Question

Q1-Briefly describe (in sentence form) the various parts of the spinal cord and summarize the functions of these general areas.

Q2-How would superficial damage to the left, anterior spinal cord likely impact physiological function of the affected individual?

Q3-Compare and contrast tonic and phasic receptors, use an example of each to support your answer.

Q-4 Propose a mechanism for Painorphin (a new synthetic opiate). It has been found to have analgesic propeties and the receptors it binds to have been localized to the dorsal horn of the gray matter of the spinal cord on axon terminals of pseudounipolar neurons.

Q-5 In your OWN words, describe the steps involved in phototransduction in rod cells. Start with a photon of light and end with an action potential in the optic nerve.

Q-6 Explain what YOU would expect to happen if a drug which blocked the cation channel in the photoreceptive cells was applied to the left eye.

Q-7 Using the patellar relfex as an example, explain the concept of spinal relfexes and why we have them.

Q-8 Legend: (+) excitatory synapse, (-) inhibitory synapse, Blue Cell (sensory), Green Cells (interneurons), Red/Orange Cells (motor neurons) red neuron motor neuron to knee extensors, orange neuron - motor neuron to knee flexors. Is the above diagram an accurate representation of a potential set of circuitry that would lead to an effective reflex (Yes/No)? Explain Why or Why Not.

Q-9 In your OWN words, using full sentences, compare and contrast the somatic motor nervous system and the autonomic nervous system (ANS).

Q-10 If a nicotinic, cholinergic receptor-agonist was dripped on the heart, how would you expect the heart to respond? Would heart rate and/or contractility increase/decrease/or show no change? Explain your answer

Answer 1

Since multiple questions have been asked the rules state that only the first question has to be answered.

The spinal cord is covered by the meninges- dura mater, pia mater and arachnoid mater. Externally, on the anterior part there is a deep fissure known as anterior median fissure, lateral to it there are two slight depressions called anterolateral sulci on both sides. The posterior median sulcus and posterior median septum are seen on the posterior aspect. The posterior intermediate sulcus and posterior intermediate septum is seen laterally on both sides. Lateral to it is the posterolateral sulcus.

The interior if the spinal cord has the white matter and the butterfly shaped grey matter. The grey matter has the anterior, lateral and posterior horns, which are divided into nuclei and laminae. Exactly at the centre is the spinal canal.

The laminae and nuclei in posterior grey horn are:

• Lamina I- Marginal nucleus
• Laminae II and III- Substantia gelatinosa of Rolando
• Laminae III, IV, V- Chief sensory nucleus
• Lamina VI- Dorsal nucleus of Clarke

In the lateral grey horn,

• Lamina VII- intermediolateral nucleus

In the anterior grey horn,

• Laminae VIII and IX- nuclei concerned with motor functions

Lamina X is seen around the central canal and has neuroglia.

The white matter has the anterior, lateral and posterior white columns.

The anterolateral sulcus denotes the exit of anterior nerve root and the posterolateral sulcus denotes the entry of posterior nerve root. The spinal cord contains collection of nerve fibres called tracts. The ascending tracts carry sensory impulses from the spinal cord to the brain and descending tracts that carry motor impulses from the brain to spinal cord. The ascending tracts are numerous and pass through the anterior, lateral and posterior white columns and the descending tracts are the pyramidal and extrapyramidal tracts. The important ascending tracts and their functions are-

• Anterior spinothalamic tract- carry impulses of crude touch amd sensation
• Lateral spinothalamic tract- carry impulses of pain and temperature
• Dorsal and ventral spinocerebellar tract- impulses of subconscious kinesthetic sensation
• Tract of Gall and tract of Burdach- tactile sensation, localization and discrimination, vibration sensations, stereognosis and conscious kinesthetic sensation.

The pyramidal tracts are concerned with voluntary movements and extrapyramidal tracts are concerned with muscle tone and posture, maintaining respiration and diameter of blood vessels, movement of head to visual and auditory stimuli, etc.