Muscle Contraction: Neuromuscular Junction & Proteins
11 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What happens to Ach in the Neuromuscular Junction?

Acetylcholinesterase destroys Ach so another muscle action potential does not arise unless more Ach is released from the somatic motor neuron.

A muscle action potential traveling alonge a transverse tubule triggers a change in voltage-gated $Ca^{2+}$ channels.

True (A)

When $Ca^{2+}$ binds to troponin on the thin filament, what sites are exposed on actin?

  • Myosin-binding sites (correct)
  • Actin-replication sites
  • Actin-binding sites
  • Myosin-replication sites

What do the myosin heads do during contraction?

<p>All of the above (D)</p> Signup and view all the answers

During muscle relaxation, tropomyosin slides back into position and?

<p>Blocks the myosin-binding sites on actin (D)</p> Signup and view all the answers

What is the role of $Ca^{2+}$ -ATPase pumps during muscle relaxation?

<p>To use ATP to restore low levels of $Ca^{2+}$ in the sarcoplasm (C)</p> Signup and view all the answers

Which protein is a component of thin filaments and covers myosin-binding sites on actin molecules when a skeletal muscle fiber is relaxed?

<p>Tropomyosin (A)</p> Signup and view all the answers

Which protein is part of the thin filament, binds to calcium ions ($Ca^{2+}$), changes shape, and moves tropomyosin away from myosin-binding sites on actin molecules, initiating muscle contraction?

<p>Troponin (C)</p> Signup and view all the answers

What is the role of contractile proteins?

<p>Contractile proteins generate force during muscle contractions.</p> Signup and view all the answers

Describe Myosin's role in muscle contraction.

<p>Myosin makes up thick filament; molecule consists of a tail and two myosin heads, which bind to myosin-binding sites on actin molecules of thin filament during muscle contraction.</p> Signup and view all the answers

Describe the role of regulatory proteins.

<p>Regulatory proteins help switch muscle contraction process on and off.</p> Signup and view all the answers

Flashcards

Neuromuscular Junction

The location where a motor neuron communicates with a muscle fiber.

Action Potential

A rapid sequence of changes in the voltage across a membrane of a nerve of muscle cell.

Synaptic Vesicles

Tiny pockets within the axon terminal that contain neurotransmitters.

Acetylcholine (Ach)

A neurotransmitter used at the neuromuscular junction to trigger muscle contraction.

Signup and view all the flashcards

Ligand-Gated Channels

Channels that open when a specific chemical (ligand) binds to them, allowing ions to pass through.

Signup and view all the flashcards

Depolarization

A rapid change in membrane potential from negative to positive, then back to negative.

Signup and view all the flashcards

T-Tubules

Invaginations of the sarcolemma that transmit action potentials deep into the muscle fiber.

Signup and view all the flashcards

Sarcoplasmic Reticulum

A network of tubules in muscle cells that store and release calcium ions.

Signup and view all the flashcards

Calcium (Ca2+)

Ion released from the sarcoplasmic reticulum that triggers muscle contraction.

Signup and view all the flashcards

Troponin

A complex of three proteins (troponin C, troponin I, and troponin T) involved in muscle contraction.

Signup and view all the flashcards

Tropomyosin

A protein that blocks the myosin-binding sites on actin molecules in relaxed muscle.

Signup and view all the flashcards

ATPase

An enzyme that catalyzes the breakdown of ATP to ADP and phosphate, releasing energy for muscle contraction.

Signup and view all the flashcards

Myosin

The thick filament protein that binds to actin and is responsible for generating force during muscle contraction.

Signup and view all the flashcards

Actin

The thin filament protein that contains myosin-binding sites and interacts with myosin during muscle contraction.

Signup and view all the flashcards

Contractile Proteins

Proteins that generate force during muscle contractions

Signup and view all the flashcards

Regulatory Proteins

Proteins that switch the contraction process on and off.

Signup and view all the flashcards

Excitation-Contraction Coupling

The process linking the muscle action potential to muscle contraction.

Signup and view all the flashcards

Cross-Bridge Cycle

The sequence of events involving the binding of myosin to actin, power stroke, detachment of myosin, and return of the myosin head to its original position.

Signup and view all the flashcards

NA+/K+ pump

Pumps that use ATP to maintain proper ion balance in muscle cells.

Signup and view all the flashcards

Ca2+ pump

Pumps that use ATP to regulate sarcoplasmic reticulum calcium levels

Signup and view all the flashcards

Influx of Na+ ions

Sodium (Na+) ions rushing into the muscle fiber.

Signup and view all the flashcards

Efflux of K+ ions

Potassium (K+) ions that flow out of the muscle.

Signup and view all the flashcards

Myosin molecule consist of…

Tail and two heads. Binds to binding-sites of actin.

Signup and view all the flashcards

Actin

The main component of the thin filament.

Signup and view all the flashcards

Tropomyosin

Covers myosin-binding sites on actin molecules to prevent it from binding when. muscle fiber is relaxed.

Signup and view all the flashcards

Calcium Ions (Ca2+)

Binds to troponin, changes shape, moves tropomyosin when muscle contraction begins

Signup and view all the flashcards

Troponin

Regulatory protein that calcium ions bind to. Involved in muscle contraction.

Signup and view all the flashcards

Excitation

Muscle action potential to muscle contraction.

Signup and view all the flashcards

Contraction

Involved in the the binding to actin and detaching of myosin during muscle contraction.

Signup and view all the flashcards

Ion pump

Maintains proper balance in muscle cells.

Signup and view all the flashcards

Study Notes

  • Ach or Acetylcholine in the Neuromuscular Junction allows the muscle contraction to occur

Neuromuscular Junction Step-by-Step

  • Action potential travels down the axon
  • Calcium channels open causing an influx of Ca2+ ions to enter the Axon terminus
  • Synaptic vesicles release Acetylcholine (Ach)
  • Ach has only 1 millisecond to bind to; Ligand/chemical gated channels on the muscle fibers
  • Na+ channels open causing an influx of positive Sodium ions in the muscle fibers
  • Wave Depolarization occurs

"Wave of Depolarization"

  • An action of potential travels down T-Tubules
  • Sarcoplasmic Reticulum releases Calcium ions

Contraction

  • Calcium (Ca2+) binds to Troponin
  • Tropomyosin uncovers binding sites on Actin
  • Myosin heads bind to Actin
  • Muscle contraction subsequently begins as Myosin binds to Actin

Regulatory and Contractile Proteins:

  • Contractile proteins generate force during muscle contractions
  • Regulatory proteins determine if any part of contraction will occur by switching it on or off

Contractile Proteins:

Myosin

  • Makes up the thick filament
  • Molecule is comprised of a tail and two Myosin heads
  • Myosin heads bind to Myosin-binding sites on Actin molecules of the thin filament during muscle contraction Actin
  • Main component of the thin filament
  • Each Actin molecule has a Myosin-binding site where the Myosin head of thick filaments binds during muscle contraction

Regulatory Proteins:

Tropomyosin

  • Thin filament component
  • Covers Myosin-binding sites on Actin molecules when the skeletal muscle fiber is relaxed Troponin
  • Thin filament component
  • Binds to Calcium ions, changes shape moving the Tropomyosin away from Myosin-binding sites on Actin molecules
  • Myosin then binds to Actin to allow a contraction

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Muscle Contraction: The Neuromuscular Junction Explained - PDF

Description

Explore the step-by-step process of muscle contraction, starting from the action potential traveling down the axon to the binding of Myosin heads to Actin. Understand the crucial role of Acetylcholine (Ach) in the Neuromuscular Junction. Learn about regulatory and contractile proteins.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser