The Integumentary system Flashcards
integumentary system
The role of the components in performing the functions of the integumentary system:
components of the integumentary system:
• skin
• Hair
• Nails
• exocrine glands
• functions of relevant components of the integumentary system:
• vitamin D synthesis
• Protection
• cutaneous sensation
• excretion
• The components and processes involved in temperature regulation:
• the role of the hypothalamus, sweat glands, arterioles and hair erector muscles
• the effect of sweating and shivering on body temperature
• the effect of vasoconstriction and vasodilation on body temperature
Skin
• The largest organ in the body– surface area of 1.5-2m2
• It contains accessory structures: glands, hair and nails
• Thickness varies over the body – palms and soles are thickest
• Made to two layers with a subcutaneous layer which covers and protects the underlaying structures
• Epidermis– outer layer
• Dermis– deeper layer
• Hypodermis –the subcutaneous layer
Epidermis
• Composed of layer of stratified keratinised squamous epithelium.
• No blood vessels or nerves
• Grows outwards and cytoplasm is replaced by keratin as the cells reach the surface and die (squames)
• Squames rub off and are replaced.
• Full replacement takes around one month
• Protective waterproof barrier
Dermis
• A tough elastic layer containing the proteins elastin and collagen
• Contains:
• Arterioles and capillaries
• and lymph vessels
• sensory nerve endings
• sweat glands and their ducts
• hairs, Arrector pili muscles
• sebaceous glands.
• Also contains immune cells – mast cells and macrophages
Receptor cells
Receptor cells - these act as transducers– converting sensory information into electrical energy for the specific stimulus they detect Remember…
Stimulus, receptor, coordination, effector, response Action potential, neuromuscular junctions
Sweat Glands
Two types
• Eccrine – majority all over body - clear watery fluid, pores on the surface lead to bodies in the subcutaneous layer
• Apocrine – armpits and groin area via hair follicles – more viscous fluid and odour, active from puberty, specialised type creates ear wax
• Main function is to support thermoregulation
Hair
• Grow outwards from the follicle as the cells move away from the bulb the cytoplasm changes to keratin
• Colour determined by genetics -the amount and type of melanin produced.
• White hair is produced when the melanin production ceases in the follicle.
• Arrector Pili muscle (smooth) contraction causes hair to stand away from the skin and causes ‘Goosebumps’
• Sebaceous glands secrete sebum – oily antimicrobial substance that prevents drying and cracking of skin
Nails
• Hard horny keratin plates that protect the tips of toes and fingers
• The root is embedded in the skin, cells in the geminal matrix divide and push out causing growth
• Subject to physical as well as pathogenic damage, no blood supply so take a long time to heal
Functions of the skin
• Protection=Physical barrier against water loss and infection. Contains melanocytes that produce melanin which protects against harmful UV rays. Limits absorption.
• Formation of vitamin D=Lipid based substance called 7-dehydrocholesterol is converted to vitamin D by sunlight which used to make calcium and phosphate for bone maintenance.
• Cutaneous sensation=Specialised cells concentrated in specific areas such as fingertips that provide environmental information
Effects of aging on the skin (core A link)
• Dermis and epidermis thins and elasticity reduces – easy to tear and wrinkles and sagging caused
• Thermoregulation becomes less efficient – heat/cold injuries more common
• Less sebum produced – dry skin
• Vitamin D synthesis decreases – weaker bones
• Loss of pigmentation causes grey/white hair and less hair
Atopic means sensitivity to allergens
• Eczema is the name for a group of inflammatory skin conditions that cause itchiness, dry skin, rashes, scaly patches, blisters and skin infections.
• There are seven different types of eczema:
• atopic dermatitis – Atopic Eczema
• contact dermatitis
• dyshidrotic eczema
• nummular eczema
• seborrheic dermatitis
• stasis dermatitis.
• For lighter skin, eczema can present as red, inflamed skin.
• For darker skin tones, eczema can present as brown, purple, grey or ashen
Layers of the epidermis
• The epidermis is made up of five layers.
• The outer layer: the stratum corneum is 10-15 layers of cells thick and when dry the stratum corneum is approximately 10μm thick.
• It has been described with a bricks and mortar construction with a lipid matrix holding the cells in place.
• It acts as a physical barrier retaining water and preventing the passage of antigens
Causes
• There is no known single cause for atopic eczema. There is substantial evidence indicating a strong genetic susceptibility.
• It leads to a dysfunctional skin barrier and immune system dysregulation
• The gene that makes the protein filaggrin is essential for the conversion of eratinocytes to the protein/ lipid squames that make up the outermost varrier laver of the skin.
• Loss of filaggrin function causes skin barrier dysfunction and loss of water leading to dryness and itching.
• Also make the skin susceptible to allergens, leading to hyperreactivity and induction of immunoglobulin E (IgE) autoantibodies.
• Also predisposes the skin to colonization or infection by microbes, such as Staphylococcus aureus, also leading to an inflammatory response and further damage to the skin barrier.
Atopic eczema
• The most common type of eczema in children but can also develop in adults. Around 70–90% of cases occur before 5 years of age, with a high incidence of onset in the first year of life.
• It’s a chronic condition that can ‘flare up’ as well as clear completely at times – linked to environmental exposure to just about anything – many people will come to learn their triggers and avoid them.
• IL-4 and IL-13, two cytokines known to drive the inflammatory response are present in atopic eczema in response to allergens on the skin surface. This causes itching, breakdown redness and heat
Data and statistics
• Atopic eczema is common, and the prevalence is increasing
• About 10–30% of children (mainly face, hands, inside elbows backs of knees)
• About 2–10% of adults
• Rates of active disease are highest among children (0-17 years; 12.3%) and older adults (75+ years; 8.7%)
• There is no difference in prevalence based on sex and ethnicity
• Around 70–90% of cases occur before 5 years of age, with about 45% of cases beginning in the first 6 months of life and about 60–65% of cases in the first year of life
• It is most common where both parents are effected, 80% chance in children
Impact on the body systems
• Skin changes during flare ups may include:
• Blisters with oozing and crusting
• Dry skin all over the body, or areas of bumpy skin on the back of the arms and front of the thighs
• Ear discharge or bleeding
• Raw areas of the skin from scratching
• Skin colour changes, such as more or less colour than the normal skin tone
• Skin redness or inflammation around the blisters
• Thickened or leather-like areas, which can occur after long-term irritation and scratching
Will need a multidisciplinary approach – dermatologist
Treatments (NICE)
• A stepped approach is recommended for the management of atopic eczema:
• Emollients are the first-line treatments during both acute flares and remissions of the condition.
• The use of topical steroids should be considered for red, inflamed skin. The lowest potency and amount of topical corticosteroid necessary to control symptoms should be prescribed, depending on the severity of the flare.
• If there is persistent, severe itch, or urticaria, a one-month trial of a non-sedating antihistamine should be considered.
If itching is severe and affecting sleep, a short course of a sedating antihistamine should be considered if appropriate.
• If there is severe, extensive eczema, a short course of oral corticosteroids should be considered.
• if eczema is weeping, crusted or there are pustules with fever or malaise secondary bacterial infection should be considered and antibiotic treatment should be prescribed
