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Control and Coordination - 1
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Nervous system introduction.

Abhishek Abhay
Faculty at CHANAKYA IAS Academy DELHI

Unacademy user

  2. IMPORTANCE OF CONTROL AND COORDINATION A living being does not live in isolation. It has to constantly interact with its external environment and has to respond properly for its survival. For example; when a hungry lion spots a deer, the lion has to quickly make a move so that it can have its food. On the other hand, the deer needs to quickly make a move to run for its life. The responses which a living being makes in relation to external stimuli are controlled and coordinated by a system, especially in complex animals. * In keeping with the general principles of body organization in multicellular organisms, specialized tissues are used to provide these control and coordination activities.

  3. ANIMALS - NERVOUS SYSTEM .The nervous system is composed of speciaized tissues, called nervous tissue .The nerve cell or neuron is the functional unit of the nervous system. .It is the nervous system which is mainly responsible for control and coordination in complex animals Neuron: Direction message travels Nucleus(cellbody Axon terminals Soma Myelin Sheaths Dendrites Neuron is a highly specialized cell which is responsible for transmission of nerve impulses. The neuron consists of the following parts: Cyton or cell body: Axon . The cell body or Cyton is somewhat star-shaped, with many hair-like structures protruding out of the margin. These hair-like structures are called dendrites. Dendrites receive the nerve impulses Axon: This is the tail of the neuron. It ends in several hair-like structures, called axon terminals. The axon terminals relay nerve impulses. Myelin Sheath: There is an insulator cover around the axon. This is called myelin sheath. The myelin sheath insulates the axon against nerve impulses from the surroundings.

  4. TYPES OF NEURON Sensory neuron: These neurons receive signals from a sense organ. Motor neuron: These neurons send signals to a muscle or a gland. Association neuron: These neurons relay the signals between sensory neuron and motor neuron. Afferent Autonom Pain receptors in skin Axon ot afferent neuron Spinal I Cord Cell body of canglia Cell body of afferent Hot object Ventral I Dendrite of afferent Axon of efferent neuron Spinal cord Acetytcholine root Cell body of efferent neuron Voluntany ILow threshold 1 mechanoreceptors Ie touch) Direction of Proprioceptors nch, Cold T Chemical Muscle contracts and withdraws part boing stimulated Sensory Neuron/Afferent n Motor Neuron/Efferent Neuron