smooth muscle - test 2
How do you stop phosphorylatin of the myosin light chain- 2
Decrease Ca++ back to resting levels take PO4 off - myosin light chain phosphatase
smooth muscle contraction nervous innervation deals with what system
autonomic
when muscle contracts what changes
blood vessel diameter
where will you find epinephrine, vasopressin, angiotensin
blood vessels
muscle fiber length has a broader or narrower range than skeletal muscle
broader
describe entry from the extracellular fluid. Are they more efficient or less? How is the range?
calcium enters through membrane calcium channels- ligand gated, voltage gated, mechanically gated - more efficient - more range
what allows mechanical contraction in smooth muscle
dense areas
what holds the filaments in place like the z lines in skeletal proteins
dense bodies
what allows electrical connection in smooth muscle
gap junction
changing composition of extracellular fluid with activity is a __ factor
local - oxgen, acidity, osmolarity
Describe the binding of Ca++ in the SR -5
hormone receptor G protein PO3 IP3 IP3 receptor - release IP3 Ca++ release
may include GI hormones, epinephrine, vasopressin, angiotensin
hormones
chemicals released from nearby cells
paracrine agents
what are the two sources of calcium
sarcoplasmi reticulum entry from extracellular fluid
most smooth muscle is this type. Electrically coupled through gap junctions, self excitable= myogenic, has pacemaker activity
single unit smooth muscle
smaller blood vessels airways uterus stomach, intestines urinary bladder can generate an action potential
single unit smooth muscle
describe the structure of smooth muscle
small cells, single nucleus, arranged in sheets No t- tubules - less sarcoplasmic reticulum
Why do we have different muscles - skeletal vs smooth (4)
smooth muscles contractions have to be longer and slower and more efficient all muscles contract, generally at one time Contract over a wider muscle length range Control more complicated and varied
what is the function of smooth muscle
surrounds hollow organs and tubes and regulates flow through them and/or propels fluid through them
where are NTs released from
varicosities
do smooth muscles have cross bridge cycling
yes
during contraction does the sliding filament apply?
yes
found in hair follicles- pilierection changes to eye muscle- lens control large arteries and airways
multiunit smooth muscle
not as electrically coupled more nervous system innervation don't have pacemaker activity
multiunit smooth muscle
not common, cells function independently, rich nerve innervation
multiunit smooth muscle
what does cyclic AMP inhibit
myosin light chain kinase -- relaxes smooth muscle
what pushes myosin head up to next myosin
myosin light chain- regulatory
do smooth muscle cells have troponin
no
describe filaments of smooth muscles
not parallel not sacromeres not striated
what does a smooth muscle look like during contraction
not parallel- so muscle smooshes up
describe the phosphorylation process in smooth muscle (6
1. increased Ca++ in cytosol 2. binds to calmoolin protein 3. activates myosin light chain kinase when bound 4. phosphorylates myosin light chain 5. Myosin /actin combine 6. crossbridge cycling
What binding sites do both skeletal muscle and smooth muscles have
ATP binding site actin binding site
with entry into the extracellular fluid what type of dihdropuridine receptor is it
Ligand gated Ca++ channel
is the sarcoplasmic reticulum more or less developed in smooth muscle
less developed
