NCERT Notes Class 10 Control and Coordination

NCERT Class 10 Science Notes Chapter 6: Control and Coordination in the living organism mean the ability to control and coordinate different body functions to complement each other. Separately control means the ability of our body to have power of regulation over any mechanism whereas coordination means the process by which all the different parts of the body work together to produce the desired outcome. You will find the NCERT Control and Coordination Notes for Chapter 6 Class 10 Notes here.

Control and Coordination in Animals

In lower animals i.e. every phylum of invertebrates (except Sponges) control and coordination are achieved with the help of the basic form of the nervous system. In sponges, the coordination is dependent on their cilium generating the signals to respond to any stimuli as they lack a nervous system. Whereas in vertebrates there is well-developed nervous system and endocrine system that oversees the whole process of control and coordination. 

Nervous System

The nervous system of all animals is made up of specialized cells called nerve cells or neurons. These specialized cells are responsible for responding to stimuli and then coordinating the body’s actions. This is why nerve cells are called the “structural and functional unit” of the nervous system. 

Structure of Neuron

Neurons are the structural unit of the nervous system. A neuron is normally an elongated and branched cell. It has three parts: cell body or cyton, dendrites, and axon.

1. Cell body or Cyton: The cell body is like a normal cell where there is a central nucleus that is surrounded by dense cytoplasm. The nucleus is surrounded by Nissl’s granules which are rough endoplasmic reticulum which help in protein synthesis. Other than Nissl’s granules it also consists of other cell organelles like; the Golgi apparatus, endoplasmic reticulum, mitochondria, etc.
2. Dendrites: These are numerous, short, branched cytoplasmic processes that project out of the cell body. They act as the receiver of impulses and then transmit them to the cyton.
3. Axon: It is a single, thin, long, fiber that arises from the cyton. It has a thin layer of cytoplasm and branching at the end called the axon terminal. It is responsible to transmit impulses from the cell body to the next neuron. Some nerve fibers are covered by myelin sheaths made of fats, however, myelin sheaths are not continuous there are gaps called Nodes of Ranvier between each sheath. Some other nerve fibers lack these myelin sheaths.

Diagram of Neuron

Synapse

It is the functional junction or point of contact between the axon of a neuron and the dendrite of the neuron or between the neuron and other cells. In between the axon and dendrite or axon and another cell, there is a fine gap called the synaptic cleft. The synaptic cleft helps in the transfer of information in the form of neurotransmitters like acetylcholine. The electrical impulse travels to the end of the axon terminal and stimulates the release of neurotransmitters into the synaptic cleft that then reaches the receptor region of the other neuron or cell. 

Human Nervous System

The human nervous system consists of three parts;

The Central Nervous System

The main processing unit of all information is the CNS which consists of the brain and the spinal cord.

Central Nervous System

The Brain

The brain is located in the cranial cavity protected by the bony skull.  It is a soft whitish organ that weighs around 1.2 to 1.4 kg. The brain is surrounded by three layers of meninges; the inner thin pia mater, the middle vascular arachnoid membrane, and the thick outer dura mater. In between the three layers of the meninges, there is the cerebrospinal fluid. The brain is divided into three regions the forebrain, midbrain, and hindbrain. 

Forebrain

The main part of the brain is responsible for thinking. It consists of the cerebrum, olfactory lobes, and diencephalon. 

• Cerebrum: It is the largest part of the brain that is made up of two halves; the left and right hemispheres. The two hemispheres are joined together by a densely large network of myelinated fibers called the corpus callosum. Each cerebral hemisphere is divided into four lobes which control different activities of the body like muscular activities, touch, smell, temperature, hearing, and sight. Both hemispheres are covered by a greatly folded outer region of nerve cells called the cerebral cortex. The hemispheres contain motor, sensory, and association areas.  
• Olfactory lobes: It is a short club-shaped structure that forms the anterior part of the brain. Each lobe is made of two parts the anterior olfactory bulb, and the posterior olfactory tract. A pair of olfactory nerves arise from the olfactory lobes that are responsible for the sense of smell.
• Diencephalon: It is located below the cerebrum and is part of the forebrain. It consists of two main regions; the thalamus and the hypothalamus. The thalamus is covered by the cerebrum; it is responsible for conducting sensory information from the sense organs like the eye, ear, and skin to the cerebrum. The hypothalamus is located below the thalamus, it is responsible for controlling the body temperature, hunger, thirst, sleep, blood pressure, and heart rate, and is responsible for releasing neuro-hormones that control the functioning of the pituitary gland.

