous glands ↳ holocrine glands that secrete oil called sebum ↳ holocrine: releases secretions and ruptures the cell at the same time · Sweat glands (sudoriferous lands) ↳ apocrine sweat glands: Secrete their products into hair follicles by form of merocrine secretion ↳ eccrine sweat glands: (also called merocrine sweat glands) and they discharge their secretions directly onto the surface of the skin -these glands are smaller and more numerous, they use sensible persperation -regulation of body temp (cooling) -excretion of water and electrolytes. · mammary glands are anatomically related to apocrine sweat glands · ceruminous glands are modified sweat glands in the ear that make earwax (cerumin) 3. Nails · nails are keratinized epidermal cells that protect the tips of the fingers and toes · grows from the nail root, through the nail body, to a free edge · know the general anatomy of the nail