Muscle anatomy and physiology
1 / 31

Muscle Anatomy and Physiology - PowerPoint PPT Presentation

Muscle Anatomy and Physiology The Neuromuscular Junction / Motor Unit Anatomy: Max=>Min Muscle, fasciculus, fiber, fibrils, filaments Epimysium, perimysium, endomysium “Bundles within bundles” Contractile units: SARCOMERES Thin: actin, troponin, tropomysim Thick : myosin

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Presentation

Muscle Anatomy and Physiology

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Muscle anatomy and physiology l.jpg

Muscle Anatomy and Physiology

The Neuromuscular Junction / Motor Unit

Anatomy max min l.jpg

Anatomy: Max=>Min

  • Muscle, fasciculus, fiber, fibrils, filaments

  • Epimysium, perimysium, endomysium

  • “Bundles within bundles”

Contractile units sarcomeres l.jpg

Contractile units:SARCOMERES

  • Thin: actin, troponin, tropomysim

  • Thick: myosin

  • Z-lines, A-band, I-band, H-Zone

Motor units l.jpg

Motor Units

  • Motor Neuron + Muscle fiber(s)

  • TERMS:

    • Twitch: Single contraction & relaxation of a motor unit

    • Tetanus: Sustained contraction by summing “twitches”

    • Recruitment: Smooth moves – How many units needed?

How many units l.jpg

How Many Units?

  • The number of Motor Units recruited for a task depends on: 1. Demand

    2. Duration

Excitation contraction coupling l.jpg

Excitation - Contraction Coupling

  • Pre-Synaptic Terminal (Nerve): Acetylcholine released

  • Post-Synaptic Terminal (Motor Endplate): Ach stimulates by binding =>Muscle fiber depolarization

  • Contraction!

Excitation l.jpg


  • Resting Membrane Potential: Membranes separate charges: Polarized

  • Depolarization: Charge reversal across membrane

Slide9 l.jpg

Action Potential (AP) Depolarization travels along membrane

AP travels along sarcolemma=> T-tubules => sarcoplasmic reticulum => Terminal Cisternae => Calcium released

Sarcomeres shorten l.jpg

Sarcomeres Shorten


Sliding filament theory l.jpg

Sliding Filament Theory

  • The Action Potential reaches the Terminal Cisternae

  • Calcium released binds to Troponin

  • Tropomysin “moves” out of the way

  • Myosin-Actin Crossbridges formed

Contraction l.jpg


  • All-or-None “Twitch”

  • Sarcomere units shorten by thin and thick filaments “sliding” past each other

Slide13 l.jpg

The Physiology of Muscle

Contraction and ATP

Take five l.jpg

Take “Five”:

Draw and Label The Neuromuscular Junction:

Page 158

*What is the chemical


One more visit to that neuromuscular junction l.jpg

One More Visit to that Neuromuscular Junction:

  • Acetylcholine released

  • Binds with Ach-Receptors – linked to Na+ Channels

  • Na+ influx – DEPOLARIZES Motor endplate


  • Etc. Etc. Etc.

What happens to the acetylcholine l.jpg

What Happens to the Acetylcholine?

  • Good Question Sherlock:

  • Homework:

    • Describe the fate of Acetylcholine

    • Think diabolically of poisons that could interfere with the normal function of the neuromuscular junction…

Toxins neuromuscular junction l.jpg

Toxins: Neuromuscular Junction

  • Affecting Production, Release, Binding or degradation of Acetylcholine

    • Nerve Gas: Inhibit degradation

    • Black Widow Toxin: Massive release of Acetylcholine

    • Botulism: Inhibits Acetylcholine Release

Death by sarin acetylcholine accumulates in nmj l.jpg

Death by Sarin: Acetylcholine accumulates in NMJ

  • Runny nose, eyes, drooling, sweating,

  • Difficulty breathing, tight chest

  • Nausea, vomiting, loss of “control”

  • Twitching, jerking, staggering

  • Headache, confusion, coma and convulsions

Something lighter please l.jpg

Something Lighter Please

  • Check out this cool site for specific exercises!


Muscle energetics l.jpg

Muscle Energetics

Where does all that atp come from l.jpg

Where Does All That ATP Come From?

  • Energy for work is supplied by the breakdown of “FUELS”


  • Glucose is preferred for intense work

  • Fats are the “slow burners” and use lots of Oxygen

Energetics of contraction continues l.jpg

Energetics of Contraction - Continues

  • ATP-PC: fast, limited

  • Anaerobic Glycolysis: Cytosolic breakdown of Glucose without O2 – Forms Lactic Acid

  • Aerobic Oxidation: slow,but plentiful supply of ATP

All three contribute apt at all times l.jpg

All Three Contribute APT at All times…

  • Supply Rate and Demand Rates

    • ATP-PC: Fastest Rate – 10 seconds max

    • Anaerobic Glycolysis: 2-5 minutes max

    • Aerobic (Oxidative Phosphorylation): Slowest rate, almost endless capacity

The marathon l.jpg

The Marathon:

  • Hours of exercise possible

  • Uses ATP from aerobic (oxidative) sources

  • Oxygen Delivery!

The half mile or l.jpg

The Half-Mile…or:

  • More Intense

  • Bursts Lasting 2-5 minutes with rests

  • Using Anaerobic Glycolysis

  • Lactic Acid Buildup

The sprints and jumps l.jpg

The Sprints and Jumps

  • Less than 10 seconds duration

  • Very Intense

  • Creatine Stores in Muscles contribute to CP-ATP production

Creatine phosphate l.jpg

Creatine Phosphate:

  • Increase ATP-PC contribution of energy

  • Used in Maximum intensity-short term work

  • May extend work effort a few seconds…or repititions

  • Useless without training…

One last crazy engebretsen simulation l.jpg

One Last Crazy “Engebretsen Simulation”

  • 5 Volunteers to be the “Motor Neuron”

  • 1 Volunteer to be “Post-Synaptic Membrane”

  • 6 Sarcolemma-Triad volunteers

  • 2 Terminal Cisternae volunteers

  • The rest are sarcolemmas joining hands 

Muscle fatigue l.jpg

Muscle Fatigue:

  • More Complicated than you think:

    • ATP depletion very rare: usually seen with max efforts - cramps

    • Lactic ACIDOSIS slows all functions

    • Psychological fatigue…Central perception of exhaustion

Muscle fiber types fast ii iia vs slow i l.jpg

II Myosin

Fast, Force, Fatigue

“White”: Glycogen



I Myosin

Slow, Endure

“Red”: Myoglobin, mitochondria,



Muscle Fiber Types: Fast (II, IIa) vsSlow (I)

Slide31 l.jpg

We Made It!

  • Login