In this chapter, we will learn about the neural system of humans, mechanisms of neural coordination like transmission of nerve impulse, impulse conduction across a synapse and the physiology of reflex action.
Hyderabad: This series of articles will focus on neural system and mechanisms of neural coordination in a human body.
Neural control and coordination
• The functions of the organs/organ systems in our body must be coordinated to maintain homeostasis.
• Coordination is the process through which two or more organs interact and complement the functions of one another.
• For example, when we do physical exercises, the energy demand is increased for maintaining an increased muscular activity. The supply of oxygen is also increased. The increased supply of oxygen necessitates an increase in the rate of respiration, heart beat and increased blood flow via blood vessels. When physical exercise is stopped, the activities of nerves, lungs, heart and kidney gradually return to their normal conditions. Thus, the functions of muscles, lungs, heart, blood vessels, kidney and other organs are coordinated while performing physical exercises.
• In our body, the neural system and the endocrine system jointly coordinate and integrate all the activities of the organs so that they function in a synchronised fashion.
• The neural system provides an organised network of point-to-point connections for quick coordination.
• The endocrine system provides chemical integration through hormones.
• In this chapter, we will learn about the neural system of humans, mechanisms of neural coordination like transmission of nerve impulse, impulse conduction across a synapse and the physiology of reflex action.
• The neural system of all animals is composed of highly specialised cells called neurons which can detect, receive and transmit different kinds of stimuli.
• The neural organisation is very simple in lower invertebrates (for example: in Hydra it is composed of a network of neurons).
• The neural system is better organised in insects, where a brain is present along with a number of ganglia and neural tissues.
• The vertebrates have a more developed neural system.
Human neural system
• The human neural system is divided into two parts —
(i) The central neural system (CNS)
(ii) The peripheral neural system (PNS)
• The CNS includes the brain and the spinal cord, and is the site of information processing and control.
• The PNS comprises all the nerves of the body associated with the CNS (brain and spinal cord).
• The nerve fibres of the PNS are of two types —
— Afferent fibres
— Efferent fibres
• The afferent nerve fibres transmit impulses from tissues/organs to the CNS.
• The efferent fibres transmit regulatory impulses from the CNS to the concerned peripheral tissues/organs.
To be continued…
Dr. Modala Mallesh
Palem, Nakrekal, Nalgonda