Control and coordination are essential functions in an organism that enable it to respond to various stimuli and maintain homeostasis. These functions are carried out by the nervous system and hormonal system in higher organisms.
Definition of Control and Coordination Control: It refers to the regulation of various functions of an organism to maintain equilibrium. It ensures that all the body parts function in synchronization with one another. Coordination: It is the process through which different organs and systems of the body work together in a smooth and efficient manner.
Need for Control and Coordination
Response to External Stimuli: Organisms constantly interact with their environment. They need to respond to various external stimuli such as light, temperature, sound, etc. For example, the pupils of our eyes contract in bright light.
Response to Internal Stimuli: Internal stimuli like hunger, thirst, etc., also need a response. The control system ensures that the body responds to these needs appropriately.
Maintaining Homeostasis: Homeostasis is the maintenance of a constant internal environment. Control and coordination help in maintaining the right temperature, pH, and other factors within the body.
Growth and Development: Proper coordination ensures that all parts of the body grow and develop at the right rate.
Reproduction: Control and coordination play a vital role in the reproductive process, ensuring that it occurs at the right time and in a proper manner.
Healing and Defense: The body needs to respond to injuries and infections. A well-coordinated control system ensures that wounds heal properly, and the body can defend itself against diseases.
Nervous System in Animals
The nervous system is a complex and highly specialized network that plays a pivotal role in coordinating and controlling the functions of an animal's body. It enables animals to perceive and respond to stimuli, both internal and external, and maintain homeostasis. This article delves into the structure, functions, and different types of nervous systems found in various animal species.
Structure of the Nervous System
The nervous system can be broadly divided into two main parts:
(i)Central Nervous System (CNS): Comprising the brain and spinal cord, the CNS acts as the control center for the entire body.
(ii)Peripheral Nervous System (PNS): Consisting of nerves and ganglia, the PNS connects the CNS to the rest of the body, including limbs and organs.
Neurons: The Building Blocks
Neurons are specialized cells that transmit electrical impulses. They consist of a cell body, dendrites, and an axon. The synapse is the junction between two neurons where neurotransmitters facilitate communication.Neurotransmitters are chemical messengers that transmit signals across the synapse from one neuron to another. They bind to receptors on the receiving neuron, triggering an electrical impulse. How the neurons function
All information from our environment is detected by the specialised tips of some nerve cells. These receptors are usually located in our sense organs, such as the inner ear, the nose, the tongue, and so
Gustatory receptors will detect taste while olfactory receptors will detect smell.
This information, acquired at the end of the dendritic tip of a nerve cell sets off a chemical reaction that creates an electrical impulse.
This impulse travels 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 start a similar electrical impulse in a dendrite of the next neuron.
This is a general scheme of how nervous impulses travel in the body
Reflex Action & Reflex Arc
The reflex arc is a fundamental concept in neurobiology, representing the simplest unit of the nervous system that enables an organism to respond to stimuli without conscious thought.
It plays a vital role in immediate and involuntary responses, often crucial for survival. Let's delve into the structure, components, and function of the reflex arc.
A reflex action is an automatic, involuntary, and immediate response to a specific stimulus. It is a protective mechanism that allows an organism to respond quickly to changes in its environment without the need for conscious thought.
Definition of Reflex Arc
A reflex arc is a neural pathway that controls an automatic response to a stimulus, known as a reflex action. It allows an immediate reaction without the need for conscious thought, enabling the body to respond quickly to potential threats or changes in the environment.
How Reflex Arc functions
(i)The receptor is the sensory organ that detects the stimulus, such as the skin sensing heat.
(ii)This neuron transmits the impulse from the receptor to the central nervous system (CNS).
(iii)Integration Center Located in the CNS, usually the spinal cord processes the sensory information and generates an appropriate response.
(iv)Motor Neuron carries the impulse from the CNS to the effector.
(v)The effector is the muscle or gland that carries out the response, such as a muscle contracting to withdraw a hand from a hot object.
Human Brain is the epicenter of thought, emotion, memory, and control over the body. It is the most complex organ in the human body and plays a pivotal role in defining our experiences, behaviors, and personalities.
Human Brain together with Spinal chord constitutes central nervous system. It is responsible for thoughts, interpretation and origin of control for body movements.
Parts of Human Brain
It is made up of cerebrum, hypothalamus and thalamus
Controls the reproductive functions, body temperature, emotions, hunger and sleep.
It is relay center
It consists of cerebellum, pons and medulla oblongata
Controls the breathing, heartbeat, sleep, wakefulness and motor learning.
