Exam 2: BSC2085/ BSC 2085 (Latest 2024/ 2025 Update) Anatomy and Physiology I | Qs & As| 100% Correct| Grade A (Verified Answers)

Exam 2: BSC2085/ BSC 2085 (Latest 2024/ 2025 Update) Anatomy and Physiology I | Qs & As| 100% Correct| Grade A (Verified Answers) Q: What are the 5 strata of keratinocytes in thick skin Answer: 1. Stratum basale 2. Stratum spinosum 3.Stratum granulosum 4. Stratum lucidum (missing in thin skin) 5.Stratum corneum Bottom to top Q: What is the Stratum Basale? Answer: -Is attached to basement membrane by hemidesmosomes -Forms a strong bond between epidermis and dermis -Forms epidermal ridges (basis of fingerprints) -Dermal papillae (tiny mounds)- projections from the dermis-Increase the area of basement membrane and ttrengthen attachment between epidermis and dermis -Has many basal cells, or germinative cells Q: What determines fingerprints? Answer: Determined by genetics and uterine environment during fetal development. Q: Do identical twins have the same fingerprints? Answer: No Q: What are specialized cells of Stratum Basale? Answer: 1. Merkel cells- specialized epithelial tactile cells Found in hairless skin Respond to touch (trigger nervous system) 2. Melanocytes Contain the pigment melanin Scattered throughout stratum basale Q: What is the Stratum Spinosum? Answer: "the "spiny layer" -Produced by division of stratum basale -Eight to ten layers of keratinocytes bound by desmosomes -Cells shrink until cytoskeletons stick out (looks spiny) - under normal histological preperations -Continue to divide, increasing thickness of epithelium -Contain dendritic (Langerhans) cells, active in immune response - defend against microorganisms that get past superficial layers of epidermis and defend against superficial skin cancers Q: Describe the Stratum Granulosum layer Answer: -the "grainy layer", Stops dividing, starts producing: 1. Keratin A tough, fibrous protein Makes up hair and nails 2. Keratohyalin Dense granules Cross-link keratin fibers Note: as keratin accumulates, the cell flatten and its plasma membrane thickens and becomes less permeable Q: Describe the Stratum Lucidum Answer: the "clear layer" -Found only in thick skin -Covers stratum granulosum -Cells here are flattened, densely packed with keratin and are devoid of organelles Q: Stratum Cornuem Answer: -the "horn layer" (latin cornu=horn) -Exposed surface of skin (15 to 30 layers of keratinized cells) lasts about 2 weeks -Water resistant, not water proof! -Shed and replaced every two weeks -All exposed skin surfaces (except the anterior of the eyes) undergo cornification (keratinization) - formation of protective, superficial layers of cells filled with keratin Q: Cells of Stratum Granulosum Answer: -Produce protein fibers -Dehydrate and die (organelles disintegrate) -Create tightly interlocked layer of keratin surrounded by keratohyalin -Keratohylain cross links keratin and dehydrates cell Q: Keratinization Answer: -The formation of a layer of dead, protective cells filled with keratin Occurs on all exposed skin surfaces except eyes Q: What is the skin life cycle? Answer: Skin life cycle -It takes 7 to 10 days for a cell to move from stratum basale to stratum corneum -Once there, cells may remain at stratum corneum for an additional 2 weeks before shedding off Q: Two types of perspiration Answer: Insensible and sensible Q: What is Insensible perspiration Answer: -Interstitial fluid lost by evaporation through the stratum corneum -Lose approx. 500mL or 1 pint of H2O per day Q: What is sensible perspiration? Answer: Water excreted by sweat glands Q: What are dehydration results? Answer: -From damage to stratum corneum (e.g., burns and blisters [insensible perspiration]) -From immersion in hypertonic solution (e.g., seawater [osmosis]) -skin is NOT water proof! Q: What is hydration? Answer: -Results from immersion in hypotonic solution (e.g., freshwater [osmosis]) -Causes swelling of epithelial cells, evident on the palms and soles Q: What pigments influence skin color? Answer: 1. Carotene 2. Melanin -Blood circulation (red blood cells) can also affect skin color Q: What is Carotene? Answer: -Orange-yellow pigment -Found in orange vegetables Carrots, squashes - if overconsumption, can turn skin orangish -Accumulates in epidermal cells and fatty tissues of the dermis -Can be converted to vitamin A - used for maintenance of epithelia and photoreceptor function Q: What is Carotenemia? Answer: Over consumption of orange vegetables ex Carrots, squashes Q: What is Nyctalopia and what causes it?