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Reflex action and Reflex arc
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What are Reflex actions?
Closing of eyes when a bright light is focused on your eyes is a reflex action.
Reflex actions save us from danger when there is a painful or dangerous stimulus.
Reflex actions are fast, immediate, automatic and involuntary responses of the body.
Reflexes occur without our thinking. Brain is not involved in the execution of several reflexes.
What is Reflex arc? What are the components of the Reflex arc? Mention their functions?
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The structural and functional unit that carries out reflex action is called a Reflex arc.
Component of Reflex arc: Reflex arc is consisting of five parts. They are Receptor, sensory nerve or
afferent nerve, Interneuron or Association neuron, motor nerve or efferent nerve, and Effect-or
organ.
Functions of components of Reflex arc:
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Receptor - Receives information and generates impulses.
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Sensory Nerve - Carries information from the receptor to the inter neurons in the spinal cord.
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Interneuron - Processes the information and generates responses.
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Motor Nerve - Carries the information from the spinal cord to effector organ.
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Effector organ - Receives the information from the effectors neuron and shows the appropriate
response.
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Write a short note on conditional Reflexes.
Conditioned reflexes are not inherited.
These reflexes are acquired due to repeated actions.
Human beings are not exception to these conditioned reflexes.
Conditional reflexes are not same in all individuals and are not inherited.
Ivan Pavlov’s experiment and dog to demonstrate conditioned reflexes explain?
Ivan Pavlov a Russian scientist conducted a number of experiments on conditional reflexes. His
experiments on dog have become very famous.
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It is a common observation that when a dog sees food it salivates. He rang a bell when the dog was
given food. After doing this for few days he noticed that the dog started salivating when it heard the
bell even if the food was not given.
Dog associated with sound of the bell with food and assumed that whenever the bell rang food was
given
In expectation of food, saliva started flowing from its mouth.
Human beings are no exception to this. Conditional reflexes are not same in all individuals and not
inherited.
What is decade of the Brain?
The decade 1990 to 2000 is known as "Decade of Brain" and large number of scientists is working
hard to understand the working of human brain.
Fill up the blanks
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The information about a stimulus is analysed by _______ of spinal cord.
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The weight of the brain in the total weight of the body is _______
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In reflex action the sensory nerve carries the information to _______ in spinal cord.
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Out standing in attention when we hear our National Anthem is a _______
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The cerebral cortex alone has _______number of neurons.
KEY
1. Interneuron
2. 2%
3. Interneuron
4. Conditional Reflexes.
5. 2.6 billion
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