A+P Review #2

Question 1

Define: Osteocyte

Answer 1

*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

Question 2

Define: Osteon

Answer 2

*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

Question 3

Define: Osteoprogenitor cell (osteogenic cells)

Answer 3

*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

Question 4

Define: Osteoblast

Answer 4

*Bone building (grow bone) and found in endosteum (living periosteum)
*Continues as osteocyte once surrounded by matrix trap

Question 5

Define: Osteoclast

Answer 5

*Cells responsible for reasorbing (breakdown matrix to release calcium) bone (remodels bone)
*Secretes lysosomal enzymes and may phagocytize the demineralized products and dead osteocytes

Question 6

Define: Calcium Hydroxyapatite

Answer 6

*Hard, tough strong crystals (made from calcium phosphate)
*Resists applied pressure w/out breaking (provides skeleton w/ strength)

Question 7

Define: Endosteum

Answer 7

*Inner covering of the bone (thin CT)
*Lines all structures inside bone including trabeculae/spongy bone, and inside haversian canal

Question 8

Define: Medullary Cavity (Marrow Cavity)

Answer 8

*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)

Question 9

Define: Epiphyseal Plate

Answer 9

*Area of active bone lengthening

Question 10

Define: Condyle

Answer 10

*Rounded process that usually articulates w/ another bone
Ex. Occipital condyle of occipital bone

Question 11

Define: Fissure

Answer 11

*Deep groves that separate large regions fo the brain

Question 12

Define: Suture

Answer 12

*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)

Question 13

Define: Syndesmosis

Answer 13

*Joints where two bones are joint together by one or more ligament
Ex. Distal joints between tibia and fibula

Question 14

Define: Amphiarthrosis

Answer 14

*A slightly moveable joint

Question 15

Define: Articulation

Answer 15

*Point of contact between two or more bones; between bone and cartilage/between teeth and bone

Question 16

Define: Hyperextension

Answer 16

*Excess extension, moving a part beyond anatomical position

Question 17

Define: Adduction

Answer 17

*Moving a part towards the midline

Question 18

Define: Inversion

Answer 18

*A medial movement of the sole of the foot (inwards rotation)

Question 19

Define: Tendon

Answer 19

*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

Question 20

Define: Bursa

Answer 20

*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

Question 21

Define: Epimysium

Answer 21

*CT sheath that surrounds the entire muscle

Question 22

Define: Endomysium

Answer 22

*CT surrounding a muscle fiber

Question 23

Define: Sarcolemma

Answer 23

*Outer membrane covering of a skeletal muscle fiber

Question 24

Define: Sarcomere

Answer 24

*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

Question 25

Define: H Zone

Answer 25

*Center of A band and contains only thick filament

Question 26

Define: Myofibril

Answer 26

*1 of many contractile filaments that make up a striated muscle fibers

Question 27

Define: Thick Filament

Answer 27

*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)

Question 28

Define: Tropomyosin

Answer 28

*Forms a long chain covering the active site, preventing actin-myosin interaction
-Looks like a vine

Question 29

Define: Myosin

Answer 29

*A mechanochemical enzyme (motor protein) that hydrolyzes ATP (moves towards positive end)
-Head: binds actin and ATP
-Neck: Level arms
-Dimerization motifs/cargo binding

Question 30

Define: Acetylcholine

Answer 30

*Neurotransmitter involved w/ the central and peripheral nervous system and synthesized by the cholinergic neurons
-The target of many of the deadliest neurotoxins

Question 31

Define: Twitch Contraction

Answer 31

*A brief contraction of all muscle fibers in the motor unit in response to a single stimulus from 1 motor neuron

Question 32

Define: Unfused Tetanus

Answer 32

*See partial muscle relation occurring between contractions

Question 33

Define: Muscle Fatigue

Answer 33

*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)

Question 34

Define: Recruitment

Answer 34

*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

Question 35

Define: Intercalated disc

Answer 35

*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

Question 36

Define: Agonist

Answer 36

*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)

Question 37

Define: Synergist

Answer 37

*Help prime mover by adding extra force to same movement/reduces undesirable/unnecessary movements

Question 38

Define: Motor Unit

Answer 38

*Single motor neuron and many skeletal fibers
-Muscle fibers controlled by motor neuron

Question 39

Define: Origin

Answer 39

*Where the muscle attaches to immovable bone

Question 40

Define: Insertion

Answer 40

*Where the muscle attaches to moveable bone

Question 41

Define: Fascicle

Answer 41

*Compartments that contain bundles of muscle cells