are involuntary reactions to stimuli (internal or external) that are processed in the brain
or spinal cord
stimulate responses in the voluntary skeletal muscles
, producing movement. They are typically very quick to respond (within milliseconds), since skeletal muscles
have very fast contractions
can be simple
Simple (basic) reflexes
responses to stimuli.
Acquired (conditioned) reflexes
- Ex. Knee-jerk (patellar) reflex; withdrawing your hand from a hot object
are a result of practice and learning or training.
of the autonomic nervous system
to respond. These effectors
are smooth muscles
, and their response is much slower than that of somatic reflexes
- Ex. Salivation at the smell of food
are classified structurally
according to the location
of cell bodies
that integrate the response and the number
involved in the reflex pathway.
Monosynaptic reflex arc
Figure 8.2.1 - A monosynaptic reflex arc. The sensory neuron detects the hammer hitting the knee and directly activates the leg muscle effectors to contract.
Polysynaptic reflex arc
Figure 8.2.2 - A polysynaptic reflex arc. The sensory neuron detects the ball on the foot. Interneurons in the cerebellum integrate the sensory input and determine the appropriate muscle response to be able to kick the ball.