In: Anatomy and Physiology
A needle is inserted into the right somatosensory nucleus of the thalamusin the central nervous system and the area is injected with GABA.
1. Through what structure does a primary sensory neuron from the hand enter the central nervous system?
2. Where does the first synapse for this somatosensory pathway occur?
3. Describe the type(s) of sensory information carried by this pathway.
4. Name and describe two different classes of primary sensory receptors that are associated with this pathway.
5. Discuss the common features that all primary sensory receptors possess.
6. If an adrenergic substance had been injected instead of GABA, how would this have altered neural transmission? Explain.
1. Primary sensory neuron from the hand enter the central nervous system through the dorsal nerve root of the spinal cord. the cell bodies that carry somatic sensations are present in the dorsal nerve root ganglion.
2. The first synapse for different somatic sensations occur at different levels
The lateral spinothalamic tract carries pain and
temperature sensations; first synapse for this sensation occur at
the posterior
horn cells in the region of substantia gelatinosa of spinal
cord
The ventral /anterior spinothalamic tract carries light touch, pressure, tickle, and itch sensations; first synapse for this sensation occur at the posterior horn cells in the region of substantia gelatinosa of the spinal cord but about 8 to 10 spinal segments above or below the entered spinal segment.
Dorsal column medial lemniscal pathways carries conscious proprioception that is the sensations of proprioception, two-point discrimination as well as vibrations; first synapse for this sensation occur in the nucleus gracilis and nucleus cuneatus.
3. The type of sensation carried by this pathways are Touch both fine touch & crude touch, Temperature, Pain, Pressure, Tactile localization, Tactile discrimination, Vibratory sensation, Stereognosis (ability to identify an object by feeling/ touching it)
4. Receptors are sensory nerve endings that ends in peripheral organs as capsulated or non-encapsulated structures which when stimulated produce a series of impulses & are transmitted via afferent nerves to the central nervous system
Basically there are two types of receptors; Exteroceptors & Interoceptors
Exteroceptors
Interoceptors
5. The common features that all primary sensory receptors possess are