Anatomy Lecture 5 PDF

Lecture Learning Objectives 1. Recall the primary functions and components of each accessory organ of the integument​ 1. Hair Primary Function: Protection, regulation of body temperature, and sensory input. Components: ○ Hair Medulla...

Lecture Learning Objectives 1. Recall the primary functions and components of each accessory organ of the integument​ 1. Hair Primary Function: Protection, regulation of body temperature, and sensory input. Components: ○ Hair Medulla Cortex Cuticle: hardest keratin layer that provide strength and wears off at tip ○ Hair Shaft: The visible part above the skin. ○ Hair Follicle: Tube that surrounds hair root, contains 3 layers. Connective Tissue root sheath: outer layer, part of dermis External and Internal root sheath: inner layers, from epidermis ○ Hair Bulb: The base of the hair follicle, containing actively dividing cells. Hair papilla: holds cells at base of bulb epithelium, melanocytes in this structure produce hair color Hair matrix: dividing portion of bulb, where keratinization of cells occurs to produce hair cells Root hair plexus: cluster of sensory nerve endings ○ Holocrine glands that secrete sebum: Associated with hair follicles, they secrete sebum to lubricate hair and skin. ○ Sebaceous follicles: large glands not directly associated with hair follicles, secrete directly onto epidermis ○ Arrector Pilli Muscle: Attach from dermal papillae to stratum basale, Cause of “goosebumps”, formed by mesenchymal differentiation 2. Nails Primary Function: Protection of the distal phalanges and enhancement of fine motor movements. Components: ○ Nail Plate: The hard part of the nail.  ○ Nail Bed: The skin beneath the nail plate. ○ Lunula: The white, crescent-shaped area at the nail’s base. ○ Nail Folds: bound by nail groove ○ Nail Root: forms the nail matrix ○ Nail Matrix: The tissue under the nail responsible for growth. ○ Eponychium: cuticle ○ Hyponychium: thickened stratum corneum underlying free surface of nail (finger tip) 3. Sweat Glands Primary Function: found in dermis and subcutaneous layer, Thermoregulation through sweat production and excretion of waste products. Contain myoepithelial cells Types: ○ Merocrine Glands: Found all over the body, they release sweat directly onto the skin surface to cool the body. ○ Apocrine Glands: Found in areas like the armpits and groin, they release sweat into hair follicles and are associated with body odor. 4. Sebaceous Glands Primary Function: Secretion of sebum to lubricate and waterproof the skin and hair. Components: a. Sebum: An oily substance that protects and moisturizes the skin. 5. Mammary Glands - Specialized and modified apocrine sweat glands (function in pregnant females) - Function: lactation 2. Recall the embryological development of integument’s accessory organs​ The embryological development of the integument’s accessory organs (hair, nails, sweat glands, sebaceous glands) originates from interactions between the ectoderm and mesoderm during early development. Here’s a breakdown of how each accessory organ forms: Hair Origin: Hair development begins in the ectoderm of the epidermis but is heavily influenced by underlying mesodermal signals. Lanugo: first hairs 1. Replaced by courser hair and terminal hairs in axillary and pubic regions (face in chest in males) Melanoblasts migrate to hair bulbs and differentiate into melanocytes providing color to hair Developmental Process: 1. Hair Follicle Budding: Stratum germinativum cells proliferate into dermis forming hair bud 2. Proliferation & Keritization: Cells proliferate forming hair bulb, which extends into underlying mesoderm. Epithelial cells in hair bulb produce hair through keratinization 3. Hair Follicle Development: Mesenchymal cells surround the invaginating bud, forming the hair papilla, which regulates hair follicle growth. 4. Root Sheath formation: Root sheaths are derived from respective tissue- epidermal root sheath and dermal root sheath Sweat Glands Origin: Sweat glands are derived from epidermal ectoderm. Developmental Process: Merocrine sweat glands 1. Outgrowths of stratum germinativum, cellular buds, grow deeper into mesenchyme 2. Central cells degenerate, creating lumen of sweat gland duct 3. Deeper epidermal cells differentiate into secretory cells and myoepithelial (specialized smooth muscle) which function shortly after birth Apocrine sweat glands 1. Similar development as eccrine but begin as outgrowths of hair follicles; Open into upper part of hair follicles, superficial to sebaceous glands 2. Localized to axilla, pubic, and perineal regions and peripheral to nipples and do not function until puberty Sebaceous Glands Origin: Sebaceous glands develop from ectodermal cells, closely associated with developing hair follicles. Developmental Process: a. Hair Follicle Budding: As the hair follicle invaginates into the dermis, sebaceous gland primordia form as lateral outgrowths. b. Gland Differentiation: The cells in these outgrowths differentiate into sebocytes, which produce sebum. i. Sebum helps form vernix caseosa mixing with epidermis skin cells c. Maturation: Sebaceous glands begin functioning after birth, contributing to skin and hair lubrication. 3. List the three types of hair and describe how they change with age​ Summary of Hair Changes with Age: Lanugo: Present during fetal development, shed before or shortly after birth. Vellus: Covers the body throughout childhood, with some areas converting to terminal hair during puberty. Terminal Hair: Appears in more areas after puberty, with possible thinning or balding in adulthood and increased growth in other areas (ears, nose) as people age. 4. Visually identify the accessory organs and their components histologically ​ 5. Compare the similarities and differences of between the two different types of sweat glands including connection, secretion, location, control, and function ​ 6. Explain the clinical relevance and diagnostic applications of the integument discussed in class​ - Incisions perpendicular to lines of cleavage may gap, delay healing, and cause additional scar tissue  - Incisions parallel to lines of cleavage gap less, heal faster, and create less scar tissue Striae: skin stretches beyond its capacity, collagen fibers are torn skin turgor: skins flexibility and resilience due to water content 7. Describe the three types of skin cancer and their cellular origins​ Basal Cell Carcinoma: Originates from basal cells in the stratum basale; slow-growing and rarely metastasizes. Squamous Cell Carcinoma: Arises from squamous cells in the stratum spinosum more aggressive than BCC with a higher risk of metastasis. Melanoma: Develops from melanocytes in the stratum basale; the most dangerous form due to its high potential for metastasis. 8. Compare the layers affected by different degree burns and describe medical complications​ Summary of Layers Affected: First-Degree Burns: Affect the epidermis only. Second-Degree Burns: Affect the epidermis and dermis (partial-thickness). Third-Degree Burns: Affect the epidermis, dermis, and possibly subcutaneous fat (full-thickness). Fourth-Degree Burns: Extend into muscle, tendon, and bone. General Medical Complications Across All Burn Types: Infection: Risk increases with the depth of the burn. Scarring and Contractures: Deeper burns, especially second- and third-degree, can result in significant scarring and loss of mobility. Fluid Loss: Severe burns, particularly second-degree and above, can cause fluid imbalances and shock. Thermal Dysregulation: Loss of skin reduces the body’s ability to regulate temperature.