#1
Which of the following is not a function of the muscular system?
Producing hormones
ExplanationMuscular system primarily functions in movement, posture, and heat production.
#2
Which type of muscle is under voluntary control?
Skeletal muscle
ExplanationVoluntary control is exerted over skeletal muscles, used for deliberate movements.
#3
Which muscle type is responsible for peristalsis in the digestive tract?
Smooth muscle
ExplanationSmooth muscles in the digestive tract contract rhythmically to propel food through peristalsis.
#4
Which type of muscle is found in the walls of blood vessels?
Smooth muscle
ExplanationSmooth muscles in blood vessel walls regulate vessel diameter and blood pressure.
#5
Which structure connects muscle to bone?
Tendon
ExplanationTendons attach muscle to bone, transmitting forces generated during muscle contraction.
#6
What is the term for the ability of a muscle to respond to a stimulus?
Excitability
ExplanationExcitability is the property of muscle cells to respond to stimuli with electrical changes, initiating contraction.
#7
Which molecule binds to troponin to initiate muscle contraction?
Calcium ions
ExplanationCalcium ions bind to troponin, triggering a conformational change that exposes myosin binding sites on actin.
#8
Which protein primarily makes up the thick filaments in muscle fibers?
Myosin
ExplanationMyosin is the main protein in thick filaments, responsible for muscle contraction.
#9
What is the role of calcium ions in muscle contraction?
Binding to troponin, exposing myosin binding sites
ExplanationCalcium ions bind to troponin, allowing myosin heads to attach to actin, initiating contraction.
#10
What is the primary function of the sarcoplasmic reticulum in muscle cells?
Storing and releasing calcium ions
ExplanationSarcoplasmic reticulum stores calcium ions, releasing them upon muscle stimulation for contraction.
#11
Which neurotransmitter is responsible for initiating muscle contraction at the neuromuscular junction?
Acetylcholine
ExplanationAcetylcholine is released at neuromuscular junctions, initiating muscle contraction.
#12
What is the term for the functional unit of a muscle fiber, consisting of a single motor neuron and all the muscle fibers it innervates?
Motor unit
ExplanationMotor unit comprises a motor neuron and all muscle fibers it controls, acting as a functional unit.
#13
What is the role of ATP in muscle contraction?
Providing energy for cross-bridge cycling
ExplanationATP hydrolysis provides energy necessary for myosin heads to attach and detach during muscle contraction.
#14
What is the main function of the transverse tubules (T-tubules) in muscle fibers?
Conduction of action potentials
ExplanationT-tubules allow action potentials to penetrate deep into muscle fibers, triggering calcium release.
#15
Which of the following statements about muscle fatigue is true?
It is primarily due to the accumulation of lactic acid.
ExplanationLactic acid build-up contributes to muscle fatigue by interfering with muscle contraction.
#16
Which hormone stimulates muscle growth and protein synthesis?
Testosterone
ExplanationTestosterone promotes muscle growth by enhancing protein synthesis.
#17
Which enzyme breaks down acetylcholine to terminate its action at the neuromuscular junction?
Acetylcholinesterase
ExplanationAcetylcholinesterase breaks down acetylcholine, terminating its action and allowing muscle relaxation.
#18
Which component of the sarcomere contains the thin filaments?
I band
ExplanationI band contains thin filaments, composed of actin, in the sarcomere.
#19
Which regulatory protein covers the myosin-binding sites on actin in relaxed muscle?
Tropomyosin
ExplanationTropomyosin covers myosin-binding sites on actin in the absence of calcium ions, preventing muscle contraction.