The nervous system (speaker notes)
The NS is a network of neurons (specialized cells) that links different body parts to coordinate their activity. The system is divided into the Central nervous system (CNS) and the peripheral nervous system (PNS) which consist of the sensory and somatic nerves. The NS transmits messages between the body parts by electrical and chemical (neurotransmitters) signals. Generally sensory nerves transmit signals from sensory organs to the brain while motor nerves transmit signals from the brain to the muscles and the glands (effectors) (Guytona & Hall, 2006).
The CNS consists of the brain and the spinal cord. While the brain receives signals from other parts, processes the signals and sends necessary instructions to the effector organs the spinal cord connects the brain and the other parts maintaining two way communication between these parts and the brain. The CNS also comprises the autonomic NS which control the involuntary activities (Kaplan, Oesce, & Kazmierczak, 2003).
The PNS connects the other body parts and the CNS through 31 pairs of spinal nerves and 12 pairs of cranial nerves. The cranial nerves save for the vagus nerve, control the face, head, neck and shoulders while the spinal nerves control the rest of the body. The The enteric nervous system is a subset of the PNS that encompasses the vagus nerves and mainly controls the GIT. It can function independent of the rest of the NS (Kaplan, Oesce, & Kazmierczak, 2003).
The endocrine system (ES) collaborates with the NS in regulating the activities of the body. The ES consist of glands that release hormones, under the instructions of the brain, which are transported to target cells via the blood where they bind to specific receptors to elicit responses. The hormones regulate functions such as growth, metabolism, reproduction, digestion etc. The ES and the NS are connected via the hypothalamus at the base of the forebrain (Kronenberg, Melmed, Polonsky, & Larsen, 2008).
In conclusion the NS is a communication network connecting and regulating all the body parts. It comprises of the CNS and the PNS each comprising the sensory and the motor nerves. The NS works in conjunction with the ES to regulate the activities of the body.
References
Guytona, A., & Hall, J. (2006). Textook of medical physiology . Pennsylvania: Elsevier Saunders.
Kaplan, L., Oesce, A., & Kazmierczak, S. (2003). Clinical Chemistry: Theory, Analysis and Correlation. New York: Mosby Inc.
Kronenberg, H., Melmed, S., Polonsky, K., & Larsen, P. (2008). Kronenberg: Williams Textbook of Endocrinology. Saunders Elsevier: Philadelphia.
