BSC 3096 Chapter 13

response

Contraction of quadriceps Relaxation of hamstrings

Is the patellar tendon reflex a monosynaptic or polysynaptic reflex? polysynaptic monosynaptic both neither

both

Autonomic reflexes are also called reflexes. Why?

visceral reflexes because many of them involve internal organs (the viscera)

hoose the correct statement about the knee-jerk reflex. The function of this reflex is to cause the limb to move away from painful stimuli. A monosynaptic pathway causes the quadriceps muscle to contract, while a polysynaptic pathway triggers a crossed extensor reflex. The integrating center for this reflex is in the brain; consequently, an abnormal knee-jerk reflex suggests brain damage. A monosynaptic pathway causes the quadriceps muscle to contract, while a polysynaptic pathway causes the antagonistic muscle to relax.

A monosynaptic pathway causes the quadriceps muscle to contract, while a polysynaptic pathway causes the antagonistic muscle to relax.

afferent neuron

Action potential travels through sensory neuron

Identify the FALSE statement. Some reflexes are genetically determined. All reflexes require input from the brain. Adipose tissue is controlled by autonomic efferents. Muscle spindles are stretch receptors. Proprioceptors detect limb position and movement.

All reflexes require input from the brain.

What is the purpose of alpha-gamma coactivation? Explain how it occurs.

Alpha-gamma coactivation allows muscle spindles to continue functioning when the muscle contracts. When the muscle contracts, the ends of the spindles also contract to maintain stretch on the central portion of the spindle.

Match each of the following phrases associated with the crossed extensor reflex in the correct sequential order.

An individual steps on a thumbtack Pain stimulates nociceptor Sensory neurons delivers information to the spinal cord Withdrawal reflex pulls limb away from tack, Crossed extensor reflex supports body

What is the outcome of a muscle stretch reflex? Relaxation of the agonist muscle Contraction of the antagonist muscle Contraction of the agonist muscle Inhibition of alpha motor neuron activity

Contraction of the agonist muscle

Which outcome of the flexion reflex in the leg reflects the crossed extensor reflex? Contraction of the quadriceps in the ipsilateral leg Contraction of the sartorius muscles in both legs causing the legs to cross Contraction of the flexor muscles in the contralateral leg Contraction of the quadriceps in the contralateral leg

Contraction of the quadriceps in the contralateral leg

A patient has damage to alpha motor neurons. Which of the following would you expect? Decreased contraction of smooth muscle fibers Decreased contraction of extrafusal muscle fibers Increased heart rate Increased muscle tone

Decreased contraction of extrafusal muscle fibers

List the three types of sensory receptors that convey information for muscle reflexes.

Golgi tendon organ, the muscle spindle, and joint capsule mechanoreceptors

How does a muscle spindle sense muscle stretch when the muscle is shortened? There is no effect of muscle shortening on spindle activity. The length of the muscle does not affect the spindle. Spring-like structures in the spindle cause the spindle to recoil as the muscle shortens keeping it the same relative length as the muscle. It doesn't. Muscle spindles are not active when the muscle is shortened. Intrafusal fibers actively shorten the spindle to maintain the same relative length.

Intrafusal fibers actively shorten the spindle to maintain the same relative length.

Which of the following statements is true about the patellar tendon reflex (i.e., the knee jerk reflex)? It requires the brain. It has a polysynaptic component. It has a monosynaptic component. It involves reciprocal inhibition. It is a stretch reflex.

It has a polysynaptic component. It has a monosynaptic component. It involves reciprocal inhibition. It is a stretch reflex.

Skeletal muscle reflexes can be either monosynaptic or polysynaptic. Which of the following statements is true regarding monosynaptic versus polysynaptic skeletal muscle reflexes? Polysynaptic reflexes are composed of only two neurons between the stimulus and target cell, while monosynaptic reflexes contain three or more neurons. Monosynaptic reflexes are composed of only two neurons between the stimulus and target cell, while polysynaptic reflexes contain three or more neurons. Both monosynaptic and polysynaptic reflexes are composed of only two neurons between the stimulus and target cell. Both monosynaptic and polysynaptic reflexes are composed of three or more neurons between the stimulus and target cell.

Monosynaptic reflexes are composed of only two neurons between the stimulus and target cell, while polysynaptic reflexes contain three or more neurons.

What is the stimulus that initiates a flexion reflex? Pain Touch Loss of balance Sound

Pain

________ monitor the position of skeletal muscles and joints. Stretch receptors Baroreceptors Proprioceptors Chemoreceptors

Proprioceptors

Target

Quadriceps muscle Hamstring muscle

A patient had damage to interneurons. When testing the patellar tendon reflex, which of the following would be found to be affected? Signaling in sensory neurons Signaling to hamstrings Stimulus to muscle spindles Signaling to quadriceps

Signaling to hamstrings

Some autonomic reflexes are spinal reflexes; others are integrated in the brain. List some examples of each.

Spinal reflexes: urination and defecation. Cranial reflexes: control of heart rate, blood pressure, and body temperature.

integrator

Synapse of sensory neuron in spinal cord

Which is TRUE about muscle spindles? They send information about muscle stretch to the CNS. They are innervated by gamma motor neurons. They contain sensory neurons. They are tonically active.

They send information about muscle stretch to the CNS. They are innervated by gamma motor neurons. They contain sensory neurons. They are tonically active.

How many synapses occur in the simplest autonomic reflexes? Where do the synapses occur?

Two neuron-neuron synapses in the spinal cord and the autonomic ganglion, and one neuron-target synapse.

The simplest reflex requires a minimum of how many neurons? How many synapses? Give an example.

