PNS Basics
These specialized receptors in the skin respond to changes in temperature, pressure, and pain.
What are sensory receptors?
These receptors respond to changes in temperature.
What are thermoreceptors?
This part of the spinal cord contains myelinated axons that connect different parts of the nervous system.
What is white matter?
An example of this type of reflex is the knee-jerk response.
What is a stretch reflex?
The spinal cord has this many pairs of spinal nerves.
What are 31 pairs?
This part of the PNS controls involuntary muscles and glands.
What is the autonomic nervous system?
Sensory receptors for touch, pressure, and vibration.
What are mechanoreceptors?
This fills the central canal of the spinal cord.
What is cerebrospinal fluid (CSF)?
This type of reflex results in withdrawal from a painful stimulus.
What is a flexor (withdrawal) reflex?
This plexus is responsible for innervating the upper limbs.
What is the brachial plexus?
These are nerves that carry both sensory and motor fibers.
What are mixed nerves?
An example of this type of receptor is the one found in the retina that responds to light stimuli.
What are photoreceptors?
The nerve tracts responsible for transmitting motor information down from the brain.
What are descending tracts?
This part of the brain directly influences voluntary motor control and skilled movements.
What is the primary motor cortex?
This is the longest nerve in the body. It extends from the lumbar plexus down to the foot.
What is the sciatic nerve?
This connective tissue covering bundles multiple fascicles to form a nerve.
What is the epineurium?
These receptors detect stretching of organs such as the lungs and bladder.
What are baroreceptors?
The gray matter of the spinal cord is divided into these three main horns.
What are the dorsal, ventral, and lateral horns?
These motor pathways originate in the brainstem and control axial muscles that help maintain posture.
What are indirect (extrapyramidal) pathways?
This is a collection of nerve roots at the end of the vertebral column.
What is the cauda equina?
These fiber carry impulses toward the CNS from sensory receptors.
What are afferent fibers?
These receptors adapt slowly or not at all to a constant stimulus.
What are tonic receptors?
These interneurons receive sensory input in the dorsal horns of the gray matter.
What are somatic sensory neurons?
These tracts send information about muscle and tendon stretch to the cerebellum.
What are spinocerebellar tracts?
These two regions have enlargements where nerves that supply the upper and lower limbs emerge.
What are cervical and lumbosacral enlargements?