Midbrain

It is the small region of the brain that acts as the connection between the forebrain and the hindbrain. It is responsible for relaying sensory information from sense organs to the cerebrum and controlling the reflex movements of the head, neck, trunk, eye muscles, pupil, and shape of the eye lens. 

Hindbrain

It is located in the lower region of the brain near the start of the spinal cord. It consists of three parts; cerebellum, pons, and medulla.

• Cerebellum: The second largest part of the brain after the cerebrum and is located at the roof of the hindbrain. It is responsible for posture, balance, and coordination of the body during walking, swimming, dancing, etc.
• Pons: It is located just above the medulla. It is responsible for the regulation of respiration.
• Medulla: It is located at the base of the hindbrain and continues into the spinal cord. It is responsible for controlling breathing movements, heartbeat rate, blood pressure, swallowing, coughing, vomiting, and sneezing.

Spinal cord

The spinal cord is a soft, long, whitish, and cylindrical mass of nerve fibers that extends from the medulla to the lumbar region of the vertebral column. The spinal nerve arise from it. It is protected by the bony vertebral column inside which there are three layers of meninges and cerebrospinal fluid same as the brain.

Peripheral Nervous System

The network of nerves that arise from the brain and spinal cord spreads throughout the body conducting impulses between the CNS and the body. It comprises two main types of nerves:

• Cranial nerves: These are the nerves that arise from the brain. There are 12 pairs of cranial nerves in humans that spread throughout the head except for the 10th cranial nerve that extends up to the abdomen. They are either sensory/motor or mixed sensory-motor. Mammals, reptiles, and birds have 12 pairs of cranial nerves whereas fishes and amphibians have 10 pairs. 
• Spinal nerves: These are the nerves that arise from the spinal cord and spreads throughout the body’s whole length. There are 31 pairs of mixed (sensory and motor both) spinal nerves; 8 in the cervical (neck) region, 12 in the thoracic (chest) region, 5 in the lumbar (abdominal) region, 5 in the sacral (hip) region, and 1 in coccyx (tail bone) region. 

Autonomic Nervous System

Autonomous means “self-governing”, so these nervous systems as considered self-governing nervous systems. It controls those functions which we cannot control as per our will i.e. involuntary actions like activities of internal organs e.g. movement of food through the stomach, flow of blood, etc. As it controls the function of internal or visceral organs of the body, it is also called the visceral nervous system. It can be categorized into two categories;

• Sympathetic Nervous System: It causes a “fight and flight” response of the body by heightening the activity of the body’s organs like increasing the heart rate, respiration rate, etc.
• Parasympathetic Nervous System: It causes the conservation of energy by slowing down the functioning of the body’s organs by calming the body like slowing down the breathing rate and heartbeat during sleep.

Reflex Actions and Reflex Arc

Any sudden, immediate, involuntary, and mechanical response to a stimulus that is done without the will of the body is called reflex action. Mostly these reactions are controlled by the spinal cord and thus called spinal reflex action; however, some reflex actions are also controlled by the brain and are called cerebral reflex action. 

Examples of Reflex Action

• Our pupil contract when bright light falls on them.
• We tend to close our eyes when something is about to come in contact with it.
• We start to sneeze and cough when something enters our nose or throat.
• We tend to withdraw our hand or leg when suddenly anything hot/cold or sharp/pointy objects come in contact.
• Our mouth starts watering when we see something tasty.

