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Questions and Answers
What is required for cross bridge formation in sarcomeres?
What is required for cross bridge formation in sarcomeres?
- A high concentration of potassium
- Availability of calcium and ATP (correct)
- An increase in myoglobin
- Increased levels of sodium
Which event marks the beginning of muscle relaxation?
Which event marks the beginning of muscle relaxation?
- Increase in calcium concentration
- End of neural stimulation (correct)
- Decrease in muscle fiber length
- Release of ATP
What happens to the DHP receptors when the muscle is in a relaxed state?
What happens to the DHP receptors when the muscle is in a relaxed state?
- They return to their resting size and shape (correct)
- They release additional calcium
- They remain in the same position
- They enter an active state
What is the role of the power stroke in muscle contraction?
What is the role of the power stroke in muscle contraction?
What facilitates the quick release of energy for muscle contractions?
What facilitates the quick release of energy for muscle contractions?
How does calcium concentration affect muscle contractions?
How does calcium concentration affect muscle contractions?
What must occur for calcium channels to close during muscle relaxation?
What must occur for calcium channels to close during muscle relaxation?
What is the outcome of repeated attachment and detachment of myosin heads?
What is the outcome of repeated attachment and detachment of myosin heads?
What is the primary reason for pumping calcium ions away from the sarcomeres?
What is the primary reason for pumping calcium ions away from the sarcomeres?
What stops the influx of sodium at the neuromuscular junction?
What stops the influx of sodium at the neuromuscular junction?
What type of protein pump is responsible for continuously removing sodium from the muscle cell?
What type of protein pump is responsible for continuously removing sodium from the muscle cell?
What occurs when acetylcholine is no longer present at the neuromuscular junction?
What occurs when acetylcholine is no longer present at the neuromuscular junction?
What initiates the action potential at the neuromuscular junction?
What initiates the action potential at the neuromuscular junction?
What happens to the DHP receptors after the action potential is removed?
What happens to the DHP receptors after the action potential is removed?
What is the role of the t-tubules in muscle contraction?
What is the role of the t-tubules in muscle contraction?
What characterizes the resting condition of a muscle cell?
What characterizes the resting condition of a muscle cell?
Which receptors are involved in detecting voltage changes during muscle contraction?
Which receptors are involved in detecting voltage changes during muscle contraction?
What happens when the voltage-sensitive dihydropyridine receptors change shape?
What happens when the voltage-sensitive dihydropyridine receptors change shape?
What initiates depolarization in a muscle fiber cell?
What initiates depolarization in a muscle fiber cell?
What is the role of the sodium ATPase protein pump in the muscle cell?
What is the role of the sodium ATPase protein pump in the muscle cell?
What is the primary function of the ryanodine calcium release channels?
What is the primary function of the ryanodine calcium release channels?
Why does calcium flow from the sarcoplasmic reticulum into the sarcomeres?
Why does calcium flow from the sarcoplasmic reticulum into the sarcomeres?
Which of the following best describes the complex involving dihydropyridine receptors and ryanodine receptors?
Which of the following best describes the complex involving dihydropyridine receptors and ryanodine receptors?
Where is calcium stored in muscle cells before contraction?
Where is calcium stored in muscle cells before contraction?
What is the primary function of the sarco/endoplasmic reticulum calcium ATPase protein pumps?
What is the primary function of the sarco/endoplasmic reticulum calcium ATPase protein pumps?
Why does the sarcoplasmic reticulum need to concentrate calcium ions?
Why does the sarcoplasmic reticulum need to concentrate calcium ions?
How does calsequestrin assist in calcium ion storage within the sarcoplasmic reticulum?
How does calsequestrin assist in calcium ion storage within the sarcoplasmic reticulum?
What happens when the gates allowing calcium release from the sarcoplasmic reticulum are closed?
What happens when the gates allowing calcium release from the sarcoplasmic reticulum are closed?
What challenge does the positive charge of calcium ions present in the sarcoplasmic reticulum?
What challenge does the positive charge of calcium ions present in the sarcoplasmic reticulum?
What role do ATP energy resources play in muscle contraction?
What role do ATP energy resources play in muscle contraction?
What mechanism allows calsequestrin to facilitate continual calcium ion uptake into the sarcoplasmic reticulum?
What mechanism allows calsequestrin to facilitate continual calcium ion uptake into the sarcoplasmic reticulum?
Which protein pump is responsible for removing calcium from the sarcomeres after muscle stimulation?
Which protein pump is responsible for removing calcium from the sarcomeres after muscle stimulation?
What is the primary role of calcium ions in muscle contraction?
What is the primary role of calcium ions in muscle contraction?
How does posture influence muscle force production?
How does posture influence muscle force production?
Which proteins are involved in the regulation of muscle contraction?
Which proteins are involved in the regulation of muscle contraction?
What is the sliding filament theory primarily associated with?
What is the sliding filament theory primarily associated with?
What characteristic of the troponin protein contributes to its function during muscle contraction?
What characteristic of the troponin protein contributes to its function during muscle contraction?
What is the significance of the cross bridge formation in muscle contraction?
What is the significance of the cross bridge formation in muscle contraction?
Which component of the sarcomere is primarily affected by changes in joint angle?
Which component of the sarcomere is primarily affected by changes in joint angle?
Which aspect of muscle physiology does the sliding filament theory NOT directly address?
Which aspect of muscle physiology does the sliding filament theory NOT directly address?
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Study Notes
Muscle Force and Posture
- Muscle force can be affected by the position of the muscles relative to the bones they attach to.
- Certain postures can allow muscles to generate greater forces than others.
###Â Sliding Filament Theory
- The sliding filament theory explains how muscles contract.
- Myosin heads bind to actin filaments, forming a cross bridge.
- Calcium ions are crucial for cross bridge formation.
Role of Calcium in Contraction
- Calcium is stored in the sarcoplasmic reticulum and released when an action potential reaches the muscle fiber.
- Calcium binds to troponin, causing a conformational change and exposing the active site on actin.
- This allows the myosin heads to bind to actin and initiate the power stroke.
Role of T-Tubules
- T-tubules are extensions of the sarcolemma that penetrate deep into the muscle fiber.
- They carry the action potential into the interior of the muscle cell.
- Voltage sensitive receptors in the t-tubules are linked to calcium channels in the sarcoplasmic reticulum.
###Â Muscle Relaxation
- Muscle relaxation begins with the cessation of neural stimulation.
- This causes the calcium channels to close, preventing further calcium release from the sarcoplasmic reticulum.
- Calcium is pumped back into the sarcoplasmic reticulum by the sarco/endoplasmic reticulum calcium ATPase (SERCA) pump.
Role of Calsequestrin
- Calsequestrin is a protein in the sarcoplasmic reticulum that binds to calcium ions.
- It helps to buffer the positive charge of the calcium ions, enabling more calcium to be stored in the sarcoplasmic reticulum.
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