Histo lec semis

• epidermis - epithelial layer of ectodermal origin, outermost layer of the skin
• dermis - layer of mesodermal connective tissue, thickest layer divided into papillary and reticular layer
• epidermal ridges - extension of the epidermis to dermis
• epidermal papillae - in a way also connects the dermis to the epidermis
• unbroken skin - considered as the first line of defense against any infection whether its viral, bacterial, fungal and any infectious microorganism
• Thermal regulatory - has something to do with the production of sweat.
• skin cell synthesizes what is called vitamin D3.
• vitamin d3 - precursor of vitamin D
• vitamin D - important regulator of calcium metabolism and proper bone formation, so vitamin D is usually broken down by UV light in the skin
• pheromore - sort of scent, chemicals produced by animals to attract mates for reproduction purposes, produced by apocrine sweat glands and other
• apocrine sweat gland - found on armpits, groin area, nipples, and areolae
• travels to the kidney to be converted to the active form of vitamin D which is the one that regulates metabolism
• cells in the epidermis - keratinocytes, langerhan (skin macrophage), malanocytes (produces melanin), merkel cells (censory cell)

  
• where are capillaries located?

  dermis
• layers of epidermis?

  stratum basale (basal, alive), stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
• stratum basale - A single layer of basophilic cuboidal or columnar cells. Characterized by intense mitotic activity and contains progenitor cells for all the epidermal layers
• the source of skin cells?

  statum basale
• stratum spinnosum - Thickest layer, especially in the epidermal ridges. Synthesis of much keratin and other proteins takes place. Characteristically exhibit spinous processes
• precursor for your keratin?

  tonofibrils
• contains prickle cells?

  stratum spinosum
• stratum granulosum - known as keratohyalin granules. has lamellar granules
• lamellar granules - are cysteine rich and histidine rich proteins considered as the precursors of the protein filaggrin. Lipid in nature, water cannot easily pass through them. allows the skin to retain as much water as it can to maintain the water volume in the human body
• • stratum lucidum - clear layer, thin, translucent layer of flattened eosinophilic keratinocytes held together by desmosomes. Considered a subdivision of the stratum corneum. Only well seen in thick skin
• stratum corneum - Most differentiated cells in the skin. Layers of squamous, keratinized cells filled with birefringent filamentous keratins. Squames. Top most layer
• layer of dead skin cells?

  stratum corneum
• predominant cell type of the epidermis?

  keratonocytes
• melanocytes - Neural crest-derived ,A dendritic cell that is scattered among the basal cells of the stratum basale. Produce and distribute melanin into keratinocytes. Cells that produce the protein melanin, the pigment, the one that give our skin a pigment.

  
• precursor of melanin?


  tyrosine
• Tyrosinase - convert tyrosine into your dihydroxyphenylalanine (DOPA)
• langerhans - dendritic cells, antigen presenting cells in the epidermis. it processes characteristic, tennis racquet-shaped Birbeck granules. Most clearly seen in the spinous layer.
• merkel cells - Function is cutaneous sensation, Abundant in highly sensitive skin like that of fingertips and at the bases of some hair follicles. Located in the stratum basale
• important in our ability to feel textures?

  merkel cells
• layers of the dermis?

  papillary and reticular layer
• considered peg and socket in our skin?the reason why we have footprints and fingerprints

  dermal-epidermal interdigitation
• papillary layer - Thin, Includes the dermal papillae ,Consists of loose connective tissue, Types I and III collagen fibers, fibroblasts and scattered mast cells, macrophages, and other leukocytes
• supports the epidermis, topmost layer of the dermis?


  papillary layer
• reticular layer - Much thicker, Consists of dense irregular connective tissue, More fibers and fewer cells than the papillary layer, A network of elastic fibers is also present
• where the target of when you have insulin injected?

  subcutaneuous layer
• merkel cells - tonic receptors for sustained light touch and for sensing an object's texture, tactile disc.

  
• free nerve endings - Most numerous neuronal receptors in the epidermis - Terminate in the stratum granulosum