The cerebrum is the largest part of the brain. It is further divided into four lobes Frontal Lobe
The frontal lobe is located at the front of the brain and is associated with the following functions:
Cognitive Functions: Responsible for higher-level thinking, problem-solving, decision-making, and planning.
Motor Functions: Controls voluntary movements of specific body parts.
Personality and Behavior: Influences personality traits and social behavior.
Speech Production: Contains Broca's area, which is essential for speech production and language comprehension.
The parietal lobe is situated behind the frontal lobe and has the following functions:
Processes sensory information from various parts of the body, including touch, temperature, and pain.
Helps in understanding spatial orientation and the body's position in space.
Plays a role in coordinating visual information with hand movements.
The temporal lobe is located on the sides of the brain and is involved in:
It Contains the auditory cortex, responsible for processing auditory information.
It Plays a crucial role in the formation and retrieval of long-term memories.
This is Involved in understanding spoken language.
Its Influences emotions and the perception of stimuli.
The occipital lobe is located at the back of the brain and is primarily responsible for:
Visual Processing: Contains the primary visual cortex, responsible for interpreting visual information received from the eyes.
Visual Perception: Helps in recognizing shapes, colors, and spatial relationships.
Protection and Support
The brain is protected by the skull and is cushioned by cerebrospinal fluid.
It is also shielded by the blood-brain barrier, which prevents harmful substances from entering the brain.
A plant hormone is a chemical substance which is produced naturally in the plant and regulate growth and physiological processes o bring about control and coordination of various activities in plants.
The plant hormones regulate many functions in plants.
growth of root, stem and leaves (cell division, cell elongation and cell differentiation)
growth of fruits
opening and closing of stomata
germination of seeds
flowering of plant etc.
There are four major types of plant hormones which are involved in the control and coordination in plants:
Abscisic acid (ABA)
Movements in Plants
Unlike animals, plants are sessile, meaning they are fixed in one place and cannot move from one location to another. However, plants exhibit a variety of movements, either growth-induced or nastic, in response to environmental stimuli.
These movements play a crucial role in their survival, growth, and reproduction.
Types of Plant Movements
Tropic Movements (Tropisms)
These are directional growth movements in response to external stimuli.
The movement is either towards (positive) or away from (negative) the stimulus.
Types of Tropic Movement
Phototropism: Movement in response to light. For instance, plant stems grow towards light (positive phototropism), while roots generally grow away from it (negative phototropism).
Geotropism (Gravitropism): Movement in response to gravity. Roots exhibit positive geotropism as they grow downwards, while stems show negative geotropism by growing upwards.
Hydrotropism: Movement in response to water. Roots grow towards moisture sources, exhibiting positive hydrotropism.
Thigmotropism: Movement in response to touch. Seen in climbing plants like peas, where tendrils coil around a support.
These are non-directional movements in response to external stimuli.
They are not growth-induced but result from turgor changes in specific cells.
Types of Nastic Movement
Nyctinasty: Diurnal movement of leaves or petals, such as the closing of mimosa (touch-me-not) leaves during the night or when touched.
Thermonasty: Movement in response to temperature changes, like the opening of tulip flowers in warm conditions.
It is a structure which secretes a specific substances in body.
Hormones are the chemical messengers that regulate the biological processes in living organisms.
They are produced by ductless glands i.e. their secretion is directly releases into the blood.
They are released in traces i.e. in a very little quantity.
They act on specific tissues or organs called target organs.
They are organic compounds.
They are generally slow in action.
They act away from the site of production.
Control And Coordination Short Answer Type
What is the difference between a reflex action and walking? Ans: Reflex action is a process by which we do something without thinking about it or without being in control of reactions. It is done by only the spinal cord without the help of brain.
While walking is a process which is done by thinking or it is performed by the brain unlike reflex action.
What happens at the synapse between two neurons? Ans: The electrical impulses set off release of some chemicals at the synapse between two neurons. These chemicals cross the synapse and start a similar electrical impulse in a dendrite of the next neuron.
Which part of the brain maintains posture and equilibrium of the body? Ans: Posture and equilibrium of the body is maintained by midbrain.
How do we detect the smell of an agarbatti (incense stick)? Ans: The smell of agarbatti is detected by the forebrain. There are separate areas of association where sensory impulses or information are interpreted by putting them together. These impulses of smell are detected by forebrain.
What is the role of the brain in reflex action? Ans: The nerves from all over the body meet in the bundle in the spinal cord. Reflex arcs are formed in the spinal cord itself although the information input also goes on to reach the brain.
What are plant hormones? Ans: The chemical substances released by various part of plants to control growth and various activities are called plant hormones.
