Class 10 Science - Chapter 2: Control and Coordination

Class 10 Science - Chapter 2: Control and Coordination Detailed Colorful CBSE Notes 1. Introduction Control and Coordination is the process by which living organisms regulate body activities and respond to changes in their surroundings. It helps organisms survive and maintain balance in the body. 2. Coordination in Animals Animals coordinate their activities through the nervous system and endocrine system. The nervous system provides quick responses while hormones provide slower but long-lasting responses. 3. Nervous System The nervous system controls and coordinates all body activities. Main Parts: • Brain • Spinal Cord • Nerves Neuron: Neuron is the structural and functional unit of the nervous system. Parts of Neuron: • Dendrites • Cell Body • Axon Functions: • Receive impulses • Transmit impulses • Help communication within the body 4. Reflex Action Reflex action is a quick and automatic response to a stimulus. Examples: • Pulling hand away from a hot object • Blinking of eyes Reflex Arc: Receptor → Sensory Neuron → Spinal Cord → Motor Neuron → Effector Importance: • Provides quick protection • Prevents injury 5. Human Brain The brain is the control center of the body. Forebrain: • Thinking • Memory • Intelligence • Voluntary actions Midbrain: • Visual and auditory reflexes Hindbrain: • Balance • Posture • Breathing • Heartbeat Protection of Brain: • Skull • Cerebrospinal Fluid 6. Coordination in Plants Plants do not have nerves but show movements due to stimuli. Plant Movements: • Tropic Movements • Nastic Movements Tropic Movements: Growth movements in response to stimuli. Types: 1. Phototropism – response to light 2. Geotropism – response to gravity 3. Hydrotropism – response to water 4. Thigmotropism – response to touch 5. Chemotropism – response to chemicals 7. Plant Hormones Plant hormones control growth and development. Auxins: • Promote growth • Responsible for phototropism Gibberellins: • Increase stem growth Cytokinins: • Promote cell division Abscisic Acid: • Inhibits growth • Causes dormancy 8. Endocrine System The endocrine system consists of glands that secrete hormones. Hormones are chemical messengers that regulate body functions. Major Endocrine Glands: • Pituitary Gland • Thyroid Gland • Adrenal Gland • Pancreas • Testes • Ovaries 9. Important Human Hormones Pituitary Hormone: • Controls growth Thyroxine: • Regulates metabolism • Requires iodine Adrenaline: • Emergency hormone • Prepares body for stress Insulin: • Controls blood sugar level Testosterone: • Male sex hormone Estrogen: • Female sex hormone 10. Feedback Mechanism The body maintains hormone levels through feedback mechanisms. Example: When thyroxine level increases, the pituitary gland reduces TSH secretion. This helps maintain balance in the body. 11. Differences to Remember Nervous System vs Endocrine System Nervous System: • Fast response • Electrical impulses • Short duration Endocrine System: • Slow response • Hormones • Long duration Tropic Movement vs Nastic Movement Tropic: • Direction dependent • Growth movement Nastic: • Direction independent • Non-growth movement 12. NCERT Important Questions 1. What is a reflex action? 2. Draw and explain reflex arc. 3. What are the functions of the forebrain? 4. Explain phototropism. 5. Name four plant hormones. 6. What is the role of thyroxine? 7. Why is iodine necessary? 8. Differentiate between nervous and endocrine systems. 9. What is coordination? 10. Explain feedback mechanism. 13. Quick Revision Sheet • Neuron is the functional unit of the nervous system. • Brain is protected by skull and cerebrospinal fluid. • Reflex actions are controlled by spinal cord. • Auxin helps plant growth. • Adrenaline is the emergency hormone. • Insulin controls blood sugar. • Thyroxine regulates metabolism. • Phototropism is movement towards light. • Hydrotropism is movement towards water. • Endocrine glands secrete hormones.