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