Bio

• Integumentary System

  The outermost layer of the body; consists of different parts (skin, hairs, nails, and the glands along with the nerves on the skin)

  
• Integumentary System

  • Acts as our defense against physical harm and helps with the body temperatures' regulation
• Functions of the Integumentary System

  • Acts as physical protection against pathogens
  • Absorbs and helps heal abrasions, cuts and other injuries
  • Cushions the body from heavy impacts
  • Protects the body from the UV rays and sunburn
  • Excretes body waste
  • Regulates one's body temperature and enables them to stay cool
  • Helps one sense heat and cold and perceive other sensations
  • Synthesizes vitamin D
• Types of Tissues in the Integumentary System

  • Epithelial Tissue
  • Connective Tissue
  • Subcutaneous Tissue
• Skin

  Largest and heaviest organ in the body (weighs about six pounds or more and is approximately 2 millimeters thick)
• Skin


  • Thinner on sensitive areas like eyelids, and thicker on surfaces that take more stress, like the soles of your feet
  • One inch of the skin contains nearly 19 million cells
  • Composed of three layers, with nerves that recognize different sensations in each layer

  
• Epidermis


  Outermost layer of the skin; function: hydration, producing new skin cells, protection, skin color

  
• Cells in the Epidermis


  • Keratinocytes
  • Melanocytes
  • Langerhans cells
• Stratum Corneum


  Top layer of the epidermis; has fats that prevent water from easily entering or leaving one's body; where keratinocytes become corneocytes (strong, dead keratinocytes, and they act as protection from harm, including abrasions, light, heat and pathogens)
• Stratum Lucidum


  Thin, transparent layer of keratinocytes that are becoming less round and have a flatter shape
• Stratum Granulosum


  Where the keratinocytes' granules are observable when using a microscope
• Stratum Spinosum


  Includes sticky proteins called "desmosomes" which holds keratinocytes together; helps make your skin flexible and strong
• Stratum Basale (Stratum Germinativum)


  Deepest layer of the epidermis; where new skin cells develop; also contains the keratinocyte stem cells, which produce the protein keratin; also contains melanocytes which are responsible for producing melanin

  
• Dermis

  Middle and thickest layer of the skin; consists of two layers; all connective tissues, nerve endings, sweat glands, oil glands and hair follicles exist in the dermis

  
• Dermis


  • Varies in thickness across the body (thinnest over the eyelids, where it's 0.6 millimeters thick, and it's thickest over the back, where it's 4 millimeters thick)
  • Functions: supporting epidermis, feeling different sensations, producing sweat, keeping skin moist, producing hair

  
• Outer Papillary Layer


  Top layer of the dermis; consists of collagen fibers, fibroblast cells, fat cells, blood vessels (capillary loops), nerve fibers, touch receptors (Meissner corpuscles) and cells that fight bacteria (phagocytes); extends to the basement layer of the epidermis layer

  
• Types of Receptors in the Outer Papillary Layer


  • Mechanoreceptors
  • Pacinian corpuscles
  • Meissner corpuscles
  • Ruffini corpuscles
  • Merkel complexes
  • Thermoreceptors
  • Nociceptors
• Inner Reticular Layer


  Thick; bottom layer of the dermis; contains blood vessels, glands, hair follicles, lymphatics, nerves and fat cells; surrounded by a net-like structure of elastin fibers and collagen fibers that support the skin's overall structure, as well as allow it to move and stretch

  
• Glands in the Skin


  • Sudoriferous / Sweat glands
  • Sebaceous glands
  • Mammary glands
  • Ceruminous glands
• Hypodermis


  Innermost layer of the skin; fatty layer that helps insulate the body; thickness differs across your body

  
• Hypodermis

  • Functions: connection, insulation, protection, storing energy
• Components of the Hypodermis

  • Adipose tissue
  • Blood vessels
  • Connective tissue
  • Fibroblasts
  • Hair follicles
  • Lymphatic vessels
  • Macrophages
  • Nerves
  • Sweat gland

  
• Accessory Organs of the Integumentary System

  • Nails
  • Hair
• Nails

  Protects the ends of fingers and toes
• Parts of the Nail

  • Nail plate
  • Nail bed
  • Cuticle
  • Matrix
  • Lunula
• Hair

  On the head helps keep heat in the body; eyelashes and eyebrows help protect eyes from dirt and water; made of a protein called keratin
• Parts of the Hair

  • Hair shaft
  • Hair follicle
  • Hair bulb
• Goosebumps


  Caused by the integumentary system when hair erector muscles connected to the hair follicles and skin contract, making the hair stand up
• Skeletal system


  The framework of the body, consisting of bones and other connective tissues, which protects and supports the body tissues and internal organs
• Skeleton contains 206 bones in adults and over 270 bones in babies
• Bone structure (typical 4 layers)


  • Periosteum - covers and protects the bone's exterior
  • Compact bone - supports and protects the tissue within
  • Spongy bone - porous, honeycombed material found inside of most bones which allows the bone to be strong yet lightweight
  • Bone marrow - fills the gaps between the spongy bone, including red bone marrow responsible for blood cell production and yellow bone marrow containing fat cells
• Spongy bone


  Does not have osteons, but has trabeculae (lattice-like arrangements of osteocytes) which are basically little beams in the bone
• Compact bone


  Hard exterior composed of repeating osteons (basic structural unit of compact bone)
• 5 functions of the skeletal system


  • Movement - provides points of attachment for muscles
  • Support - provides support to the body and keeps internal organs in place
  • Protection - protects internal organs from damage
  • Makes blood - red and white blood cells are formed by bone marrow
  • Storage - bones store minerals like calcium and phosphorus
• Bone cells

  • Osteocytes - mature bone cells embedded in the bone matrix
  • Osteoblasts - bone building cells
  • Osteoclasts - break down bone
  • Bone lining cells
• Bone ossification


  The process by which bone is formed, including endochondral ossification which uses hyaline cartilage as the model for long bone formation
• Bone remodeling


  The replacement of old bone tissue by new bone tissue, allowing bones to adapt to stresses by becoming thicker and stronger
• 2 major skeletal system parts


  • Axial skeleton - includes the skull, spine, ribs and sternum
  • Appendicular skeleton - the appendages of the body, including the shoulders, arms, hips, and legs

  
• 4 basic bone shapes


  • Long
  • Short
  • Flat
  • Irregular
• Genetics


  The scientific study of genes and how they affect heredity