Control and Coordination — Practice

Question 1

Which part of the brain controls balance?

Accepted Answer

✦ Answer: Cerebellum. Located at the back, below cerebrum. Controls balance, coordination, posture.

Question 2

Which gland produces insulin and what does it do?

Accepted Answer

✦ Answer: PANCREAS produces insulin. Insulin LOWERS blood sugar by helping cells absorb glucose. Deficiency causes diabetes.

Question 3

Describe a reflex arc with an example.

Accepted Answer

Step 1 — Definition.
  Reflex arc = the path along which nervous signals travel in a reflex action.

Step 2 — Path.
  RECEPTOR → SENSORY NEURON → SPINAL CORD → MOTOR NEURON → EFFECTOR (muscle)

Step 3 — Example: touching hot pan.
  • Skin sensor (receptor) detects heat
  • Sensory neuron carries signal to spinal cord
  • Spinal cord IMMEDIATELY sends signal back via motor neuron
  • Motor neuron tells arm muscle to contract
  • Hand JERKS BACK before brain even knows about pain

Step 4 — Why so fast?
  Signal doesn't go all the way to brain — bypasses for SPEED. Spinal cord handles it.

Step 5 — Other reflex examples.
  Knee jerk, blinking when something approaches eye, sneezing, coughing.

Step 6 — Importance.
  Reflexes PROTECT body before conscious thought can react. Survival mechanism.

✦ Answer: A reflex arc is RECEPTOR → SENSORY NEURON → SPINAL CORD → MOTOR NEURON → EFFECTOR. Example: touching a hot pan — signal goes from skin to spinal cord (not brain), back to arm muscle, jerking hand away. FAST because bypasses brain. Protective response.

Question 4

Discuss the role of the endocrine system with examples of important hormones.

Accepted Answer

Step 1 — What is endocrine system?
  Network of GLANDS that produce HORMONES — chemical messengers travelling in BLOOD to target organs.

Step 2 — Pituitary (master gland).
  Located at base of brain. Controls many other glands.
  Hormones: Growth hormone, ADH (water balance), Oxytocin (childbirth).
  Growth hormone disorders: dwarfism (deficiency), gigantism (excess).

Step 3 — Thyroid (neck).
  Produces THYROXINE (needs iodine).
  Controls metabolism, body temperature, growth.
  Hypothyroidism: tired, weight gain (treat with thyroxine pills).
  Hyperthyroidism: weight loss, anxiety.
  Iodine deficiency: GOITRE (thyroid swells). Iodised salt prevents this.

Step 4 — Pancreas.
  Produces INSULIN (lowers blood sugar) and GLUCAGON (raises blood sugar).
  DIABETES (type 1 or 2): insufficient or ineffective insulin.
  Treatment: insulin injections (type 1), diet/exercise/medication (type 2).
  India has ~80 million diabetics — 'diabetes capital'.

Step 5 — Adrenal (above kidneys).
  Produces ADRENALINE during stress/danger.
  Effects: heart rate↑, breathing↑, pupils dilate, sugar released for energy.
  'FIGHT OR FLIGHT' response. Survival mechanism.

Step 6 — Sex hormones.
  TESTES: testosterone (male sexual development).
  OVARIES: estrogen, progesterone (female sexual development, menstruation, pregnancy).
  Puberty: surge in these hormones.

Step 7 — Comparison with nervous system.
  NERVOUS: fast (electrical), short-term effect, specific target.
  ENDOCRINE: slow (chemical), longer-term, broader effect (via blood reaches all organs).
  Together they coordinate body.

Step 8 — Diseases.
  Hormone imbalances cause major diseases. Endocrinology is a major medical specialty.

Step 9 — Indian context.
  Indian Diabetes Federation tracks 80M+ diabetics.
  AIIMS has world-class endocrinology departments.
  Indian iodised salt programme drastically reduced goitre.

✦ Answer: Endocrine system = glands that secrete hormones via blood. Key hormones: PITUITARY (growth — master gland), THYROID (thyroxine — metabolism), PANCREAS (insulin — sugar; diabetes if low), ADRENAL (adrenaline — fight/flight), SEX HORMONES (puberty, reproduction). Slower but longer-lasting than nervous system. Indian context: 80M+ diabetics; iodised salt has reduced goitre dramatically.

Practice — Control and Coordination

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