Advantages of Reflex Action

• This process helps to protect our body in response to any harmful stimuli without wasting time in thought processing.
• Saves our brains from overloading.
• Helps in the survival of those animals which lack an efficient thought process.

Reflex Arc

The pathway that is taken by a nerve impulse and its response in a reflex action is called the reflex arc. The process involves the following steps;

Stimulus ⇢ Receptor organ ⇢ Sensory neurons ⇢ CNS (mostly spinal cord) ⇢ Motor neuron ⇢ Effector organ ⇢ Response

Components of a reflex arc are:

• Receptor: It is present in the sense organs of the body (like skin, eye, nose, etc.) that receive the stimulus.
• Sensory (afferent) neurons: The nerve fibers that are responsible for the transmission of the stimulus to the spinal cord (CNS).
• Integration center/ modulator: The spinal cord (CNS) acts as the immediate processor of the information and transmits the response to the motor neuron with the help of relay neurons.
• Motor (efferent) neurons: It transmits the response from the spinal cord to the effector organ of the body which will act on it.
• Effector: The organ that executes the response sent by the spinal cord. 

Example: In the diagram above the hand came in contact with a hot pan. The receptors present in the skin receive the stimulus i.e. heat. The sensory neuron carries the information of the stimulus to the spinal cord where it is immediately processed and a response is transmitted by the relay neurons to the motor neurons. The motor neuron carries the response to the effector muscle that will remove the hand immediately from the hot pan. This whole process takes just a fraction of a second to take place.

Endocrine Gland

Ductless glands secrete their secretion (hormones) directly into the blood. Examples are; the pituitary gland, thyroid glands, etc.

Different endocrine glands are present in humans. For example, Gonads, the Pituitary, Thyroid, Pancreas, Pineal, Hypothalamus, and adrenal glands.

Hypothalamus

Hypothalamus is part of both the nervous system and the endocrine system. It regulates the function of the pituitary gland. It is present below the thalamus.

Hypothalamus

Hormones Released: 

• Releasing hormone (RH): Helps in the stimulation of the pituitary gland, for example; Gonadotropin Releasing Hormone (GnRH) stimulates the secretion of gonadotropins.
• Inhibiting hormone (IH): Helps in inhibiting the activated pituitary gland to stop its secretion, for example; somatostatin inhibits the secretion of growth hormone.

Pituitary Gland

The pituitary Gland is called the master gland as it regulates the function of all the glands of the body. Have three lobes; the anterior lobe, intermediate lobe, and posterior lobe. Present just below the hypothalamus.

Pituitary glands

Hormones Released:

• Growth hormone (GH): Promotes and regulates the growth of the body. Its deficiency in childhood will cause dwarfism and excess can cause gigantism.
• Adrenocorticotropic hormone (ACTH): It stimulates the adrenal glands to produce corticosteroid hormone that helps in regulating stress.
• Thyroid-stimulating hormone (TSH): It stimulates the thyroid glands to secrete thyroxin hormone.
• Follicle Stimulating Hormone (FSH): It is a gonadotropin that stimulates the male testis to produce sperm cells, and in females, it stimulates the ovaries to produce the ovum.
• Luteinizing hormone (LH): It is a gonadotropin that stimulates the production of testosterone in males and progesterone in females.
• Prolactin hormone (PRL): Regulates the growth of mammary glands and the formation of milk in females during pregnancy and lactation. 
• Melanocyte Stimulating Hormone: Regulates the formation of melanocytes that produces melanin pigment responsible for the color of skin.
• Oxytocin: Stimulation rigorous contraction in the uterus during childbirth and release of milk from mammary glands during lactation.
• Vasopressin or Antidiuretic hormone (ADH): Regulates the concentration of water and electrolytes in the body.

Pineal Gland

• It is a small reddish, pea-sized gland.
• Location: Between the two cerebral hemispheres
• Hormones: It releases melatonin (sleep hormone) that regulates the sleep-wake cycle of the body.

