Control and Coordination We know that living things produce response to stimulus to protect themselves. Nervous system and hormonal systems help the organisms to produce responses to stimuli. Nerve cells play an important role in the development of nervous system. role in detecting the stimuli. Nerve cells are also called as neurons.
Each neuron has different parts like cell body, nucleus, dendrites, axon and nerve endings. The neurons that are present in the sense organs have specialized tips called as receptors. These receptors detect the stimuli and converts it into electrical impulses. The receptors that are present in the nose are called olfactory receptors.
They detect the smell. The receptors that are present in the tongue and helps in detecting the taste are called gustatory receptors. The neurons carry the information to different parts of the nervous system.
This is called nerve conduction. The neurons collect the nerve impulses by their dendrites and pass them to other neurons by their nerve endings. The nerve endings of one neuron and dendrites of other neuron are not attached directly to one another.
There is some gap between them. This gap or this junction is called as synapse. At the end of the nerve terminals, the electrical impulse is converted to a chemical signal.
This chemical crosses the gap and reaches the dendrites of another neuron. There it again converted into electrical signal. The neurons that carry the information from sense organs to brain or spinal cord are called sensory neurons. The neurons that carry the information from brain or spinal cord to muscles or glands are called motor neurons.
There are two pathways in which responses are produced to stimuli. In one pathway, information about the stimulus passes to spinal cord, spinal cord to brain. Now the response is generated in the brain and it passes down back to spinal cord and it finally reaches the muscles. This is a long pathway and takes considerable amount of time to produce responses.
In this short pathway, information about the stimuli passes to spinal cord, where it is processed quickly and the responses are produced. But, in some situations, organisms need to produce very quick responses to protect themselves from the dangerous stimuli. In such cases, they take a short pathway. These responses reach the muscles and cause immediate movements. This kind of quick responses are called reflex actions.
The pathway by which a reflex action is executed is called reflex arc. Receptors, sensory neurons, relay neurons, motor neurons and effectors are the components of the reflex arc. The nervous system is divided into central nervous system and peripheral nervous system. Central nervous system consists of brain and spinal cord. Peripheral nervous system consists of nerves.
Brain is an important and delicate organ, so it has to be protected well. Brain is covered by a fluid-filled balloon-like structure made up of three layers. These layers are called meninges and the fluid present in between these layers is called cerebrospinal fluid. These layers and the fluid, they protect the brain from shocks and injuries.
Brain along with the meninges is protected by an outer bony case called as cranium. Cranium is a hard structure that is made up of bone. Brain is the main coordinating center of our body. It receives the information from all parts of the body and integrates it. The main functions of our brain are thinking, decision making, storing information, producing emotions and controlling body functions.
Our body functions are of two types, voluntary and involuntary. The functions that are under our control are called voluntary functions. Writing, talking, dancing, clapping, these are the examples of voluntary functions controlled by our brain. The actions that are not under our control are called involuntary actions.
Digestion, heartbeat, sneezing are the some examples of involuntary actions controlled by human brain. Now let us see which part of the brain controls which functions. The brain has three main parts namely the forebrain, midbrain and hind brain.
Let us see about forebrain. The thought process takes place in the forebrain. Forebrain has regions which receives sensory impulses from various receptors. The forebrain has different centers for hearing, smell, sight, etc.
The information from different sense organs is analyzed and compared with the information already stored in our brain. Based on this analysis, the forebrain takes a decision and sends it to the area of the brain which controls the movements of our olentary muscles. For example, if we are playing football, our eyes sends the information about the position of the ball to the area of which analyzes it. After analysis, a decision is taken and the information is sent to the area of the brain which executes it. It causes the necessary movements in our muscles and makes us kick the ball in right direction with right force.
The sensation of hunger and feeling full. is also controlled by a separate area of forebrain. Next we see midbrain.
Midbrain controls the visual and auditory reflexes. It also has center for controlling the movements of our eye and eyelids. Hindbrain.
Hindbrain has three parts namely pons, medulla oblongata and cerebellum. These parts control the involuntary functions of our body. Pons controls our sleep and wake cycle and breathing. Medulla controls heart rate, breathing, blood pressure and more involuntary functions. Next, cerebellum.
It is responsible for precision of voluntary actions and maintaining posture and balance of the body. Walking in a straight line, riding a bicycle, drawing an art, all these are possible because of cerebellum. These are the different parts of the brain and their functions.
Coordination implants. Do plants respond to stimuli? Yes, plants respond to stimuli like sunlight, water, soil, touch, chemicals etc.
Most of these responses are in the form of movements. For example, stems bending towards sunlight, sunlight, roots growing towards soil or water, tendrils of plants coiling around the support, closing of leaves of touch-me-not plant when it is touched. How do plants produce movements?
Animals produce movements. with the help of nervous system and muscular system. But in plants, both the nervous system and muscular system are not present.
The movements in plants are caused either by growth or by changing the shape of the cell. Which movements in plants are caused due to growth? The movements in plant parts like stem moving towards sunlight, roots growing towards soil, tendrils coiling around some support, pollen tube growing towards the the ovule are caused due to growth.
In fact, these movements are the responses for different stimuli. The directional movements that are shown by plants in response to environmental stimuli are called tropic movements. The movement of plant parts towards sunlight is called Phototrophism, example stem bending towards sunlight. Movement of plant parts towards the soil is called Zeotrophism, example roots growing towards soil.
Movement of plant parts towards the water is called hydrotrophism. Roots growing towards water. Movement of plant parts in the direction of an object that it touches is called tigmotrophism. Tendrils coiling around a support.
