38 Questions
What happens during the relaxation phase of muscle fibre tension?
Calcium ions are pumped back into the sarcoplasmic reticulum
Which statement is true about tetanus in muscle contraction?
Muscle fibre is stimulated so rapidly that it cannot relax between stimuli
What causes rigor mortis to occur in muscles after death?
No fresh ATP available to detach myosin and actin complexes
What is the primary function of the intercalated discs in cardiac muscle?
Facilitate communication between adjacent cardiac muscle cells
During which phase of muscle fibre tension does no contraction occur?
Latent period
What maintains muscle tone in skeletal muscles?
A small amount of contraction within the muscle fibre
What characterizes smooth muscle cells?
Controlled by autonomic nervous system
How does summation differ from twitch contraction?
Summation occurs when twitches are added together, while twitch contraction is a singular event
What is the functional unit of skeletal muscle?
Sarcomere
Which protein allows the muscle to return to its initial length after being stretched?
Titin
What is the primary function of troponin in muscle contraction?
Interacts with calcium
What is the role of tropomyosin in muscle contraction?
Reacts with troponin
What happens after the action potential travels to the skeletal muscle fibre?
Excitation-contraction coupling
Which protein interacts with actin during muscle contraction?
Myosin
What specific receptors on the surface of transverse tubules are activated by voltage?
Dihydropyridine receptors
Which protein contains a myosin binding site on actin?
Tropomyosin
What is the role of Ca2+ released by the sarcoplasmic reticulum?
Binds to the Ca2+ binding site on troponin
What happens when ATP is hydrolyzed during the cross bridge cycle?
Detaches myosin from actin
Which molecule energizes the myosin by splitting ATP during muscle contraction?
Pi
During muscle contraction, what role does tropomyosin play with respect to myosin heads binding to actin?
Prevents it by binding to myosin heads
What is the main role of the dihydropyridine receptors on the transverse tubules?
Initiate a permeability change in the sarcoplasmic reticulum
What initiates the power stroke during muscle contraction?
$\text{ADP and Pi}$ bound to myosin
What is the role of troponin in muscle contraction?
Troponin binds to calcium ions and moves tropomyosin aside to expose the actin binding sites for myosin.
How does titin protein contribute to muscle function?
Titin is a large protein that provides elasticity and stabilizes the position of the myosin filaments in the sarcomere.
Explain the process of excitation-contraction coupling in muscle cells.
Excitation-contraction coupling is the process by which an action potential triggers calcium release from the sarcoplasmic reticulum, leading to the formation of cross-bridges between actin and myosin filaments.
What is the function of tropomyosin in muscle contraction?
Tropomyosin regulates the interaction between actin and myosin by blocking the myosin binding sites on actin in the absence of calcium ions.
How do actin filaments contribute to muscle contraction?
Actin filaments provide the binding sites for myosin heads, allowing the formation of cross-bridges and the sliding of filaments during muscle contraction.
What is the primary function of the troponin complex in muscle cells?
The troponin complex regulates the interaction between actin and myosin by binding calcium ions and initiating muscle contraction.
How does tropomyosin contribute to muscle relaxation?
Tropomyosin covers the myosin binding sites on actin in the absence of calcium ions, preventing cross-bridge formation and promoting muscle relaxation.
What is the significance of actin-myosin cross-bridges in muscle contraction?
Actin-myosin cross-bridges generate force by sliding past each other, leading to the shortening of sarcomeres and muscle contraction.
How does the sliding filament theory explain muscle contraction?
The sliding filament theory states that muscle contraction occurs when actin filaments slide past myosin filaments, causing the sarcomere to shorten.
What role does the troponin-tropomyosin complex play in regulating muscle contraction?
The troponin-tropomyosin complex blocks myosin binding sites on actin in the absence of calcium ions, preventing muscle contraction.
Troponin is a fibrous protein found in skeletal muscle cells.
False
Titin is responsible for the power stroke during muscle contraction.
False
Tropomyosin interacts with calcium ions during muscle contraction.
False
Actin filaments are made up of myosin and actin proteins.
False
Excitation-contraction coupling is the sequence of events that link the muscle contraction to the action potential at the neuromuscular junction.
True
Group of muscle fibres is enveloped by which connective tissue.
perimysium
Test your knowledge on muscle contraction, rigor mortis, and the phases of muscle fiber tension. Learn about the changes in sarcomere length during contraction and the events that occur in the latent and contraction phases.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
