Introduction

 How can one precisely locate a small ant making its way through the heel? How is one able to differentiate if the water is cold, very cold, warm, or hot? How is one able to touch nose or any part of the body without even looking at it? The nervous system is unique in the vast complexity and each minute literally millions of bits of information from the different sensory nerves/organs, and then integrates all these to determine responses to be made by the body. 

The nrevous system has two major divisions : Central Nervous System (CNS) and Peripheral Nervous System (PNS). Brain and Spinal cord form the CNS while the PNS includes components of the nervous system outside the brain and spinal cord. It consists of spinal nerves along with their roots and branches, cranial nerves, and neuromuscular junctions. Two major divisions of PNS are somatic nervous system and autonomic nervous system.

The sensory system is a part of the nervous system responsible for processing sensory information. It consists of the sensory receptor cells, neural pathways, and parts of the brain involved in sensory perception. Most activities of the nervous system are initiated by sensory experiences that excite sensory receptors, whether visual receptors in the eyes, auditory receptors in the ears, tactile receptors on the surface of the body, or other kinds of receptors. The sensory information enters the central nervous system (CNS) through peripheral nerves and is conducted immediately to multiple sensory areas in (1) the spinal cord at all levels; (2) the reticular substance of the medulla, pons, and mesencephalon of the brain; (3) the cerebellum; (4) the thalamus; and (5) areas of the cerebral cortex.

Information is transmitted in the CNS mainly in the form of nerve action potentials, called simply “nerve impulses,” through a succession of neurons,one after another. The central nervous system contains billions of neurons. Incoming signals enter this neuron through synapses located mostly on the neuronal dendrites, but also on the cell body. A special feature of most synapses is that the signal normally passes only in the forward direction, from the axon of a preceding neuron to dendrites on cell membranesof subsequent neurons. 

 After the end o f the course,students will be able to learn about 

1. Organization of the nervous system

2. Synapses and its types

3. Type of sensory receptors and their respective stimuli

4. Transmission of signals in neuronal pools

5. Sensory pathways for transmission of sensory information into the CNS

6. Pain and its types

7. Endogenous analgesic system (pain suppression)

Further Reading:

 1. TEXTBOOK OF MEDICAL PHYSIOLOGY, GUYTON,A.C, 13TH Edition 

  2. HUMAN ANATOMY & PHYSIOLOGY (Marieb, Human Anatomy & Physiology) , 10th Edition

  3. REVIEW OF MEDICAL PHYSIOLOGY ,GANONG,W.F, 25th Edition

Evaluation Criteria

1. Oral Quiz/Assignment  (Class)

2. Class tests

3. Written Exam (Send-up)

4. Oral/Viva/Practical exam