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Class X
CH- 7 Control and Coordination
Syllabus of Control and co-ordination in animals and plants: The metal oxides are then reduced to the corresponding metals by using suitable reducing agents such as carbon.
The highly reactive metals such as sodium, calcium, aluminium, etc., are used as reducing agents because they can displace metals of lower reactivity from their compounds. |
1. Control and coordination - Control and Coordination in humans occurs through the nervous system and hormonal system called the endocrine system.
2. Nervous system - Nervous tissue is made up of an organized network of nerve cells or neurons and is specialized for conducting information from one part of the body to another through electrical impulses.
The nervous system uses electrical impulses to transmit messages.
The nervous system receives information from our sense organs and acts through our muscles.
3. Types of nerves- There are three types of nerves, cranial nerve, spinal nerve and visceral nerve.
3. Receptors- It is a group of cells sence organs like ear, nose, skin, tongue and eyes. All information from our environment is detected by special tips of some nerve cells of receptors called neurons.
4. Neurons - Cells of the nervous system are called neurons. Neuron is the largest cell in our body. It consists of three part dendrites, axon and cotton.
All information acquired at the end of the dendritic tip of the nerve cell produces a chemical reaction that creates an electrical impulse.
5. A general scheme of how nervous impulses travel in the body - The impulse runs from the dendrite to the cell body, and then along the axon to its end. At the end of the axon, the electrical impulse sets off the release of some chemicals. These chemicals cross the gap or synapse and initiate a similar electrical impulse in the dendrite of the next neuron.
6. Parts of Nervous System and its functions
- Nervous system consists of two systems central nervous system and peripheral nervous system.
Central nervous system consists of brain and spinal cord that control a response towards all stimulus.
Peripheral nervous system contains the cranial nerves related to the nerves arising from the brain and spinal cord.
7. Central nervous system consists of brain and spinal chord :
The brain is the main coordinating center of the body. It has three major parts or regions, namely the fore-brain, mid-brain, and hind-brain.
Fore-brain is the main thinking part of the brain. It has regions that receive sensory impulses from various receptors. Different areas of the fore-brain are specific for hearing, smell, vision, etc.
The motor areas control the movement of voluntary muscles, for example, our leg muscles.
Mid-brain and hind brain - Involuntary actions are controlled by the mid-brain and hind-brain.
Involuntary actions including blood pressure, salivation and vomiting are controlled by the medulla in the hind-brain. Activities such as walking in a straight line, riding a bicycle, lifting apencil also controlled by medulla.Thahese are possible due to a part of the hind-brain called the cerebellum. It is responsible for the accuracy of voluntary actions and maintaining the posture and balance of the body.
Bony box - The brain is a delicate organ protected by a box called bony-box. Inside the box, the brain is contained in a fluid-filled balloon that subsequently provides shock absorption.
Spinal cord- spinal cord conducts sensory information from peripheral nervous system to the brain.
The vertebral column or backbone protects the spinal cord.
8. Changes in plant cell - Plants have no specialized tissue for conducting information and cells, do not have any specific proteins to change shape. Plant cells change shape by changing the amount of water in them, causing swelling or shrinkage there and hence changes in size.
9. Tendrils -Some plants climb other plants through soft stem tendrils that are sensitive to touch. When they come into contact with a support, the part of the tendril that comes in contact with the object does not grow as fast as the part of the tendril is away from the object. This causes tendon circles to form around the object thus stick to it.
10. Phototropism- Phototropism is the growth of plant's in response to light stimulus.
There are two types of phototropism: positive and negative.
Positive phototropism is growth toward a light source, and negative phototropism is growth away from a light source.
11. Geotropism - The upward and downward growth of shoots and roots, respectively, known as geotropism, in response to the pull of earth or gravity.
There are two types of phototropism: positive and negative.
Positive phototropism is growth toward a light source, and negative phototropism is growth away from a light source.
11. Geotropism - The upward and downward growth of shoots and roots, respectively, known as geotropism, in response to the pull of earth or gravity.
12. Hydrotropism- The development of parts of the plant due to its reaction to water is known as hydroelectricity. Example- The root of the plant grows in humid air bending towards a high relative humidity level.
13. Chemotropism- The growth of parts of the plant's reaction to chemical compounds is known as chemistry. An example of chemotropism in the development of pollen tubes towards the ovaries.
14. Electrical Impulses- When a neuron is stimulated, an action potential, moves along the neuron axon called electrical impulses.
There are limitations to the use of electrical impulses -
i. They will only reach cells that are connected by neural tissue.
ii. When an electric impulse is generated and transmitted in a cell, it will take some time to resets its system before the cell transmits a new impulse.
iii. Cells cannot continually create and transmit electrical impulses.
15. Chemical Communications- Most multicellular organisms use another means of communication between cells, namely chemical (hormons)communication.
16. Plant hormones - It helps to coordinate growth, development, and responses to the environment. They are synthesized at places away from where they act and simply diffuse to the area of action.
Plant hormones are - Auxins, gibberellins, and cytokines.
i. The function of auxins- When plants detect light as they grow, a hormone called auxin synthesized at the shoot tip helps cells grow for a long time. When the light is coming from one side of the plant, the auxin spreads towards the shadowy side of the shoot. This concentration of auxin stimulates cells to grow longer at the edge of the shoot that is away from light. Thus, the plant appears to be leaning towards the light.
ii. The function of gibberellins – Gibberellins helps in the growth of the stem.
iii. The function of cytokines - Cytokines promote cell division, and they are present in greater concentration in areas of rapid cell division, such as in fruits and seeds.
iv. Abscisic acid - Abscisic acid is a hormone that inhibits or stops growth in plants. Its effects include wilting of leaves.
17. Animals Hormones-
I. Adrenaline hormone - Adrenaline is secreted directly into the blood from the adrenal gland present in the kidneys and transported to different parts of the body.
vi. Thyroxin hormone – The thyroid gland secretes thyroxine. Iodine is an essential thyroxine hormone for the thyroid gland. Thyroxine regulates carbohydrate, protein, and fat metabolism in the body to provide the best balance for growth. In the case of iodine deficiency in our diet, there is a possibility that we may suffer from goiter. One of the symptoms of this disease is a swollen neck.
vii. Growth hormone -Growth hormone is one of the hormones secreted by the pituitary gland. The growth hormone controls the growth and development of the body. If there is a deficiency of this hormone in childhood, it leads to dwarfism.
viii. Testosterone and estrogen - Dramatic changes associated with puberty are caused by testosterone secretion in men and estrogen in women.
18. Diabetes- Insulin is a hormone produced by the pancreas and helps regulate blood sugar levels. If it is not secreted in the proper amount, the blood glucose level causes diabetes.
19. Feedback mechanism - The timing and amount of hormones released are controlled by the reaction mechanism. For example, if blood sugar levels rise, they are detected by cells of the pancreas that react by producing more insulin. As blood sugar levels fall, insulin secretion decreases.
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