How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light? Ans: The movement of leaves of the sensitive plant is neither towards nor away from stimulus like touch. While movement of shoot is towards stimulus like light. The movement of leaves of sensitive plants is not directional while the movement of shoot is directional.
Give an example of a plant hormone that promotes growth. Ans: (i) Auxins help to increase the length of plants.
(ii) Gibberellins help in the growth of stem.
How do auxins promote the growth of a tendril around a support? Ans: The tendrils are sensitive to touch. As these tendrils come in the contact with the support, the auxin diffuses towards the other side away from the support. So this part grows more rapidly than the other. This causes the tendril to circle around the support and thus climb upwards.
How does chemical coordination take place in animals? Ans: Chemical coordination takes place in animals with \the help of some chemical substances called hormones. Hormones are secreted by endocrine glands. The timing and amount of hormones released are regulated by feedback mechanisms.
Why is the use of iodised salt advisable? Ans: The use of iodised salt is advisable because iodine is necessary for the thyroid gland o produce thyroxine hormone. Thyroxine regulates carbohydrates, protein and fat metabolism in the body so as to provide the best balance for growth. Iodine is essential for the synthesis of thyroxine.
How does our body respond when adrenaline secreted into the blood? Ans: Adrenaline is secreted directly into the blood and is carried to different parts of the body. It acts on heart. As a result the heart beats faster in order to supply more oxygen to our muscles. These muscles regulate various movements of the body.
Why are some patients of diabetes treated by infections of insulin? Ans: The patients of diabetes are treated by giving injections of insulin. Insulin is a hormone which is produced by the pancreas and helps in regulating blood sugar levels. If it is not secreted in proper amounts, the sugar level in the blood rises causing many harmful effects.
What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise? Ans: The main function of receptors is to detect in formations from the environment. These receptors are located in our sense organs. There are some situations which receptors do not work properly, like mouth starts water when we feel hungry, touching a flame, knee – jerk, etc.
In these situations, they take enough time if these done by brain. To solve these problems, the nerves made muscles in a simpler way. This is done by the spinal cord.
Explain the structure and function of neurone? Ans: The neuron is the structure and functional unit of the nervous system. It contain following three parts:
(i) dendrites (ii) Cell body (iii) Axon
The impulses of information travel from dendrites to cell body and then along the axon to its end. These impulses cross the synapse at the end, the impulses travel from one neuron to the other up to the spinal cord or to the concerned part of body.
How does phototropism occur in plants? Ans: The directional or tropic movement towards the light or away from the light is called phototropism. The shoots respond by bending towards light, while roots respond by bending away from the light.
Which signals will get disrupted in case of a spinal cord injury? Ans: (i) All the signals are responses which pass from and to the brain through the spinal cord will get disturbed.
(ii) Reflex actions will be disrupted.
How does chemical coordination occur in plants? Ans: In plants, stimulated cells release chemical compounds, which are called plant hormones. Different plant hormones help to coordinate growth development and responses to the environment. They are synthesized at placed away from where they act and simply diffuse to the area of action.
What is the need for a system of control and coordination in an organism? Ans: Every little change in the environment evokes an appropriate movement in response. For example, if we want to talk to our friends in class, we whisper rather than shouting loudly. Thus, the movement to be made depends on the event that is triggering it. Therefore, such controlled movement must be connected to the recognition of various events in the environment, followed by only the correct movement in response. In other words, living organisms must use systems providing control and coordination. In multicellular organisms, specialized tissues are used to provide control and coordination activities.
How are involuntary actions and reflex actions different from each other? Ans: Involuntary Action: (i) The action which we cannot do by thinking; called involuntary action. For example, beating of the heart (ii) Involuntary actions are controlled by the brain. Reflex Action: (i) An action i.e. a response which is immediate and does not need processing by the brain is called a reflex action. For example, immediate removal of hand on touching a hot plate (ii) Reflex actions are controlled by the spinal cord.
Compare and contrast nervous system and hormonal mechanisms for control and coordination in animals. Ans: In human beings, the nervous system controls the various functions by small units called neurons. Neurons receive the information through sensory nerves and transfer them through motor nerves.
Besides this, certain important functions like sugar level, metabolism, growth and development, etc. are controlled by hormones secreted by various endocrine glands. Hence, it is true that nervous and hormonal systems together perform the function of control and coordination in human beings.
What is the difference between the manner in which movement in the sensitive plant and movement in our legs takes place? Ans: Movement in sensitive plant: Movement in the sensitive plant leaves takes place in response to touch (shock) stimulus. When terminal pulvini is touched, the stimulus is conducted to its base and the pulvini droop down. This happens due to change (decrease) in osmotic pressure causing shrinkage, when the stimulus time is over, osmotic pressure increases and the cells swell, causing to the pulvini become normal. This is an example of growth independent movement.
