Integumentary System Notes - Week 1 PDF

Integumentary System HS 1300/2300B – SYSTEMIC APPROACH TO FUNCTIONAL HUMAN GROSS ANATOMY Dr. Kelsey Adams Week 2 – January 13, 2025 1  2 Learning Objectives...

Integumentary System HS 1300/2300B – SYSTEMIC APPROACH TO FUNCTIONAL HUMAN GROSS ANATOMY Dr. Kelsey Adams Week 2 – January 13, 2025 1  2 Learning Objectives 1. Identify the major components of the integumentary system and their functions. 2. Identify the major structures of the skin, glands, and their functions. 3. Describe the role of dermal circulation. 4. Describe how the skin senses touch, pressure, and pain. 5. Explain their structure, functions, and growth processes or hair and nails. 6. Explain why mammary glands are specialized integumentary glands.  3 Overview Skin Subcutaneous Tissue Nails Hair Glands Integumentary System Conditions Skin Throughout Life 3  4 The Skin & Subcutaneous Tissue  55 Skin Body's largest organ ~7% of body weight ~1.5 to 4.4 mm thick 2 layers: 1. Epidermis 2. Dermis  66 Hypodermis Subcutaneous layer, lies deep to the dermis Composed of areolar and adipose tissues 1. Insulation 2. Shock Absorption 3. Energy Storage 4. Anchoring  77 Figure 5.1, Human Anatomy  88 Figure 5.2, Human Anatomy  9 5 Functions of the Skin 1. Protection 2. Body temperature regulation 3. Excretion 4. Production of vitamin D 5. Sensory reception 9  10 10 Epidermis Outermost skin layer Protective barrier between body and environment Keratinized stratified squamous epithelium Avascular Regenerates every 28–30 days in adults  11 11 Main Cell Types of the Epidermis 1. Keratinocytes 2. Melanocytes Keratinocyte Melanocyte 3. Tactile epithelial cells 4. Dendritic cells Dendritic Cell Tactile Epithelial Cell  12 12 Keratinocytes Most abundant epidermal cells Produced in the deepest layer Create keratin for strength and water resistance Produce antibiotics and enzymes Dead at the skin’s surface  13 13 Melanocytes Found in the stratum basale, hair follicles, inner ear, and eye Protect from UV damage Determines skin, hair, and eye colour Types: eumelanin and pheomelanin  14 14 Melanocyte Disorders Hyperpigmentation: overactive melanocytes (ex. sunspots or melasma) Hypopigmentation: underactive melanocytes (ex. vitiligo) Hyperpigmentation Hypopigmentation  15 15 Tactile Epithelial Cells Merkel cells Mechanoreceptors for light touch and pressure In basal layer (fingertips/palms) Transmit tactile signals to sensory nerve endings Alert to harmful stimuli  16 16 Dendritic Cells Langerhans cells Found in the stratum spinosum Part of immune system Monitor and process pathogens Protect against infections and skin diseases  17 17 Layers of the Epidermis Superficial to deep Stratum corneum Stratum lucidum (only in thick skin) Stratum granulosum Stratum spinosum Stratum basale (stratum geminativum) Mnemonic: "Come, Let's Get Sun Burned"  18 18 Figure 5.3, Human Anatomy  19 19 Stratum Corneum Horny layer Thick layer of dead keratinocytes Protects against abrasion and penetration  20 20 Stratum Lucidum Clear layer Found only in thick skin (palms, soles) Few rows of flat, dead keratinocytes  21 21 Stratum Granulosum Few layers of keratinocytes Keratohyaline granules form keratin Lamellar granules contain waterproofing glycolipid Cells above this layer lack nutrient access  Stratum Spinosum 22 22 "Spiny" appearance Contains intermediate filaments for strength and flexibility Houses keratinocytes and dendritic cells Provides mechanical stress resistance  23 23 Stratum Basale Deepest epidermal layer, attached to dermis Cells actively divide Contains tactile epithelial cells and melanocytes  24 24 Figure 5.4, Human Anatomy  25 25 Dermis Strong, flexible connective tissue Rich with blood vessels and nerves Layers: 1. Papillary dermis: superficial layer 2. Reticular dermis: deeper layer  26 26 Papillary Dermis Includes dermal papillae Increases surface area for gas, nutrient, and waste exchange Nourishes epidermis via capillaries Receptors for light touch and vibration Regulate body temperature  27 27 Epidermal Ridges Friction ridges Dermal elevations that increase grip Fingerprints, unique pattern for identification Figure 5.5, Human Anatomy  28 28 Reticular Dermis 80% of dermis Dense irregular connective tissue Rich nerve supply for pressure and pain sensation Vascular plexuses for nutrient delivery and temperature regulation Dermal plexus Subpapillary plexus  29 29 Cleavage Lines & Flexure Lines Cleavage lines: Separation between collagen fibers Provide skin strength Flexure lines: Deep creases in palms, wrists, soles, fingers, and toes Figure 5.5, Human