The nervous system coordinates all body activities. True or false.
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Answers
Answer:
True
Explanation:
The system which controls and coordinates all the activities of our body is THE NERVOUS SYSTEM:)
Explanation:
Control and Coordination in Humans --The nervous system helps in controlling and coordinating various activities of the human body. The three types of nerves, cranial nerves, spinal nerves and visceral nerves run through the body and help in sending and receiving messages in the form of electrical impulses.
The control and coordination in human beings take place through nervous system and hormonal system which is called endocrine system.
The five sense organs in our body, eyes, ears, nose, tongue and skin are called receptors. This is because they receive information from the environment around us. Therefore, a receptor is a group of cells in sense organ which is sensitive to a particular type of stimulus like light, sound, smell, taste, heat, etc.
All the receptors send message in the form of electrical impulses to spinal cord and brain through sensory nerves. Another type of nerves called motor nerves then transmits response from brain and spinal cord to effectors. An effector is a part of the body which responds to a stimulus according to the instructions sent from the nervous system. The muscles and glands are effectors of the body.
Human Nervous System
Nervous system coordinates the activities of our body. It controls all our behaviour, thinking and actions. It is through nervous system only that all other systems of our body work. It passes information from one internal system to another. For example, when we put food in mouth, it causes release of saliva from the salivary glands.
The Unit of Nervous System: Neurons
A neuron (or nerve cell)
The cells that make up the nervous system are called neurons. Neuron is the largest cell in the body. The structure of neuron is such that it can carry messages in the body quickly. These messages are in the form of electrical impulses or nerve impulses. There are three components of neurons. They are:
i) Cell body
ii) Dendrites
iii) Axon
The cell body of a neuron contains cytoplasm and a nucleus. There are many long and thin fibres coming out of the cell body of a neuron. The short fibres are called dendrites and the long fibre is called axon. The axon is covered with an insulating and protective sheath called myelin. It is made of fat and proteins.
The messages transmit through nervous system is in the form of electrical impulses called nerve impulses. The dendrites pick nerve impulses or messages from receptors and send them to cell body and then to axon. The axon sends these impulses to another neuron through a junction called synapse. There are three types of neurons, sensory neurons, motor neurons and relay neurons.
i) Sensory neurons transmit messages from receptors towards the central nervous system that is the spinal cord and brain.
ii) The function of motor neurons is to transmit messages from central nervous system towards the muscle cells or effectors.
iii) Relay neurons serve as link between other neurons. They are present in central nervous system.
The small gap between the two neurons is called synapse. The nerve impulses are carried over this small gap through a chemical substance called neurotransmitter.
The sensory cells or receptors are in contact with dendrite of sense organs. When there is a stimulus which acts on the receptor a chemical reaction occurs which produces an electrical impulse in it. This impulse travels from dendrite of sensory neuron to its cell body and then along the axon. At the end of axon electrical impulse release tiny amount of chemical substance in synapse and similar electrical impulse is started in the dendrite of next neuron. In this way the electrical impulse is carried in neurons till it reaches the relay neurons in spinal cord and brain. The relay neurons and motor neurons are connected in the similar way and helps bring electrical impulses from brain and spinal cord to the effectors like muscles and glands. Synapse ensures that electrical impulse travel in one direction only. This is because the chemical substance is present on one side of the gap only.
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