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