Thyroid Glands

• It has two joined lobes.
• Location: Either side of the trachea.
  Hormones: 2 hormones are released by the thyroid gland:
  • Thyroxin (T₄) and triiodothyronine  (T₃): Regulates the rate of cellular metabolism of the body thus maintaining the basal metabolic rate (BMR) of the body. 
  • Calcitonin: Lowers the calcium levels of the body.

Parathyroid Glands

• It has four small pea-shaped bodies.
• Location: back side of the thyroid glands.
• Hormones: They secrete parathormone (PTH) that regulates the levels of calcium and phosphorus in the body.

Thymus Gland

• It starts degenerating in old age.
• Location: Near the front side of the heat under the sternum.
• Hormones: It secretes thymosin which helps in the formation of lymphocytes thus strengthening the immune system.

Thymus Gland

Adrenal Glands

Adrenal Gland is two small glands. These are also called the suprarenal glands. It has two regions; the outer region is called the cortex and the inner region is called the medulla. Present on the top of each kidney.

Adrenal Gland

Hormones Released:

• Glucocorticoids: Corticoid hormones that regulate the metabolism of protein, fats, and carbohydrates in the body. It also regulates blood pressure and heart rate. Cortisol is the most abundant of all corticoids.
• Aldosterone: Regulates the water and electrolyte balance of the body.
• Sexcorticoids: Stimulates the development of secondary sexual characters in both males and females.
• Adrenaline (epinephrine) and noradrenaline (nor-epinephrine):  Controls the fight-and-flight response of the body regulating emotion, fear, anger, blood pressure, etc.

Pancreas

Pancreas is heterocrine gland. The endocrine region of the pancreas is the secretory cells of the islet of Langerhans. Present in the abdominal region, posterior to the stomach. 

Pancreas

Hormones Released:

1. Insulin: Lower the blood glucose levels by converting glucose into glycogen. When this hormone is deficient it results in diabetes mellitus that causes high glucose levels in blood and urine.
2. Glucagon: When the concentration of glucose becomes less in blood this hormone converts glycogen into glucose and increases the levels of glucose.

Ovary

• Location: Lower abdominal region.
  Hormones: 2 types of hormones present those are:
  • Estrogen and Progesterone: Female sex hormones that are responsible for ovulation, maintaining the pregnancy, development of secondary sexual characteristics, and the regulation of the menstrual cycle.
  • Relaxin: During childbirth, this hormone relaxes the uterus and pelvic region of the female.

Ovary

Testes

• Location: In scrotal sacs outside the body in the lower abdomen.
• Hormones: They secrete the hormone testosterone that regulates the development of sperm cells and secondary sexual characters in males. 

Testes

Control and Coordination in Plants

Plants lack complex control and coordination like animals as they don’t have a nervous system or glandular system but they need internal coordination to maintain growth and development. They have only chemical coordination with the help of plant hormones or phytohormones which makes them either dependent on external stimuli like light, gravitational force, etc., or growth-dependent movements like the directional movement of stem upwards and root downwards. The plant mainly shows two types of movement; nastic and tropic movements. 

Nastic movement

When the movement of the plant is non-directional due to external stimuli like light, temperature, and gravity it is called nastic movement. In this type of movement, the stimulus comes from all directions and impacts the plant as a whole. Nastic movements are of the following types;

Semimonastic movement

These movements are very quick and immediate that is caused by mechanical stimuli like touch (shock), fast wind, etc. Example: The plant “touch me not” or “chhui-mui” (Mimosa pudica) has pulvini at the base of its petiole, between leaflets which lose its turgor pressure due to loss of water when anything touches its leaves or stem and causes the folding of leaves and it droops. After some time the parenchyma cells of pulvini again regain their turgor pressure and opens up. 

Nyctinastic Movement

The non-directional movements in plants that involve diurnal variation (changes in day and night) in the position of flowers and leaves are called Nyctinastic movement or sleep movements. It is of two types;

• Photonasty: The non-directional diurnal movement caused by light is called a photonastic movement, e.g. Flower of the Dandelion opens up when the light is bright in the morning and closes when the light fades in the evening.
• Thermonasty: The non-directional diurnal movement caused by temperature is called thermonastic movement, e.g.  Flowers of tulips open when the temperature is high and close when the temperature falls.

