Y1B4M1L3 The Integumentary System PDF

Y1B4M1L3 THE INTEGUMENTARY SYSTEM ● Three layers: ○ Medulla ○ Cortex ○ Cuticle ● Germinal matrix (growth zone) – epithelial cells and melanocytes ● Hair papilla – connective tissue, houses nerves and blood vessels, nourishes germinal matrix ● Melanocyte cells - determine the hair color ● Vellus ○...

Y1B4M1L3 THE INTEGUMENTARY SYSTEM ● Three layers: ○ Medulla ○ Cortex ○ Cuticle ● Germinal matrix (growth zone) – epithelial cells and melanocytes ● Hair papilla – connective tissue, houses nerves and blood vessels, nourishes germinal matrix ● Melanocyte cells - determine the hair color ● Vellus ○ No medulla ○ Hair bulb at reticular dermis ○ At puberty, vellus will transform into terminal follicles (sex hormones) Figure 9. Hair types and characteristics HAIR CYCLE Figure 8. Hair structure ● Cutting hair does not hurt because sensory nerves are located at the base of the hair follicle. PILOSEBACEOUS UNIT ● Hair and its follicle ● Arrector pili muscle – responds to emotional states and cold temperatures; goosebumps ● Sebaceous gland – sebum ● Apocrine gland HAIR GROWTH ● Germinal matrix – cells divide by mitosis and move upwards to become keratinized ● Keratinization ○ Elimination of nucleus and organelles → Process continues ○ Fill with keratin protein ● Scalp hair ○ Grows 1/2 inch per month; 5 inches per year → Lives between 2 to 6 years ● Anagen ○ Growth stage ○ Determines the final length of the hair ○ Scalp hair has the longest anagen at 2 8 years → 90 93% of scalp follicles ○ Approximately 1 cm/month 0.37 0.47mm/day) ● Catagen ○ Involuting phase ○ Mitotic activity of the germinal matrix ceases ○ Base of the hair condenses into a club that moves upwards to the level of the arrector pili muscle and the whole inferior segment of the follicle degenerates ● Telogen ○ Resting phase ○ Lose 50 100 hairs/day → Hair diary is utilized to count ● Exogen ○ Part of telogen ○ Hair shedding phase → 1% of telogen hair follicles HAIR COLOR ● Melanocyte cells – release melanin which enter keratinized cells and gives hair its color ● Hormonal and environmental factors also affect hair color ● Melanin production decreases as we age, hair grays, and melanin production eventually stops, producing white hair HAIR TYPES AND ANAGEN DURATION ● Lanugo ○ Non-pigmented ○ Fine, soft ○ Shed at 32 36 weeks ○ 1/3 may retain after birth ● Terminal ○ Central medulla ○ Hair bulb at subcutaneous fat ○ Scalp, eyebrows eyelashes at birth Figure 10. Hair cycle and anatomy II. NATURAL SKIN CREASES A. VISIBLE SKIN LINES ● Simple lattice pattern lines ● Polygons formed by relatively deep primary creases ● Irregularly divided by finer secondary creases into triangular lines ● Divided by tertiary creases limited to the cornified layers of the epidermis ● Quaternary lines are outlines of the individual squames ABALO, ALANTUSON, ATENOR, BARSANALINA, DEDAL, DELFIN, LEE, LICAYAN, SALISE, TORNALEJO | MG 3 6 of 10 Y1B4M1L3 THE INTEGUMENTARY SYSTEM B. WRINKLE LINES E. PAPILLARY RIDGES Contraction of underlying muscles Perpendicular to axis of shortening Facial/expression lines Occupational lines ○ Creases produced by repeated muscular contractions associated with particular trades or skills ● Lines of dependency ○ Produced by effect of the gravity on loose skin or fatty tissue (e.g. chin on old age) ○ More difficult to correct ● Confined to palms, soles and flexor surfaces of the digits ● Form narrow parallel or curved arrays separated by narrow furrows ● Aperture of the sweat ducts would open at regular intervals along the summit of each ridge ● The epidermal ridges correspond to the underlying, interlocking pattern of dermal papillae; these patterns are seen in fingerprinting and dermatoglyphics ● Stable throughout life, unique to the individual and significant means of identification ● 3 major types based on tri-radii: ○ Arches - 5% → No tri-radii ○ Loops - 70% → One tri-radii ○ Whirls - 25% → Two or more tri-radii ● Whirls are more common on the right hand vs the left hand ● Males have more whirls but fewer arches than females ● Ridges are relatively narrower in females ● Adermatoglyphia - rare condition that is characterized by the lack of ridges on the skin of the fingers, toes, palms of the hand and soles of the feet ○ Mutations in SMARCAD I gene ● ● ● ● F. RELAXED SKIN TENSION LINES Figure 11. Wrinkle Lines C. CONTOUR LINES ● Borgeʼs Line ● Corresponds to the directional pull when the skin is relaxed ● Constant even in sleep but can be altered by underlying muscle contraction Figure 12. Contour Lines Figure 14. Relaxed Skin Tension Lines G. LINES OF LANGER D. FLEXURE/JOINT LINES ● Represent skin tension in rigor mortis ● Linear clefts in the skin that indicate the direction of orientation of the underlying collagen fibers ● Ideal in skin incision – no scarring ● Major markings found in the vicinity of synovial joints where the skin is attached to the underlying deep fascia ● Examples are the flexure surfaces of the palms, soles, and digits Figure 13. Flexure/joint Lines Figure 15. Lines