A+P Review #2 Flashcards
Define: Osteocyte
*Mature bone cell formed when an osteoblast becomes surrounded by its own matrix (EC) and entrapped/occupy in the lacunae
*Acts as stress/strain sensors and allows nutrients and transfer between cells through gap junctions
Define: Osteon
*Cylinders of the tissue formed from concentric layers(lamella) of EC matrix arranged around central canal holding a blood vessel
*Collagen fibers surrounding each lamella, alternating left and right
Define: Osteoprogenitor cell (osteogenic cells)
*Stem cells divide to produce cells that differentiate into osteoblasts (found in periosteum and inner lining of the marrow cavity)
*Responsible for the production of new bone matrix
Define: Osteoblast
*Bone building (grow bone) and found in endosteum (living periosteum)
*Continues as osteocyte once surrounded by matrix trap
Define: Osteoclast
*Cells responsible for reasorbing (breakdown matrix to release calcium) bone (remodels bone)
*Secretes lysosomal enzymes and may phagocytize the demineralized products and dead osteocytes
Define: Calcium Hydroxyapatite
*Hard, tough strong crystals (made from calcium phosphate)
*Resists applied pressure w/out breaking (provides skeleton w/ strength)
Define: Endosteum
*Inner covering of the bone (thin CT)
*Lines all structures inside bone including trabeculae/spongy bone, and inside haversian canal
Define: Medullary Cavity (Marrow Cavity)
*Space w/in diaphysis and contains red and yellow marrow (adipose tissue)
*Embodied in bones (of fetus); hips, ribs, sternum, vertebrae, skull, epiphysis of humerus and femur (of adults)
Define: Epiphyseal Plate
*Area of active bone lengthening
Define: Condyle
*Rounded process that usually articulates w/ another bone
Ex. Occipital condyle of occipital bone
Define: Fissure
*Deep groves that separate large regions fo the brain
Define: Suture
*Designed to support healing tissue and hold tissue edges together until they heal
*Bones of the cranium and face that are joined by fibrous joints (synarthrosis joints)
Define: Syndesmosis
*Joints where two bones are joint together by one or more ligament
Ex. Distal joints between tibia and fibula
Define: Amphiarthrosis
*A slightly moveable joint
Define: Articulation
*Point of contact between two or more bones; between bone and cartilage/between teeth and bone
Define: Hyperextension
*Excess extension, moving a part beyond anatomical position
Define: Adduction
*Moving a part towards the midline
Define: Inversion
*A medial movement of the sole of the foot (inwards rotation)
Define: Tendon
*Composed of tenocytes (water and fibrous collagen protein) of variable length
*Connects bone to muscle
-Part of muscle and contractile part of the muscle to bone
-Non-densible fibrous cord/band
-Tendons not vascularized
Define: Bursa
*Sac/saclike cavity; lined w/ a synovial membrane that secretes a viscous lubrication synovial fluid (bursal)
*Interposed between tendons and bony prominences/any other point of friction
Define: Epimysium
*CT sheath that surrounds the entire muscle
Define: Endomysium
*CT surrounding a muscle fiber
Define: Sarcolemma
*Outer membrane covering of a skeletal muscle fiber
Define: Sarcomere
*Composed of regulatory arranged contractile proteins (actin, myosin) that are responsible for skeletal muscle contraction
-Very regular, ordinary arrangement is what gives skeletal muscle fibers a striated appearance
-1 sarcomere extends from 1 Z line to next Z line
Define: H Zone
*Center of A band and contains only thick filament
Define: Myofibril
*1 of many contractile filaments that make up a striated muscle fibers
Define: Thick Filament
*Massive bundles of sub-units composed of protein myosin
-Appear in muscle where they interact w/ filaments to produce powerful contractions
-Composed of myosin (protein)
Define: Tropomyosin
*Forms a long chain covering the active site, preventing actin-myosin interaction
-Looks like a vine
Define: Myosin
*A mechanochemical enzyme (motor protein) that hydrolyzes ATP (moves towards positive end)
-Head: binds actin and ATP
-Neck: Level arms
-Dimerization motifs/cargo binding
Define: Acetylcholine
*Neurotransmitter involved w/ the central and peripheral nervous system and synthesized by the cholinergic neurons
-The target of many of the deadliest neurotoxins
Define: Twitch Contraction
*A brief contraction of all muscle fibers in the motor unit in response to a single stimulus from 1 motor neuron
Define: Unfused Tetanus
*See partial muscle relation occurring between contractions
Define: Muscle Fatigue
*Muscle is in a state of physiological inability to contract
*Occurs when:
-ATP production fails to keep pace w/ ATP use
-A relative deficit of ATP, causing contractures
-Lactic acid accumulates in the muscle
-Ionic imbalances are present (Na, K pump balance)
Define: Recruitment
*Process of increasing the # of active motor units to produce increasing levels of muscle contractions
-Based on motor neuron size
-More motor units activated = more forced produced
Define: Intercalated disc
*Enables the muscle cells to synchronize during contraction
*Contains desmosome and gap junctions
-Desmosome: hold cells together (prevent cells from separating during contraction)
-Gap junctions: Allows ions to pass from cell to cell; electrically couple adjacent cells
Define: Agonist
*Any drug/chemical molecule that binds a receptor and produces an effect [(producing specific movement) prime mover]
-Magnitude of drug effect is proportional to the amount of drug (receptor complexes formed)
Define: Synergist
*Help prime mover by adding extra force to same movement/reduces undesirable/unnecessary movements
Define: Motor Unit
*Single motor neuron and many skeletal fibers
-Muscle fibers controlled by motor neuron
Define: Origin
*Where the muscle attaches to immovable bone
Define: Insertion
*Where the muscle attaches to moveable bone
Define: Fascicle
*Compartments that contain bundles of muscle cells
