Anatomy and Physiology of Nervous System

Introduction

The nervous system serves as the body's system of inter-organ communication.

It is the method by which the environment, as well as the tissues and organs of the body itself, transmit sensations of every type. It is the mechanism by which actions are carried out by sending impulses to various bodily organs and nervous system regions.

The nervous system can be divided into two main parts:

• The central nervous system ( CNS ) that consist of:
  • The brain
  • Spinal cord

• The peripheral nervous system (PNS ) that consists of:

  • Spinal nerves -31 pairs
  • Cranial nerve -12 pairs
  • Autonomic nervous system (ANS ): sympathetic and parasympathetic nerves.

The Nerve Cell

The nervous system has nerve cells called neurons which are structural and functional units of the nervous system. Neurons are supported by a special kind of connective tissue called neuroglia.

The basic properties of a neuron are irritability, excitability, and conductivity.

Types of Nerves

• Sensory or afferent nerve
  They transport impulses to the spinal cord and brain from the skin or a sense organ.

• Motor or efferent nerve
  They transport electrical impulses from the brain or spinal cord to the various body regions where they stimulate glandular secretion and contract all different kinds of muscles.

• Mixed nerves
  It includes both sensory and motor nerves, for instance. outside of the spinal cord, nerves.

• Interneuron
  Correlating the activity of sensory and motor neurons are the neurons that stand between receptor and effector neurons. The CNS contains every interneuron.

Mechanism of Stimuli Transmission

The transmission of an impulse from its source to its effector organ always involves many neurons. As was already mentioned, nerve impulses in an axon move away from the cell body, but those in a dendrite move in the opposite direction.

There are synaptic vesicles in the synaptic knobs that house chemical transmitters like acetylcholine, noradrenaline, dopamine, etc. Synaptic vesicles break as impulses reach the synaptic knobs, releasing chemo transmitter into the synaptic cleft. The post synaptic membrane's receptor and the chemo transmitter join forces. The next neuron is activated and an impulse is produced as a result of the interaction between the receptor and the chemo transmitter. The effector organ is reached by impulses that travel in this manner from one neuron to another neuron.

Terminology used in Nervous System Disorder

• Acetylcholine: A chemical in the brain that acts as a neurotransmitter.

• Action tremor: A tremor that increases when the hand is moving voluntarily.

• Agitation:  A vague sign of one or more physical or psychological conditions in which vocal or motor behavior becomes risky or uncomfortable, disruptive or unsafe, or interferes with the provision of care in a specific setting.

• Agonist: A drug that increases neurotransmitter activity by stimulating the dopamine receptors directly.

• Akinesia: No movement

• Alzheimer's disease: A progressive degenerative disease that occurs in the brain and results in impaired memory, thinking and behavior.

• Ataxia: Loss of balance

• Athetosis: Slow, involuntary movements of the hand and feet.

• Atrophy: Wasting, shrinkage of muscle tissue or nerve tissue.

• Basal ganglia: The striatum and the significant nigra are two huge groupings of nerve cells that are located deep within the cerebral hemisphere of the brain.

• Blood-brain barrier: The protective membrane that separates circulating blood from brain cells.

• Bradykinesia: Slowness of movement

• Bradyphrenia: Slowness of though processes.

• Central nervous system: The brain and the spinal cord

• Cerebellum: A substantial, bipartite structure in the lower part of the brain that controls balance and movement coordination.

• Cerebral hemorrhage: A type of stroke occurs when a defective artery in the brain burst, flooding the surrounding tissue with blood.

• Chorea: Rapid, jerky, dance-like a movement of the body.

• Dopamine: A chemical, or neurotransmitter, that controls walking, balance, and movement and is found in the brain.

• Dyskinesia: An involuntary movement including athetosis and chorea.

• Dystonia: A slow movement or extended spasm in a group of muscles.

• Embolus: A wandering blood clot.

• Epilepsy: A brain disorder involving recurrent seizures.

• Ganglion: A cluster of nerve cells.

• Incontinence: Involuntary voiding of the bladder or bowel.

• Intra cranial pressure: The pressure inside the skull.

• Meningitis: An inflammation of the meninges, the membrane that covers the brain.

• Nigral: Of or referring to the substantial nigra.

• Palsy: Paralysis of a muscle or group of muscle

• Rigidity: Increased resistance to the passive movement of a limb.

• Serotonin: A chemical necessary for communication between nerve cells

References

• https://books.google.com/books?isbn=0865874212
• Mandal, G. (August 2013). A Textbook of Adult Health Nursing (2nd ed.). Dilllibazar kathmandu: Makalu publication house. Retrieved August 2013
• https://nursingtestbank.info/chapter-01-drug-actions-and-body-responsesfree/
• www.hopkinsmedicine.org › Health Library
• https://publications.nigms.nih.gov/medbydesign/chapter1.html