ANAPHY

• Functions of body membranes:

  • Cover body surfaces
  • Line body cavities
  • Form protective sheets around organs
• Body membranes are classified according to tissue types:

  • Epithelial membranes (cutaneous, mucous, serous)
  • Connective tissue membranes (synovial)
• Epithelial membranes contain:

  • Epithelial tissue layer
  • Connective tissue layer
• Cutaneous membrane is the skin, a dry membrane and the outermost protective boundary
• Mucous membranes are moist, line body cavities open to the exterior body surface, and are adapted for absorption or secretion
• Serous membranes line open body cavities closed to the exterior of the body, occur in pairs separated by serous fluid, and have a construction of simple squamous epithelium and areolar connective tissue
• Specific serous membranes include:

  • Peritoneum (abdominal cavity)
  • Pleura (around the lungs)
  • Pericardium (around the heart)
• Synovial membranes are made of loose areolar connective tissue only, line fibrous capsules surrounding joints, and secrete lubricating fluid to cushion organs moving against each other during muscle activity
• The integumentary system consists of the skin (cutaneous membrane) and skin appendages like sweat glands, oil glands, hair, and nails
• Functions of the Integumentary System include:

  • Insulating and cushioning deeper body organs
  • Protecting the body from mechanical, chemical, thermal damage, UV radiation, microbes, and desiccation
  • Aiding in loss or retention of body heat, excretion of urea and uric acid, and synthesizing vitamin D
• Structure of the skin:

  • Epidermis (outer layer)
  • Dermis
  • Hypodermis (subcutaneous layer)
• Epidermis is capable of being hard and tough, composed of stratified squamous epithelium, and contains keratinocytes that produce keratin
• Epidermis is avascular and composed of five layers (strata):

  • Stratum basale
  • Stratum spinosum
  • Stratum granulosum
  • Stratum lucidum
  • Stratum corneum
• Melanin is a pigment produced by melanocytes, mostly in the stratum basale of the epidermis, and its amount produced depends upon genetics and exposure to sunlight
• Epidermal dendritic cells alert and activate immune cells to a threat, while Merkel cells are associated with sensory nerve endings and serve as touch receptors called Merkel discs
• Dermis is connective tissue underlying the epidermis, with two layers: papillary layer and reticular layer
• Skin color is influenced by three pigments: melanin, carotene, and hemoglobin
• Cutaneous glands include sebaceous glands, sweat glands, hair, hair follicles, and nails
• Sebaceous glands produce sebum, which makes skin soft and moist, prevents hair from becoming brittle, and kills bacteria
• Sweat glands produce sweat, with two types: eccrine glands and apocrine glands
• Apocrine glands:

  • Ducts empty into hair follicles in the armpit and genitals
  • Begin to function at puberty
  • Release sweat that also contains fatty acids and proteins (milky or yellowish color)
  • Play a minimal role in body temperature regulation
• Hair anatomy:

  • Produced by hair follicle
  • Root is enclosed in the follicle
  • Shaft projects from the surface of the scalp or skin
  • Consists of hard keratinized epithelial cells
  • Melanocytes produce pigment for hair color
  • Hair grows in the matrix of the hair bulb in stratum basale
• Associated hair structures:

  • Hair follicle composed of an epithelial root sheath and fibrous sheath
  • Dermal region provides a blood supply to the hair bulb (deepest part of the follicle)
  • Arrector pili muscle connects to the hair follicle to pull hairs upright when we are cold or frightened
• Nails:

  • Heavily keratinized, scalelike modifications of the epidermis
  • Stratum basale extends beneath the nail bed, responsible for growth
  • Lack of pigment makes nails colorless
  • Parts of a nail: free edge, body, nail folds, root embedded in skin, growth from nail matrix
• Homeostatic Imbalances of Skin:

  • Infections and allergies include athlete’s foot, boils, cold sores, contact dermatitis, impetigo, psoriasis
  • Burns cause tissue damage and cell death, with different degrees of severity: first-degree, second-degree, third-degree, and fourth-degree
• Criteria for deeming burns critical:

  • Over 30% of body has second-degree burns
  • Over 10% of the body has third- or fourth-degree burns
  • Third- or fourth-degree burns of the face, hands, or feet, or genitals
  • Burns affect the airways
  • Circumferential burns have occurred
• Skin cancer:

  • Most common form of cancer in humans
  • Risk factors include overexposure to UV radiation
  • Types include basal cell carcinoma, squamous cell carcinoma, and malignant melanoma
• Developmental Aspects of Skin and Body Membranes:

  • Lanugo covers the body by the fifth or sixth month of fetal development but disappears by birth
  • Vernix caseosa is apparent at birth
  • Milia are small white spots common at birth and disappear by the third week
  • Acne may appear during adolescence
  • Skin changes with aging, losing elasticity and thinning
  • Skin cancer is a major threat to skin exposed to excessive sunlight
• The skeletal system is composed of bones, cartilages, ligaments, tendons, joints, and muscles.