bio 1

• Key functions of the integumentary system

  • Support
  • Protection
  • Regulation of body temperature
  • Receptor functions
• Skin


  The largest external organ of the body
• Epidermis


  • Outermost layer of the skin, with no blood vessels
  • Functions: external surface protection, waterproofing, formation of hair and nails, responsible for natural hair color

  
• Dermis


  • Second layer of the skin, acts as the skin glue
  • Functions: provides elasticity of the skin, nourishes the epidermis, receives sensory stimulation, forms the fingerprint and footprint

  
• Hypodermis/Subcutaneous


  • Lowermost layer of the skin made up of fats and adipose tissue
  • Functions: provides high energy reserve, provides insulation, provides cushion, gives body contour

  
• Layers of Epidermis


  • Stratum Corneum
  • Stratum Lucidum
  • Stratum Granulosum
  • Stratum Basale
  • Stratum Spinosum
• Melanin


  • Group of pigments primarily responsible for skin, hair, and eye color
  • Protects against UV light from the sun by scattering UV rays
• Vitamin D synthesis


  Cholecalciferol (epidermis) -> Calcidiol (liver) -> Calcitriol (kidney)
• Dermis


  • Abundant areolar connective tissue with elastin fibers
  • Blood vessels (veins, arteries, capillaries)
  • Sensory receptors (mechanoreceptors, thermoreceptors, nociceptors)
  • Follicles and glands

  
• Hair


  • Produced by the basale cells, made up of keratin protein and cuticle
  • Provides additional insulation for the body
• Nail


  • Thin, hard coverings at the tips of fingertips and toes made up of cuticle and keratin
  • Used to protect the toes and fingers
• Sebaceous gland


  Sac-like type of exocrine gland that secretes oil/sebum to lubricate the skin and hair, prevent dryness, and contribute to skin acidity
• Eccrine sweat gland


  Coiled tube-like type of exocrine gland that secretes sweat for thermoregulation and minor excretion
• Apocrine sweat gland


  Found only in some areas like armpits and anogenital area, secretes sweat that may contribute to body odor
• Other modified sweat glands

  • Ceruminous glands (earwax)
  • Ciliary glands (eye lubrication)
  • Mammary glands (milk production)
• Effects of aging on the skin


  • Becomes rougher and dryer
  • May develop benign tumors and lesions
  • Becomes slack or soggy
  • Becomes more transparent
  • Becomes more fragile
  • Becomes more easily bruised
  • Losses fat in the hypodermis
  • Develop discoloration
  • Hair becomes gray
• Skin care tips


  • Regularly cleanse skin
  • Use suitable soaps
  • Use sunscreens
  • Avoid 10 AM to 2 PM sun exposure
  • Control hypertension and diabetes
  • Avoid smoking
  • Regularly exercise and massage
  • Have adequate sleep
  • Take supplements, minerals, vitamins, and antioxidants
• The skeletal and muscular systems support, protect, and are used for locomotion in most animals
• Types of skeletal systems

  • Hydrostatic skeleton
  • Exoskeleton
  • Endoskeleton
• Hydrostatic skeleton


  Comprises a fluid held under pressure and a closed body compartment, animals control form and movement by using muscles to change the shape of fluid-filled compartments
• Exoskeleton


  A hard covering deposited on an animal's surface
• Types of skeletal systems

  • Hydrostatic skeleton
  • Exoskeleton
  • Endoskeleton
• Hydrostatic skeleton

  • Comprises a fluid held under pressure and a closed body compartment
  • Animals control form and movement by using muscles to change the shape of fluid-filled compartments
• Exoskeleton


  • A hard covering deposited on an animal's surface
  • Shells of clams and some mollusks are made up of calcium carbonate
  • Arthropods have a joint skeleton called a cuticle, a coat that is secreted by the epidermis which is made up of 30% chitin
  • Arthropods shed their exoskeleton (molting) to produce a larger one that can accommodate its larger body
• Endoskeleton


  • A hardened internal skeleton buried within the soft tissues or cells
  • In some sponges, the endoskeleton comprises hard needle-like structures made of calcium carbonate or silica called spicules
  • Some sponges have a more flexible endoskeleton composed of spongin protein
  • In vertebrates, the endoskeleton comprises bone and/or cartilage or a combination of both
  • In echinoderms, the endoskeleton is composed of ossicles, which are hard plates composed of magnesium carbonate and calcium carbonate crystals
• Functions of the skeletal system

  • Support
  • Protection
  • Movement
  • Hemopoiesis
  • Mineral storage
  • Detoxification
• Cartilage

  A connective tissue made up of collagen and chondroitin sulfate, making this tissue a strong yet flexible material
• Bone


  • A mineralized connective tissue that forms the majority of the skeleton
  • Osteoblasts are bone-forming cells that deposit a matrix of collagen
  • Osteoblasts will later on mature into osteocytes which maintain bone nutrition
  • Osteoclasts resorb (destroy) the bone and remodel damaged bones
  • Osteoclasts also aid in calcium regulation in the body
• Osteons

  • Repeating units seen in a cross-section of a hard bone
  • Each osteon has concentric layers of mineralized matrix, which are deposited around a central canal containing blood vessels and nerve cells
• Types of bones


  • Short
  • Long
  • Flat
  • Irregular
  • Sesamoid
• Long bone


  • Has two main tissue membranes: the periosteum (outer connective tissue membrane) and the endosteum (inner connective tissue membrane)
  • Has two major segments: the epiphysis (spongy bone with red bone marrow) and the diaphysis (compact bone with yellow bone marrow)
  • Cartilage surrounds the epiphyseal ends of the long bone
• Ossification


  1. Primary ossification happens after birth and is characterized by bone hardening, wherein there is an active intake and storage of calcium in the bones

  2. Secondary ossification increases bone length and happens in the epiphysis or at the epiphyseal line/disk or growth plate
• Growth hormone


  Regulates bone growth by promoting an increase in bone length and height
• Calcium has a role in attaining bone strength and hardness
• The bone also has a role in regulating calcium levels in the body
• There are 214 bones in children and 206 bones in adults. The difference in the number of bones in human development is due to the fusion of bones in the spinal column
• Divisions of the human skeleton

  • Axial skeleton
  • Appendicular skeleton
• Levers


  Being pulled by a force at a fixed point or fulcrum in the presence of a resistance
• Muscle tone


  • The partially contracted state of the muscle
  • Good muscle tone provides good body posture, a hallmark of good health
• Shivering


  Muscular contractions associated with heat production to return body temperature to normal once it goes below 35.6°C