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70 Cards in this Set
- Front
- Back
5 primary functions of the skeleton?
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1) support
2) protection 3) movement 4) storage 5) blood cell production |
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rigid, strong bone
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well suited for bearing weight
the major supporting tissue of the body |
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function of cartilage?
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provides a firm, yet flexible support within certain structures (nose, external ear, rib cartilages, trachea)
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What are ligaments?
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strong bands of fibrous connective tissue that attach to bones and hold them together
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What three things include in support system of the skeleton?
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1) rigid, strong bone
2) cartilage 3) ligaments |
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bone : protenction
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bone is hard and protects the organs it surrounds
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skull
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encloses and protects the brain
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vertebrae
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surround the spinal cord
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rib cage
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protects the heart, lungs, and other organs of the thorax
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What are the four things importnat in the skletal movement?
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1) skeletal muscles
2) joints 3) smooth cartilage 4) ligaments |
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skeletal muscles
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attach to bones by tendons
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tendons
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strong bands of connective tissue
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contraction of the skeletal muscle
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moves the bones, producing body movements
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Where are joints formed?
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where two or more bones come together
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function of joints?
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permit and control the movement between bones
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smooth cartilage
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covers the ends of bones within some joints, allowing the bones to move freely
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function of ligaments?
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allow some movement between bones but prevent excessive movements
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What are two principle minerals stored into bone?
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calcium and phosphorus
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Where is fat (adipose tissue) stored?
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within bone cavities
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many bones contain cavities filled with?
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bone marrow
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bone marrow gives rise to?
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blood cells and platelets
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three types of bone cells?
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1) osteoblasts
2) osteocytes 3) osteoclasts |
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What are osteoblasts?
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bone-forming cells
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primary function of osteoblasts?
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to lay down new bone
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after forming new bone, osteoblsats become what?
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osteocytes
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What does an osteoblast produce?
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type one collagen & osteocalcin
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type I collagen is responsive to?
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PTH (parathyroid hormone)
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When osteoblasts produce osteocalcin?
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when stiumulated by 1,25-dyhydroxyvitamin D
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osteocalcin
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a calcium-binding protein
inhibit Ca-Phosphate precipitation promotes bone resorption |
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osteoblasts are active on?
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on the outer surface of bones, where they form a SINGLE layer of cells
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osteoblasts bring about the formation of new bone by?
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by their synthesis of OSTEOID (non-mineralized bone matrix)
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What is osteoid?
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a protein mixture composed mainly of collagen that is secreted by osteoblasts and becomes mineralized to form bone
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What are osteocytes?
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are osteoblasts that have become imprisoned within the mineralized bone matrix
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function of osteocytes?
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help maintain bone by synthesizing new bone matrix molecules
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function of osteocytes? #2
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not fully known
synthesize certain matrix molecules assisting bone calcification |
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osteocytes : nutrients
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osteocytes obtain nutrients from capillaries in the CANALICULI
help concentrate them in the matrix help synthesize and replace needed elements of the matrix |
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obtaining nutrients from calillaries in the canaliculi help what?
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help to maintain mineral homeostasis with the help of the PTH and osteoblast cells
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definition of osteocyte?
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is a transformed osteoblast that is trapped or surrounded in OSTEOID as it hardens from minerals that enter during calcification
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What are osteoclasts?
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the major resorptive cells of bone
large, multinucleated cells short life span |
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osteoclasts develop from?
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1)from the hematopoietic stem cells in the bone marrow stroma and adjacent vessels
2) from mononuclear phagocytic cells |
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function of osteoclasts?
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to resorb (remove) bone during of growth and repair
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osteoclasts contain what?
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lysosomes (digestive vacuoles) filled with hydrolytic enzymes
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long bone
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femur
thigh bone humerus of arm |
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flat bone
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parietal bone of skull
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short bone
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carpals of wrist
wrist bone |
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irregular bone
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sphenoid bone from skull
vertebra |
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muscle
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consists of hundreds to thousands of muscle cells, plus connective tissue wrappings, blood vessels, and nerve fibers
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muscle are covered externally by?
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the epimysium
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fascicle
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discrete bundle of muscle cells, segregated from the rest of the muscle by a connective tissue sheath
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fascicle are surrounded by?
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perimysium
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muscle fiber
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elongated multinucleate cell; has a banded (striated) appearance
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muscle fiber are surrounded by?
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endomysium
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motor units are composed of what?
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lower motor neurons, which extend to skeletal muscles
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another name for motor unit?
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the functional unit of the neuromuscular system
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motor unit behaves as?
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a single entity and contracts as a whole when it receives an electrical impulse
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whole muscle may be controlled by?
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several motor nerve axones, which innervate many motor units within the muscle
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Does the # of motor units per individual muscle vary?
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varies greatly
(Ex) Calf - one motor axon will innervate appro. 2000 muscle fibers, out of a total of 1,200,000 muscle fibers |
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2 types of muscle contraction
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1) isometric contraction
2) isotonic contraction |
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isometric contraction
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static or holding contraction
the muscle maintains constant length as tension is increased |
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example of isometric contraction
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when the arm or leg is pushed against an immovable object
the muscle contracts, but the limb does not move |
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isotonic contraction
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the muscle maintains a constant tension as it moves
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2 types of isotonic contractions
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1) eccentric (lengthening)
2) concentric (shortening) |
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eccentric isotonic contraction
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the muscle lengthens and absorbes energy
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concentric isotonic concentration
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positive work is accomplished
energy is released to exert force or lift a weight |
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Do actin and myosin myofillaments change length during contraction of skeletal muscle fibers?
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NO! Instead, actin and myosin myofillaments slide past one another in a way that causes the sarcomeres to shoten.
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Whar happens during contraction?
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1) actin myofillaments at each end of the sarcomere slide past the myosin myofilaments toward the H zone
2) I bands shorten 3) A bands do not chenge |
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H zone during the contraction?
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the H zone narrows or even disappears as the actin myofilaments meet at the center of the sarcomere
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the last step of contraction
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as the actin myofilaments slide over the myosin myofilaments, the Z disks are brought closer together, and the sarcomere is shortened
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contracting muscle
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1) sarcomere shortens
2) actin myofilaments move toward H zone |
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fully contracted muscle
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sarcomere is shortened but A band width is unchanged
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