Integumentary System 2024 Student PDF

Unit 4: Integumentary System ORGAN SYSTEMS OF THE BODY: integumentary system Integumentary system A single organ - the skin! 16% of total body weight – the heaviest organ Protection and sensing Integument = the skin The skin is an example of a membrane...

Unit 4: Integumentary System ORGAN SYSTEMS OF THE BODY: integumentary system Integumentary system A single organ - the skin! 16% of total body weight – the heaviest organ Protection and sensing Integument = the skin The skin is an example of a membrane 2 Integumentary System: body membranes Membrane- thin, sheet-like structure that lines body cavities that consists of epithelial and connective tissue Recall: epithelial and connective tissue: Pink layer = epithelial cells Tan layer = connective tissue 3 Recall: BODY CAVITIES Ventral cavity 1. Thoracic cavity (chest cavity) a. Mediastinum b. Pleural cavities (right and left) 2. Abdominopelvic cavity a. Abdominal cavity b. Pelvic cavity c. Abdominopelvic regions (9) Dorsal cavity 1. Cranial cavity – the space inside the brain 2. Spinal cavity – the space inside the spine Membrane linings Integumentary System: body membranes Types of membranes: 1. Cutaneous membrane (stratified squamous epithelial): skin 2. Serous membranes (simple squamous epithelial): surround closed body cavities Parietal – lines the body cavity Visceral – folds inward to cover surface of organs within the body cavity 3. Mucous membranes (epithelial): surround open body cavities (come in contact w/environment) 4. Synovial membrane (connective tissue): lubricate areas of friction – joint capsules Epithelial cells within the mucous membrane vary with location (recall unit 1) Integumentary System Cutaneous membrane – the skin! Functions and fun facts: 1. Protection first line of defense keratin makes it waterproof melanin protects from UV radiation (subcutaneous) 2. Temperature regulation 3. Sense organ activity In 1 square inch of skin: 500 sweat glands 4. Excretion >1000 nerve endings Yards of blood vessels 5. Vitamin D synthesis 100 oil glands 150 pressure sensors 75 heat sensors 10 cold sensors Millions of cells 6 Integumentary System: cutaneous membrane (skin) Epidermis Thin outer layer (thin sheet of stratified squamous epithelium) Outer layer of epidermis – stratum corneum; made up of keratin (waterproof) Dermis Thick inner layer (mostly connective tissue); provides strength and support as well as elasticity (”stretch marks” – over-stretching the dermis) 7 Integumentary System Skin color 1. Melanin: color ranges from yellow to dark brown. Produced by melanocytes which produce and transfer the color to the epithelial cells (skin epithelial cells = keratinocytes) Dark skinned individuals have copious amounts of dark melanin laid down. Sunlight increases the activity of melanocytes (thus secreting more melanin) All different layers of the 2. Carotene: yellowish pigment found epidermis in the stratum corneum of the epidermis and fatty layer under the skin. Carotene + melanin produces a yellowish hue (found abundantly in those with Asian heritage). 8 Melanocytes Melanocytes Melanocytes produce melanin Melanin is packaged into vesicles (post- Golgi), released from melanocytes, and enter keratinocytes Melanin absorbs UV radiation UV radiation stimulates the production of melanin and DNA damage repair proteins The biology of skin color – unit 4 case study later today! Integumentary System Hair Follicles – pockets that are required for hair growth Most of the body is covered by hair (exceptions: lips, bottom of feet, palms of hands) Growth begins from the papilla (small bump on skin) Papilla is in contact with blood vessels When new cells are formed, the existing cells are pushed forward and filled with keratin Plucking hair – new ones will grow b/c the stem cells in the papilla are still present In 1 square inch of skin: Arrector Pili Muscle “erectors 500 sweat glands >1000 nerve endings for the hair”– smooth muscle Yards of blood vessels attached to the papilla; 100 oil glands contracts when cold and allows 150 pressure sensors 75 heat sensors the hair to stand up 10 cold sensors Millions of cells Integumentary System Sensory receptors Nerve endings – initiates a response that is interpreted by the brain Integumentary System Nails Produced by cells in the epidermis Made up of keratin Lunula (“little moon”) – where the nail meets the nail root Nail body – visible portion of the nail Nail root – underneath the cuticle (No melanin under the nail) 13 Integumentary System Skin Glands sudoriferous (sweat) eccrine: distributed all over body; secretes water (containing salt, urea, other ions) apocrine: found in the armpit; secretes thicker, milky substance; “body odor” caused by the breakdown of the secretions by bacteria sebaceous: secretes sebum (oily substance) to cover hair and skin to prevent drying; particularly active during puberty (driven by testosterone) – can lead to acne 14 NEJM 2005 Unit 4: Integumentary System Disorders  Integumentary System: disorders of the skin 2. burns First degree: surface Classified based on the depth of the burn layers of epidermis, minor discomfort and reddening (sunburn) 4th (all the way to muscle/bone) Second degree: deep epidermis layers + upper layers of dermis, blisters and severe pain Third degree: complete destruction of epidermis and dermis layers, insensitive to immediate pain due to loss of nerve endings From: 9, Dermatological Effects of Mustard Agents and Lewisite Fourth degree: extends below the subcutaneous tissue to reach the muscle or bone 16 2. burns Integumentary System: disorders of the skin Group 7 presentation – October 24 Possible disorders include…. *Impaired melanin production (albinism, vitiligo) *Acne *Burns *Vascular and inflammatory skin disorder (psoriasis, eczema) Unit 4 quiz now available on Canvas: Complete by October 7 @ 11:59 pm QUESTIONS? 19