Question 3
How does our body respond when adrenaline is secreted into the blood?
When adrenaline is secreted into the blood, 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.
Chapter 6: Control and Coordination — Quick Revision Guide
Introduction
Control and coordination in organisms is achieved through the nervous system (fast, electrical signals) and the endocrine system (slow, chemical hormones). Plants coordinate using phytohormones.
Key Points at a Glance
- Neuron: cell body + dendrites (receive) + axon (transmit) + synapse (chemical transmission between neurons)
- Reflex arc: receptor → sensory nerve → spinal cord → motor nerve → effector; involuntary, fast
- Brain: cerebrum (thinking, memory), cerebellum (balance), medulla (involuntary actions); protected by skull + CSF
- Plant tropisms: phototropism (light), geotropism (gravity), hydrotropism (water), chemotropism (chemicals), thigmotropism (touch)
- Nastic movements: non-directional; Mimosa pudica folds on touch (thigmonasty)
- Plant hormones: auxin (elongation), gibberellin (stem growth), cytokinin (cell division), abscisic acid (growth inhibitor), ethylene (ripening)
- Animal hormones: GH (growth), thyroxine (metabolism, needs iodine), adrenaline (fight-or-flight), insulin (lowers blood sugar), testosterone/estrogen (sexual characters)
- Feedback mechanism: blood sugar regulated by insulin (lowers) and glucagon (raises); homeostasis
Real-World Connections
Reflexes protect us from burns and injury; diabetes is managed with insulin injections; iodised salt prevents goitre; artificial ripening of fruits uses ethylene gas.
Quick Self-Test (5 Questions)
- What is the most important concept you learned from this chapter?
- Can you write three key equations/formulae from this chapter from memory?
- Draw a labelled diagram relevant to this chapter without looking at your notes.
- Explain one real-world application of a concept from this chapter.
- What is one common mistake students make in this chapter, and how can you avoid it?
Further Study
- NCERT Textbook Chapter 6
- NCERT Exemplar Problems
- Bright Tutorials Detailed Notes: ch06-control-coordination.html
- Bright Tutorials Practice Questions: ch06-control-coordination.html
- Previous Year CBSE Board Papers