Science: Control and Coordination: Functions of Spinal Cord, Relaxation and Its Types (For CBSE, ICSE, IAS, NET, NRA 2022)

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Functions of Spinal Cord

The spinal cord is concerned with the following three functions:

  • It controls the reflexes below the neck.
  • It conducts sensory impulses from the skin and muscles to the brain, and
  • It conducts motor responses from the brain to muscles of the trunk and limbs.

Relaxation and Its Types

The process of responding to a peripheral nerve stimulation that occurs involuntarily i.e.. , without conscious effort or thought and requires the involvement of the spinal cord. These reflexes are very rapid, automatic, stereotyped Behaviour in which the same kind of stimulus evokes for a short-lived response.

Reflex action is of two types:

  • Unconditioned reflexes: These are inborn. These include knee jerk, peristalsis, salivation on the tasting of food etc.
  • Conditioned reflexes: These are acquired and requires some sort of learning after birth. These include playing a musical instrument, knitting without looking, writing as well as reading, etc.

Peripheral Nervous System

It connects the central nervous system with the sense organs, muscles and glands of the body and, includes the sensory and motor nerves.

The peripheral nervous system consists of two subdivisions:

  • Somatic nervous system that conveys information from brain and spinal cord to skeletal muscles and regulates voluntary action.
  • Autonomic nervous system which control the involuntary action of many internal organs, smooth muscles, heart muscles and glands.
Peripheral Nervous System

Somatic Nervous System

This consists of two sets of nerves – the cranial nerves and the spinal nerves

  • 12 pairs of cranial nerves emerge from the brain. For example, optic nerve (for eyes) and auditory nerve (for ears) .
  • 31 pairs of spinal nerves emerge from the spinal cord.

Autonomic Nervous System

  • The autonomic nervous system (ANS) consists of a pair of chain of nerves and ganglia on either side of the backbone. This system controls the involuntary actions of the internal organs. There are two parts of the autonomic nervous system Sympathetic and Parasympathetic.
  • The Sympathetic Nervous System (SNS) becomes more active during times of stress. It prepares the body for action. Its action during the stress response comprise the ‘fight-or-flight response’ that is manifested largely under the influence of the hormone, adrenaline. The Parasympathetic Nervous System executes actions that do not require immediate response, for example producing of saliva and tears, digestion etc.
  • The functions of sympathetic and parasympathetic nervous systems may seem opposite to each other but in reality, they are complementary rather than being antagonistic.

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