In our day to day life, we see many visible movements. They are correlated with control and coordination. Some of them are:
- Movement of hand after touching hot object.
- Movement of cat after seeing mouse.
- Plants grown in the presence of sunlight only.
- Your movement when someone calls you loudly.
- Movement of our eye when bright light focused on it.
- After reading these examples it is clear that every movement is somewhat in control.
- All these movements take place in response to the situations in a very short amount of time.
- Such controlled movement though recognizes the various events in the environment, followed by only the correct movement in each response.
- Living organism has a special system of control and coordination.
- The nervous system controls these processes and the hormones within the body work together to create a response to a particular stimulus.
Human Nervous system:
- The special system in human body which coordinates the voluntary, involuntary and reflex actions.
- Nervous tissue consists of an organized network of nerve cells (neurons).
- The structural and functional unit of the nervous system is
- Neuron is specialised for conducting information via electrical impulses from one part of the body to another.
- Neurons receive external stimuli and send signal to brain. On this basis, brain directs particular body parts to take proper actions
- These receptors are mainly located in our sense organs, such as the inner ear, the nose, the tongue, and so on. As gustatory receptors detect taste while olfactory receptors detect the smell.
- Nervous system also helps in maintaining life processes.
Mechanism of impulse conduction:
- The end of the dendritic tip of a nerve cell takes an information.
- Here a chemical reaction takes place which creates an electrical impulse.
- From the dendrite this impulse travels to the cell body, again axon to its end.
- At the end of the axon, the electrical impulse makes release of chemicals.
- These chemicals cross the gap, and creates a similar electrical impulse in a dendrite of another neuron.
- Reflex itself means a “sudden action”.
- The sudden and automatic response of a body towards any external stimuli is said to be reflex action.
- Reflex actions don’t involve conscious area of the brain.
- Reflex actions are unconscious actions.
- These actions take place through coordination of brain as well as spinal cord.
- When sudden response is required, spinal cord gives the instruction. After that brain gives conscious response.
Central Nervous system:
- CNS plays a vital role in control and coordination of human body.
- Spinal cord is made up of nerves.
- These nerves supply information to think about.
- The thinking process is consisted of brain and takes action based on that thinking.
- Brain is the main coordinating centre of the body.
- The brain along with spinal cord constitute the central nervous system.
- CNS receives information from all parts of the body and constitutes it with respective action.
- Different parts of brain involved in taking different actions.
Note: The peripheral nervous system consisting of cranial nerves (arise from brain) facilitates the communication between the central nervous system and the other parts of the body.
Spinal nerves arise from the spinal cord.
- When an action takes place with the involvement of thinking are voluntary action.
- Voluntary actions takes place consciously.
- There is involvement of both spinal cord as well as brain.
- Voluntary actions involve eating, walking, talking.
- These actions take place without consciousness or willingness of an individual.
- Involuntary actions involve heartbeat, digestion, respiration etc.
- These actions are not in the control and coordination of CNS.
There are three parts of brain involved in different activity of nervous system:
This is the main thinking part of brain.
It receives sensory impulses from receptors.
Different regions of the fore-brain are specialised for hearing, smell, vision etc.
In a separate region all the sensory information, information from receptors and stored information in brain are interpreted. Based on this a decision is made.
Involuntary actions are controlled from here.
The midbrain has main role in the motor movement, particularly movements of the eye, and in vocational and visual processing.
It precise voluntary actions and maintains the posture and balance of the body.
The hormone system:
- The nervous system alone can’t perform all the control and coordination activities.
- Every single cell of the body is not connected through the nerve tissue.
- To fulfil the lack of nerve tissue, endocrine glands in our body, releases hormones which mix into our blood (human circulatory system) and can reach all the target cells.
- Hormones act as chemical messengers.
Hormones and their roles:
- Adrenaline – Secreted from adrenal glands.
- Growth hormone – Secreted from pituitary gland
- Insulin – Secreted from pancreas
- Sex hormones – Secreted from reproductive glands
- Thyroxin – Secreted by thyroid glands
Coordination in plants:
Plants have neither nervous system nor muscles for control and coordinaton of the activities.
Plants show movement based on dependency on growth. They are:
- Tropic movement
- Nastic movement
It is growth dependent movement. Either they show action towards or away from stimulus. Based on activity observed in plants, again tropic movement is classified into five different types:
- The term photo itself means “light”.
- It is the response of plants towards light as external stimulus.
- The upper part of plants i.e stem and leaves move towards light.
- The term ‘hydro’ means ‘water’.
- The response of plant’s shoot or root towards water is hydrotropism.
- The term ‘Geo’ is related to ‘earth’.
- Here, the stimulus is earth’s gravity.
- The movement of plants part towards soil is geotropism.
- Root of the plant always move in the favor of gravity.
- Plants respond to some chemical stimulus, called chemotropism.
- During fertilization process the movement of pollen tube towards ovule containing sugar (stimulus).
- The directional response of a plant organ to touch or physical contact with a solid object.
- This directional response takes place because induction of some pattern of differential growth.
- As several climber creepers makes round turn in solid support.
- It is growth independent movement.
- They are non-directional movements i.e doesn’t depend on the direction of stimulus.
- These movements are reversible and repeatable movements in response to a stimulus.
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