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35 Cards in this Set

  • Front
  • Back
The majority of smooth muscle is found in:
the walls of hollow organs and tubes. i.e. arteries, veins, urinary bladder, uterus, male and female reproductive tracts.
What does smooth muscle regulate?
Neurotransmitters, hormones and paracrines
How many pathways are there for regulation of smooth muscle?
Multiple
What are the two types of smooth muscle?
single-unit smooth muscle and multi-unit smooth muscle.
What are the characterists of single-unit smooth muscle?
It's electrically couples, no recruitment and forces increases via CALCIUM influx
What are the characteristics of multi-unit smooth mucle cells?
Fine control, NEUROGENIC, use recruitment.
The actin in smooth muscle is :
longer, more plentiful, lacks troponin
The myosin in smooth muscle is:
longer, heads entire length of filament, slower ATPase activity,
What opens voltage-gated Ca2+ channels in smooth muscle?
unstable membrane potentials, depolarization,
What opens chemical Ca2+ channels in smooth muscle?
neurotransmitters, blod borne hormones, locally release paracrines
Name one way cardiac muscle is different form skeletal muscle.
fibers are joined in branching networks. Cells are interconected by "gap juncitons"
What percentage of ECF is a source of Ca2+? SR?
10%. 90%
What is the level of control in cardiac muscle?
involuntary
How is a contraction initiated in cardiac muscle?
myogenic
How is cardiac muscle innervated?
autonomic nervous system?
What are the two types of myocardial cells?
contractile and autorhythmic
What percentage of myocardial cells are contractile?
99%
Do autorhythmic cells contract?
No.
Normally, contractile myocardial cells _____ initiate their own __.
Do not; AP
Autorhythmic cells are specialized for__________ and ________ __ to contractile cells
initiating, conducting AP
Contractile cells :
respond to authrhythmic cells to get a respose
The plateau phase of a cardiac contractile AP is due to:
fast opening potassium channels
C. C. AP Phase 1 due to:
inital repolarization via K+ efflux. It's fast and brief
C.C. AP Phase 2 is due to:
decrease in K+ permeability and INCREASE in Ca2+ permeability
C.C> AP Phase 3 rapid replarization is due to :
Ca2+ channels closing
K+ permeability increases
What are CI/CR channels?
calcium induced, calcium released
The SR is ___ in cardiac muscle than smooth muscle.
smaller.
What is the importance of the refractory period in a cardiac contractile cell?
limits cardiac rhythm.
Ensures filling chambers of the heart.
Why is there a longer refractory period in cardiac muscle?
To prevent tetanus.
Why does the refractory period last almost as long as the muscle twitch?
to limit how fast your heart can beat.
What is another name for cardiac autorhythmic cells?
Pacemaker cells.
Is the resting membrane potential in an autorhythmic cell stable?
No.
The rising phase of an acton potential in an autorrhythmic cell is due to:
lots of Ca2+ channels opening.
At the peak of an action potential in an auto-rhythmic cell:
Ca2+ channels close, K+ channels open
the falling phase of an action potential in cardiac AUTORHYTHMIC cells is due toL
Ca2+ channels close and K+ efflux