exercise phys chapter 5
Which of the following statements best describes sympathetic nerve stimulation?
"It is the predominant mechanism by which the autonomic nervous system exerts control during exercise" and "it causes the release of epinephrine and norepinephrine from the adrenal medulla."
The myelin sheath is segmented by small gaps every _____ to 3 mm along the length of the axon.
1
The Na+-K+ pump pumps out _____ sodium ions for every 2 potassium ions that are returned to the interior of the neuron.
3
When a membrane depolarizes, its charge changes from the resting membrane potential to _____ mV.
30
_________ is a primary neurotransmitter at the neuromuscular junction.
Acetylcholine
Slow motor units are normally recruited first in a muscle action.
True
A motor neuron and the muscle fibers it innervates is called a(n)
a motor unit
Maximal force is produced by a muscle when _____ of the motor units in a muscle is/are activated.
all
The cycling process of recruitment that allows for individual motor units to take turns resting while others are active is known as
asynchronous recruitment
Multipolar neurons predominate in the
brain
What part of the brain is known as the "seat of consciousness"?
cerebrum
The size principle order of recruitment helps to do what during submaximal muscle actions?
delay fatigue
Each ion has its own _____ gradient, which serves as its driving force across the membrane when channels are open.
electrochemical
A sprinter would have more type I fibers in their thigh muscles.
false
During an energy transformation, chemical energy presented by the action potential is transformed into electrical energy.
false
During depolarization and repolarization of a neuron, ion channels remain open for many seconds.
false
During the first few weeks of a resistance training program, large increases in strength are due entirely to muscle hypertrophy.
false
Motor units made up of type II fibers are typically recruited first due to the lower recruitment thresholds of their neurons.
false
Neurons are all uniform in shape and size.
false
Presynaptic and postsynaptic membranes must be adjoined to transfer a neurotransmitter.
false
Recruitment thresholds are uniform in all muscles.
false
Studies have shown resistance training to result in lower electromyography (EMG) recordings during maximal efforts.
false
The most common type of neuron is bipolar neurons.
false
The nervous system receives input from only environments internally connected to it.
false
The number of neuron types is known and all are classified.
false
The parasympathetic nervous system is often called the "fight-or-flight" nervous system.
false
When no impulse is being conducted, the inside of the neuron has a net positive charge.
false
Multiple motor unit summation varies the _____ produced by a muscle.
force
All of the following are functions of the parasympathetic nervous system except
heart rate increased
During repolarization, the membrane will become
hyperpolarized
Which part of the brain is known as the "homeostatic center"?
hypothalamus
The nodes of Ranvier allow action potentials to _____ from node to node along the axon.
jump
The myelin sheath is high in which content?
lipid
Excitatory neurotransmitters do the following:
make the membrane more permeable to Na+
The simplest reflex is the
monosynaptic reflex
Movement force and velocity are ultimately determined by the
motor cortex
The key to any movement is the activation of what?
motor units
Balance involves the connection between what two systems in the body?
nervous and muscular
What cells provide support and nourishment to neurons, as well as forming myelin sheaths around the axons?
neuroglia
The small gaps along the myelinated nerve are called
nodes of ranvier
Receptors are what type of molecule?
proteins
The arrangement of positive charges on the outside of a neuron and negative charges on the inside accounts for the
resting membrane potential
When muscles are generating a low amount of force, motor units with _____ are recruited first.
small axons
Target organs for autonomic nerve impulses include
smooth muscle, cardiac muscle, and endocrine glands
he ions that are predominantly located outside the neuron's cell membrane are
sodium
Axons vary in length due to the distance from the spinal cord to the
target cell
The complete summation of twitches is called
tetanus
All of the following are types of neurons except
tripolar
A motor unit is one motor neuron and all of the muscle fibers that it innervates.
true
Almost half of all energy consumption in the body is used to synthesize and maintain the Na+-K+ pump and related channels.
true
Alpha motor neurons innervate skeletal muscle and are responsible for sending signals from the central nervous system (CNS) to skeletal muscle.
true
An alpha motor neuron has relatively short dendrites but long axons
true
At progressively higher rates of action potential firing, the resultant muscle twitches can become completely summated so that there is no evidence of relaxation between twitches.
true
Muscle fibers innervated by fast-fatigue resistant motor units are capable of developing considerable amounts of force.
true
Reciprocal innervation can be affected by exercise training.
true
Salatory conduction conserves energy by reducing the energy needed by the Na+-K+ pump.
true
The Na+-K+ pump requires adenosine triphosphate (ATP) to function.
true
The all-or-none law is true only for individual motor units within a muscle, not for the whole muscle.
true
The larger the motor neuron, the higher the recruitment threshold for firing the action potential.
true
Type I muscle fibers are associated with slow motor units.
true
Unmyelinated axons use a local circuit of ionic current flow to gradually conduct the action potential along the axon.
true
When a nervous impulse occurs, sodium enters the cell before potassium leaves the cell.
true
afferent neurons carry sensory information from muscle to the central nervous system.
true
increasing the excitability of motor neurons makes high-threshold motor units easier to recruit.
true
the regulation of blood pressure and breathing falls under the autonomic nervous system control.
true
The brief period of muscle activity producing force is known as a(n)
twitch
Each of the following is the ways the body utilizes the size principle except
varying the timing of the electrical stimulus to the motor units