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Skin
Layers, cells
| Question | Answer |
|---|---|
| What are 2 main components of the integumentary system? | Cutaneous membrane (skin) and the accessory structures (hair, nails, and multicellular exocrine glands) |
| What are the functions of the skin and hypodermis? | Protection, excretion (of salts, water and organic wastes), maintenance of body temperature, production of melanin, production of keratin, synthesis of vitamin D3, storage of lipids in adipocytes, detection |
| What cells does the epidermis consist of? | Stratified squamous epithelium |
| Why does the epidermis rely on the diffusion of nutrients and oxygen within the dermis? | Epidermis is avascular |
| Which type of cell dominates the epidermis? | Keratinocytes |
| How many layers of keratinocytes make up the thin skin? | 4 (0.08mm thick) |
| Which extra layer does the thick skin have? | Stratum lucidum |
| Where can thick akin be found? | Palms of hands and soles of the feeet |
| How many layers of keratinocytes make up the thick skin? | 5 |
| What are the five layers of the epidermis? | Stratum basale, stratum spinosum, stratum granulosum, statum lucidum, stratum corneum |
| Which layer lies closest to the dermis? | Stratum basale |
| Which layer is much thicker in thick skin? | Stratum corneum |
| What does the stratum basale form that extend into the dermis? | Epidermal ridges |
| What projects from the dermis adjacent to these? | Dermal papillae |
| Why are the ridges and papillae important? (Connecting stratum basale to dermis) | Strength of the attachment is proportional to the surface area of the basement membrane |
| What type of cells make up the statum basale? | Basal cells (germinative) |
| What are basal cells? | Stem cells whose division replaces the more superficial keratinocytes |
| What type of cells do skin surfaces that lack hair contain? | Tactile cells (Merkel cells) |
| Why are these cells important? | Tactile cells are sensitive to touch, they release chemicals that stimulate nerve endings |
| How are layers of keratinocytes bound together in the stratum spinosum? | Desmosomes |
| What cells are contained within the stratum spinosum that participate in the immune response? | Dendritic (Langerhans) cells |
| How many layers of keratinocytes does the stratum granulosum consist of? | 3-5 |
| What have keratinocytes started doing by the time they reach the granulosum? | Keratin or keratohyalin |
| What happens to cells as keratin develops? | Cells grow thinner and flatter, their membranes thicken and become less permeable |
| What does keratohyalin form? | Dense cytoplasmic granules that promote dehydration of the cell, as well as aggregation and cross-linking of keratin fibres |
| What are the cells that make up the stratum lucidum like? | Flattened, densely packed, largely devoid of organelles and filled with keratin |
| What is keratinisation? | Formation of protective superficial layers of cells filled with keratin |
| Where doesn't keratinisation occur? | Anterior surface of the eyes |
| How many days does it take for a cell to move from the stratum basale to the stratum corneum? | 7-10 days |
| What is insensible perspiration? | When water from the intestinal fluids slowly penetrates to the surface to be evaporated into the surrounding air. (Unable to see or feel the water loss) |
| What is sensible perspiration? | Water loss from active sweat glands, which people are usually aware of |
| What are the layers of the dermis? | Papillary layer and reticular layer |
| Which layer has dermal papillae? | Papillary layer |
| What does the papillary layer of skin consist of? | Areolar tissue |
| What does the reticular layer of skin consist of? | Collagen and elastic fibres |
| What tissues does the hypodermis consist of? | Areolar and adipose tissues |
| What is a subcutaneous injection? | Injection by means a hypodermic needle |
| What happens to the distribution of subcutaneous fat? | At puberty its distribution changes; Men: Neck, arms, lower breath, buttocks Women: breasts, buttocks, hips, thighs |
| How do the skin secretions protect us from infection? | Sebum and sweat are mostly acidic (pH 4-4.5). Sweat from apocrine glands and drug induced sweat has been found to be slightly basic |
