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Anatomy (Fach) / Anatomy V (Lektion)
- Functions (skin) - thermoregulation - protection - Vitamin D synthesis - Sensory reception --> Innervation by the sympathetic nervous system
- Epidermis (Classification and structure) and other cells in there - origin: ectoderm - stratified squamous keratinised epithelium consisting of 5 layers (keratinocytes): 1. Stratum basale/germinativum - single stem cell layer, cell division and differentiation 2. Stratum spinosum - prickle cell layer consisting of 8-10 layers with lots of dermasomes 3. Stratum granulosum - keratohyalin granules which start to loose nuclei and organelles and turn into keratinised aquames, 3-5 layers 4. Stratum lucidum - transparent layer 5. Stratum corneum - horny layer with dead cells filled with densely packed keratin - Other cells: 1. Melanocytes - melanin-secreting cells (stratum basale) 2. Merkel's cells - mechanoreceptor cells (stratum basale) 3. Langerhans cells - phagocytic cells (stratum spinosum- and granulosum)
- Dermis (classification and structure) - highly vascular connective tissue, comprising 2 layers: 1. Papillary layer - loose connective tissue attached to the epithelium by dermal papillae which interdigitate with the epidermis 2. Reticular layer - dense irregular connective tissue connecting skin to hypodermis
- Hypodermis (Classification and structure) - adipose tissue segregated by loose CT - attaches skin to underlying structures, insulated body and provides energy storage
- Skin appendages (4) - develop from epidermis and extend into dermis and hypodermis 1. Hair - Hair follicle - down-growth of the epidermis, attached to arrector pili muscle - Hair bulb - terminal dilation of the hair follicle (matric cells - dermal papilla) - Hair - keratinised outgrowth of hair follicle 2. Sweat glands a) Eccrine - abundant, coiled tubular glands with distal secretory part, thermoregulatory and excretion b) Apocrine - limited to areola, axilla, anal, genitals, coiled tubular gland with wider lumen, becme functional at puberty 3. Sebaceous glands - branched acinar glands producing sebum (waterproofing and protection) - located between hair follicle and arrector pili muscle --> contraction enhances glandular discharge 4. Nails - Nail plate - several layers of dead compacted cells - Nail bed - beneath nail plate (dermis and epidermis)
- Nerve endings in skin (sensory, motor) 1. Sensory a) Non-encapsulated - Epidermis: between keratinocytes or attached to Merkel cells to detect pain, heat, cold and touch - Dermis: around hair follicles to detect hair displacement b) Encapsulated - Pacinian corpuscles (pressure and vibration) - Meissner corpuscles (light touch) 2. Motor - sympathetic motor nerve endings supply the vascular smooth muscle, arrector pili muscles and sweat glands
- Gut tube (Functions) - Ingestion - propulsion - secretion - mechanical and chemical digestion - absorption - defacation
- Gut tube (structure) 1. Lumen - inside of the gut 2. Mucosa/mucuous membrane - epithelium, lamina propriamuscularis mucosa 3. Submucosa 4. Muscularis externa - Inner circular and outer longitudinal muscles 5. Serosa - serous membrane producing srous watery fluid
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