of Langer ABALO, ALANTUSON, ATENOR, BARSANALINA, DEDAL, DELFIN, LEE, LICAYAN, SALISE, TORNALEJO | MG 3 7 of 10 Y1B4M1L3 THE INTEGUMENTARY SYSTEM H. KRAISSLʼS LINES III. SKIN CONDITIONS ● Exaggerated wrinkle lines obtained by studying the loose skin of elderly faces while contracting the mimetic muscles of the face ● Oriented perpendicular to the action of the underlying muscle A. ACNE VULGARIS Figure 16. Facial Skin Lines I. BLASCHKOʼS LINE ● Pattern of cutaneous mosaicism that can be observed in congenital and acquired skin conditions ● Related to early developmental boundaries or skin cell migration during embryogenesis ● Disorder of the pilosebaceous unit ● 4 key elements ○ Follicular epidermal hyperproliferation ○ Sebum production ○ Presence and activity of Cutibacterium acnes ○ Inflammation and immune response Figure 19. Acne Vulgaris B. PIGMENTARY DEMARCATION LINES ● Voigt or Futcher lines ● Abrupt changes from lighter to darker skin in a linear pattern mostly seen on the limbs, trunk or face ● Seen along embryonic suture lines in distinct pattern Figure 20. Pigmentary Demarcation Lines Figure 17. Blashckoʼs Lines Figure 18. Areas of right-angle cross of Borges' line with other lines Alhamdi, 2015 C. PERIORBITAL PIGMENTATION ● “Dark circles” ● Asymptomatic brown black non-scaly, nonerythematous pigmentation noted on the upper, lower, or both eyelids ● Accentuation of the skin creases and visible vessels ● Increased melanin in the basal epidermis and melanophages in the upper dermis ● Constitutional pigmentation Figure 21. Periorbital Pigmentations ABALO, ALANTUSON, ATENOR, BARSANALINA, DEDAL, DELFIN, LEE, LICAYAN, SALISE, TORNALEJO | MG 3 8 of 10 Y1B4M1L3 THE INTEGUMENTARY SYSTEM D. MELANOCYTIC NEVUS ● Benign neoplasms of the melanocytes Figure 22. Melanocytic Nevus E. MELANOMA ● Malignant tumor arising from melanocytic cell ○ More common for Skin Types 1, 2, and 3 ● Risk factors ○ sunburn or heavy sun exposure ○ blue or green eyes ○ blonde or red hair ○ fair complexion ○ atypical nevi ○ personal or family history of melanoma ● Warning Signs ○ Asymmetry ○ Border - irregular (should be circle) ○ Color - variation or variegation in one lesion ○ Diameter - 5mm is warning sign ○ Evolution - elevating from flat; bleeding ● Acral lentiginous melanoma ○ Melanoma occurring on the hands and feet (palms, soles, fingers, toes, and nail units) ○ Most common type of melanoma in Asia Figure 24. Vitiligo G. ALBINISM ● Hypopigmentation (skin, hair, eyes) ● Subtypes: ○ Nonsyndromic → Impaired melanin biosynthesis ○ Syndromic → Associated with non-pigmentary symptoms Figure 25. Albinism H. STRIAE DISTENSAE ● Stretch marks ● Striae Gravidarum in pregnant women ● Disruption of the lateral cohesion of the dermal collagen fibers with associated hemorrhage and cellular reaction ● Leading to the formation of poorly vascularized scar tissue ● Genetic predisposition Figure 23. Melanoma F. VITILIGO ● Common autoimmune disease that causes depigmentation through CD8 T cell-mediated destruction of melanocytes ● WelI-defined asymptomatic white non scaly macules and patches with distinct borders Figure 26. Striae Distensae IV. AGING ● Intrinsic Aging ○ Physiologic aging ○ Gradual changes in appearance and mechanical properties of the skin ○ Epidermal and dermal atrophy ABALO, ALANTUSON, ATENOR, BARSANALINA, DEDAL, DELFIN, LEE, LICAYAN, SALISE, TORNALEJO | MG 3 9 of 10 Y1B4M1L3 THE INTEGUMENTARY SYSTEM ● Extrinsic Aging ○ Photoaging ○ Result of hazardous effect of UV radiation to the human skin ● Process ○ Skin takes less time to heal → more time to recover ○ Reduction in stem cells ○ Skin becomes thinner ○ Fiber deterioration ○ Facial expressions (e.g., squinting, smiling) ○ Less immune cells (dendritic cells) ○ Overexposure to the sun can cause DNA damage REVIEW QUESTIONS 1. The most common keratins found in the basal keratinocyte: a. Keratin 5 and 10 b. Keratin 5 and 14 c. Keratin 1 and 10 d. Keratin 1 and 14 2. Where can we find the fifth layer of the epidermis? a. Arms b. Face c. Legs d. Soles 3. Which of the following statements is true? a. Each melanocyte produces melanin for 100 120 basal keratinocytes. b. Melanocytes produce only 2 types of melanin. c. Melanocytes in light skinned individuals degrade slower than in dark skinned individuals. d. Racial variation in pigmentation is due to differences in melanocyte morphology and activity rather than number and distribution. 4. Which of the following is the product of spontaneous decarboxylation of DOPAchrome? a. DHICA b. DHI c. DOPAquinone d. L DOPA Answers: 1B, 2D, 3D, 4D, 5B References: Perez, G. 2023 . The Integumentary System. Fitzpatrick's Dermatology 9th edition Gray's Anatomy 41st edition https://www.youtube.com/watch?v=GSY2g6ZIMoU https://www.youtube.com/watch?v=TuDYjv84jrw https://www.youtube.com/watch?v=ti-_ 49Gliww https://www.youtube.com/watch?v=8YrWAixytl https://www.youtube.com/watch?v=8bNBIDVstSo https://www.youtube.com/watch?v=Gj5Ui6Tjbm4 ABALO, ALANTUSON, ATENOR, BARSANALINA, DEDAL, DELFIN, LEE, LICAYAN, SALISE, TORNALEJO | MG 3 10 of 10