3121874
Description
Flashcards by Jonathan Cash, updated more than 1 year ago
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Created by Jonathan Cash
almost 9 years ago
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| Question | Answer |
| List the 11 structures of skin. | Epidermis, Dermis, Subcutaneous, Hair Follicle, Sweat Glands, Sebaceous glands, Blood vessels, nerves, collagen, elastin, arrector pili muscle |
| List the 3 layers of the skin What are the two main layers? | - Epidermis - Outer layer - Dermis - Beneath Epidermis Hypo Dermis - Beneath the Dermis |
| What is Epidermis | • 5 layers (strata) • Epithelial tissue (stratified squamous) • Avascular • Keratinocytes (produce keratin) • In a health skin, all layers are completely replaced every 25 - 40 days |
| What are the layers of Epidermis From superficial to deep | Corneum Lucidum Granulosum Spinosum Basale |
| Epidermis - Stratum Corneum | • Accounts for approx 75% of epidermal thickness : 20-30 cells thick • Made entirely of keratin • Cells overlap like tiles on a roof. Surface cells flake off. • Keratin provides a tough protective coating • Protects deeper layers from external environment • Protect against water loss |
| Epidermis – Stratum Lucidum | • Only present where the skin is thick and hairless e.g. soles of the feet • Thought to assist in the transmission of water through the skin. • Only a few cells thick. |
| Epidermis – Stratum Granulosum | • Represents the change from living cells to dead keratinised cells. Cells lose their organelles and become flattened. • Varies in thickness. Usually 3 – 5 cells thick. |
| Epidermis – Stratum Spinosum | • Often termed the ‘prickle cell layer’ due to the cells having projections on their outer surface to encourage a close cellular structure. • Minimal cell division is possible. |
| Squamous Cell Carcinoma homeostatic imbalance | • Arises from Stratum Spinosum • If not treated will spread to other sites - usually lymph nodes • Raised, red & scaley. May form concave ulcers • Common on scalp,ears, lip, back of hand. |
| Epidermis - Stratum Basale | • In contact with the dermis below • 10-25% of cells are melanocytes MELANIN • Receives nourishment from dermal blood supply • Constant cell reproduction takes place (mitosis). Old cells push upwards away from nutrient supply. • Tactile disks are present to detect light touch |
| Basal Cell Carcinoma homeostatic imbalance | • Least malignant • Most Common • Arises from the Basal Layer of the epidermis. • Begin as a shiny nodule that later develops a depressed centre and raised edge. |
| Malignant Melanoma homeostatic imbalance | • Rarest, but most deadly skin cancer. • Metastasizes rapidly to lymph and blood vessels. • Cancer of melanocytes, so appears usually as a dark area of skin. May be raised or flat and can change in shape and colour. |
| Dermis | • Underliestheepidermis. • Varies in thickness e.g.thicker on palms and soles, thin on eyelids and lips. • Two regions-Papillary and Reticular. |
| Papillary Layer | • Area under the epidermis • Makes up 20% of dermal thickness • Made up of loose areolar, collagen and elastic connective tissue. • Uneven surface that ‘dovetails’ into basal layer above. • Made up of ‘Dermal Papillae’ - finger-like projections containing capillaries and nerves. • Give characteristic lines to palms, soles and fingertips that enhance gripping and friction. |
| Reticular layer | • Deeper layer – 80% of dermal thickness. • Dense irregular connective tissue • Contains, sweat glands, sebaceous glands, hair follicles, blood vessels and nerves. • Collagen and elastin found here. • Collagen gives strength to skin. Helps attract & bind water, therefore assists in maintaining hydration. • Elastin fibres allow skin to stretch and recoil. |
| Subcutaneous Layer or Hypo Dermis | Lies beneath the dermis Anchors the skin to underlying structures. Adipose tissue cushions and insulates. Contains nerve endings that sense deep pressure and high frequency vibration. |
| Appendages of the skin Sebaceous glands | • Most are connected to the hair follicles • Secrete oily substance called sebum - acts as a lubricant for skin and an antibacterial agent. • More active in puberty |
| Two Sweat Glands (sudoriferous) | Merocrine/Eccrine Apocrine |
| Merocrine/Eccrine | • Most common • Open onto skin surface via a duct • Sweathasahighwater content. • Primaryfunction–to cool the body |
| Apocrine | • Duct empties its contents into a hair follicle • Functions mainly at puberty • Generally found in axilla and groin. • Decomposes to form body odour. |
| Arrector Pili Muscle | • Involuntary smooth muscle attached to hair follicle at one end and epidermis at the other. • Contracts in response to fear, cold and touch. • Gives skin its characteristic ‘goose bumps’. |
| Functions of the skin | • Sensation • Heat Regulation • Absorption • Protection/Immunity • Excretion • Synthesis of Vitamin D |
| Sensation | • Receptors in the dermis detect sensations • Touch, pain, heat, cold, vibration, texture and pressure. • Lay at varying depths in the dermis. |
| Heat Regulation- thermo regulation | Temperature is regulated by blood vessels in the dermis • Vasodilation • Vasoconstriction |
| Vasodilation | high temp causes blood vessels to dilate, releasing more heat - skin becomes pink. Sweat glands activated |
| Vasoconstriction | low temp, vessels constrict maintaining temp to body core, skin becomes pale |
| Absorption | Topically applied products such as drugs, chemicals and some skin care products, have the ability to be absorbed into the skin layers if they are lipid soluble. |
| Protection/Immunity | • Keratinocytes, sebum, mucous • Intact skin prevents entry of foreign substances. • Secretions from the skin form the ‘acid mantle’ which aids in creating a healthy environment. • Pigment melanin protects from ultra violet ray damage. • Adipose tissue provides protection of underlying structures. |
| Excretion | • Skin excretes waste via the sweat glands. • Water, salts, urea, uric acid and ammonia are eliminated from the body in this way. |
| Synthesis of Vitamin D | • On exposure to UV light a substance in the skin called 7 dehydrocholesterol is converted to Vit D in the liver and kidneys. • Vit D required for absorption of calcium & phosphorus |
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