Two neurons and one synapse between them (monosynaptic). The knee jerk (patellar tendon) reflex is an example.

What would happen if a person were to sustain an injury that severed the alpha motor neurons leading to the leg muscles in the crossed extensor portion of the reflex? A person would not be able to withdraw their leg in the presence of a painful stimulus. The sensory signal delivered by the afferent neuron would not be properly transduced at the spinal cord. A person would not be able to feel a painful stimulus. Upon a painful stimulus, a person would withdraw their leg and then lose their balance and possibly fall over.

Upon a painful stimulus, a person would withdraw their leg and then lose their balance and possibly fall over.

Which statements are TRUE? Visceral reflexes are controlled by autonomic neurons. Spinal reflexes do not require input from the brain. Spinral reflex movements are integrated mainly in the spinal cord. Cranial reflexes are integrated in the brain.

Visceral reflexes are controlled by autonomic neurons. Spinal reflexes do not require input from the brain. Spinral reflex movements are integrated mainly in the spinal cord. Cranial reflexes are integrated in the brain.

After stretching an intrafusal fiber, the next event is an increase in action potentials along the associated sensory neuron. a decrease in muscle tension. a decrease in muscle tone. decreased sensitivity to stretching. All of the answers are correct.

an increase in action potentials along the associated sensory neuron.

Which of the following structure(s) must always be present in order for you to have a skeletal muscle reflex arc? afferent neuron target cell stimulus efferent neuron integrator interneuron receptor

afferent neuron target cell stimulus efferent neuron integrator receptor

Somatic motor neurons that innervate skeletal muscle fibers are called alpha motor neurons. gamma motor neurons. intrafusal fibers. extrafusal fibers.

alpha motor neurons.

The sensory fibers of the muscle spindle organs synapse onto alpha motor neurons. Golgi tendon organs. joint receptors. gamma motor neurons.

alpha motor neurons.

The pathway pattern that brings information from many neurons into a smaller number of neurons is known as .

convergence

The "normal" contractile fibers of the muscle are also called the extrafusal fibers. muscle spindle fibers. intrafusal fibers.

extrafusal fibers.

Muscle Spindle

has sensory neurons that send information to the CNS is associated with two types of motor neurons conveys information about the relative positioning of bones is innervated by gamma motor neurons modulates activity in alpha motor neuron

Stretching a skeletal muscle causes sensory neurons to (increase/decrease) their rate of firing, causing the muscle to contract, thereby relieving the stretch. Why is this a useful reflex?

increase. This reflex prevents damage from overstretching.

joint capsule mechanoreceptor

is strictly a sensory receptor has sensory neurons that send information to the CNS conveys information about the relative positioning of bones

Golgi tendon organ

is strictly a sensory receptor has sensory neurons that send information to the CNS modulates activity in alpha motor neuron

The flexion reflex prevents a muscle from generating damaging tension. is an example of a monosynaptic reflex. prevents a muscle from overstretching. makes adjustments in other parts of the body in response to a particular stimulus. moves a limb away from a painful stimulus

moves a limb away from a painful stimulus

The effector in a reflex is the efferent neuron. control center. muscle or gland. afferent neuron. sensory receptor.

muscle or gland.

Which organ responds to muscle stretch? basal ganglion Golgi tendon organ myotatic unit muscle spindle

muscle spindle

receptor

muscle spindle

Match the structure to its description. A. muscle spindles B. Golgi tendon organs C. both maintain muscle tone at rest through tonic activity

muscle spindles

The effectors in reflexes are the ______. afferent and efferent neurons sensory neurons and the interneurons muscles and glands sensory neurons and the muscles spinal cord and the brain

muscles and glands

A ________ reflex has/have at least one interneuron placed between the sensory and motor neuron. nonsynaptic monosynaptic polysynaptic nonsynaptic reflex and a monosynaptic

polysynaptic

Is the cross extensor reflex a monosynaptic or polysynaptic reflex? monosynaptic polysynaptic both neither

polysynaptic

Stretching of a muscle spindle causes reflexive inhibition of the muscle stretching of the tendon reflexive contraction of the muscle the spindle resides in activation of antagonistic muscles

reflexive contraction of the muscle the spindle resides in

Somatic reflexes involve muscles; (or visceral) reflexes are controlled by autonomic neurons.

skeletal, autonomic

All neural reflexes begin with a(n) that activates a receptor.

stimulus

stimulus

stretch of the muscle

The Golgi tendon organ responds primarily to muscle .

stretch, contraction, contraction, decreases, alpha motor neuron

Muscle spindles are ________ receptors and cause reflex ________, whereas Golgi tendon organs respond primarily to ________ and cause a ________ reflex. tension, contraction, stretch, contraction stretch, contraction, tension, relaxation stretch, relaxation, tension, contraction tension, relaxation, stretch, relaxation

stretch, contraction, tension, relaxation

Alpha-gamma coactivation causes __________. the muscle spindle to remain active during skeletal muscle contraction contraction of a motor unit and inhibition of the muscle spindle the relaxation of both intrafusal and extrafusal fibers contraction of a muscle spindle and relaxation of a motor unit

the muscle spindle to remain active during skeletal muscle contraction

Spinal interneurons prevent muscle antagonists from interfering with an intended movement by activating reverberating circuits. initiating a crossed extensor reflex. initiating a stretch reflex. the process of reciprocal inhibition. initiating a tendon reflex

the process of reciprocal inhibition.

What is the function of alpha-gamma coactivation? to activate antagonistic muscles to maintain spindle function when the muscle contracts to cause reflex inhibition of the muscle to stretch the tendon

to maintain spindle function when the muscle contracts

Because of tonic activity in neurons, a resting muscle maintains a low level of tension known as .

tone