skeleton + muscles ch 36

types of skeleton

exoskeleton, endoskeleton

skeleton made up of …

bone and cartilage, with muscle attached to the outside, bones are held together by ligaments and move due to the forces produced by muscles which are attached to the bones by tendons.

functions of human skeleton

support and shape, protection - of internal organs, movement - bone gives muscles base against which to pull, blood cell production - by bone marrow, transmission of sound waves in the middle ear, storage of calcium and phosphorus

axial skeleton 1. skull (cranium)

made up of 22 fused bones, has sutures, protects the brain, has fixed upper jaw and movable lower jaw

axial skeleton, 2. vertebral colum (backbone)

33 vertebrae, cervical/neck - 7, thoracic/chest - 12, lumbar/back - 5, sacral/hip - 5 fused, coccyx/tail - 4 fused

discs

made of cartilage lie between the vertebrae, acting as shock absorbers and allowing for spinal flexibility.

slipped discs

when outer fibrous coat of the cartilage disc becomes torn or damaged, it bursts and the soft elastic muscle in the centre pushes onto nerves causing pain in the spine

axial skeleton 3. sternum and ribs

protect lungs and help in breathing

appendicular skeleton 1.

pentadactyl limbs - arms and legs

appendicular skeleton 2. girdles

pectoral (shoulder) girdle consists of collarbone(clavicle) and shoulder blade (scapula) forms a connection with vertebral column and arms

bones

206 adult, 350 newborn, bones - 8% body mass, three types flat bone - skull, long bone - femur, short bones - tarsal/carpal

cartilage

flexible fiberous protein - collagen, collagen fibres are embedded in matrix of calcium and phosphorus, lacks blood vessels and nerves, depends on material diffusing through the cells, its slow to heal - covers the tips of bones meet in joints, reduces friction, acts as a shock absorber

periosteum

fibrous coat

compact bone

made of osteoblasts embedded in matrix 70% inorganic, 30% protein, calcium salts give bone strength, protein gives flexibility, mostly in shaft(diaphsis) of bone and as a layer around ends of bones

spongy bones

contains numerous hollows to minimise weight, spaces filled with red bone marrow

hollow centre (medullary cavity)

contains inactive yellow bone marrow, stores fat

bone growth

embryonic cartilage is replaced with bone after 8 weeks in the uterus, osteoblasts are bone cells responsible for ossification - conversion of cartilage to bone, produce collagen and a hard compound-calcium phosphate forms around collagen fibres, osteoblasts trapped and become dormant. increase in bone length due to growth plate found between epiphysis and diaphysis, plate cartilage continually formed turned to bone

bone development

bone continually broken down and built up again x10, bonedigesting cells in the medullary cavity digest the bone that lines the cavity, release calcium, osteoblasts make new bone

renewal of bone

bones are stressed by physical activity they become thicker and stronger - osteoblasts are stimulated, growth + sex hormones increase size of bones, parathormone removes calcium from bone increase blood calcium levels

joints

2 or more bones meet, immovable - skull/pelvis, slightly movable - spinal column, movable - ball and socket/hinge

synovial joint - knee

bones layer of cartilage, held by capsule of liagments - elastic enough to allow the require rand of movement, cartilage acts as shock absorber, allows free smooth movement between the bones, synovial membrane - secretes synovial fluid into the joint, synovial fluid lubricates and reduces friction, provides nourishment for living cartilage

skeletal muscle

concerned with body movement - can contract quickly but tires easily, voluntary

smooth muscle

found in internal structures, contracts slowly and slow to tire, involuntary

cardiac muscle

involuntary, have many mitochondria contracts strongly doesnt tire easy

antagonistic muscle

pairs of muscles working as opposites to control movement, bending arm - biceps contract and triceps relax, straighting arm - triceps contract and biceps relax

musculoskeletal disorder

study either osteoporosis or arthritis

arthritis

joint inflammation

osteoarthritis

cartilage on tips of bones wears away as person ages, underlying bones enlarge and more synovial fluid forms

rheumatoid arthrithis

immune system attacks the joint and causes pain and inflammation, synovial membranes are attacked first, joint swells and becomes damaged and deformed

osteoporosis

the loss of protein, causes bone to become brittle, caused by bone replacement slowed down, more common in menopausal women

rickets

lack of calcium or vit D, bone grows but isnt hardened by calcium salts