Question

Write a short essay on the interaction of the special senses with the autonomic nervous system

Answer 1

The functional unit of the nervous system is the neuron. Neurons connect with each other by synapses to create a complex network that conveys electrical impulses all around the body. The function of this system is to take in information from the external and internal environments and to initiate an appropriate response.

• The brain and spinal cord form the control centre of this network and consist of dense accumulations of nervous tissue.

• The brain can be seen to be divided into fore, mid and hindbrains. Each part of the brain performs a different function and is vital for the survival of the animal.

• To ensure that the brain functions normally it is protected externally by a bony cranium and three layers of meninges and internally by the ventricular system consisting of canals filled with cerebrospinal fluid. In addition, every blood vessel entering the brain is wrapped in a layer of protective cells forming the blood–brain barrier, which prevents potentially harmful substances reaching the brain tissue.

• The whole body is supplied by the peripheral nerves. These are given off as cranial nerves from the brain and spinal nerves from the spinal cord.

• There are five special senses, each of which is vital for the survival of the individual.

• External stimuli, e.g. sight and sound, are perceived by specialised receptor cells located within the special sense organs.

• Information from the receptor cells is transmitted by nerve impulses to the brain by cranial nerves. It is interpreted within specific centres in the brain and a response is initiate

These senses permit the central nervous system to produce reactions for the stimuli and maintain body homeostasis. ... Special senses detect the sensations of taste, smell, hearing, equilibrium, and sight, only in special sense organs in the head region (a phenomenon known as “cephalization").

The sympathetic nervous system can accelerate heart rate, widen bronchial passages, decrease motility of the large intestine, constrict blood vessels, increase peristalsis in the esophagus, cause pupillary dilation, piloerection (goose bumps) and perspiration (sweating), and raise blood pressure.

Afferent messages carry sensations such as heat, cold, or pain. Some evolutionary theorists suggest that the sympathetic nervous system operated in early organisms to maintain survival since the sympathetic nervous system is responsible for priming the body for action. One example of this priming is in the moments before waking, in which sympathetic outflow spontaneously increases in preparation for activity.