Class 10 Science Control and Coordination Notes

Class 10 Science Control and Coordination Notes

Introduction

  • Control and coordination is the process by which organisms respond to stimuli and maintain internal stability (homeostasis).
  • Achieved by the nervous system and hormonal system.

1. Nervous System in Humans

  • Structure: Brain, spinal cord, nerves
  • Function: Transmit messages in the form of electrical impulses

Parts of Nervous System

  1. Central Nervous System (CNS): Brain + spinal cord
    • Controls voluntary and involuntary actions
  2. Peripheral Nervous System (PNS): Nerves connecting CNS to body
    • Sensory neurons: Carry messages from sense organs → CNS
    • Motor neurons: Carry messages from CNS → muscles/glands

Reflex Action

  • Definition: Automatic, involuntary response to a stimulus
  • Pathway (Reflex Arc): Stimulus → Sensory neuron → Spinal cord → Motor neuron → Effector → Response
  • Example: Pulling hand from hot object

2. Hormonal System

  • Hormones: Chemical messengers secreted by glands, transported by blood.
  • Function: Control long-term processes like growth, metabolism, reproduction

Major Endocrine Glands & Hormones

GlandHormoneFunction
PituitaryGrowth hormoneStimulates growth
ThyroidThyroxineControls metabolism
AdrenalAdrenalineFight or flight response
PancreasInsulinRegulates blood sugar
Ovaries/TestesEstrogen/TestosteroneControls reproduction

3. Coordination in Plants

  • Plants lack nervous system, but respond to stimuli via tropisms.

Types of Tropisms

  1. Phototropism: Response to light (positive → towards light)
  2. Geotropism/Gravitropism: Response to gravity (roots → positive, stem → negative)
  3. Hydrotropism: Response to water
  4. Thigmotropism: Response to touch (e.g., tendrils of climbing plants)
  • Plant hormones (phytohormones):
    • Auxins: Promote cell elongation
    • Gibberellins: Promote growth and seed germination
    • Cytokinins: Promote cell division
    • Ethylene: Ripening of fruits