What is a reflex arc? Give an example.

A reflex arc is the neural pathway that controls a reflex action. Path: Stimulus → Receptor (sensory organ) → Afferent/Sensory nerve → Spinal cord (integration centre) → Efferent/Motor nerve → Effector (muscle or gland) → Response. Example: Touching something hot — heat (stimulus) is detected by skin receptors, impulse travels via sensory nerve to spinal cord, motor nerve carries response impulse to hand muscles which contract and pull the hand away. The whole process bypasses the brain, making it very fast.

What is the role of adrenaline?

Adrenaline (also called epinephrine) is secreted by the adrenal glands (on top of kidneys) during stress, fear, or danger. It prepares the body for 'fight or flight': (1) Increases heart rate and blood pressure; (2) Dilates pupils; (3) Increases blood sugar levels (by stimulating glycogen breakdown); (4) Redirects blood from skin/gut to muscles; (5) Increases breathing rate. It is why your heart pounds when you are frightened.

What is the difference between nervous system and endocrine system?

Nervous system: transmits electrical impulses through nerve fibres; action is rapid (milliseconds) but short-lasting; response is localised. Endocrine system: transmits chemical messages (hormones) through bloodstream; action is slower but long-lasting; response is widespread (affects entire body). Both systems work together — the hypothalamus (part of brain) links them by controlling the pituitary gland (master endocrine gland).

Nervous System and Hormones

Control and Coordination • Class 10 Science • NCERT • CBSE

The nervous system controls and coordinates body activities through electrical impulses. A reflex arc is the path of an impulse during a reflex action. The endocrine system uses hormones (chemical messengers). Insulin (from pancreas) controls blood sugar; adrenaline (from adrenal gland) is the fight-or-flight hormone.

Frequently Asked Questions

What is a reflex arc? Give an example.: A reflex arc is the neural pathway that controls a reflex action. Path: Stimulus → Receptor (sensory organ) → Afferent/Sensory nerve → Spinal cord (integration centre) → Efferent/Motor nerve → Effector (muscle or gland) → Response. Example: Touching something hot — heat (stimulus) is detected by skin receptors, impulse travels via sensory nerve to spinal cord, motor nerve carries response impulse to hand muscles which contract and pull the hand away. The whole process bypasses the brain, making it very fast.
What is the role of adrenaline?: Adrenaline (also called epinephrine) is secreted by the adrenal glands (on top of kidneys) during stress, fear, or danger. It prepares the body for 'fight or flight': (1) Increases heart rate and blood pressure; (2) Dilates pupils; (3) Increases blood sugar levels (by stimulating glycogen breakdown); (4) Redirects blood from skin/gut to muscles; (5) Increases breathing rate. It is why your heart pounds when you are frightened.
What is the difference between nervous system and endocrine system?: Nervous system: transmits electrical impulses through nerve fibres; action is rapid (milliseconds) but short-lasting; response is localised. Endocrine system: transmits chemical messages (hormones) through bloodstream; action is slower but long-lasting; response is widespread (affects entire body). Both systems work together — the hypothalamus (part of brain) links them by controlling the pituitary gland (master endocrine gland).

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