HSC Science (General) 12th Board ExamMaharashtra State Board
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With the ·Help of a Neat and Labelled Diagram, Describe Reflex Arc. - HSC Science (General) 12th Board Exam - Biology

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Questions

With the help of a neat and labelled diagram, describe reflex arc.

Sketch and label reflex arc

Solution

Reflex arc: The pathway of nerve fibres along which the reflex impulse travels is known as
reflex arc.
It is always unidirectional from receptor organs to the effector organ, via. CNS. Reflex arc is the structural and functional unit of reflex action.
Components of simple reflex arc:
Simple reflex arc is formed of five components as given below:
i. Receptor organ:
It is a specialized part of body called sense organ that receives the stimulus and converts it into the impulse. e.g. skin, eye, tongue, nose and ears.

ii. Sensory or Afferent neuron:
It carries sensory nerve impulse from receptor organ to CNS. Its cyton is located in dorsal root ganglion. Its dendron is long and connected to receptor, while the axon enters in the grey matter of spinal cord to form a synapse.
iii. Associated or Intermediate neuron:
It is present in the grey matter of spinal cord. It receives sensory impulse, interprets it and generates motor impulse. 
iv. Motor or effector neuron:
Its cyton is present in the ventral horn of grey matter and axon travels through ventral
root. It conducts motor impulse from spinal cord to effector organ.
v. Effector organ:
It is a specialized part of the body which is excited by receiving the motor impulse. It gives proper response to the stimulus. e.g. Muscles and glands.

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Question 7.1.3 | 3.00 marks
 2015-2016 (July) (with solutions)
Question 7.2 | 3.00 marks
Solution With the ·Help of a Neat and Labelled Diagram, Describe Reflex Arc. Concept: Reflex Action and Reflex Arc.
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