Muscle Physiology Advanced Study Notes

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What function of skeletal muscle is least dependent on its connections to other tissues?

Heat generation (correct)

Movement

Stability

Protection of organs

Which muscle type does not contract spontaneously?

Smooth muscle in digestive tract

Cardiac muscle

Skeletal muscle (correct)

Smooth muscle in blood vessels

What is the role of Ca2+ in the muscle action potential?

None - Ca2+ only regulates contraction (correct)

Repolarisation

Hyperpolarisation

Depolarisation

What is the role of T-tubules in skeletal muscle function?

Ensure the muscle is excited as quickly and evenly as possible Signup and view all the answers

A motor unit containing few muscle fibres produces:

Fine movements Signup and view all the answers

Curare completely blocks cholinergic transmission at the neuromuscular junction. It will therefore cause:

Complete paralysis & relaxation Signup and view all the answers

When a whole motor nerve is stimulated electrically, increasing strength of stimulus causes the muscle to contract more strongly. Why is the all-or-none law apparently not obeyed?

A motor nerve contains many motor units. Greater stimulation causes additional motor units to become active. Signup and view all the answers

Which organs are capable of generating heat?

Skeletal muscle only Signup and view all the answers

What component of a sarcomere does the I-band represent?

The portion of thin filaments (on both side of the Z line) not overlapping with thick filaments Signup and view all the answers

Which of the following correctly describes the sarcomere during contraction?

A-band is constant, I band gets smaller, Z-lines move closer together. Signup and view all the answers

If a muscle is stretched until the zone of overlap disappears,

it can no longer contract Signup and view all the answers

At the molecular level, the energy source for contraction is

ATP Signup and view all the answers

The energy-dependent rotation of the myosin head during muscle contraction is responsible for:

Pusing the actin filament Signup and view all the answers

What is the first step in the contraction of a skeletal muscle fibre?

An action potential is triggered at the neuromuscular junction Signup and view all the answers

What is the role of the sarcoplasmic reticulum in skeletal muscle?

Store Ca2+ and release it when triggered by an action potential Signup and view all the answers

During excitation-contraction coupling, troponin binds Ca2+. How does this enable contraction to occur?

Troponin shifts to expose the myosin binding site on the actin filament Signup and view all the answers

While Ca2+ is present in the sarcoplasmic reticulum:

The muscle will continue to contract Signup and view all the answers

During peak activity muscles cannot generate enough energy (ATP) from oxygen-dependent metabolism. What happens in this situation?

Energy is derived from oxygen-independent mechanisms Signup and view all the answers

Accumulation of lactic acid in contracting skeletal muscle is also called the 'oxygen debt'. What does this mean?

Lactic acid is a waste product of oxygen-independent glucose metabolism. It is converted back into glucose during recovery, consuming oxygen. Signup and view all the answers

Study Notes

Muscle Advanced - Study Notes

Skeletal Muscle Function Least Dependent on Connections: Skeletal muscle's least dependent function on connections to other tissues is movement.
Muscle Type Without Spontaneous Contraction: Skeletal muscle is the only type that does not contract spontaneously.
Role of Ca2+ in Muscle Action Potential: Ca2+ regulates muscle contraction, not depolarization, hyperpolarization, or repolarization.
Role of T-Tubules in Skeletal Muscle Function: T-tubules ensure the muscle is excited quickly and evenly.
Motor Unit and Fiber Production: A motor unit with few muscle fibers produces fine movements.
Curare's Effect on Neuromuscular Junction: Curare blocks cholinergic transmission, causing paralysis and relaxation at the neuromuscular junction.
All-or-None Law in Muscle Contraction: The all-or-none law does not hold for muscles needing graded potential, and greater stimulation results in more motor units becoming activated.
Heat Generating Organs: Skeletal muscle and the liver are capable of generating heat.
I-band Component of Sarcomere: The I-band represents the portion of thin filaments not overlapping with thick filaments.
A-band Component of Sarcomere: The A-band represents the area where thick and thin filaments overlap.
Sarcomere Contraction: During contraction, the A-band stays constant, the I-band gets smaller, and the Z-lines move closer together. The zone of overlap increases.
Muscle Contraction and Overlap: Stretching a muscle until overlap disappears prevents contraction.
Contraction Energy Source: The energy source for muscle contraction at the molecular level is ATP.
Myosin Head Rotation: Myosin head rotation during muscle contraction is involved in binding, releasing, and pulling the actin filaments.
First Step in Skeletal Muscle Fiber Contraction: The first step involves an action potential triggered at the neuromuscular junction.
Sarcoplasmic Reticulum's Role: The sarcoplasmic reticulum stores and releases calcium which is crucial for muscle contraction.
Troponin and Contraction: Troponin binds Ca2+ enabling tropomyosin to expose the myosin-binding site on the actin filament, initiating contraction.
Oxygen-Dependent vs. Independent Metabolism: During peak activity, muscles primarily rely on oxygen-independent energy sources or they fatigue when oxygen-dependent metabolism cannot keep pace with ATP demands.
Lactic Acid Accumulation: The accumulation of lactic acid in skeletal muscle during high activity is also known as "oxygen debt." Lactic acid is a byproduct of oxygen-independent glucose metabolism, and is eventually converted back into glucose during recovery.

Studying That Suits You

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

Description

Dive into the advanced concepts of muscle physiology with this quiz. Explore topics such as skeletal muscle function, the role of calcium in muscle contractions, and the effects of neuromuscular junction blockers like curare. Perfect for deepening your understanding of muscle action potential and motor units.