Catos Muscle Phys Ii Cardiac And Smooth Muscle

Front 1

Smooth General Ideas

Back 1

No striations, lack order of actin and myosin
No troponin
Only some SR and mito
Thin:Thick 15:1
Small, elongated cells
Line hollow organs

Front 2

Smooth muscle features

Back 2

Slow sustained contraction over broad length range due to "disorganization)
Lower resting mem pot -70
Autonomic Innervation
Not attached to bone
Embedded in ECM of col & elastin

Front 3

Smooth
W/o troponin, how does smooth muscle work?

Back 3

Ca binds to calmodulin, which activates myosin light chain kinase, which phosphorylates myosin. Phosphorylated myosin can interact w/ actin, and contraction ensues.

Front 4

Smooth method of relaxation?

Back 4

MLC Phospatase dephophorylates myosin, muscle relaxes (Ca taken up by SR)

Front 5

Smooth
Unitary vs multiunit
Latch?

Back 5

Multiunit-don't contract together or react to stretch, pilomotor
Unitary-most common,cells electrically couple together via gap jx. Depolarized by stretch. Ex: Latch-(GI) muscles can remain contracted min-hrs, can't be modified by neural or horomonal input.

Front 6

What affects cardiac contractility?

Back 6

Autonomic nervous input and external agents.

Front 7

In cardiac muscles, what is the role of extracellular Ca (3)

Back 7

Activate muscle contraction
Trigger Ca induced Ca release
Increase force of contraction of SR
(release is incomplete, in comparison to sk muscle where it is complete)

Front 8

Cardiac Muscle General Features

Back 8

Small cells
Form syncitium
Intercalated Disks (MA,FA,GJx)
High # of Mito
Ext. Ca drugs affect contractility
Striated
Non-elastic at rest
Passive tension increases w/ length (volume)
Relies on extracellular Ca

Front 9

How are gap junctions vital for cardiac muscle?

Back 9

They allow for optimum electric coupling.

Front 10

In cardiac muscle atrial and ventricular cells?

Back 10

Atrial
Decreased SR
Absent T-tubule
Ventricular
Laterally cnxting T-tubule

Front 11

Cardiac: Pos ionotropic effect:

Back 11

increases force on cardiac muscle contraction

Front 12

Digitalis is used after an MI or stroke. Why?

Back 12

It allows the living cardiac cells to work harder to make up for the incapacitated ones.
Blocks Na pump, which inhibits Na/Ca exchanger, thus elevating intracellular Ca.

Front 13

Latch contraction in smooth muscle cells occurs when:

Back 13

myosin light chain dephosphorylates while myosin is bound to actin.

Front 14

Stretching unitary smooth muscle cells

Back 14

causes depolarization

Front 15

No troponin, calmodulin instead, in:

Back 15

Smooth muscle cells

Front 16

In cardiac muscles, twitch tension cannot summate to produce tetnus bc

Back 16

action potentials are only as prolonged as the elevation of intracellular ca, and cardiac muscle relies on extracellular ca.