Functions of the Nervous System

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BODY SYSTEMS
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BODY SYSTEMS
The endocrine and nervous system are among the most important of body system with
tight regulation involved. They control important aspects of human function and maintenance of
an internal environment. The current paper is a discussion of the functions of the nervous system,
the endocrine system, and their interrelation. The functions of the neurons in the nervous system
and functions of hormones in the endocrine system will be discussed to show how they
coordinate the functions of different parts of the body. Feedback regulation mechanisms will also
be discussed.
Nervous System
Stimulation and communications in the nervous system are more immediate unlike the
hormonal stimulation in the endocrine system that is slower and more prolonged (Waugh and
Grant 2010).
The communication method in the nervous system is through an action potential or a
nerve impulse which is basically a propagated electrical impulse (Barrett, Barman, Boitano, and
Brooks, 2009). There is always more than one neuron involved in the transmission of a nerve
impulse from its origin to the target organ. However, no contact is there between these neurons
and the impulse passes from neuron to the other via a gap called a synapse (Hall 2015).
The neurons are divided into three categories; motor, sensory, and interneuron (Hall
2015). A basic reflex arc which uses all three neurons will be used to demonstrate this function
(Barrett, Barman, Boitano, and Brooks, 2009).

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A reflex arc is a fast response to a stimulus that does not involve the brain but passes
through the spinal cord involving all three neuron types (Barrett, Barman, Boitano, and Brooks,
2009). It starts with a stimulus for example heat applied to the hand. The sensory nerves in the
hand through sensory receptors initiate an action potential and propagates it to the spinal cord. At
the level of the spinal cord, there are sensory pathways to the brain, but an interneuron loops
back to the grey matter of the spinal cord and sends an impulse to the motor neurons supplying
muscle groups in the hand leading to a motor response in this case withdrawal of the hand from
the heat source (Barrett, Barman, Boitano, and Brooks, 2009).
The neural action is possible through generation and propagation of nerve impulses. It is
initiated by a sensory nerve or when transmitted from one nerve to another (Barrett, Barman,
Boitano, and Brooks, 2009). It is by movement of charged ions across the nerve membranes. The

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inside and outside of the membrane have different charges, called the resting membrane
potential. Sodium ions are extracellular while potassium ions are intracellular (Barrett, Barman,
Boitano, and Brooks, 2009). When stimulated, the permeability of the membrane to these ions
changes. Sodium floods into the cell creating a depolarizing action potential which moves along
the entire nerve from point of stimulation towards the resting potential (Barrett, Barman,
Boitano, and Brooks, 2009).
For a nerve impulse to pass a synapse, neurotransmitters have to be involved. The arrival
of an impulse at a presynaptic neuron releases neurotransmitter which is usually synthesized by
the neuron and stored in vesicles at the presynaptic membrane. The neurotransmitters move
across the synaptic cleft to act on the receptors on the post-synaptic membrane. The impulse is
thus propagated when an action potential is initiated in the post-synaptic neuron.
The Endocrine System.
The endocrine system is another system that relies on communication and signaling to
control different body functions (Nussey and Whitehead 2013). The signaling and
communication, however, is through hormones. It comprises the following main organs; the
hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid gland, adrenals,
reproductive glands and the endocrine pancreas among others (Melmed 2016)