Download Reflexes

Reflexes
I.
General
a. Description
b. Components:
i. receptor,
ii. sensory neuron,
iii. integration center- generally within CNS; may involve
simply a synapse (monosynaptic) or may involve
interneurons (polysynaptic)
iv. motor neuron
v. effector
c. Somatic reflexes involve skeletal muscle responses; when
they occur, the cerebral cortex will be notified and you will be
aware of the event! Visceral reflexes involve ANS effectors (ex,
smooth muscle) and the cerebral cortex will not necessarily be
notified.
II.
Somatic Spinal Reflexes: 2 specific examples to know
a. The stretch reflex
-monosynaptic
-receptors are specialized muscle cells embedded within
whole muscles: intrafusal muscle fibers
-sensory neurons monitor the degree (type Ia fibers and
type II fibers) and rate of stretch (type Ia fibers) of the
intrafusal muscle fibers
-the whole production (receptor cells and sensory
neuron endings) is called a muscle spindle
-when the muscle is stretched, sensory neurons send
impulses and “tell” motor neurons to activate their
muscles. This increases tone of the muscle and
prevents over-stretching.
-the stretch reflex is accompanied by a reflex that
causes antagonistic muscles to relax (reciprocal
inhibition).
b. The withdrawal (flexor) reflex
-polysynaptic
-also accompanied by reciprocal inhibition reflex
III. Visceral Reflexes- will be covered with the ANS!