Question | Answer |
Which have gap junctions: unitary or multiunit smooth muscle? | Unitary |
Trur or false: Multiunit smooth muscle afferent fibers stimulate multiple muscle fobers at once | False: each fiber is stimulated by a single affernet fiber |
Multiunit or unitary smooth muscle possesses pace maker activity | Unitary |
Two type of unitary smooth muscle. Which are not associated with generation of AP? | 1. Phasic 2. Tonic |
Tonic or phasic unitary smooth muscle exhibits continuous contractions? | Tonic |
Phasic smooth muscle show ___ contractions. Where are they found? | 1. Rhythmic 2. Parastalsis in GI tract |
Tonic smooth muscls are found where? | Blood vessels and arteries |
What is muscular distrophy? | Degeneration of muscle replces with adipose and connective tissue |
MD is sex-linked affecting what ratio of males? | 1:3500 |
MD is a defect of what? | 1. Sarcolemma of the muscle 2. Ultimately kills the muscle |
What is myesthenia gravis? | 1. ACH receptor sites become damages 2. Less ACH gets into muscles 3. Weaker contractions |
Smooth muscles are devoid of ___ because thich and thin filaments are not organized inot sarcomeres. What is a smooth muscle's resting state membrane potential? | 1. Striation 2. -50 to -60 mV |
1. Smooth muscle activated by what? 2. Skeletal muscles are activated by what only? | 1. Stretching, hormones and neurotransmitters 2. Neurotransmitters |
Smooth muscle exibits ___cycling of cross bridges, ___ onset of contraction~relaxtion, ___force contraction, __Percent shortening and ___energy requirement | 1. Slow 2. Long 3. High 4. High 5. Low |
SIngle init fibers contain what which permits fasrt spread of electricity^ | Gap junctions |
Where are single unit smooth fibers found? | GI tract, bladder, uterus, uretur |
Rhythmic or phasic contractions are due to what? | 1. Ca+ channels 2. Ca+ action potentials |
Tonic contraction AKA what? | Continuous contraction |
T or F: Multiunit smooth muscles contain gap junction | False |
Each fiber of a multiunit muscle acts like a what? Where are they found? | 1. Single motor unit 2. Iris, ciliary muscle of eye, vas deferens |
Smooth muscle has no ___ and less developped __ than skeletal and cardial muscle | 1. No T-tubules 2. Less SR |
Smooth muscle contains bulges of motor nerve fibers that are under nervous control called what? | Vericosities |
Action potential release NT from synaptic vessicles that are stored in the ___ | Varicosities |
Depolarization of the AP opens what kind of channels? Allows for an increase of Ca+ where? | 1. Voltage gates Ca+ channels 2/ Increase in intracellular Ca+ |
2 other ways Ca+ can get inot the cell? | 1. Ligand-gated channels 2. Inostisol triphosphate gated Ca+ channels |
Increases intracellular Ca+ causes Ca+ to bind to what? This can bind how many Ca+? | 1. Calmodulin protein 2. 4 |
The calcium-calmodulin activated what? | Kinase |
Activated kinase is responsible for doing what? | Phosphorylates myosin |
Phosphorylated myosin binds to what to form what? How many ATP used? | 1. Binds to actin to form cross bridges 2. 1 |
Myosin is dephosphroylated by what and when? Does it let go right away? | 1. Dephosphorylated by myosin light chainb phosphates when intracellular Ca+ decreases 2. Yes |
What enables the myosin to remain attached without the use of excess ATP? This phenomena maintains what type of contraction? | 1. Latch bridge mechanism 2. Tonic contraction |
Latch-bridges make smooth muscle very __ ___. | Fatigue resistant |
When do the smooth muscle fibers finally relax? | When SR takes back in the Ca+ via Ca+ATPase |
Cardial muscles contain gap junctions called what? They are continuous whit the __ of the muscle. | 1. Intercalated disks 2. Sarcolemma |
Intercalated disks allow the two atria to act as a giant cell. WHat is this called? | Syncytium |
T-tubules in cardial muscles are located where? | Z-disks |
In cardiac muscles, the SR releases Ca+ where? This causes what channels to open to allow Ca+ to difuse into the muscle? | 1. Sarcoplams 2. (slow) voltage gated Calcium /Na+ chanel (same as skeletal) |
What id the reason for plateau phase in cadial muscle? | Sustained depolarization of cadial cells caused by Ca+ entering through voltage-gated sensitive Ca+ channels |
Is depol of the heart muscle directly responsible for contractions? | No, contraction does not occur unless Ca+ enters the cells |
Describe artherosclerosis and uniary bladder hypertrophy | |