NCERT Class 10 Science Chapter 7: Control and Coordination YouTube Lecture Handouts

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NCERT Class 10 Science Chapter 7: Control and Coordination

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Brain Teasers!!

  • Which part maintains posture and balance?

  • Which is a growth inhibiting plant hormone?

  • What is autonomic and somatic nervous system?

  • Which gland is called as master gland?

  • What are guard cells? Why its shape changes?

Growth & Movement

  • Nervous and hormonal systems together perform the function of control and coordination in human beings

  • Movements can be or cannot be connected to growth

  • But if its growth were to be stopped, these movements would not happen. Seed germinates and grows is related to growth.

  • A cat running, children playing on swings, buffaloes chewing cud – these are not movements caused by growth.

  • When bright light is focused on our eyes or when we touch a hot object, we detect the change and respond to it with movement in order to protect ourselves

  • The movement to be made depends on the event that is triggering it – whether we are polite or we shout loudly

Image of a Animals – Nervous System

Image of a Animals – Nervous System

Image of a Animals – Nervous System

Image of a Animals – Nervous System 2

Image of a Animals – Nervous System 2

Image of a Animals – Nervous System 2

Animals – Nervous System

  • Touching hot plate – you respond

  • 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 on. So gustatory receptors will detect taste while olfactory receptors will detect smell.

  • Information at end of tip sends in nerve impulse. Moves from dendrite to axon and chemicals cross the gap or synapse and start impulse in next neuron

  • It is thus no surprise that nervous tissue is made up of an organized network of nerve cells or neurons, and is specialised for conducting information via electrical impulses from one part of the body to another.

  • Dendrite → cell body → axon → axonal end

  • Is there a difference in how sugar and food taste if your nose is blocked?

Reflex Action

Image of a Reflex Action

Image of a Reflex Action

Image of a Reflex Action

Image result for reflex arc gif

Brain Teaser

Image result for reflex arc gif

  • Jumping out of a moving bus; pulling hand away from flame

  • One seemingly simple way is to think consciously about the pain and the possibility of getting burnt, and therefore move our hand.

  • Thinking is a complex activity, so it is bound to involve a complicated interaction of many nerve impulses from many neurons.

  • Body consists of dense networks of intricately arranged neurons

  • Process of detecting the signal or the input and responding to it by an output action might be completed quickly. Such a connection is commonly called a reflex arc

  • Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle

Human Brain

  • CNS = Brain + Spinal Cord

  • Voluntary and Involuntary Actions

  • Role of PNS – Somatic (voluntary) and Autonomic (involuntary)

  • Autonomic is either sympathetic or parasympathetic

  • Thinking involves more complex mechanisms and neural connections. These are concentrated in the brain, which is the main coordinating centre of the body. The brain and spinal cord constitute the central nervous system.

  • Writing, talking, moving a chair, clapping at the end of a program are examples of voluntary actions

  • The communication between the central nervous system and the other parts of the body is facilitated by the peripheral nervous system consisting of cranial nerves arising from the brain and spinal nerves arising from the spinal cord.

  • Spinal cord originates in medulla

Parts of Brain

  • The fore-brain is the main thinking part of the brain. It has regions which receive sensory impulses from various receptors. Separate areas of the fore-brain are specialized for hearing, smell, sight and so on - control the movement of voluntary muscles, for example, our leg muscles

  • So, in between the simple reflex actions like change in the size of the pupil, and the thought out actions such as moving a chair, there is another set of muscle movements over which we do not have any thinking control. Many of these involuntary actions are controlled by the mid-brain and hind-brain. All these involuntary actions including blood pressure, salivation and vomiting are controlled by the medulla in the hind-brain.

  • Think about activities like walking in a straight line, riding a bicycle, picking up a pencil. These are possible due to a part of the hind-brain called the cerebellum. It is responsible for precision of voluntary actions and maintaining the posture and balance of the body.

Parts of Brain

  • Forebrain

  • -Thalamus – sensory perception, sleep and wake cycle

  • -Hypothalamus – respiration, BP and body temperature regulation

  • -Pineal gland – melatonin – sleep wake cycles and sexual development

  • Midbrain - The midbrain and hindbrain together compose the brainstem. The midbrain regulates movement and aids in the processing of auditory and visual information.

  • Hindbrain - The hindbrain assists in the regulation of autonomic functions, maintaining balance and equilibrium, movement coordination, and the relay of sensory information.