| What are Langerhans cells? | Dendritic cells that contain large granules called Birbeck granules |
| What is xerosis? | Dry skin |
| What are potential causes of dry skin? | Thyroid disorders, weather, central heating/air con, hot baths & showers, harsh soaps, sun exposure, sun exposure, atopic dermatitis and psoriasis |
| What are the two types of sweat glands? | Eccrine and apocrine glands |
| What type of glands are they? | Exocrine |
| Where are apocrine glands stimulated? | Mainly in armpits, genital area and around the nipples |
| What does apocrine gland sweat contain? | Proteins, fats, and other substances that often result in thicker and stickier sweat. This causes sweat odour. |
| Which sweat glands have the larger lumen? | Apocrine glands |
| What do eccrine gland secretions do? | Help to control body temperature |
| Where are eccrine glands located? | All over the body, and in high density in the palms, soles of the feet, and scalp areas |
| What are emollients? | Moisturising treatments applied directly to the skin that help reduce water loss |
| What are different forms of emollients? | Soap substitutes, bath additives, moisturising creams and ointments |
| What is a humectant? | A humectant is a substance that binds with water molecules to increase the water content in the skin itself. It increases the surface of the skin's capacity to hold water |
| What is the effect of occlusion on the skin? | Provides a layer of oil on the skin's surface to slow down water loss |
| What does a lubricant do? | Reduces friction whenever anything rubs against the skin |
| How does oestrogen affect sebaceous glands? | Reduces the size and activity |
| How do androgens affect sebaceous glands? | Increases their size and activity |
| What is the pruritus? | Itching |
| Which neurons trigger itching? | Somatosensory neurons expressing the channel TRVPI |
| Which neurotransmitters are related to itching? | Gastrin-releasing peptide (GRP) -> only found in spinal cord Natriuretic polypeptide b (Nppb) -> released by heart and some somatosensory neurons |
| Which neurotransmitter is more abundant? | Nppb |
| What are the cardinal signs of inflammation? | Tumour, dolor, rubour, calour, (function laesa) |
| What is the first stage of inflammation? | Irritation |
| What is the discharging of pus called? | Suppuration |
| What happens during the granulation stage? | Wounds of tiny, rounded tissue are formed during healing |
| What are the different types of inflammation? | Acute and chronic inflammation |
| Describe the process of acute inflammation? | -Arterioles that supply the damaged area with blood dilate which results in increased blood flow -Capillaries become more permeable, so fluid can move into interstitial spaces -Neutrophils and some macrophages migrate out of the capillaries and venules |
| What are corticosteroids? | An anti-inflammatory medicine which is structurally similar to cortisol |
| What are the different forms of corticosteroids? | Tablets, injections, inhalers and topical steroids |
| What are short-term anti-inflammatory effects of corticosteroids? | -Reduced inflammatory cell activation -Decreased IgE synthesis -Reduced mucosal oedema and decreased local generation of inflammatory prostaglandins and leukotrienes by inhibition of phospholipase A2 -Beta-adrenoreceptor up-regulation |
| What are long-term effects of corticosteroids? | -Reduced T-cell cytokine production, reduced dendritic cell signalling to T-cells -Reduced eosinophil and mast cell deposition in bronchial mucosa -Reversal of excess epithelial cell shedding and goblet cell hyperplasia |
| What are the five main types of topical corticosteroids? | Solutions, lotions, creams, ointments, gels |
| What are the 4 classes of potency for topical corticosteroids? | Mild topical corticosteroids, moderate topical corticosteroids, potent topical corticosteroids and very potent topical corticosteroids |
| When would mild topical corticosteroids be used? | Mild cases of inflammation such as insect bites |
| What potency of corticosteroid would be used for atopic eczema? | Moderate topical corticosteroids |
| What is potency? | Measurement of how powerful the effect of the medication will be |
Created by:
SandersE
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