Chapter 13

stimulus

All neural reflexes begin with a _______ that activates a sensory receptor.

Somatic motor neurons

Efferent division that controls skeletal muscles

Autonomic neurons

Efferent division that control smooth and cardiac muscle, glands, and adipose tissue

F

T/F Spinal reflexes require input from the brain

F, within

T/F Cranial reflexes are integrated outside of the brain

1. efferent division that controls the effector
2. Integrating region within the central nervous system
3. time at which the reflex develops
4. the number of neurons in the reflex pathway

Neural reflexes can be classified by:

spinal cord

Where are spinal reflexes integrated?

cranial reflexes

reflexes that are integrated in the brain are called what?

T

T/F spinal and cranial reflexes can be modulated by a higher input from the brain

F

T/F many reflexes are learned instead of innate

monosynaptic reflex

What is the name of the simplest reflex?

monosynaptic reflex

this reflex is name for the single synapse between the two neurons in the pathway: an afferent sensory neuron and an efferent somatic motor neuron.

one

how many synapses does a monosynaptic reflex have?

polysynaptic reflex

this reflex have three of more neurons in the pathway and at least two synapses

interneuron in spinal cord

Where does the first synapse of a polysynaptic reflex end?

excitation or inhibition

Modulation in polysynaptic pathways may involve _____ and ______.

input from the brain

Some visceral reflexes are spinal reflexes that can take place without ___________.

hypothalamus, thalamus, brain stem

Where specifically are autonomic reflexes integrated into the brain? (3)

polysynaptic

All autonomic reflexes are what kind of reflex?

autonomic reflexes are all polysynaptic, with at lease one synapse in the CNS between the sensory neurons and the preganglionic autonomic neuron, and an additional synapse in the ganglion between the preganglionic and postganglionic neurons.

autonomic reflexes and their synapses

tonic activity, a continuous stream of action potentials that creates ongoing activity in the effector.

many autonomic reflexes are characterized by what?

skeletal muscle, joint capsules, and ligaments

proprioceptors are located where? (3)

input sensory neurons

Proprioceptors carry ________ to the CNS

output signal

Somatic motor neurons carry _______.

activate somatic motor neurons to the muscle fibers

if there is a muscle contraction then the CNS will do what?

sensory input activated inhibitory interneuorns in the CNS, and these interneurons inhibit activity in somatic neurons controlling the muscle

If a muscle needs to be relaxed what will happen in the CNS?

F, excitation causes contraction

T/F relaxation always causes contraction in skeletal muscle

F

T/F there are inhibitory neurons that synapses on skeletal muscles to cause them to relax

excitatory input by the somatic motor neuron

relaxation of the muscle results from the absence of what?

synapses within the CNS

inhibition and excitation of somatic motor neurons and their associated skeletal muscles must occurs where?

extrafusal muscle fbers

normal contractile fibers (effectors)

excitatory and inhibitory interneurons

the CNS integrates the input signal using networks and pathways of

alpha motor neurons

Somatic motor neurons that innervate skeletal muscle contractile fibers are called what?

extrafusal fibers

action potentials in alpha motor neurons causes what to contract?

muscle spindles, golgi tendon organs, and joint receptors

what are the three types of proprioceptors found in the body?

joint receptors

these receptors are found in capsules and ligaments around joints in the body.

muscle spindles and golgi tendon organs

these receptors lie inside skeletal muscles and sense changes in muscle length and tension (2)

muscle reflexes

the sensory output of muscle spindles and golgi tendon organs activates what?

muscle spindles

stretch receptors that send information to the spinal cord and brain about muscle length and changes in muscle length

muscle spindles

small, elongated structures scattered among and arranged parallel to the contractile extrafusal muscle fibers

jaw

every skeletal muscle in the body has muscle spindles except where?

in muscle spindles

where are intrafusal fibers located?

intrafusal fibers

connective tissue CAPSULE that encloses a group of small muscle fibers

intrafusal fibers

these fibers are modified so that the ends are contractile but the central region lack myofibrils

gamma motor neurons

the contractile ends of the intrafusal fibers have their own innervation from what?

sensory nerve endings that are stimulated by stretch

noncontractile central region of each intrafusal fiber is wrapped by what?

sensory receptors

muscle spindles and golgi tendon organs are _______ in muscle.

on alpha motor neurons innervating the muscle in which the spindle lies

the sensory nerve endings that is located in the central region of intrafusal fibers project to the spinal cord and synapse directly where?

resting, active

when a muscle is at its ______ length, the central region of each muscle spindle is stretched enough to activated the sensory fibers. As a result, sensory neurons from the spindles are tonically ____, sending a steady stream of action potentials to the CN

muscle tone

when muscle at rest maintains a certain level of tension

parallel

muscle spindles are anchored in ____ to the extrafusal muscle fibers

stretch reflex

the reflex pathway in which muscle stretch initiates a contraction response

muscle spindle

this part of the muscle sends tonically active sensory neuron with information to the CNS

F, resting

T/F sensory neurons are tonically active when muscle fibers are contraction

F, presence of gamma motor neurons in a normal muscle keeps the muscle spindles active, no matter what the muscle length is.

