Chapter 6 Integumentary System 09 16 2013 o Hair o Hair is composed of hard keratin which is very compact and tough o Each individual hair is called a pilus pili and grows from a tube called hair follicle o Same hair density from person to person o Same number of hairs gestation pregnancy o May shed these hairs in the womb o Lanugo fine unpigmented hair of a fetus during the last three months of o Vellus hair fine pale hair present on head of newborn hair of children face stomach etc o Terminal hair longer coarser more pigmented hair o Head eyebrows o Cell division happens in matrix o Cell division pushes hair outwards o Shaft is the long portion of the hair o Piloerector muscle wraps around the hair and causes it to stand up by contracting o Goosebumps o Medulla middle portion of hair o Cortex superficial to medulla o Cuticle squamous cells that overlap o Alopecia thinning of the hair resulting in baldness o Hair is shed before it can emerge from the hair shaft o Follicles begin to form vellus hair instead of terminal hair o Worsens with Lack of nutrients poor diet anorexia eating disorders o Hair alternates between stages of hair growth degeneration and resting o Different from male patterned baldness o Pattern baldness hair thins in certain regions of the scalp faster than other high testosterone o Genetic cause only dominant in males expressed in presence of o Hirsutism excessive and undesirable hair growth in unhairy regions o Common in women with hypersecretion of testosterone Nails o Composed of thick keratin in paraellel o In most mammals nails are in the form of claws hooves o Made up of keratin still o Free edge white on tip of the nail where it extends off the top of the skin o Nail body is the main portion of the nail o Lunule white portion on the bottom of the nail o Looks like half moon o Eponychium cuticle o Chapter 7 Bone Tissue 09 16 2013 o In addition to providing support protection and movement of the body the skeleton is also responsible for electrolyte balance acid base balance and formation of blood cells o Bones are made up of osseous tissue bone marrow cartilage adipose tissue nervous tissue and fibrous connective tissue o Bones are categorized based on shape o Flat o Long o Short o Irregular Long Bone o Diaphysis shaft of long bone o Epiphysis Made up of spongy bone knob like projections o Articular cartilage found where two bones meet o Reduces friction o Outside covering of bone periosteum o Under periosteum is the endosteum o Epiphyseal line bone lengthening covered in hyaline cartilage o Nutrient foramina opening in the bone to allow blood vessels to enter and exit the bone WHY To supply nutrients to the bone and get rid of waste product o In children and adolsescents the diaphysis is separated from the epiphyses by a plate of cartilage called the epiphyseal plate which is the site of bone growth and breakdown during these years o Osteoclasts are more active at the side farthest from the medullary cavity o Osteoblasts are more active at the side closer to the medullary cavity o Breakdown bone o Form bone o After adolescence the epiphyseal plate will seal off leaving a line visible by the x ray o Males age 21 o Females age 18 o Flat Bone o Sutures keep bones together o Sandwich of compact bone spongy bone compact bone Bone Cells o Osteogenic cells stem cells that give rise to all other types of bone cells o Osteoblasts bone forming cells simple cuboidal layer under endosteum and periosteum nonmitotic o Synthesize soft material of bone matrix which is then hardened o Osteocytes former osteoblasts that are stuck within the matrix residing in cavities called lacunae o All lacunae are interconnected by channels called canaliculi o Osteocytes send extensions through canaiiculi to communicate o Osteoclasts bone dissolving cells on the surface of the bone o Several stem cells fused together up to 50 nuclei o Calcium remodeling Bone Matrix o Organic matter synthesized by osteoblasts includes collagen protein carbohydrate complexes o Provides some flexibility to the bones preventing them from o Sacrificial bonds break under stress to dissipate shock and quickly reform o Inorganic matter mainly calcium phosphate salt also calcium carbonate snapping other minerals Compact Bone o Compact bone very dense solid bone o Osteons Ring structures that form concentric circles that look like the rings of a tree o In the middle of them are blood vessels and nerves o Red artery high in oxygen Blue vein low in oxygen Yellow nerves to feel pain o Osteons are connected to each other o Pathway of bloodflow and therefore nutrients o Nutrient foramina perforating canals volkman canals central canals osteocytes in lacunae adjacent osteocytes via canaliculi o Wastes will move in the opposite direction Spongy Bone o Spongy bone is hard and calcified o Covered by endosteum filled with bone marrow o Arranged into a latticework of bone called spicules o Also contains plates of bone called trabeculae which help to absorb stress and impact o No central canals o Because it s arranged differently not very thick o Makes the skeleton lighter o This is good because if we were all compact we would be too heavy Bone Marrow o Bone marrow is tissue that fills the medullary cavities of smooth and to move compact bone o Red blood cells white blood cells and yellow bone marrow o Red bone marrow responsible for formation of blood cells most abundant during childhood o After childhood most red bone marrow becomes yellow bone marrow which is mainly composed of adipose tissue o Not involved in blood cell formation o Still find red bone marrow in femur sternum hips ribs humerus and vertebrae after childhood o Conversion of red to yellow starts distally and moves proximally Bone Remodeling o Even when bones are not growing they are constantly remodeled replacing about 10 of the skeleton per year o Bone can become wider even when it is not lengthening according to use o Bone becomes wider due to weight gain active lifestyle o Osteoblasts are more active during this than osteoclasts o Bone is laid down in areas where the greatest stress is encountered o After epiphyseal plates seal off bone breakdown by osteoclasts and bone formation by osteoblasts is approximately equal o Bone is formed through mineralization mineral deposition in which calcium and phosphate are removed from the bone and laid down to form bone o These minerals are laid down in the mineralized form of hydroxyapatite crystals which are