write the note on co-ordination
human being 9th
Answers
Answer:
The coordination of body organs implies that the various organs present in the body interact and complement the functions of one another. It implies that the body organs do not work independently rather they work in a synchronized fashion. In the human body, the neural system and the endocrine system jointly coordinate and integrate all the activities of the organs so that they function in a synchronized fashion. It is known as neural coordination. The neutral system provides an organized network of point-to-point connections for a quick coordination. The neural system provides a rapid coordination among the organs. This connection is with the help of a network of nerves in the body. The neural coordination is fast and short-lived.
Answer:
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.
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.
Organs of Human Nervous System
The main organs of human nervous system are:
• Brain
• Spinal cord
• Nerves
The brain is located inside the skull of the head. The spinal cord is a thick nerve which is located in the cavity of backbone. The upper end of spinal cord is attached to the brain. The nerves are distributed in all parts of the body. They are like wires.
The brain and spinal cord are connected to all the sense organs and other parts of the body through nerves.
The three types of nerves in our body are:
• Cranial nerves
• Spinal nerves
• Visceral nerves
The cranial nerves connect all parts of the head to brain, spinal nerves connect all the remaining parts of the body to spinal cord and visceral nerves connect internal organs of the body to spinal cord and some to brain.
The cranial nerves, spinal nerves and visceral nerves are of two types, sensory nerves and motor nerves. Sensory nerves are those which carry message from body to brain and spinal cord and motor nerves are those which carry message from brain and spinal cord to the body parts for action.
Functions of Brain
• Brain receives nerve impulses which carry information from the sense organs of the body.
• Brain responds to these impulses by sending instructions to muscles and glands which function accordingly.
• Brain correlates stimuli from different sense organs and produce appropriate and intelligent response.
• It coordinates the activities of the body.
Explanation:
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