3. Integumentary System

Pregunta	Respuesta
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
Image: 13d7ed04-7314-4b4a-b5ed-9259e20de271 (image/png)	Image: 517204c2-833d-497c-8699-961adbcd4e07 (image/jpg)
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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	Creado por Jonathan Cash hace más de 9 años