Thus, movement happens at a point different from the point of touch (stimulus). So, the information that a touch has occurred is communicated through electrical – chemical means from cell to cell, but not through specialized tissues. Plant cells change in shape by changing the amount of water in them, resulting in swelling or shrinking, during movement. Movement in our legs: Our legs are provided with nerves which are connected to muscles. To lift the leg, he brain passes information to nerves.
The information travels as an electrical impulse. On reaching the leg muscles, the impulse is converted into a chemical signal and the muscles contract to lift the leg. Movement of legs takes place due to muscle contraction and relaxation, which is under the control of our nervous system.
In the nervous system, electrical impulses are generated for quick transmission of information. But there are limitations:
(i) Impulses will reach only those cells that are connected by the nervous tissue.
(ii) Once an electrical impulse is generated in a cell and transmitted, the cell takes some time to generate another impulse. That is, cells cannot continuously create and transmit electrical impulses.
Hormones are chemical messengers that diffuse to all cells of the body. The body cells using special molecules on their surfaces, recognize information and even transmit it. Hormones are synthesized at places away from where they act.
Hormones can reach all cells of the body (through blood in animals) regardless of nervous connections, and it can be done steadily and persistently.
Name the system in animals which help in the process of control and coordination. Ans: (i) Nervous system
(ii) Hormonal (Endocrine) system
Name the largest cell in the human body. Ans: Nerve cell or neuron.
Have the old parts of the shoot and root changed direction? Ans: The old parts of roots and shoots of plant change their directions slightly (very less), while new parts move more.
What are the main divisions of nervous system? Ans: The nervous system is broadly divisible into two parts:
(i) Central nervous system, (ii) Peripheral nervous system
Give four examples of simple human reflexes. Ans: (i) Knee – jerk reflex in which the leg is involuntarily extended forward as a result of a sharp tap below the knee – as in a relaxed (freely hanging) leg.
(ii) Closing of the eyelids when an object suddenly approaches the eye or when a strong beam of light is flashed cross.
(iii) Withdrawal of the hand on pricking a pin or a horn.
(iv) Movement of the diaphragm.
Design an experiment to demonstrate hydrotropism. Ans: Positive hydrotropism can be demonstrated with terminated seedlings, which are allowed to grow on ground. The soil below the roots is separated by a polythene partition. The left side is kept moist but the right side is kept ry.
The radicals at first grow in a downward direction due to the effect of gravity (positive geotropism), but after some time, the roots bend toward the moist soil (positive hydrotropism). This is evidently due to the closeness of the germinating roots to water.
Write two differences between the response of the plants and response of the animals to stimuli? Ans. There are no specialised tissue in plants to conduct the information.
Presence of specialised protein in animal muscle cells allow it to change shape whereas plant cells change shape by changing the amount of water in them.
State how concentration of auxins stimulates the cells to grow longer on the side of the shoot which is away from light? Ans. When growing plant detect light, a hormone called auxins is synthesized at the shoot tip, which helps the cells to grow longer.
When the light is coming from one aide of the plant, auxins diffuses towards the shady side of the shoot.
The concentration of auxins stimulates the cells to grow longer on the side of the shoot which is away from light.
In this way, the plant appears to bend towards light.
How does our body maintain blood sugar level? Ans. Normally, blood glucose level increases after eating a meal.
When blood sugar level rises, cells in pancreas releases insulin, causing the body to absorb glucose from the blood and lowering the blood sugar level to normal.
When blood sugar level drops oo low, the level of insulin declines and other cells in pancreas release glucagon, which causes the liver to convert stored glycogen back into glucose and release into the blood.
How does feedback mechanism regulate the hormone secretion? Ans. The feedback mechanism regulates the timing and amount of hormone to be secreted, e.g., if a person has more sugar in his blood, it is detected by the cells of the pancreas. As a result, more insulin will be secreted to control the sugar level. In the reverse situation, the secretion of insulin will be depleted.
Explain how the human body responds when adrenaline is secreted into the blood? Ans. When an organism confronts any scary situation, adrenaline is secreted from the adrenal gland and sent directly into blood which is then circulated to various parts of the body, resulting into the following:
The heart starts beating faster. As a result, more amount of oxygen is supplied to the muscles.
The blood supply to the digestive system and the skin is reduced due to contraction of muscles around small arteries. This diverts the blood to the skeletal muscles.
The breathing rate also increases from because of the contractions of the diaphragm and rib muscles.