Movement of plant parts towards a chemical stimulus is called chemotrophism. Example, pollen tube growing towards the ovule. What causes the tropic movements in plants?
Tropic movements in plants are caused due to some special chemical compounds called as phytohormones. For example, if the plant tip has to bend towards right, the cells in the left side part of the tip get elongated. It makes the plant bend towards right. The elongation of cells in the left half of the plant tip is caused due to a phytohormone called as auxin. Name the major phytohormones and write their functions.
The five major phytohormones are auxins, gibberellins, cytokinins, ethylene and abscisic acid. Auxins. Auxins stimulate the cells to grow longer.
They are responsible for the tropic movements in plants. They are mostly concentrated in the young shoot and root tips. Gibberellins.
Gibberellins also helps in the stem and root elongation in plants. Cytokinins. Cyt means cell. Kinesis means division. This means the cytokinins, they promote cell division.
They are concentrated in the fruits and seeds where rapid cell division takes place. Abscisic acid. This hormone acts as a growth inhibitor.
This helps in the wilting of leaves. Ethylene. This phytohormone stimulates the ripening of fruits.
So these are the five major phytohormones and their functions. Hormones in animals. What is the second way of control and coordination in animals?
In animals, the second way of control and coordination is done by endocrine system. The endocrine system is comprised of various endocrine glands like pituitary gland, thyroid gland, adrenal glands, pancreas, testis and ovaries. These glands secrete some special chemical compounds called hormones.
What are the functions of hormones? and how are they supplied to different parts of our body. Hormones help to control many body functions such as growth, repair and reproduction. Hormones are secreted by glands in very small quantity. These hormones reach different parts of our body through blood circulatory system.
Once a hormone is released into the bloodstream, it is supplied to all parts of the body. But it acts only on its target tissue or organ. How do hormones help our body in producing a response towards a stimulus? Let us understand the functioning of hormones with an example.
If a person is attacked by a dog, then he should either fight with the dog or run away from the dog. Here, the dog's attack is the stimulus and man running or escaping is the response. When we are in such a situation, a hormone called adrenaline is secreted by adrenal glands.
It helps in the fight or flight situation. In dangerous situation we have to fight or flight. For both the processes our muscles need large amounts of glucose and oxygen. The main function of adrenaline is to increase the supply of oxygen and glucose to our skeletal muscles.
Even though adrenaline is supplied to all parts of the body, only few organs accept it and functions accordingly. Adrenaline mainly affects our eyes, blood vessels, heart and muscles. Due to the action of adrenaline, the heart beats faster and supplies more oxygen to our muscles.
The blood to the digestive system and skin is reduced due to contraction of muscles around small arteries in these organs. This blood is diverted to skeletal muscles. Adrenaline also increases the breathing rate by increasing the muscular movements of diaphragm and rib muscles.
This is how adrenaline helps us to produce a response during a dangerous or harmful stimuli. Why is it important to have iodized salt in our diet? How is it connected to our endocrine system? It is advised to consume iodized salt in the place of normal salt because iodine is an important mineral required for our body. Iodine is essential for making a hormone called thyroxine in our body.
This hormone is produced by thyroid gland which is present at our neck region. The main function of thyroxine is to control the metabolism of carbohydrates, proteins and fats. Thyroid hormone plays a crucial role in regulating metabolism.
Metabolism is the process by which our body converts food into energy and energy into food, vice versa. An underactive thyroid can slow down metabolism, leading to weight gain, fatigue and other symptoms. On the other hand, an overactive thyroid can speed up metabolism, causing weight loss and other symptoms.
If we do not have sufficient iodine in our diet, it may lead to low production of thyroxine and causes a disease called as goiter. Swollen neck is the main symptom of goiter. Which hormone is responsible for the formation of this disease? for our growth. Growth hormone secreted by pituitary gland is responsible for regular growth of our body.
The growth of skeletal muscles and bone is under the control of growth hormone. Deficiency of growth hormone leads to a condition called dwarfism where stunted growth is observed. In some people, overproduction of growth hormone leads to a condition called gigantism. In this case, people grow very tall and looks unusual. Which hormone is called as male hormone and why is it called so?
Testosterone is called as male sex hormone. It is called so because it helps in the the development of secondary sexual characters like growth of moustache, growth of beard, development of testes and production of sperms in boys. Which hormone is called as female sex hormone and why it is called so? Estrogen is called as female sex hormone. It is called so because it helps in the development of secondary sexual characters in females like development of breasts, beginning of menstruation, development of ovaries etc.
Why do doctors suggest some people to eat less sugar and starchy foods in their diet? Doctors suggest some people to eat less sugar and starchy foods because they are suffering from a disease called as diabetes. Our blood contains glucose.
The normal level of glucose in our blood is 99 mg per 100 ml of blood. If our blood glucose level raises, then a hormone called insulin is secreted by our pancreas. Insulin controls the raised blood sugar levels.
But in some people, due to the malfunctioning of insulin-producing cells of pancreas, very less insulin is produced, which leads to high level of blood sugar. Such condition is called as diabetes. High levels of Blood sugar causes harmful effects on our body. Diabetic people are more prone to heart, kidney, eye and nerve diseases.
Now, let us see how to draw some important diagrams of this lesson. Let us begin with drawing human brain in easy steps. Now, let us see how to draw Reflex Arc.
Now we will see drawing human endocrine system in easy steps. Thanks for watching. Please like the video.
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