Anaphy (Skin and Tissues).pdf

Serous Membranes (Serosae) Body Membranes - Line body cavities that are Functions of Body Membranes: closed to the exterior (e.g.,...

Serous Membranes (Serosae) Body Membranes - Line body cavities that are Functions of Body Membranes: closed to the exterior (e.g., peritoneum in the abdomen, Cover body surfaces, such as the skin pleura around the lungs, and covering the entire body. pericardium around the heart). Line body cavities, ensuring that These membranes occur in pairs internal structures are protected from the (visceral and parietal layers) and external environment. are separated by serous fluid to Form protective sheets around reduce friction. Simple organs, providing an additional layer of squamous epithelium and defense and preventing friction. areolar connective tissue Types of Body Membranes: 1. Epithelial Membranes: 2. Connective Tissue Membranes: ○ These are simple organs made ○ Synovial Membranes up of an epithelial tissue layer - These membranes line the and a connective tissue layer. fibrous capsules around joints, bursae, and tendon sheaths. Cutaneous Membrane (Skin) They secrete lubricating synovial fluid to cushion organs - This is the outermost protective and reduce friction during boundary, also known as the movement. Loose areolar skin. It is a dry membrane connective tissue only (no composed of a keratinized, epithelial tissue) stratified squamous epithelium (epidermis) and a dense connective tissue (dermis). Integumentary System Mucous Membranes (Mucosae) Components: - Moist membranes that line body cavities opening to the exterior, Skin (Cutaneous Membrane): The such as the digestive, largest organ of the body, acting as the respiratory, urinary, and primary barrier to the external reproductive tracts. They are environment. adapted for absorption or Skin Appendages: Include sweat secretion. Construction glands, oil glands, hair, and nails. - Epithelium type depends on site - Loose connective tissue Functions of the Integumentary System: (laminate propia) Cover: Insulates and cushions deeper body organs  Protection: Structure of the Skin ○ Mechanical damage (bumps, cuts), chemical damage (from acids or bases), thermal damage (from heat or cold), UV radiation (from sunlight), microbes (bacteria), and desiccation (drying out). Temperature Regulation: Aids in body heat loss or retention, controlled by the nervous system. Excretion: Helps in excreting urea, uric acid, and sweat. Vitamin D Synthesis: UV rays from sunlight trigger the production of vitamin D in the skin. The skin is composed of three main layers: Epidermis: Outer layer of the skin capable of being hard and tough. Composed of stratified squamous epithelium and contains keratinocytes, which produce keratin, a fibrous protein that provides toughness and water resistance. It is avascular, meaning it has no blood supply of its own. The epidermis has five layers (strata) from deepest to superficial: A. Stratum Basale (stratum germinativum): - The deepest layer where cells undergo mitosis. Lies next to dermis. Cells undergo mitosis New cells are produced and pushed upwards to more superficial layers. B. Stratum Spinosum: - Cells in this layer become flatter and are increasingly keratinized. C. Stratum Granulosum - Cells are flattened, and organelles begin to deteriorate, filling with granules.  - Serve as touch receptors called Merkel discs D. Stratum Lucidum - Dermis Connective tissue Underlies the - Found only in thick, hairless skin (e.g., epidermis palms, soles). Formed from dead cells. E. Stratum Corneum Dermis: - The outermost layer, consisting of dead, keratinized cells that prevent water loss Connective tissue layer beneath the and provide a durable protective layer. epidermis, providing strength and flexibility. Two layers: ○ Papillary Layer: The upper dermal region containing (dermal papillae), which create fingerprints and improve grip. It contains capillary loops, pain receptors, and touch receptors.On palm and sole surfaces, papillae increase friction and gripping ability. Fingerprints are identifying films of sweat ○ Reticular Layer: The deeper Melanin: Produced by melanocytes layer containing blood vessels, found mostly in the stratum basale. sweat and oil glands, and Melanin pigment colors range from lamellar corpuscles(deep yellow to brown to black, and its pressure receptors). It is rich in production is influenced by genetics and collagen and elastic fibers that sunlight exposure. give skin its toughness and elasticity. Melanosomes Other features of the dermis include - Accumulated melanin in membrane cutaneous sensory receptors (for pain, bound granules temperature, and touch), phagocytes(to - intracellular organelles that are uniquely prevent bacterial infections), and blood generated by pigment cells in the skin vessels. and eye Hypodermis (Subcutaneous Layer): Epidermal dendritic cells - Alert and activate immune cells to a Not technically part of the skin but threat (bacterial or viral invasion) anchors it to underlying organs. Composed mostly of adipose tissue, Merkel cells providing insulation and cushioning for - Associated with sensory nerve endings deeper tissues.  ○ Bruising: Black and blue marks indicating hematomas (blood clots under the skin). Appendages of the Skin Cutaneous Glands: 1. Sebaceous (Oil) Glands: ○ Found all over the skin except palms and soles. ○ Produce sebum (oil), which keeps skin soft and moist and prevents hair from becoming brittle. ○ Sebum has antibacterial properties. Pigmentation and Skin Color ○ Most sebaceous glands empty Three pigments contribute to skin into hair follicles, while others color: open directly onto the skin ○ Melanin: Yellow, surface. reddish-brown, or black ○ Glands activated at puberty pigment produced by melanocytes. ○ Carotene: An orange-yellow 2. Sweat (Sudoriferous) Glands: pigment from vegetables like A. Eccrine Glands: Produce sweat carrots. (water, salts, vitamin C, and ○ Hemoglobin: Red coloring waste) and open directly onto from oxygen-rich blood in the skin surface. They play a dermal capillaries. major role in body temperature regulation. B. Apocrine Glands: Found in the Skin color can indicate health armpits and genital areas. These conditions: glands release sweat containing ○ Redness (Erythema): Due to fatty acids and proteins, which inflammation, fever, or may contribute to body odor. hypertension. They begin to function at ○ Pallor: Blanching due to fear, puberty and have a minimal role anemia, or low blood pressure. in temperature regulation. ○ Jaundice: Yellowish skin due to liver disorders. Hair: Associated hair structures Produced by hair follicles, with the Hair follicle root enclosed in the follicle and the shaft - Composed of an epithelial root sheath projecting from the surface. and fibrous sheath The hair shaft is composed of Dermal region provides a blood supply to the keratinized epithelial cells. hair bulb (deepest part of the follicle) Hair grows in the matrix of the hair bulb Arrector pili muscle connects to the hair follicle located in the stratum basale. to pull hairs upright when we are cold or Hair structure includes the medulla, frightened cortex, and cuticle (the outermost layer). Nails: Heavily keratinized modifications of the epidermis, serving as protective coverings for the fingers and toes. Nails grow from the nail matrix located under the skin at the base of the nail. The visible part of the nail is the nail body, while the free edge extends beyond the fingertip. Parts of a nail Free edge - Body is the visible attached portion Nail folds - are skin folds that overlap the edges of the nail; the cuticle is the proximal edge Hair Anatomy - Root of nail is embedded in skin Central medulla - Growth of the nail occurs from nail Cortex surrounds the medulla matrix Cuticle on outside of cortex - Most heavily keratinized region of the hair  Extent of a burn is estimated using the rule of Homeostatic Imbalances of the Skin nines 1. Infections and Allergies: Body is divided into 11 areas for quick Athlete’s foot (Tinea pedis) estimation - A fungal infection causing itchy, red, Each area represents about 9 percent of peeling skin, typically between the toes. total body surface area The area surrounding the genitals (the Boils (furuncles) and Carbuncles: perineum) represents 1 percent of body - Boils: Inflammation of hair follicles. surface area - Carbuncles: Clusters of boils caused by bacteria. Cold Sores (fever blisters) - Caused by human herpesvirus 1, resulting in blisters that itch and sting. Contact Dermatitis - Allergic reaction due to exposure to chemicals, causing itching, redness, and swelling. Impetigo - Bacterial infection causing pink, fluid-filled raised lesions around the mouth and nose. Classification of Burns: Psoriasis First-degree burns (superficial burn): Only - A condition triggered by trauma, damage the epidermis. Symptoms include infection, hormonal changes, or stress. redness and swelling. Red, scaly lesions that itch, burn, and may crack or bleed. Second-degree burns (partial-thickness burn): Damage the epidermis and part of the dermis. Burns Skin becomes red, painful, and blistered. - Burns cause tissue damage and cell death, often due to heat, electricity, UV Third-degree burns (full thickness burn): radiation, or chemicals. Destroy both the epidermis and dermis, rendering the burned area painless due to nerve Associated Dangers: damage. Requires skin grafts for healing. Protein denaturation and cell death. Dehydration and electrolyte imbalance. Fourth-degree burns (full-thickness burn): Increased risk of infection and circulatory shock. Extends damage to deeper tissues such as bones Results in loss of body Luis and infection from and muscles, requiring surgery and potentially the invasion of bacteria leading to amputation.  3. Malignant Melanoma: Critical Burns Criteria: The deadliest but accounts for only 5% Second-degree burns covering over 30% of skin cancers. of the body. Arises from melanocytes and Third- or fourth-degree burns covering metastasizes rapidly to lymph and blood more than 10%. vessels Burns on critical areas such as the face, hands, feet, or genitals. ABCDE Rule for Detection: Burns affecting the airway. Asymmetry: Two sides of the mole do Circumferential burns around limbs or not match. the body. Border: Irregular or unsmooth edges. Color: Multiple colors present. Skin Cancer Diameter: Larger than 6 mm. - Most common form of cancer in humans Evolution: Changes over time. - Most important risk factor is overexposure to ultraviolet (UV) radiation in sunlight and tanning beds Fetal Development: - Cancer can be classified two ways Lanugo - Fine downy hair covering the fetus, 1. Benign means the neoplasm (tumor) has disappears by birth. not spread 2. ​Malignant means the neoplasm has Vernix caseosa: invaded other body areas - Oily covering present at birth. Most Common Types: Milia - Small white spots on the skin, usually 1. Basal Cell Carcinoma: disappear by the third week after birth. Most common and least malignant. Arises from stratum basale cells (no Developmental Aspects of Skin and Body longer make keratin), forming shiny Membranes dome shaped nodules with central ulcers. Adolescence: Acne: Common skin condition due to hormonal 2. Squamous Cell Carcinoma: changes. Caused by UV exposure. Arises from the stratum spinosum, Aging: appearing as scaly, red papules that can Skin becomes thinner and less elastic. ulcerate. Increased risk of skin cancer due to Early removal allows a good change of prolonged sun exposure. cure Balding and graying are genetically May metastasize to lymph nodes. influenced, with other contributors like stress and medication.