T/F the release of tension on the center of the intrafusal fibers will cause the afferent neurons to slow their firing rate or stop firing altogether.

...

when alpha motor neurons fire, the muscle shortens and releases tension on the muscle spindle capsule. Simultaneously, gamma motor neurons innervating the contractile ends of the muscle spindle fire, which causes the ends of intrafusal fibers to contract

contraction of the spindle ends

what causes the central region of the spindle to lengthen and maintain stretch on the sensory nerve endings?

active

spindle remains ____ when the muscle contracts

alpha-gamma coactivation

Excitation of gamma motor neurons and alpha motor neurons at the same time is called

yes

when extrafusal muscle fibers are at resting length, are sensory neurons tonically active?

alpha motor neurons

what receives the tonic input from muscle spindles?

decrease

without gamma motor neurons, muscle contraction cause the spindle firing rate to _____.

stretched

alpha-gamma coactivation keeps the spindles ____ when the muscle contracts

golgi tendon organ

these receptors are found at the junction of tendons and muscle fibers, placing them in series with the muscle fibers

golgi tendon organ

what responds primarily to the tension that a muscle develops from an isometric contractions

isometric

this type of contraction causes a relaxation reflex

f

T/F golgi tendon organ is more sensitive to muscle stretch than the muscle spindles

golgi tendon organ

composed of free nerve endings that wind between collagen fibers inside a connective tissue capsule

inhibitory

afferent input from activation of the golgi tendon organ excited ____ interneurons in the spinal cord.

excessive contraction that might injure the muscle

golgi tendon organs prevent what?

myotatic unit

collection of pathways controlling a single joint

monosynaptic stretch reflex

simplest reflex in a myotatic unit

sesnory neuron from the muscle spindle and the somatic motor neuron to the muscle

the monosynaptic stretch reflex involves which two neurons?

flexion reflexes

polysynaptic reflex pathways that cause an arm or leg to be pulled away from a painful stimulus

divergent pathways

flexion reflexes rely on what kind of pathways in the spinal cord?

crosses extensor reflex

flexion reflexes are usually accompanied by what other reflex?

divergence

this allows the sensory signal to permit a single stimulus to control two sets of antagonistic muscle groups as well as to send sensory information to the brain.

reflex, voluntary, rhythmic

3 types of movement

reflex movement

least complex movement and is integrated primarily in the spinal cord

T

T/F reflex movements can be modulated by input form higher brain centers.

postural reflexes

these reflexes help us maintain body position as we stand or move through space and are integrated in the brain stem

postural reflexes

these reflexes require continuous sensory input form visual and vestibular sensory systems and from the muscles themselves

voluntary movement

this is the most complex type of movement. They require integration at the cerebral cortex and they can be initiated at will without external stimuli

rhythmic movements

this type of movement is the combination of reflex and voluntary movements

cerebral cortex

rhythmic movements are initiated and terminated by input from which part of the brain?

rhythmic

central pattern generators (CPGs) are interneurons that are activated during which type of movement?

brain stem and cerebellum

which parts of the brain control postural reflexes and hand and eye movements?

cerebral cortex and basal ganglia

which parts of the brain help intiate voluntary movement?

spinal cord

this part of the body integrates spinal reflexes and contains central pattern generators.

thalamus

this part of the brain relays and modifies signals being sent from the spinal cord, basal ganglia, and cerebellum to the cerebral cortex

F

T/F reflex movements require input from the cerebral cortex

spinal cord, brain stem, and cerebellum

proprioceptors provide information to which parts of the brain

F, directly goes to the cerebellum

T/F sensory input from the vestibular apparatus go to the spinal cord, cerebral cortes, and cerebellum

basal nuclei, cortical association areas, cerebellum

planning movement happens where in the brain?

motor cortex

initiating movement happens where in the brain?

corticospinal tract

a group of interneurons controlling voluntary movement that run form the motor cortex to the spinal cord, where they synapse directly onto somatic motor neurons

parkinson's disease

this disease is caused by the loss of basal ganglia that release dopamine

visceral movement

moves products in hollow organs, controlled by ANS, some create own action potentials