Anatomy  30 Hypodermis Located beneath the skin Contains areolar and adipose tissue Anchors skin, insulates, stores energy Provides cushioning and protection Distribution varies by sex  31 Skin Colour Melanin: main pigment, made from tyrosine Carotene: yellow-orange pigment from foods, adds warm hue Hemoglobin: oxygenated blood gives rosy undertone in light-skinned individuals v v Melanin Carotene Hemoglobin  32 Appendages of the Skin  33 Nails Scalelike epidermal modification made of hard keratin Free edge: extends past fingertip Nail plate: covers nail bed Root: base of nail Nail folds: skin around nail Eponychium: cuticle Figure 5.6, Human Anatomy  34 Hair Found everywhere except palms and soles Flexible strand of dead, keratinized cells Root: embedded in skin Shaft: projects above skin’s surface Made of tough, durable hard keratin  35 Hair Structure 3 concentric layers of keratinized cells 1. Medulla—central core 2. Cortex—surrounds medulla 3. Cuticle—outermost layer  36 Additional Hair Structures Hair follicles: structure in skin where hair grows Hair bulb: base, contain matrix for hair and pigment production Root plexus: sensory nerve network around hair bulb  37 Figure 5.7, Human Anatomy  38 Arrector Pili Muscle Smooth muscle attached to hair follicle Hair stands erect when arrector pili contracts (goosebumps) Thermoregulation and protection  39 Types and Growth of Hair 1. Vellus hairs 2. Terminal hairs 3. Lanugo  40 Vellus Hair Fine, short, lightly pigmented Covers body, especially face, neck, arms Light insulation and sensory perception (airflow, touch) Present in children and adults  41 Terminal Hair Thick, coarse, pigmented Found on scalp, eyebrows, eyelashes, armpits, groin Develops during puberty Provides insulation, protection, and secondary sexual characteristics  42 Lanugo Fine, soft, unpigmented hair Covers fetus in the womb, shed before or shortly after birth Provides warmth and protection  43 Hair Thinning and Baldness Androgenetic Alopecia: hereditary, hormone-driven thinning at the crown and hairline (men) or overall thinning (women) Alopecia Areata: autoimmune disorder, patchy hair loss on scalp and body Androgenetic Alopecia Alopecia Areata  44 Hair Thinning and Baldness Telogen Effluvium: temporary thinning due to stress, illness, or hormonal changes Age-Related Thinning: gradual thinning with age, influenced by hormones and genetics Telogen Effluvium Age-Related Hair Thinning  45 Sebaceous Glands Found everywhere except palms and soles Secrete sebum via holocrine secretion Most are associated with hair follicles  46 Function of Sebum Lubrication Barrier Antimicrobial Hair Conditioning  47 Figure 5.8, Human Anatomy  48 Sudoriferous Glands Widely distributed on body Sweat is a blood filtrate 99% water with salts and metabolic wastes  49 Types of Sweat Glands 1. Eccrine gland 2. Apocrine gland  50 Eccrine Glands Most abundant Ex. palms, soles, and forehead Produce odourless, watery sweat Small, coiled glands open onto skin surface Thermoregulation skin hydration, microbial defence  51 Apocrine Glands Found in axillary, anal, and genital areas Open into hair follicles Activated during puberty Produce thick, milky sweat with musky odour  52 Modified Apocrine Glands 1. Ceruminous glands: produce ear wax, protect the ear 2. Mammary glands: produce milk, activated by hormones 3. Ciliary glands: lubricates eyelashes, prevents dry eyes Ceruminous Glands Mammary Glands Ciliary Glands  53 Figure 5.8, Human Anatomy  54 Integumentary System Conditions  55 Burns First-degree: affects only the upper epidermis Second-degree: damages epidermis and upper dermis; blisters form Third-degree: destroys skin thickness; area appears white, red, or blackened  56 Figure 5.9, Human Anatomy  57 Skin Cancer Basal cell carcinoma: Least malignant, most common Squamous cell carcinoma: Arises from keratinocytes of stratum spinosum Melanoma: Melanocyte cancer, most dangerous type Figure 5.10, Human Anatomy  58 Infections Acne vulgaris: inflammation of sebaceous glands, caused by blocked hair follicles, bacteria, and excess oil Warts: growths caused by human papillomavirus (HPV), contagious through direct contact or contaminated surfaces Ringworm: fungal infection, ring-shaped rash contagious through contact  Aging Skin Skin thins and becomes less elastic Skin inflammations become more common Prone to rashes and infection 59  60 Summary Integumentary system protects your body from external harm and regulates temperature Includes skin, hair, nails, and glands Barrier and sensory interface Aging leads to skin changes and decreased wound healing