Anatomy and pattern recognition ski sense and pain Flashcards
The Integumentary System
Made up of:
• The skin
• The accessory organs such as nails and hair
• accessory glands; e.g. sweat / sebaceous
• Supporting muscles / nerves
Overview of the skin
• Largest body organ; average 2 square metres and 5kg (about 16%)
• Main parts:
Epidermis; superficial, thinner, epithelial
Dermis; deeper, thicker, connective tissue
Hypodermis/subcutaneous layer;
• areolar and adipose tissue
• connected to dermis and underlying tissue via connective fibres
• Storage for fat and blood vessels to skin
• Sensitive to pressure due to nerve endings
Epidermis
Stratified squamous epithelium
Important to prevent water loss, injury,
and stop chemicals and micro- organisms entering
Dermis
• Dermal blood vessels carry nutrients to upper layers of skin and help to regulate temperature.
• contains nerve fibres, sensory receptors, hair
follicles, sebaceous glands, and sweat glands.
Epidermal ridges
Fingerprints (epidermal ridges) formed due to
dermal papillae and interpapilliary pegs of
epidermis
• Sweat glands open on ridges; form fingerprints
• Amplify vibrations triggered when fingertips
brush across an uneven surface,
• Better transmission of signals to sensory nerves involved in fine texture perception.
• Assist in gripping rough surfaces and surface
contact in wet conditions.
Dermis – reticular region
• Net-like bundles of connective tissue; collagen
/ elastic fibres
• Provide strength and elasticity to skin
• Thicker = 4/5 of dermis
Spaces between fibres contain:
• Adipose cells
• Hair follicles
• Sebaceous (oil) and sudoriferous
(sweat) glands
Nail growth
Rate dependent on:
• Age, health, nutrition
• Season, time, and temperature
• Finger/toenails
• Length of digit
Skin glands
• Modified sweat glands, called ceruminous glands, secrete wax in the ear canal.
• Mammary glands, another type of modified sweat gland, secretes milk
Functions of the skin
PROTECTION
VIT D PRODUCTION
TEMPERATURE REGULATION
EXCRETION & ABSORPTION
SENSATION
Vitamin D production
• Certain molecules in skins activated by UV light
• Liver/kidneys modify molecule to form Vitamin D compounds
• Calcitrol helps in absorption of calcium from GI tract
Thermoregulation
Releasing sweat for evaporation (increase/decrease)
Adjusting blood flow within capillary network in dermis
• Acts as a blood reservoir (8-10% blood volume)
• Amount increases during moderate exercise to release heat
• Strenuous activity constricts vessels (to supply muscles/heart); temperature rises
Excretion
• ~400ml water evaporates daily in addition to >200ml sweat
• Also excretes salts, CO2, ammonia and urea
absorption
Negligible water-soluble substances but some lipid-soluble:
• Vitamins A,D,E and K
• O2 and CO2
Can absorb some toxins, including
• Acetone (nail varnish remover)
• Heavy metal salts (e.g. lead, mercury, arsenic)
• Some natural plant toxins
Skin as a sensory organ
Skin is the largest sensory organ in the body
• Contains numerous sensory receptors – nerve endings within the dermis, close to the epidermis
• Pain receptors (nociceptors) – sense tissue damage
• Thermoreceptors – sense temperature changes
• Mechanoreceptors – sense touch – pressure, stretch, tension, blood pressure
Pain
• Superficial somatic pain; skin
• Deep somatic pain; muscles, joints, tendons etc.
• Visceral pain; of deeper tissues/organs. May not feel localised stimuli of somatic pain
• Referred pain; visceral pain felt in/deep to skin overlying/remote from organ
• Phantom limb sensation: patient continues to experience pain after amputation
Wound healing
• Inflammation, in which blood vessels dilate and become more permeable, causing tissues to become red and swollen, is the body’s
normal response to injury
• A deeper injury with broken blood vessels involves the formation of a blood clot
• More complex as multiple layers involved; results in scar tissue
