Skin Flashcards
How does the skin provide sensation
Skin is largest sensory organ with sensors for touch, pressure, pain and temp
How does th skin themroreg
Skin has insulate props as well as the ability to dissipate excess heat, fat layers are insulator
What are the skins metabolic functions
Production of vitamin d3 utilising uv light
Significant store of energy reserve in form of subcutaneous fat
What are the three layers of the skin
Epidermis
Dermis
Hypodermis
What is the epidermis
Composed of a keratinised stratified squamous epi
No blood vessels
What su the Dermis
Composed of layer of fibrocollagenous and elastic connective tissue that contains blood vessels, neves and sensory receptors
What is the hypodermis
Composed mainly of adipose tissue with scattered septa of bundles of collagen running perpendicular to the surface of the skin which helps anchor the skin to the underlying deep fascia
How many layers divides epidermis and what are they
4 Stratum basale Stratum spinosum Stratum granulosum Stratum corneum
What su the stratum basale
Basal layer
Single layer of cells sitting on basal lamina
Serve as stem cells for epidermis and. Mitosic division produce most cells of epidermis
What is the stratum spinosum
Prickle cell layer
Displaces cells upwards
Many desmosomes attaching to eachother
What is stratum granulosum
Cells large num of dense cytoplasmic granules - keratohyaline granules whic contain fligarrin which promotes aggregation of cytokeratin intermediate filaments –> keratin
Most abundant cell in is keratinocytes
What is stratum corneum
Composed of dead squamous Cells packed with keratin
Cells are coated with contents fo keratinosomes which helps glue keratin together and make it water resistant
What are melanocytes
Appear as pale cells with prominent dark nuclei in basal cell layer
Prod melanin
Form melanoproteins
What are langerhans cells
Resident macrophages of epidermis
What are merkel cells
Touch receps found in basal layer of epidermis
Where is the dermis
Directly beneath epidermis of variable thickness
What is the most superficial part of the dermis
Thin papillary dermis which forms dermal papillae which project up and Interdigitate with epidermis papillae at rete ridges
What does the papillae dermis is consist of
Fine collagen and elastic tissue
What is the deeper part of the dermis known as
Reticular Dermis
What does the reticular dermis consist of
Dense irregular connective tissue with thick collagen fibres and elastic fibres embedded in reactively small amount ECm
What does the hypodermis consist of
Mostly adipose tissue occasional bands of dense irregular connive tissue
Aka subcutis
What are the epidermal skin appendages
Hair follicles
Sebaceous glands
Sweat glands
What is a hair follicle
Tubular structure
Through epidermis and Dermis and into hypodermis
5 layers
At bottom hair bulb whic contains dermal hair papillae
What does a hair shafts contan
Cells and keratin and meals oxygen in hair bulb control colour
What are sebaceous glands
Associated with hair follicle
Produce sebum - keeps skin soft and supple
Holocrine secretion
What are arrector pili muscles
Small band smooth muscle associated with hair follicle
From dermis
Receives innervation from symp nervous syst
What are the two types of sweat glands
Eccrine and apocrine
What are eccrine glands
Found everywhere in the skin
Gland is a coiled tube with a duct leading to skin
Watery sweat to skin surface
What is an apocrine gland
Similar structure to eccrine
But restricted to areas such as axillae, groin
Produce milky fluid
Ducts end on hair shaft
What are the 3 plexuses of the skin
Dermis - papillary plexus
Subcutis - cutaneous plexus
Subcutaneous plexus
What is the sensory innervation of the skin
Skin largest sensory organ of body
Free nerve endings - thermo receps, mechanoreceps, nociceptors
Encapsulated nerve endings - meissners corpuscle, pacinian corpuscle
How dos the skin provide protection
Protects against chemical, thermal and mechanical insults
Protects against bacterial and fungal invasion
Protects against desiccation
Protects against uv light
