Chapter 13, Problem 1O

Summary Introduction

To discuss:

The anatomy, physiology, and functions of the central nervous system (CNS) with attention to the stimulants effect on its function.

Concept introduction:

The nervous system is a complex network of nerve cells. Nerves are the basic unit of the nervous system. The nervous system is classified into two major divisions’, central nervous system and peripheral nervous system. The peripheral nervous system is subdivided into sensory division (afferent) and motor division (efferent).

Explanation of Solution

Pictorial representation:

Anatomy and physiology of the central nervous system: Spinal cord and brain are classified under the central nervous system, which is protected by the vertebral column and the cranium. Cranial nerves, peripheral nerves and spinal nerves belong to the PNS, which is protected by connective tissue. The PNS is classified into sensory and motor divisions. Sensory or afferent neurons conduct signal toward the CNS in response to stimuli, such as heat and light. Motor or efferent neurons send signal to the gland cells and the muscle cells.

The cerebellum accepts signals from the sensory systems, spinal cord and other regions of the brain. After receiving the signals, motor movements are regulated by the CNS. Posture, balance, and coordination are regulated by the cerebellum. The anterior region of the brain consists of two hemispheres that are separated by a fissure. It is accountable for sensory as well as neural functions. It co-ordinates the voluntary functions in the body.

The membranous covering of the brain and the spinal cord is known as meninges. This layer along with the cerebrospinal fluid (CSF) offers protection to the CNS.  Brain stem is the central stalk of the brain, consists of Pons, medulla oblongata, as well as the mid-brain and extends downward to form the spinal cord.

The spinal cord is long, thin and tubular structure. It is made up of support cells and nervous tissue. It spreads from the medulla oblongata present in the brainstem toward the (vertebral column) lumbar region. The major functions of the spinal cord connectthe PNS with the brain and transmission of nerve impulses.

Attention to the stimulant effect over the functions of the CNS:

The drugs that are involved in the stimulation of the spinal cord and the brain are known as stimulant drugs. These drugs work by mimicking the neurotransmitters of the nervous system (sympathetic).

Amphetamine stimulant, Methylphenidate, Phentermine, and Sumatriptan are some of the categories of CNS stimulant drugs. Amphetamine and the caffeine drugs are involved in the stimulation of the cerebral cortex region of the brain. Analeptics and caffeine drugs effects are seen in the brainstem and medulla oblongata. They are involved in the stimulation of the respiration process. Anorexiant group acts partially on the hypothalamus and cerebral cortex for suppressing the appetite.

Conclusion

CNS drugs induce the brain andincrease the rapidity of mental and physical activities. These drugs are used in the treatment of prolonged fatigue, obesity and unnecessary sleep and so on.