Muscle Physiology and Muscle Physiology and AnatomyAnatomy
“The Last Chapter”!
ASSIGNMENTASSIGNMENTRead Pages 7:152-170Answer: Content Review –
page 191Questions: 1-11
“Gross” Anatomy Requirements Identify 20 Major MusclesFor Exam: Know 3 Muscles (of
the 20 major muscles) Origin: Most stable attachment
Insertion: Most mobile attachment Action: What movement(s) Exercise specific for that muscle
Example:Example:Biceps Brachii (p. 181):
Origin: Scapula, Superior to glenoid fossa, and coracoid process
Insertion: Radial TuberosityAction: Flex and supinate
arm and forearmExercise: Curls
Other “Gross” TermsOther “Gross” TermsPrime Mover: The major
muscle in a movementSynergist: “Helpers”Antagonists: “Opposers”Fixators: Stabilizing the
proximal joint
Functions: Muscular Functions: Muscular SystemSystem
MovementPostureRespirationCirculationProduce HeatCommunication
Characteristics of Characteristics of Skeletal Muscle TissueSkeletal Muscle TissueContractility: Shorten with force Excitability: Respond to stimulusExtensibility: Limited
stretch”ability”Elasticity: Recoil to resting length
Three Types of Muscle Three Types of Muscle TissueTissueSmooth: Found in walls of
hollow organs, blood vessels and glands
Cardiac: Heart muscleSkeletal: Attached to bone* Compared by striations,
shape, control, nuclei and function
Striations: “Stripes”Striations: “Stripes”
Skeletal: YESSmooth: NOCardiac: YES
Shape and NucleusShape and NucleusSkeletal: Long
cylinder “fiber”Smooth:
“spindle shape”Cardiac:
Branched
Multiple, peripheral
Single, central
Single, central
Control and Autorhythmicity Skeletal:
Voluntary- NO Smooth:
Involuntary- YES Cardiac:
Involuntary-YES
Muscle StructureMuscle StructureConnective Tissue: Epimysium
(Fascia) wraps muscle, Perimysium wraps fascicles, and endomysium wraps muscle fibers
Bundles of Bundles: Muscle ->fascicles->fibers->myofibrils-> myofilaments
Muscle Cell (Fiber) Muscle Cell (Fiber) StructureStructureSarcomeres: The real contractile
elements of muscle cellsMyofilaments: Thick (myosin) and
Thin (actin, troponin, tropomyosin) overlap to create the “striations” visible in the microscope
Muscle Cell StructureMuscle Cell StructureNuclei: Multiple (many fused cells),
peripheralMitochondria: Many, near
sarcomeresTransverse Tubules, Terminal
Cisternae: Internal extension of cell membrane – Action Potential transmission
Excitable TissuesNervous and MuscularRespond to stimulus -
transmitting electrical signalSpecial quality of membrane
proteins: pumps and channels
Resting PotentialOutside is
More Positive than Inside
K+: Inside > Outside
Na+: Out > In
Excitable Cells: It’s All Excitable Cells: It’s All About Membranes!About Membranes!
Membrane channels and Pumps keep Na+ OUT: This makes the
inside RELATIVELY Negative:
Resting (waiting) Membrane PotentialResting Membrane
Potential = -70 mV
DepoloarizationDepoloarization
Rapid Charge reversal when stimulated
Na+ channels open - flooding inside with Na+
K+ channels close
Time: msec
MembranePotential(inside)
mV
-65
TH
0
Depolarization
RMP
Threshold voltage
Na+ Channels Open
RepolarizationRepolarization
Na+ Channels closeK+ channels reopenCharge separation returns to
resting values: Na+/K+ Pumps “kick out” leaking Na+
Inside becomes negative again
mV
Time
Repolarization
Na channels CLOSEK channels OPENK moves OUT
Action Potential FACTS:Action Potential FACTS:All or None PrincipleRefractory Period: During
“recovery” from AP, cell cannot be re-stimulated
Conduction along membrane is like “dominos”
Entire Cell Depolarizes
Action PotentialAction PotentialThe “Domino Effect” of
depolarization along an entire cell membrane
Includes Depolarization and Repolarization to reestablish the Resting Potential
And Now: “Interactive And Now: “Interactive PhysiologyPhysiology
Muscle Cell Anatomy
Have a Nice Week!Have a Nice Week!
Quiz on Tuesday