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)
