30 Questions
What is the purpose of the perimysium in muscle tissue?
To separate fascicles
Which structure in a muscle fiber serves as the contractile unit of a myofibril?
Sarcomere
What is the function of the sarcolemma in a muscle fiber?
Form the plasma membrane of the muscle fiber
What is the role of the endomysium in muscle tissue?
Provide electrical insulation to muscle fibers
Which structure provides a storage site for calcium ions within a muscle fiber?
Terminal cisternae
What is the main function of the superficial fascia in muscle tissue?
Encase groups of muscles
What is the fuel source that is used first during muscle contraction?
Creatine phosphate converted to ATP
Which type of muscle fiber has a higher myoglobin and mitochondrion content?
Type I (Slow-Twitch)
What type of contraction involves the muscle shortening as it contracts?
Concentric
What causes the buildup of lactate in muscles during anaerobic respiration?
Incomplete conversion of lactate back to glucose
Which type of muscle fiber is primarily responsible for explosive energy production?
Fast-Twitch (Type IIb)
What is the first step in the breakdown of ATP during muscle contraction?
ATP splits into ADP and P
What is the main function of acetylcholinesterase (AChE) in the neuromuscular junction?
To break down acetylcholine (ACh) after it has initiated muscle contraction
Which principle governs the recruitment of motor units during muscle contraction?
The smallest motor units are recruited first, followed by larger ones as demand increases
What is the role of troponin during the sliding filament model of muscle contraction?
To bind with calcium ions and cause tropomyosin to expose the myosin binding sites on actin
What is the primary function of the motor end plate in the neuromuscular junction?
To bind with acetylcholine and initiate muscle contraction
During the power stroke of muscle contraction, what is the primary energy source utilized by myosin?
ADP
What is the primary role of the synaptic vesicles in the neuromuscular junction?
To store and release acetylcholine into the synaptic cleft
What is the main function of myosin in muscle contraction?
To form the thick filaments and provide binding sites for actin
What is the role of tropomyosin in muscle contraction?
It covers the myosin binding sites on actin (thin filaments)
Which of the following is NOT a component of the A-band in a sarcomere?
Z-disc
What is the function of titin in muscle contraction?
It binds myosin to the Z-disc
What is the significance of the motor unit in muscle contraction?
It allows for graded muscle contraction
What is the principle behind the 'all or none' response in muscle contraction?
All muscle fibers in a motor unit contract at the same time
What happens during the eccentric phase of a bench press (lowering portion)?
The load exceeds the force of contraction, causing myosin to detach from actin and increasing muscle repair and strength.
What are the two factors that determine the amount of muscle tension produced?
Recruitment of motor units and rate of recruitment (coding frequency)
Which statement about hypertrophy and atrophy is correct?
Hypertrophy is an increase in myofilaments, while atrophy is a decrease in myofilaments.
Which statement about cardiac muscle is incorrect?
Cardiac muscle fibers are long and cylindrical, with a surrounding epimysium.
What distinguishes multi-unit smooth muscle from visceral (single-unit) smooth muscle?
Multi-unit smooth muscle has individual motor neuron terminals for each fiber, while visceral smooth muscle has a single innervation point.
What is a common effect of aging on muscle mass?
A 10% decrease in muscle mass between ages 30-50, followed by a 40% decrease by age 80.
Test your knowledge on the layers of connective tissue in muscles, including epimysium, perimysium, endomysium, and superficial fascia. Learn about the functions of these layers and how they provide protection, sites for blood vessel and nerve distribution, and attachment points for muscles to the skeleton.
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