(05) Smooth Muscle I Flashcards
- In bipeds, Because of gravity, urine can be passed from kidney to urinary bladder very ______.
- In quadripeds, requires more action. There is smooth muscle on the _______, ________, ________.
- Needs to be _________ on the gall bladder to secrete ______ into the _______.
- passively
- ureters, urinary bladder, sphincter
- smooth muscle, bile, small intestine
(Smooth muscle contraction controls a diverse array of physiologic functions)
- Vascular - regulation of _______
- Airway - _____ and _____
- G.I. - _____, _______, ______
- Gallbladder - _____, _____
- Urinary Bladder - _____, _____
- Uterus - _____, _____
- blood pressure
- constriction, relaxation
- peristalsis, segmentation, transit
- storage, emptying
- storage, empyting
- accomodation, delivery
Skeletal, Cardiac, Smooth
- striated?
- voluntary?
- nonstriated?
- involuntary?
- Does cardiac muscle have autonomic nervous system regulation?
- skeletal, cardiac
- skeletal
- smooth
- cardiac, smooth
- yes
Biologically, does smooth muscle behave like striated muscle?
How so?
Does it have sarcomeres or striations?
- yes
- Has overlap of actin and myosin, giving rise to contraction
- no, no
- Activation of vascular smooth muscle usually accomplished by _______ fiber that releases ______ which causes ________ to retract.
How fast is the response?
- autonomic efferent nerve, acetylcholine, cholinergic
- slow - usually takes about 30 seconds
Skeletal vs. Smooth
- Stress (250 mN/mm2)
- T1/2 Pmax (half time to maximal force development)
- Velocity (L0/sec)
- JATP (umol/g/min) (energy consumption)
- Economy (effieciency)
DON”T MEMORIZE THE NUMBERS
- (250 mN/mm2) vs. (223 mN/mm2) (similar)
- 0.2 sec vs. 70.0 sec (much slower)
- 1.9 vs. 0.12 (much slower)
- 50 vs 1.2 (much more effiecient)
- 930 vs 6
What does the T tubule (in skeletal muscle) system allow?
What does this cause?
How fast does this occur?
- the rapid spread of the action potential from the neuron into the skeletal muscle cell
- triggers calcium release from within
- on the order of ms
What do you have instead of T tubules in Smooth muscle?
What do these do?
- Caveolae (subplasmalemmal invaginations) (connexin proteins)
- spread depolarization through smooth muscle (at a much slower rate than skeletal - don’t have the proliferation)
What type of regulation do smooth muscle cells have (vs. skeletal muscle)?
Where does smooth muscle get Ca++ from?
What does Ca+ do once it is in the cell?
Why is the storage difference important in calcium channel antagonists?
- thick filament regulation (vs. thin filament)
- Extracellularly, some store Ca++ in sarcoplasmic reticulum, can be one, the other, or both
- activates calcium binding protein on the calmodulin, this then activates myosin light chain kinase (MLCK), the phosphorylation of myosin is the regulartory event - what triggers myosin/actin interaction
- in one muscle bed may have an effect on intracellular release of calcium, in another may have extracellular effect
What are the three major kinds of Ca++ channels?
- voltage gated, ligand gated (neurotransmitter or hormone), IP3-gated
- Voltage-gated Ca+ channels - are _______ channels that open with _____
- Ligand-gated Ca+ channels - are _____ channels that open with _____
- IP3-gated Ca+ channels - Are _____ channels that open with _____
Why have 3 systems?
- sarcolemmel, depolarization
- sarcolemmel, receptor occupancy
- sarcoplasmic, IP3 production
- Fail safe system, if one of these gets messed up you have other systems
(Relaxation of Smooth Muscle)
- _____ - slow rate of _____ and _____.
What transports the Ca+? How about in cardiac?
- _____ - _____ phophorylates and opens _____ channels causing _____.
- ______
(Types of Potassium channels in smooth muscle)
- _____-gated K channels - mediate _____
- _____ activated K channels - involved in control of ______
- _____ sensitive K channels - Contribute to membrane conductance of _____ and _____
- Calcium removal, Ca+ efflux, relaxation,
Ca+-ATPase, H+/Ca+ exchanger
- Protein Kinase (PKA) - cAMP, potassium, repolarization
- Potassium channels
(Types)
- voltage, bronchoconstriction
- calcium, basal tension in smooth muscle
- ATP, airway, bladder
What does the Ca-CaM-MLCK complex do in smooth muscle?
- activated myosin
(This is for smooth muscle)
- What is the point called Lmax (optimal muscle length)
- What happens when you get to the far right of this graph? (examples….) Why is this bad?
- Muslce lengthat which forced output of the smooth muscle is at maximum
- Bloat, parturition - get shearing of myofilaments when they get stretched this much and therefore the recovery time is very high - the sheared stomach is then inactive and stuff just sits there
- pressure in vivo (within living) is correlate of ________ in vitro (in glass)
- Volume is in vivo correlated of muscle length
- forced output
What is the name of the equation? What is F? What is V? What are a and b?
What does this show?
- Hill equation, Force, Velocity, constants
- at very high loads, that muscle fiber in vivo is operating at a very low short velocity, but when load is small the lifter can lift at a very high velocity
Where are phasic contractions found? What type of response is this?What would happen if this force wasn’t phasic.
Where are tonic contractions found? Why? How long can these contractions be maintained?
- in the proximal portion of the stomach, peristaltic, food would just sit there
- the distal part of the stomach (sphincters), to prevent reflux, minutes to hours
