Skin And Wound Healing Flashcards
(11 cards)
What are the two major classes of skin
Hirsute: thin hairy skin that covers most of the body (for insulation)
Glabrous: covers the surfaces of palms, soles and flexor surfaces of digits
What are the five layers of epidermis
- Stratum Corneum (most superficial): provides mechanical protective layer against abrasion, light, heat and chemicals
- Stratum Lucidum: smooth almost translucent layer found in thick skin of palms, soles of feet, keratinocytes (dead and flattened cells packed with eleidin) produce keratin which protects the skin
- Stratum Granulosum
- Stratum Spinosum
- Stratum Basale (innermost)
What is keratinization and growth of the epidermis
It is the replacement of cell contents with the protein keratin occurs as cells move to skin surface (over 2-4 weeks) in 1mm of skin
What happens with the dermis
In the fingers, soles and feet dermal papillae arranged in parallel lines given a ridged appearance = finger prints
Tough and elastic (connective tissue and collagen fibres which act as shock absorbers) rupture in elastic fibres = stretch marks
Dermal cells - fibroblasts, macrophages, mast cells found in dermis
Dermal structures - small blood and lymph vessels, sensory endings, sweat glands, ducts hairs arrest or Lili muscles and sebaceous glands.
What sensory receptors are in the skin
Meissner’s corpuscle: detects any light as pressure
Pacinian corpuscle: detects deep pressure
Info travels from these receptors to spinal cord by sensory nerves to sensory area of cerebrum
What are the different types of sweat glands
Eccrine: open watery substance not fully active in infants in palms, soles of feet, axillae, groins
Apocrine: sweat glands activate during puberty and secrete alongside hair follicles mix with bacteria on skin
Sebaceous glands: secrete into hair follicles, scalp, face, axillae and groin. Prevents cracking and drying on exposure to heat and sunlight less active in elderly and infants.
What are the functions of the skin
Protection: skin forms waterproof layers a superficial keratinised layer that protects deeper more delicate structures, acts as a barrier
Regulation of body temp: core body remains at 36.8 heat produced by metabolic reactions and lost via radiation, evaporation, conduction, convection
Formation of vitamin D
Absorption: drugs eg nicotine patches, chemicals eg mercury, medication eg chemotherapy
Excretion: urea, aromatic substances, NaCl in sweat
What causes the skin to age
The skin and mucous membrane becomes thin and fragile, fewer capillaries and cell proliferation is decreased results in slower healing of glands.
Elastic fibres are reduced making skin appear dry and wrinkled and collagen fibres become less flexible.
Melanocytes decrease causing greying of hair and skin
How does skin develop in foetus
Epidermis develops from single layer of ectoderm, by end of 4th week thin outer layer of flattened cells cover the embryo.
Brown adipose tissue develops from 17-20 weeks gestation
From 18 weeks vernix caseosa devleops
From 9th week lanugo (thin hairs around) body begin to form which is shed from 36 weeks
What are the stages of wound healing
Inflammation: first few hours wound surfaces become inflamed and blood clot (mainly fibrin) and cell debris fills gap between them.
Proliferation: epithelial cells proliferate around the wound allowing epidermis to meet and grow from down up until full thickness, clot above new tissue becomes scab. Fibroblasts secrete collagen fibres as bacteria removed by phagocytosis.
Maturation: granulation tissue replaced by fibrous scar tissue, rearrangement of collagen fibres occurs and strength of wound increases, scar becomes less vascular. Scar tissue is shiny no sweat glands hair follicles or sebaceous glands.
How does pressure damage cause harm to people
Pressure ulcers develop when large amount of pressure applied to area of skin over short period of time, disruption of blood flow to skin skin becomes deprived of oxygen and nutrients. Conditions like type 2 diabetes can also make a person vulnerable to pressure ulcers, pressure causes pinching of blood vessels stopping blood flow.