Tropic Movement

When the direction of an external stimulus (like light, water, etc.) determines the growing movement in a plant, it is called tropism. The movement in tropism can be of two categories; positive tropism when the plant part moves towards the stimuli and negative tropism when the plant part moves against the stimuli. Tropisms are of the following types;

Phototropism: Movement of plant parts in response to light i.e. shoot usually grows towards the light and shows positive phototropism whereas roots grow away from light and show negative phototropism.

Tropic Movement of Plant

Geotropism: Movement of plant parts in response to the gravitational force of the earth i.e. roots usually grow towards gravitational pull and show positive geotropism whereas shoot usually grows away from the gravitational pull and shows negative geotropism.

Chemotropism: Movement of plant parts in response to chemical stimulation i.e. when a plant part grows towards the stimulant it shows positive chemotropism whereas when the plant part grows away from the stimulant it shows negative chemotropism.

Hydrotropism: The movement of the plant part towards water i.e. the movement of the root underground towards the water source is an example of positive hydrotropism.

Thigmotropism: Movement of plant part in response to the touch of a foreign object. Like in the case of creeping plants, the stem grows alongside the support.

Hormonal Control in Plants

There are mainly 5 types of plant hormones or phytohormones that are produced in plants in very minute quantities. Like animal hormones, they are produced in one part and diffuse to the other parts for the physiological process. All these 5 plant hormones can be divided into two groups;

• Growth promoters: Auxins, gibberellins, and cytokinins promote the growth of plants by stimulating cell division, cell enlargements, flowering, fruiting, etc. 
• Growth inhibitors: Abscisic acid and ethylene induce dormancy, abscission, and stress.

Plant Hormones

Given below is the table of all the plant hormones:

Plant Hormones	Description	Functions
Auxins	It is synthesized at the tips of the root and the shoot. Indole-3-acetic acid is its naturally occurring form.	Promotes cell enlargement, cell differentiation, stem growth, fruit growth, and cell division. Regulates plant tropisms. Induces the development of seedless fruits i.e. parthenocarpy. Induces apical dominance. Can be used as herbicides.
Gibberellins	Also known as Gibberellic acid. Synthesis occurs in the areas of rapid cell division like fruits and seeds.	Promotes growth by overcoming dormancy. Act as an antagonist to ABA. Promotes growth in stem, leaves, internodes, etc. Promotes the internodal growth just before flowering (bolting) in cabbages, beets, etc. Induces parthenocarpy in plants like tomatoes.
Cytokinins	Synthesis occurs in young fruits, shoot buds, and root apices. The first natural cytokinin is zeatin.	Promotes fruit growth, the opening of stomata, and cell division. Helps in morphogenesis, and breaking dormancy of seeds and buds. Delays the aging of leaves and increases the shelf life of vegetables.
Ethylene	It is a gaseous phytohormone synthesis largely in ripening fruits.	Promotes horizontal growth in seedlings, ripening of fruits, root growth, root hair formation, yellowing of leaves, and senescence. Helps in breaking the dormancy of buds, and seeds.  Stimulates abscission in leaves, flowers, and fruits.
Abscisic Acid (ABA)	It is also called stress hormones.	Inhibits plant growth by inducing dormancy in seeds, and buds. Promotes closing of stomata during desiccation and other stress and thus causing wilting of leaves. Promotes abscission and senescence of leaves. Increases plant’s tolerance towards stress.

FAQs on Control and Coordination

What comprises the brain stem?

The midbrain, pons, and medulla are collectively called the brain stem.

Give Some Functions of the Brain.

The brain regulates bodily functions such as thinking, memory, emotion, and coordination of movement.

What is the Function of the Central Nervous System?

The central nervous system coordinates and controls activities of the body by processing sensory information and sending out motor responses.