reflex action important pts
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Hey friend here is your answer.....
Answer :
Reflex action does not involve conscious thought . Rather , it is an automatic response to a stimulus requiring swift action . For example, you instantly blink when a strong like this flashed in your eyes some other examples are
❀ Withdrawing one's hand instantly when it touches a hot object accidentally .
❀ Protecting once held with one's hands, or bending it down or sideways to save it from and object rushing towards it .
❀ Adjusting one's posture to avoid falling .
❀ Coughing , sneezing , yawning and hiccuping .
Reflexes do not involve the brain directly . It is the spinal cord, with the help of the peripheral nervous system, which effects such instant responses . The mechanism of action is different from that involved in involuntary activities controlled by the autonomic nervous system . In the case of reflex action, a message from the sensory cells, or receptors that have been stimulated is sent via sensory neurons, which sinapse on motor neurons situated in the spinal cord . The motor neurons send messages directly to the effector organ . This route of transmission of impulses (messages) is called a reflex arc .
As most reflex actions are meant to protect us from danger, they require a shorter route of transmission .
A doctor tests the condition of the muscles of a leg by testing the knee-jeŕk reflex . The doctor taps on a tendon just below the knee with hammer . This tap stretches a group of muscles in the front of the thigh called the quadriceps femoris . This stimulus activate stretch receptors within the muscles, which send an impulse to the spinal cord via a sensory neuron . The axon of this sensory neuron has two branches . One of the branches synapses on a motor neuron , which carries an impulse back to the quadriceps femoris , triggering their contraction . The other branch synapses on an interneuron , a connecting neuron which synapses on another motor neuron that carries an impulse to the hamstring muscles at the back of the thigh . The hamstring muscles relax in response to this impulse. The knee jeŕks upwards due to the simultaneous contraction of the quadriceps femoris and relaxation of the hamstring muscles .
Hope it helps you......
Answer :
Reflex action does not involve conscious thought . Rather , it is an automatic response to a stimulus requiring swift action . For example, you instantly blink when a strong like this flashed in your eyes some other examples are
❀ Withdrawing one's hand instantly when it touches a hot object accidentally .
❀ Protecting once held with one's hands, or bending it down or sideways to save it from and object rushing towards it .
❀ Adjusting one's posture to avoid falling .
❀ Coughing , sneezing , yawning and hiccuping .
Reflexes do not involve the brain directly . It is the spinal cord, with the help of the peripheral nervous system, which effects such instant responses . The mechanism of action is different from that involved in involuntary activities controlled by the autonomic nervous system . In the case of reflex action, a message from the sensory cells, or receptors that have been stimulated is sent via sensory neurons, which sinapse on motor neurons situated in the spinal cord . The motor neurons send messages directly to the effector organ . This route of transmission of impulses (messages) is called a reflex arc .
As most reflex actions are meant to protect us from danger, they require a shorter route of transmission .
A doctor tests the condition of the muscles of a leg by testing the knee-jeŕk reflex . The doctor taps on a tendon just below the knee with hammer . This tap stretches a group of muscles in the front of the thigh called the quadriceps femoris . This stimulus activate stretch receptors within the muscles, which send an impulse to the spinal cord via a sensory neuron . The axon of this sensory neuron has two branches . One of the branches synapses on a motor neuron , which carries an impulse back to the quadriceps femoris , triggering their contraction . The other branch synapses on an interneuron , a connecting neuron which synapses on another motor neuron that carries an impulse to the hamstring muscles at the back of the thigh . The hamstring muscles relax in response to this impulse. The knee jeŕks upwards due to the simultaneous contraction of the quadriceps femoris and relaxation of the hamstring muscles .
Hope it helps you......
stylishtamilachee:
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ANS:
______________________________
1.An immediate and involuntary response given to a stimulus from the environment is called the reflex action.
____________________________
2.Sometimes we react to an incident without any thinking on our body or control over the reaction.
______________________________
3.This is a response given to a certain stimulus from the surroundings.
_____________________________
4.In such situations,proper control and co-ordination is achieved even without the intervention of the brain.
_____________________________
5.Spinal cord is the centre of co-ordinatin for reflex action.
____________________________
AN EXAMPLE OF REFLEX ACTION:
_____________________________
When our hands touches a hot object,the receptor in the skin detects the stimulus.
____________________________
The sensory neurons send the impulses in the relay neuron in the spinal cord.
___________________________
The impulses are then sent to motor neurons which cause the muscle of the hand to move away from the object.
____________________________
______________________________
1.An immediate and involuntary response given to a stimulus from the environment is called the reflex action.
____________________________
2.Sometimes we react to an incident without any thinking on our body or control over the reaction.
______________________________
3.This is a response given to a certain stimulus from the surroundings.
_____________________________
4.In such situations,proper control and co-ordination is achieved even without the intervention of the brain.
_____________________________
5.Spinal cord is the centre of co-ordinatin for reflex action.
____________________________
AN EXAMPLE OF REFLEX ACTION:
_____________________________
When our hands touches a hot object,the receptor in the skin detects the stimulus.
____________________________
The sensory neurons send the impulses in the relay neuron in the spinal cord.
___________________________
The impulses are then sent to motor neurons which cause the muscle of the hand to move away from the object.
____________________________
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