Control & Coordination (Class 10)

Cheatsheet Content

1. Introduction to Control and Coordination Definition: The process by which various organs of an organism work together in a systematic and regulated manner to produce a proper response to a stimulus. Need for Control & Coordination: To maintain homeostasis, adapt to the environment, and perform complex functions like growth and reproduction. Modes: Animals: Nervous system and Endocrine system. Plants: Chemical coordination (Phytohormones). 2. Nervous System in Animals (NCERT Page 114) 2.1 Neurons (Nerve Cells) - Structural & Functional Unit Structure: Dendrite: Receives information. Cell Body (Cyton): Processes information. Axon: Transmits information away from the cell body. Nerve Ending: Releases neurotransmitters. Synapse: Microscopic gap between two neurons where information is chemically transmitted (from axon terminal of one neuron to dendrite/cell body of another). Nerve Impulse: Electrochemical signal transmitted along a neuron. 2.2 Types of Neurons Sensory Neurons: Carry signals from receptors to the CNS. Motor Neurons: Carry signals from CNS to effectors (muscles/glands). Relay/Interneurons: Connect sensory and motor neurons within the CNS. 2.3 Human Nervous System (NCERT Page 115) Central Nervous System (CNS): Brain and Spinal Cord. Processes information and controls responses. Peripheral Nervous System (PNS): Nerves originating from CNS. Cranial Nerves: Arise from the brain. Spinal Nerves: Arise from the spinal cord. Function: Connects CNS to all parts of the body. 3. Human Brain (NCERT Page 116) Protection: Skull (Cranium) and Meninges (3 membranes) with Cerebrospinal fluid. Main Parts: Part Location Functions (PYQ Focus) Forebrain (Cerebrum) Front & upper part Thinking, learning, memory, voluntary actions, interpreting sensory info (touch, smell, sight, hearing). Midbrain Between forebrain & hindbrain Connects forebrain & hindbrain, controls involuntary actions like reflex movements of head, neck, trunk in response to visual/auditory stimuli, eye movements. Hindbrain Base of skull Cerebellum: Precision of voluntary actions, maintaining posture & balance (e.g., walking, riding a bicycle). Pons: Regulates respiration, connects different parts of brain. Medulla Oblongata: Controls involuntary actions like heartbeat, breathing, blood pressure, salivation, vomiting, sneezing, coughing. 4. Spinal Cord (NCERT Page 117) Location: Extends from Medulla Oblongata down the vertebral column. Function: Relays messages between brain and rest of the body. Controls reflex actions (e.g., withdrawal reflex). 5. Reflex Actions and Reflex Arc (NCERT Page 117-118) Reflex Action: A sudden, involuntary, and rapid response to a stimulus, controlled by the spinal cord. (e.g., withdrawing hand from hot object). Reflex Arc: The pathway taken by nerve impulses during a reflex action. Components: Receptor: Detects stimulus (e.g., skin). Sensory Neuron: Carries signal to spinal cord. Relay Neuron (Interneuron): In spinal cord, connects sensory to motor neuron. Motor Neuron: Carries signal from spinal cord to effector. Effector: Muscle or gland that responds (e.g., muscle contracting). Significance: Quick responses for survival, minimizes damage. 6. Coordination in Plants (NCERT Page 120) Plants lack a nervous system and muscles. Coordination occurs through chemical means (plant hormones/phytohormones). Responses: Immediate Response to Stimulus: (e.g., touch-me-not plant, Mimosa pudica ). Involves electrical-chemical means and rapid changes in water content of cells. No growth involved. Growth-related movements (Tropic Movements): Directional movements in response to stimuli, due to differential growth. 6.1 Plant Hormones (Phytohormones) - (NCERT Page 122) Hormone Functions (PYQ Focus) Auxins Cell enlargement & differentiation, fruit growth, phototropism, geotropism. (Synthesized at shoot tips). Gibberellins Stem elongation, seed germination, breaking dormancy. Cytokinins Promote cell division, rapid cell growth (fruits, seeds), delay leaf aging. Abscisic Acid (ABA) Inhibits growth, causes wilting of leaves, promotes dormancy in seeds and buds (stress hormone). 