Muscle Physiology and Muscle Physiology and AnatomyAnatomy

“The Last Chapter”!

ASSIGNMENTASSIGNMENT

Read 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” Terms

Prime Mover: The major muscle in a movement

Synergist: “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 Structure

Connective 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 Potential

Outside 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 Potential

The “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