48 Questions
What is the function of afferent neurons?
Carry sensory information to the central nervous system
What is the role of the sodium-potassium pump in maintaining resting membrane potential?
Transport 3 NA+ molecules out and 2 K+ molecules into the cell
What characterizes C fibers in the context of nerve conduction?
Unmyelinated fibers with slower conduction
What occurs during the refractory period of a neuron?
Hyperpolarization due to slowly closing K channels
What is saltatory conduction?
Propagation of action potential in myelinated neurons
Where are upper motor neurons housed?
White matter of the cerebral cortex and spinal cord
What is the primary role of white matter in the nervous system?
Facilitate communication between different regions of the brain
What happens when a stimulus reaches the threshold in a neuron?
Action potential is initiated
What is the function of the Node of Ranvier in nerve conduction?
Action potential gets refueled
What is the primary role of neurotransmitters in nerve conduction?
Relay signals to another nerve cell
What is the primary factor responsible for repolarization of a depolarized neuron?
Slow closure of K+ channels
What is the primary role of myelin in nerve conduction?
Facilitate saltatory conduction
Which type of muscle architecture is characterized by fibers running parallel to the long axis of the muscle?
Fusiform
Which type of contraction yields zero velocity?
Isometric
What occurs during an eccentric contraction?
Negative work
Which component plays a role in muscle function and movement, alongside muscle fibers?
Fascia
What is the primary factor affecting muscle force output changes with respect to speed?
Attachment and reattachment of cross-bridge linkages
Which type of muscle architecture is characterized by fibers obliquely attaching to the tendon from one side?
Unipennate
What is the most accurate method for measuring muscle cross-section?
MRI
What happens during active insufficiency?
Minimal force production at the shortest muscle length
What does hypertrophy lead to?
Increase in muscle size
What is the role of the series elastic component in muscle function?
To store and release elastic energy during muscle contraction
What is the primary factor affecting muscle force output changes with respect to speed?
Attachment and reattachment of cross-bridge linkages
What is the difference between speed and velocity?
Speed is a scalar quantity, while velocity is a vector quantity
What initiates muscle contraction?
Nerve impulse creating an action potential
What dictates the activation of smaller motor units first?
Henneman’s size principle
What is the primary function of muscle spindles?
Detect changes in muscle length
What is the role of Golgi tendon organs (GTO) in muscle function?
Modulate muscle force and contribute to proprioception
What is the classification of muscle fibers based on force production and fatigue resistance?
Slow-twitch (Type 1) and fast-twitch (Type 2)
What determines muscle control and precision?
Motor units
What contributes to the body's ability to detect dynamic and static position in space?
Kinesthetic system
What system works in conjunction with the kinesthetic system to maintain equilibrium and balance?
Vestibular and visual systems
What is the primary function of Type 1A and Type 2 sensory nerve endings in muscle spindles?
Detect changes in muscle length
How do hypotonic and hypertonic individuals display deviations in muscle tone?
Affecting their ability to hold the body against gravity
What contributes to the recruitment and grading of muscle contraction?
Simultaneous activation and rate coding
What occurs in response to changing demands, such as Type 1 fibers in newborns for quick movements?
Muscle fiber type adaptation
What tool is used to measure muscle activation by inserting a fine needle into the muscle or adhering an electrode to the muscle?
Electromyography (EMG)
Which type of contraction involves no change in joint angle and allows static or non-moving contraction control type movements?
Isometric contraction
In which type of contraction does the muscle undergo constant shortening through limb excursion?
Isotonic contraction
Which type of contraction involves the muscle lengthening due to external forces such as gravity?
Eccentric contraction
What type of contraction involves contracting at a constant rate or speed with the same amount of external resistance applied through the entire range of motion?
Isokinetic contraction
What is the term for the deformation of tissues over time when subjected to constant or suddenly applied load?
Creep
Which characteristic refers to the resistance to external forces that cause permanent deformation in muscles?
Viscoelasticity
What refers to the ability of a muscle to elongate under force and return to its normal length when released?
Extensibility
What is the term for the amount of deformation a structure can sustain before succumbing to distress?
Strain
What is the term for the deformation of tissues over time when subjected to constant or suddenly applied load?
Creep
What does EMG measure in terms of muscle activity?
Muscle activation
What is the term for the muscles that are not the prime mover but act in the same manner to assist in performing an activity?
Synergist
Study Notes
Muscle Physiology and Functional Movement
- Muscle contraction begins with a nerve impulse creating an action potential.
- Contraction is caused by the interaction between actin and myosin, following the sliding filament theory.
- Muscle fibers are classified into slow-twitch (Type 1) and fast-twitch (Type 2) with varying force production and fatigue resistance.
- Muscle fiber type adaptation occurs in response to changing demands, such as Type 1 fibers in newborns for quick movements and Type 1 fibers in toddlers for posture.
- Motor units, consisting of a motor neuron and its associated muscle fibers, determine muscle control and precision.
- Henneman’s size principle dictates that smaller motor units are activated first, leading to the recruitment of slow-twitch fibers.
- Motor unit recruitment can grade muscle contraction through simultaneous activation and rate coding.
- Muscle spindles and Golgi tendon organs (GTO) modulate muscle force and contribute to proprioception and kinesthesia.
- Muscle spindles have sensory nerve endings (Type 1A and Type 2) that detect changes in muscle length and contribute to postural tone.
- Hypotonic and hypertonic individuals display deviations in muscle tone, affecting their ability to hold the body against gravity.
- The kinesthetic system, involving muscle spindles and GTO, contributes to the body's ability to detect dynamic and static position in space.
- The vestibular and visual systems work in conjunction with the kinesthetic system to maintain equilibrium and balance.
Test your knowledge of muscle physiology and functional movement with this quiz. Explore topics such as muscle contraction, fiber types, motor unit recruitment, and the role of muscle spindles and Golgi tendon organs in proprioception and kinesthesia.
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