6.2 Tropic Movements (NCERT Page 121) Phototropism: Response to light. Shoots grow towards light (positive phototropism). Roots grow away from light (negative phototropism). Mediated by Auxins. Geotropism (Gravitropism): Response to gravity. Roots grow downwards (positive geotropism). Shoots grow upwards (negative geotropism). Chemotropism: Response to chemicals. Growth of pollen tube towards ovule (positive chemotropism). Hydrotropism: Response to water. Roots grow towards water (positive hydrotropism). Thigmotropism: Response to touch. Twining of tendrils around a support. 7. Endocrine System in Animals (NCERT Page 123) Definition: System of ductless glands that secrete hormones directly into the bloodstream. Hormones: Chemical messengers that regulate various physiological processes. Feedback Mechanism: Regulates hormone secretion. (e.g., High blood sugar $\to$ Pancreas releases insulin $\to$ Blood sugar decreases $\to$ Insulin secretion reduces). 7.1 Major Endocrine Glands and Hormones (NCERT Page 124-125) Gland Location Hormone Function (PYQ Focus) Deficiency/Excess (Disorders) Pituitary (Master Gland) Base of brain Growth Hormone (GH) Regulates growth and development. Deficiency: Dwarfism; Excess: Gigantism. Thyroid Neck Thyroxine Regulates metabolism (carbohydrates, fats, proteins). Deficiency: Goitre (due to iodine deficiency), Hypothyroidism. Pancreas Behind stomach Insulin, Glucagon Insulin: Decreases blood glucose level. Glucagon: Increases blood glucose level. Insulin deficiency: Diabetes Mellitus. Adrenal Top of kidneys Adrenaline (Epinephrine) "Fight or flight" hormone; prepares body for stress (increases heart rate, blood pressure, blood glucose). Testes (Males) Scrotum Testosterone Male secondary sexual characteristics, sperm production. Ovaries (Females) Abdomen Estrogen, Progesterone Estrogen: Female secondary sexual characteristics. Progesterone: Maintains pregnancy. 8. Important Diagrams (NCERT) Structure of Neuron (Page 114, Fig. 7.1) - Labeling and function. Reflex Arc (Page 118, Fig. 7.2) - Pathway of nerve impulse. Human Brain (Page 116, Fig. 7.3) - Labeling of Forebrain, Midbrain, Hindbrain (Cerebrum, Cerebellum, Medulla). Endocrine Glands in Human Male & Female (Page 124, Fig. 7.6) - Location of glands. 9. Key Concepts for PYQ Analysis Distinguish between Nervous and Hormonal Control: Nervous: Fast, short-lived, localized, electrochemical. Hormonal: Slow, long-lasting, widespread, chemical. Importance of Feedback Mechanism: For precise regulation of hormone secretion. Role of Auxin in Phototropism: Auxin moves to shaded side, causing cells there to grow longer, bending the shoot towards light. Functions of Cerebellum: Balance, posture, precision of voluntary actions. Function of Medulla Oblongata: Involuntary actions (heartbeat, breathing, BP). Causes and Management of Diabetes: Insulin deficiency, controlled by insulin injections/diet. Goitre: Caused by iodine deficiency, leading to low thyroxine production. 10. Sample Questions & Answers (PYQ & NCERT Based) Q1: What is the function of receptors in our body? Name the receptors present in the skin. (NCERT Qs / PYQ) A1: Receptors are specialized cells or groups of cells that detect stimuli from the environment. They convert these stimuli into electrical signals (nerve impulses) that are sent to the central nervous system for interpretation. In the skin, receptors like thermoreceptors (for temperature), mechanoreceptors (for touch and pressure), and nociceptors (for pain) are present. Q2: Distinguish between reflex action and walking. (NCERT Qs / PYQ) A2: Reflex Action: It is a sudden, involuntary, and unconscious response to a stimulus, controlled by the spinal cord (e.g., withdrawing hand from a hot object). It is rapid and protective. Walking: It is a voluntary action, consciously controlled by the cerebrum (forebrain). It involves thinking, planning, and coordinated muscle movements. Q3: What is the role of the brain in reflex action? (PYQ) A3: While reflex actions are