37 Questions
What triggers the release of Ca2+ from the sarcoplasmic reticulum (SR) during muscle contraction?
Na+ influx into the muscle cell
During relaxation, which of the following is responsible for breaking down acetylcholine (ACh) in the synaptic cleft?
Active transport pumps for Ca2+ back into SR
What is the main cause of rigor mortis that occurs after death in skeletal muscles?
Continued ATP synthesis
What is the role of troponin during muscle contraction?
Initiating sliding filament mechanism
What process triggers muscle action potential that spreads over sarcolemma and down into the transverse tubules?
Movement of troponin-tropomyosin complex
What leads to the shortening and generation of force in a muscle cell during contraction?
Binding of Ca2+ to troponin
What is the initial event that triggers the release of acetylcholine (ACh) into the synaptic cleft?
Calcium influx through voltage-gated calcium channels
What causes the inside of the muscle cell to become positive, leading to the triggering of a muscle action potential?
Sodium influx due to ligand-gated sodium channels opening
What is the role of troponin when calcium binds to it in muscle contraction?
Moving tropomyosin away from actin's binding site
What leads to the reorientation of myosin heads during muscle contraction?
ATP detachment from myosin and actin
What event marks the end of a muscle action potential and the beginning of muscle relaxation?
Acetylcholinesterase (AChE) breaking down acetylcholine (ACh)
What is responsible for moving tropomyosin to cover actin's binding sites during muscle relaxation?
Acetylcholinesterase breaking down ACh
What is the correct definition of 'Extension' in terms of joint motions?
An increase in the angle between articulating bones, usually in frontal plane
Which movement involves the action of 'Circumduction'?
A combination of flexion/extension and abduction/adduction
What characterizes 'Smooth Muscle' tissue?
Found in walls of hollow organs, nonstriated with single centrally located nucleus
Which muscle action involves 'Upward Rotation'?
Inferior angle moves laterally
In relation to joint movements, what does 'Adduction' involve?
Movement of bone toward midline, usually in frontal plane
What does 'Endomysium' refer to in muscle composition and structure?
Separates individual muscle cells
'Hyperplasia' is best described as:
Increase in number of muscle fibers
'Excitability' in muscle tissue refers to:
Ability to respond to stimuli and produce electrical signals
'Radial Flexion or Deviation (ABD)' involves:
Moving wrist outwards or away from midline; deviate toward radius
'Negative Feedback' mechanism serves to:
Reverse the original stimulus
Which type of skeletal muscle fiber is characterized by being red in color and having lots of mitochondria, myoglobin, and blood vessels?
Type I, slow oxidative, slow-twitch
Which type of skeletal muscle fiber is designed for anaerobic movements for short durations and is characterized by being white in color with few mitochondria and blood vessels?
Type IIb, fast glycolytic fibers, fast-twitch
How is a motor unit defined in relation to skeletal muscles?
One motor neuron and all the skeletal muscle cells it innervates
Which type of skeletal muscle fiber splits ATP at a very fast rate and is used for walking and intermediate intensity activities?
Type IIa, fast oxidative-glycolytic (FOG)
What characterizes Type IIb skeletal muscle fibers in terms of energy production?
Anaerobic metabolism
What is the main function of motor unit recruitment in muscle contractions?
Coordinating precise movements
In muscle physiology, what does the term 'all-or-none response' refer to?
The threshold for motor unit activation
Why do precise movements require smaller motor units with fewer fibers?
To allow finer control
What is the purpose of muscle tone involving the involuntary contraction of a small number of motor units?
Maintaining posture
Which group of muscles provides stability and movement for the shoulder joint?
Infraspinatus, teres minor, subscapularis
Why are forearm muscles typically categorized into anterior and posterior groups?
To allow for flexion and extension movements
What is the primary function of bones surface markings such as processes?
To provide support for muscle attachment
How do bone depressions differ from processes in terms of function?
They provide space for soft tissues or nerves
Which feature characterizes the upper extremity anatomy in terms of bones?
Comprises bones like scapula, clavicle, humerus, and metatarsals
What is the primary role of the hand muscles responsible for thumb movements?
Enabling opposition and abduction of the thumb
Test your knowledge of the process at the neuromuscular junction with this quiz! Explore the sequence of events from the arrival of action potential to muscle activation through calcium release and sodium influx.
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