Integument Flashcards
What are the layers of the skin?
From outside to inside:
Epidermis - epidermal barrier: stratified squamous epithelia -> multiple layers of flattened cells
Dermis: with nerve and blood vessels and tough connective tissue
Hypodermis: Subcatenouns fat and connective tissue
What are the main functions of the integument?
Protection: Microorganisms, physical injury, temperature, UV (synthesis of vitamin D), immunologic barrier
Homoestasis: prevent water loss, Thermoregulation
Sensory reception (nerve endings)
How is Vitamin D in the skin produced?
7-dehydrocholesterol stored in the skin -> under the direction of UV light and heat Vitamin D3 is formed
What is the structure of the Epidermis look like?
Keratinocytes -> Keratinized (protein) + Lipid, stratified (mulit-layer), squamous (flatterned) epithelium
What are the layers of the Epidermis? EXAM
From inside to outside -> they produce keratinocytes -> differentiate on their way outside
Basale (stratum germivativum)-youngest: single layer attached to Dermis -> dividing through mitosis -> pushed outwards
-Spinosum
-Granulosum
-Lucidum (thick - only on hands and soles)
-Corneum
What are keratinocytes and how are they connected?
Produced by basal cells -> skin cells within the epidermis are connected through cellular junctions that connect to keratin (intermediate) filaments (Desmosomes)
What are melanocytes?
-located in stratum basale and they produce melanin (Eumalin - brown/black or Pheomelanin: yellow/red (UV reactive)
Where do melanocytes originate?
Like neuron cells, they migrate from the neural crest
(melanoma is a severe form of cancer because it migrates easily)
Where exactly is Melanin produced?
In the Melanocytes (Golgi-Endosome -> Melanosome) and they are transferred through extension (microtubules) into keratinocytes to protect the nucleus from UV damage
What is the function of the basal membrane?
-Adhesion between Epidermis and Dermis: Hemidesmosome
-Selective molecular filter
What is the function of the Dermis?
-Provides nutrition to the Epidermis (contains blood vessels)
What does the Dermis consist of?
Mostly collagen (strong structural protein), and ground substance (proteoglycan provide polar charge and attracts water -> turgor (maintains water in the skin)
What are the two layers in the Dermis?
-Papillary: increases surface area for adhesion to Epidermis
-Reticular: “hide”, thicker layer with blood vessels
What is the blister on the skin?
When the Epidermis separates from the Dermis -> can happen with strong robbing
What is the difference between thick and thin skin?
The thick skin has stratum lucidum and a thicker stratum corneum
Where are the nerve endings located to sense pain, temperature, vibration, etc. on the skin?
In the dermis
How is temperature regulated in the skin?
-Arteriovenous anastomoses (no nutritional blood flow bc no capillaries) arteriole to venule
-Sweat glands
-Arrector pili muscles (Sympathetic NS: NE to alpha/ß receptor -> Piloerrection when scared or cold (goosebumps)
-Sebum (sebaceous glands, oily substance as barrier to reduce heat loss)
Why is there decreased blood flow on the skin in cold environments?
Because blood is a source of heat, and we don’t want to loose heat -> kept in the center of the body in cold environments
What are the sweat glands?
-Exocrine glands that secrete substances into a duct
-Innervated by sympathetic NS:
ACh -> muscarinic receptor (weird bc sympathetic usually secrete NE to alpha/ß receptor)
What happens if an antimuscarinic drug is taken in the heat?
Risk for overheating b/c less ability to sweat
What types of sweat glands are there?
Eccrine: most numerous, open through pores; 99% water and some waste and salts
Apocrine: in axillary, anal, and genital areas opens into hair follicle duct and lubricates hair follicle -> oily
-it mixes with bacteria
What are modified apocrine glands
Ceruminous glands: secrete ear wax
Mammary glands: secrete milk
What are sebaceous glands?
-exocrine glands located everywhere except palms, soles, sides of
feet
-secrete sebum: oily substance to prevent heat loss on the skin
What does sebum consist of?
-Triglycerides, cholesterol, cellular debris -> make it oily
-Prevents evaporation of moisture: bc as an oil it doesn’t mix with water and prevents water loss
-Hormonally regulated: Androgen and estrogen increase production of sebum (puberty -> more sebum ->bacteria causes acne -> estrogen decrease sebum production (child control drug)
What is the Pilosebaceous unit?
Hair follicle: Errectopilomuscle (cause the hair to stand) + sebum production (lubricates)
What is the cyclical growth of the hair follicle?
Anagen: growth phase - hair is thickest and longest
Catagen: transitional
Telogen: resting phase -> hair falls out and will be replaced
How can drugs interfere with cyclical growth?
Produce more hair in the anagen growth phase
Male hair baldness, growth of eyelashes
How are nails structured?
On top, there is the nail plate, with the Lunula on the end - next to Eponychium (Cuticle)
Underneath: Nail bed: epidermis -> Pink bc lots of blood flow: nail matrix (Nail will grow normal unless Nail bed is damaged)
