reflexes

what is a reflex?

rapid motor response to a stimulus

what are the types of reflexes?

intrinsic, acquired, spinal, cranial, somatic, autonomic

what are the 5 parts of a reflex arc?

receptor, sensory neuron, integration center (CNS, motor neuron, effector

what does monosynaptic mean?

one synapse between sensory and motor neurons in CNS, no interneuron

what does polysynaptic mean?

more than one synapse between sensory and motor neurons via 1 or more interneurons

what is an agonist?

muscle that produces a particular movement

what is an antagonist?

muscle that reverses the movement

what are the somatic spinal reflexes?

stretch reflex (knee jerk), (golgi) tendon reflex, withdrawal (flexor) reflex, crossed extensor reflex

describe the stretch reflex

ipsilateral, mono, and polysynaptic reflex

in a stretch reflex, what does muscle stretch leading to contraction do?

prevents overstretching

Which neurons are involved in the monosynaptic stretch reflex controlling the agonist muscle?

One sensory neuron, One motor neuron

Reciprocal inhibition of the antagonist muscle occurs through which type of reflex pathway?

polysynaptic

Which neurons are involved in the polysynaptic pathway controlling the antagonist muscle?

One sensory neuron, One interneuron, One motor neuron

What type of receptor detects stretch in skeletal muscle?

muscle spindle

what are the two types of muscle fibers in a muscle spindle?

intrafusal muscle fibers, extrafusal muscle fibers

what are at the ends of intrafusal muscle fibers?

actin, myosin, gamma efferent fibers

what are the two types of afferent endings in the central area of an intrafusal muscle fiber?

primary sensory, secondary sensory

how is primary sensory stimulated?

rate and amount of stretch

how is secondary sensory stimulated?

amount of stretch

what are extrafusal muscle fibers?

contractile alpha motor efferent fibers

describe the tendon reflex

ipsilateral, polysynaptic control of agonist and antagonist

in a tendon reflex, muscle contraction results in what?

reflex relaxation

what does the tendon reflex prevent?

over contraction of muscle

what is the receptor of the tendon reflex?

golgi tendon organ

where is the receptor for the tendon reflex located?

muscle/tendon junction

what is the stimulus for the tendon reflex?

over contraction of agonist/stretching of tendon

describe a flexor (withdrawal) reflex

ipsilateral, polysynaptic

what is the stimulus for the flexor (withdrawal) reflex?

pain, something noxious

what is the result for a flexor (withdrawal) reflex?

withdrawal of the threatened body part

what is responsible for the contraction of agonists in a flexor reflex?

flexors

what is responsible for the relaxation of antagonists in a flexor reflex?

extensors

what is contralateral control?

sensory neuron also initiates impulse to control opposite side

what is an intersegmental reflex?

ascending and descending branches of sensory neuron that involve different levels of the spinal cord