| Question |
Answer |
| Skeletal muscle |
striated, voluntary |
| Smooth muscle |
non-striated, involuntary, single/ multiunit |
| Cardiac muscle |
striated, involuntary, autorhythmicity |
| Basic functions of muscle |
movement, maintain posture, heat generation |
| Characteristics of muscle |
excitability, contract-ability, extensibility, elasticity |
| Sarcolemma |
plasma membrane with t-tubules |
| Sarcoplasm |
cytoplasm of muscle cell |
| Sarcoplasmic reticulum |
smooth er, calcium ion storehouse |
| Myofibrils |
organized proteins responsible for contraction |
| Myofilaments |
cytoskeleton |
| I band |
light band, thin filaments, myosin |
| A band |
dark band, thick filaments, actin |
| Z line |
middle |
| H band |
center area |
| Myosin properties needed for contraction |
-ATP site closely associated with actin binding site
-Position of the myosin
-release of ADP, so muscle can relax & new ATP can bind |
| Troponin- Tropomyosin complex |
serve as a switch for muscle contraction and muscle relaxation
tropomyosin must be moved for myosin cross bridges to attach actin- requires ca++ |
| Motor unit |
a lower motor neuron & all of the skeletal muscle fibers stimulated by branches of its axon, larger units= more force, smaller units= finer degree of neural control |
| Muscle twitch |
occurs when muscle is stimulated with a single electric shock, a quick contraction then relaxation |
| Latent period |
time stimulus is applied until contraction begins |
| Contraction |
beginning of contraction to peak |
| Relaxation |
peak to end of contraction |
| All or none |
a given response will be produced to its maximum extent in response to any stimulus equal to or greater than threshold response
ex- action potential to twitch |
| Temporal summation |
asynchronous contraction, twitches alternate to produce a continuous maintenance of force |
| Spatial summation |
recruitment, more cells = more force |
| Elastic components function |
smooth out muscle behavior, absorbs some of the tension as a muscle contracts, elastic recoil help muscle return to resting length |
| slow twitch |
small, rich in myoglobin (oxygen), sustain aerobic |
| fast twitch |
larger, lots of thick & thin, low myoglobin (oxygen), less blood flow, fast to fatigue |
| Golgi tendon organs |
can stop a muscle contraction, protective device, senses the tension muscle exerts on its tendons |
| Muscle spindles |
senses muscle length, muscle that require the finest degree of control have the most
extrafusal: insert into tendons on each side
intrafusal: several thin muscle cells in connectrive tissue sheath |
| Final common pathway |
motor pathway, consisting of the motor neurons by which nerve impulses from many central sources pass to a muscle |
| Smooth muscle cells |
filaments in a spiraling pattern, no striations, can stretch greatly, big active range, gap junctions |
| single unit/ multiple unit |
single: cells work as a collective group, lots of gap junctions
multiple: each cell functions independently, few gap junctions ex- eye |
Ch.18 LTI-MA 509