primarily controlled by the spinal cord to ensure a quick response, the information about the reflex action is also sent to the brain. The brain is not directly involved in initiating or executing the reflex response but it becomes aware of the action after it has occurred. This awareness allows us to learn from such situations and take conscious corrective measures if needed in the future. Q4: How are involuntary actions and voluntary actions controlled in the body? (NCERT Qs / PYQ) A4: Voluntary Actions: These are actions that are under our conscious control, such as walking, talking, writing. They are controlled by the cerebrum (forebrain) of the brain. Involuntary Actions: These are actions that are not under our conscious control, such as heartbeat, breathing, digestion, blood pressure, salivation, vomiting. They are controlled by the midbrain and hindbrain (specifically the medulla oblongata and cerebellum). Q5: How does chemical coordination occur in plants? Give an example. (NCERT Qs / PYQ) A5: Chemical coordination in plants occurs through plant hormones or phytohormones. These are chemical compounds produced in one part of the plant and transported to other parts to influence growth, development, and responses to the environment. For example, Auxins are produced at the shoot tips and promote cell elongation, responsible for the bending of the plant shoot towards light (phototropism). Q6: What is the significance of the feedback mechanism in the control of hormone secretion? (PYQ) A6: The feedback mechanism is crucial for maintaining the precise and optimum levels of hormones in the body. It ensures that hormones are secreted only when needed and in the correct amounts. For instance, if the blood sugar level rises, the pancreas is stimulated to secrete insulin, which lowers blood sugar. Once blood sugar returns to normal, the secretion of insulin is reduced. This prevents both under-secretion and over-secretion of hormones, thus maintaining homeostasis. Q7: Why is the use of iodised salt advisable? (NCERT Qs / PYQ) A7: Iodised salt is advisable because iodine is essential for the thyroid gland to synthesize thyroxine hormone. Thyroxine regulates carbohydrate, protein, and fat metabolism in the body. Deficiency of iodine in the diet can lead to insufficient production of thyroxine, resulting in a condition called goitre, characterized by a swollen neck (enlarged thyroid gland), and can also cause mental retardation in children. Q8: Name the hormone that regulates blood sugar level in humans. Name the gland which secretes it. Explain its role in keeping the blood sugar level constant. (PYQ) A8: The hormone that regulates blood sugar level in humans is Insulin . It is secreted by the Pancreas . Role: When the blood sugar level rises (e.g., after a meal), the pancreas detects this and secretes insulin. Insulin acts on body cells, promoting the uptake of glucose from the blood into cells for energy or converting excess glucose into glycogen for storage in the liver and muscles. This process reduces the blood glucose level back to normal. If insulin is deficient or its action is impaired, it leads to diabetes mellitus. Q9: What are tropic movements? Describe phototropism with the help of a diagram. (NCERT Qs / PYQ) A9: Tropic movements are directional growth movements of plants in response to environmental stimuli. These movements are typically slow and result from differential growth in different parts of the plant. Phototropism: It is the growth movement of a plant in response to light. Shoots generally show positive phototropism (grow towards light), while roots show negative phototropism (grow away from light). Mechanism: When light falls on a plant shoot from one direction, auxins (plant hormones) migrate to the shaded side of the shoot. The higher concentration of auxins on the shaded side stimulates the cells there to grow longer and faster than the cells on the illuminated side. This differential growth causes the shoot to bend towards the light source. Light Shoot (positive phototropism) Root (negative phototropism)