Integumentary System Flashcards
Two components of the Integumentary System?
Skin and Associated Structures (hair; oil; sweat glands; sensory receptors; nails)
Skin
cutaneous membrane) [Largest organ in the body; covering the external surface]
Integumentary System Functions
- Regulates body temperature 2. Stores blood 3. Protects body fro external environment 4. Detects cutaneous sensations 5. Excretes and absorbs substances 6. Synthesis of vitamin D
Dermatology
The medical specialty that deals with structure; function and disorders of the integumentary system.
What are the 3 layes of integumentary system?
- Epidermis (part of the skin) 2. Dermis (part of the skin) 3. Subcutaneous tissue (not part of the skin)
Epidermis definition
Thinner; superficial portion composed of epithelial tissue; avascular
Layer composition of Epidermis
keratinized stratified squamous epithelium
4 Princle Types of Cells
Keratinocytes; Melanocytes; Intraepiderml macrophages; Merkel Cells
Keratinocytes
[90%; arranged in 4-5 layers; protein produced=keratin] Several distinct layers in various stages of development. 4 Strata (layers of the epidermis)-[most regions of the body; some exceptions] 1. Stratum Basale 2. stratum spinosum 3. stratum granulosum 4. stratum corneum (thin) 5 Strata (layers of the epidermis)-Exceptions [areas of greatest friction; fingertips; palms; soles] 1. Stratum Basale 2. stratum spinosum 3. stratum granulosum 4. stratum lucidium 5. stratum corneum
Keratin
tough; fibrous protein that helps protect the skin and underlying tissue from abrasions; heat; microbes & chemicals
Lamellar Granules
release a water repellent sealant
Function of Lamellar Granules
- decreases water entry and loss 2. Inhibits entry of foreign materials
Where do Melanocytes come from?
Develop from ectoderm of a developing embryo
Function of Melanocytes
Produce the pigment; melanin
Melanin
a yellow-red or brown-black pigment that contributes to skin color and absorbs damaging UV light.
Melanin Transfer
- Melanocytes have long slender projections that extend between keratinocytes and transfer melanin granules to them. 2. Once inside keratinocytes; melanin granules will cluster to form a protective veil over the nucleus on the side of the skin surface. 3. This is used to shield the DNA material; preventing UV damage from the sun 4. Note: melanocytes are susceptible to damage by UV light
Orgin of Intraepidermal macrophages
Red bone marrow
Function of Inraepidermal macrophages
migrate to the epidermis and participated in immune responses mounted against microbes that invade the skin and easily damaged by UV light.
Role of Intraepidermal macrophages
help other cells of the immune system recognize an invading microbe and destroy.
Merkel Cells (tactile cells)
Are least numerous; and are found in the deepest layer of the epidermis
Function of Merkel Cells
contact the flattened process of a sensory neuron (nerve cell) [aka: Merkel Disc or tactile disc]
What are the 5 Strata (Layers of Epidermis)
- Stratum Basale 2. stratum spinosum 3. stratum granulosum 4. stratum Lucidium 5. Stratum Corneum
Stratum Lucidum Location/Components
Present only in fingertips; palms; soles Components: Four to six rows of clear flat dead keratinocytes with large amounts of keratin
Stratum Granulosum
- 3-5 rows of flattened keratinocytes; organelles are beginning to degenerate 2. Keratohyalin protein (to convert keratin intermediate filaments to keratin) 3. Lamellar granules (release lipid-rich; water-repellent secretion)
Stratum Spinosum
- 8-10 rows of many-sided keratinocytes with bundles of keratin intermediate filaments 2. projections of Melanocytes 3. intradermal macrophages (Langerhan?s cells)
Stratum Basale
Components: 1. single row of cuboidal or columnar keratinocytes that contain scattered keratin intermediate filaments (tonofilaments) 2. stem cells which undergo cell division to produce new keratinocytes 3. Melanocytes 4. tactile epithelial cells associated with tactile disc; scattered among keratinocytes.
Stratum Corneum
Few to fifty or more rows of dead; flat keratinocytes; mostly containing keratin.
