Muscle Physiology and Anatomy “The Last Chapter”!
ASSIGNMENT Read Pages 7: Answer: Content Review – page 191 Questions: 1-11
“Gross” Anatomy Requirements Identify 20 Major Muscles For 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: Biceps Brachii (p. 181): Origin: Scapula, Superior to glenoid fossa, and coracoid process Insertion: Radial Tuberosity Action: Flex and supinate arm and forearm Exercise: Curls
Other “Gross” Terms Prime Mover: The major muscle in a movement Synergist: “Helpers” Antagonists: “Opposers” Fixators: Stabilizing the proximal joint
Functions: Muscular System Movement Posture Respiration Circulation Produce Heat Communication
Characteristics of Skeletal Muscle Tissue Contractility: Shorten with force Excitability: Respond to stimulus Extensibility: Limited stretch”ability” Elasticity: Recoil to resting length
Three Types of Muscle Tissue Smooth: Found in walls of hollow organs, blood vessels and glands Cardiac: Heart muscle Skeletal: Attached to bone * Compared by striations, shape, control, nuclei and function
Striations: “Stripes” Skeletal: YES Smooth: NO Cardiac: YES
Shape and Nucleus Skeletal: Long cylinder “fiber” Smooth: “spindle shape” Cardiac: Branched Multiple, peripheral Single, central
Control and Autorhythmicity Skeletal: Voluntary- NO Smooth: Involuntary- YES Cardiac: Involuntary-YES
Muscle 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) Structure Sarcomeres: The real contractile elements of muscle cells Myofilaments: Thick (myosin) and Thin (actin, troponin, tropomyosin) overlap to create the “striations” visible in the microscope
Muscle Cell Structure Nuclei: Multiple (many fused cells), peripheral Mitochondria: Many, near sarcomeres Transverse Tubules, Terminal Cisternae: Internal extension of cell membrane – Action Potential transmission
Excitable Tissues Nervous and Muscular Respond to stimulus - transmitting electrical signal Special 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 About Membranes! Membrane channels and Pumps keep Na + OUT: This makes the inside RELATIVELY Negative: Resting (waiting) Membrane Potential Resting Membrane Potential = -70 mV
Depoloarization Rapid Charge reversal when stimulated Na+ channels open - flooding inside with Na+ K+ channels close
Time: msec Membrane Potential (inside) mV -65 TH 0 Depolarization RMP Threshold voltage Na + Channels Open
Repolarization Na+ Channels close K+ channels reopen Charge separation returns to resting values: Na+/K+ Pumps “kick out” leaking Na+ Inside becomes negative again
mV Time Repolarization Na channels CLOSE K channels OPEN K moves OUT
Action Potential FACTS: All or None Principle Refractory Period: During “recovery” from AP, cell cannot be re-stimulated Conduction along membrane is like “dominos” Entire Cell Depolarizes
Action Potential The “Domino Effect” of depolarization along an entire cell membrane Includes Depolarization and Repolarization to reestablish the Resting Potential
And Now: “Interactive Physiology Muscle Cell Anatomy
Have a Nice Week! Quiz on Tuesday