#1
What is the primary function of skeletal muscles?
Facilitating movement
ExplanationMuscles enable movement by contracting and relaxing.
#2
Which type of muscle is under involuntary control and is found in the walls of internal organs?
Smooth muscle
ExplanationSmooth muscle contracts involuntarily, controlling internal organ movements.
#3
What is the name of the structural and functional unit of a muscle, surrounded by endomysium?
Muscle fiber
ExplanationMuscle fibers are individual units containing contractile elements.
#4
Which muscle is responsible for extending the knee joint?
Quadriceps femoris
ExplanationThe quadriceps femoris extends the knee joint, aiding in activities like walking and running.
#5
Which type of muscle fiber is characterized by a high resistance to fatigue and is well-suited for endurance activities?
Type I
ExplanationType I muscle fibers have high oxidative capacity, making them suitable for prolonged activity.
#6
Which protein is primarily responsible for muscle contraction?
Myosin
ExplanationMyosin interacts with actin to generate muscle force.
#7
What is the term for the point where a nerve and a muscle meet?
Neuromuscular junction
ExplanationSignals from nerves stimulate muscle fibers at the neuromuscular junction.
#8
What is the main neurotransmitter responsible for transmitting signals from nerves to skeletal muscles?
Acetylcholine
ExplanationAcetylcholine transmits nerve signals to initiate muscle contraction.
#9
Which connective tissue surrounds the entire muscle and helps transmit force generated by muscle contraction to the bones?
Epimysium
ExplanationEpimysium surrounds the entire muscle and connects it to bones via tendons.
#10
In a muscle contraction, what happens to the distance between the Z lines of a sarcomere?
Decreases
ExplanationThe Z lines move closer together during muscle contraction.
#11
Which muscle is responsible for abducting the shoulder and is often referred to as the 'lateral deltoid'?
Deltoid
ExplanationThe deltoid muscle abducts the shoulder, moving the arm away from the body.
#12
What is the role of myoglobin in muscle cells?
Oxygen transport
ExplanationMyoglobin stores and releases oxygen in muscle cells, facilitating aerobic respiration.
#13
Which energy system is predominantly used during short bursts of intense physical activity, such as weightlifting?
ATP-PC system
ExplanationThe ATP-PC system provides immediate energy for short bursts of activity.
#14
What is the function of the sarcoplasmic reticulum in muscle cells?
Regulation of calcium ions
ExplanationThe sarcoplasmic reticulum stores and releases calcium ions, crucial for muscle contraction.
#15
During aerobic respiration, what molecule is produced as a byproduct and can cause muscle fatigue?
Lactic acid
ExplanationLactic acid accumulates during intense exercise, contributing to muscle fatigue.
#16
Which muscle is responsible for flexing the forearm at the elbow joint?
Biceps brachii
ExplanationThe biceps brachii contracts to flex the forearm at the elbow.
#17
What is the primary function of the T-tubules in muscle cells?
Conduct action potentials
ExplanationT-tubules transmit action potentials deep into the muscle fiber for synchronized contraction.
#18
Which enzyme is responsible for breaking down acetylcholine in the synaptic cleft during neuromuscular transmission?
Cholinesterase
ExplanationCholinesterase degrades acetylcholine, terminating the signal at the neuromuscular junction.
#19
What is the primary role of satellite cells in skeletal muscle?
Cell repair and regeneration
ExplanationSatellite cells play a key role in repairing and regenerating damaged muscle tissue.