Steps in Keratinization
- Newly formed cells in the stratum basale; slowly push to the surface 2. Cells move from one layer of the epidermal layer to the next; accumulating more keratin 3. Nutrients and oxygen diffuse to the ?avascular? epithelium from the blood vessels in the dermis 4. Cells closer to the blood vessels receive more nutrients and oxygen; cells as they rise are farther from the blood vessels and begin to die
How long does Keratinization take?
appoximately 4-6 wees
When does the rate of cell division increase in the Stratum Basale?
increases when outer layers of the epidermis are stripped away (ie: abrasions; burns)
Dandruff
Excessive amount of keratinized cells shed from the skin of the scalp.
Dermis composition
dense irregular connective tissue; collagen and elastic fibers
Functions of Dermis
- Gives the skin great tensile strength 2. Stretch and recoil
Characteristics of Dermis
- Thicker than the epidermis (variable depending on where in the body)-Greatest at soles and palms 2. Blood vessels; nerves; glands and hair follicles
Cells of Dermis
- Fibroblasts 2. Macrophages (few) 3. Adipocytes (few; near the boundary of the subcutaneous layer)
Two principle layers of the dermis
- Papillary Region (thinner; superficial) 2. Reticular region (thicker; deep)
Papillary Region
- 1/5 of the total dermal layer 2. Contains: thin collagen + fine elastic fibers 3. Dermal papillae (small nipple shaped structures that project into the undersurface of the epidermis) 4. Contents of the Dermal Papillae: a. Capillary loops (blood vessels) b. Meissner corpuscles (touch/pressure nerve endings) c. Free nerve endings (temperature; light touch and itching)
Reticular Region
- 4/5 of the total dermal layer 2. Net-like layer attached to the subcutaneous layer 3. Contains: bundles of thick collagen fibers; scattered fibroblasts; wandering cells (macrophages); adipocytes in deepest part with coarse elastic fibers 4. Collagen fibers are more ?regular? in the reticular region and form a ?net-like? orientation. This orientation gives skin more resistance to stretching. 5. Spaces between fibers are filled with: blood vessels; nerves; hair follicles; sudoriferous sweat glands; sebaceous glands 6. Function: provides skin with strength; extensibility (the ability to stretch); elasticity (ability to return to pre-stretch shape)
Epidermal ridges (fingerprints) def.
Bond between the dermis and epidermis on the surfaces of the palms; soles and fingertips
Epidermal ridges function
- Increased surface area (increases number of corpuscles of touch and tactile sensitivity) 2. Increase grip; by increasing friction
Subcutaneous AKA: Hypodermis
(deep to the dermis; NOT part of the skin)
Hypodermis Layer composition
and adipose tissue; Fibers extend from the dermis and anchor the skin to this subcutaneous layer and CT (fascia) found around muscles and bones
Hypodermis Function
Storage for fat
Hypodermis associated structures
Nerve endings (aka: lamellated corpuscles) sensitive to pressure; large blood vessels
What are the three pigments that give skin color?
Melanin; Hemoglobin; Carotene
Melanin Def.
[varies skin color from pale yellow to reddish-brown] Two forms of melanin: 1. Pheomelanin [yellow to red] ? 2. Eumelanin [brown to black] ? hair
Melanocytes
melanin-producing cells; most numerous in epidermis of darker skinned area (penis; nipples; areolae); face; limbs; mucus membranes Number of melanocytes is about the same in all people; the difference in skin color is due to the amount of pigment these cells produce and transfer to keratinocytes
Melanin Orgin
synthesized from amino acid; tyrosine in the presence of tyrosinase
Melanin Organelle
melanosome synthesizes melanin
Hemoglobin
epidermis; skin color is pink to red depending on the oxygen content of the blood in the capillaries of the skin
Carotene
[yellow-orange pigment] Pre-curser to vitamin A; used to synthesize pigments for vision
Accessory structures of the skin
Hair; Glands; Nails
Hair Location
most skin surfaces; exception: palms; fingertips; soles; plantar surfaces of the feet
Hair Function
- Limited; but some protection from the sun rays 2. Decreases heat loss from scalp 3. Eyelashes/eyebrows protect the eyes from debris 4. Nostrils and hair in the ear protect structures from debris 5. Sensing light tough via hair root plexes
Composition of Hair
Dead; keratinized epidermal cells