  • -Pons is a component of the brainstem, which acts as a bridge connecting the cerebrum with the medulla oblongata and cerebellum. The pons assists in the control of autonomic functions, as well as states of sleep and arousal.

  • -Cerebellum relays information between muscles and areas of the cerebral cortex that are involved in motor control. This hindbrain structure aids in fine movement coordination, balance and equilibrium maintenance, and muscle tone.

Structure

  • Inside the box, the brain is contained in a fluid-filled balloon which provides further shock absorption.

  • Vertebral column or backbone which protects the spinal cord.

  • The simplest notion of movement at the cellular level is that muscle cells will move by changing their shape so that they shorten.

  • Muscle cells have special proteins that change both their shape and their arrangement in the cell in response to nervous electrical impulses. When this happens, new arrangements of these proteins give the muscle cells a shorter form.

Coordination in Plants

  • When we touch the leaves of a chhui-mui (the ‘sensitive’ or ‘touch-me-not’ plant of the Mimosa family), they begin to fold up and droop. When a seed germinates, the root goes down, the stem comes up into the air. But there is no nervous tissue, nor any muscle tissue. How does the plant detect the touch.

  • The plants also use electrical-chemical means to convey this information from cell to cell, but unlike in animals, there is no specialised tissue in plants for the conduction of information

  • Directional movement of a seedling is caused by growth.

  • Instead of the specialised proteins found in animal muscle cells, plant cells (guard cells) change shape by changing the amount of water in them, resulting in swelling or shrinking, and therefore in changing shapes.

Movement by Growth

  • Response to light (shoot responds)

  • Response to geotrophism (root responds)

  • Speed of movement varies

  • Tendrils move up the fences but they are sensitive to touch. When they come in contact with any support, the part of the tendril in contact with the object does not grow as rapidly as the part of the tendril away from the object. Growth is directional and it appears as if the plant is moving.

  • If ‘hydro’ means water and ‘chemo’ refers to chemicals, what would ‘hydrotropism’ and ‘chemotropism’

  • Chemotropism is the growth of pollen tubes towards ovules

  • Speed of movement varies: The movement of the sensitive plant in response to touch is very quick. The movement of sunflowers in response to day or night, on the other hand, is quite slow. Growth-related movement of plants will be even slower.

How We Communicate?

  • Cells cannot continually create and transmit electrical impulses. It is thus no wonder that most multicellular organisms use another means of communication between cells, namely, chemical communication.

  • Different plant hormones help 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

  • When growing plants detect light, a hormone called auxin, synthesized at the shoot tip, helps the cells to grow longer (elongation). When light is coming from one side of the plant, auxin diffuses towards the shady side of the shoot.

  • Gibberellins: growth of stem

  • Cytokinins promote cell division, and it is natural then that they are present in greater concentration in areas of rapid cell division, such as in fruits and seeds and promote growth & plants need signal to stop growing.

  • Abscisic acid is one example of a hormone which inhibits growth. Its effects include wilting of leaves

Animal Hormones

  • Pituitary (associated with brain) – unpaired gland

  • Adernal

  • Thyroid

  • Pancreas

  • If we rely only on electrical impulse – activity would be limited

  • Chemical signals can be sent across body - adrenaline from adrenal glands - As a result, the heart beats faster, resulting in supply of 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 diverts the blood to our skeletal muscles. The breathing rate also increases because of the contractions of the diaphragm and the rib muscles.

  • We don’t respond to light as plants do. Plants will grow leaves in many places on the plant body, for example, but we do not grow fingers on our faces.

  • Thyroid gland – thyroxine - Iodine is necessary for the thyroid gland to make thyroxin hormone. Thyroxin regulates carbohydrate, protein and fat metabolism in the body so as to provide the best balance for growth. Iodine is essential for the synthesis of thyroxin. In case iodine is deficient in our diet, there is a possibility that we might suffer from goiter (swollen neck)

  • Pituitary (growth hormone) – small (dwarfism) or giant person - regulates growth and development

  • Changes in puberty - secretion of testosterone in males and oestrogen in females

  • Pancreas – insulin – (diabetes) - This 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. If the sugar levels in blood rise, they are detected by the cells of the pancreas which respond by producing more insulin. As the blood sugar level falls, insulin secretion is reduced.

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