Endocrine System in Humans – Long Answer Questions (CBSE Class 10 Science)
Medium Level (Application & Explanation)
Q1. Explain how the endocrine system coordinates body functions using hormones. Compare it with the nervous system using two examples from daily life.
Answer:
The endocrine system uses hormones as chemical messengers. These are released by ductless (endocrine) glands directly into the bloodstream. The blood carries them to target organs, where they bring changes such as speeding up, slowing down, or modifying organ functions.
In contrast, the nervous system sends electrical signals through nerves, which act faster but for a shorter period.
Example 1: Before an exam, the adrenal glands release adrenaline, causing an increased heart rate, faster breathing, and alertness—a quick response to stress.
Example 2: After eating sweets, the pancreas releases insulin, which helps cells absorb glucose and reduces blood sugar—a slower, longer-lasting effect.
Thus, the endocrine system supports long-term regulation (growth, metabolism), while the nervous system provides instant actions. Both systems work together to maintain body balance (homeostasis).
Q2. Why is the pituitary gland called the “master gland”? Describe its hormones, functions, and consequences of imbalance.
Answer:
The pituitary gland, located at the base of the brain, is called the “master gland” because it controls other endocrine glands and regulates many body functions.
Important hormones include:
Growth hormone (GH): Controls body growth.
Thyroid Stimulating Hormone (TSH): Stimulates the thyroid gland to make thyroxine.
Adrenocorticotropic Hormone (ACTH): Stimulates the adrenal glands.
Key functions: Regulates growth, controls metabolism indirectly via TSH, supports stress response via ACTH, and helps in water balance and reproduction.
Imbalances:
GH deficiency in childhood causes dwarfism (short stature).
Excess GH causes gigantism (abnormally tall).
If TSH is affected, thyroid function and metabolism get disturbed.
Therefore, the pituitary acts like a central coordinator, ensuring that other glands work properly and that body functions stay balanced.
Q3. Describe the structure, hormone, functions, and disorders of the thyroid gland. Why is iodine important?
Answer:
The thyroid gland lies in the front of the neck, below the Adam’s apple. It produces thyroxine, a hormone that needs iodine for its synthesis.
Functions of thyroxine:
Controls metabolism—how the body uses food to produce energy.
Supports normal growth and brain development.
Helps regulate weight and energy levels.
Disorders:
Goitre: A swelling in the neck due to iodine deficiency; the thyroid enlarges to work harder.
Hypothyroidism: Low thyroxine causing tiredness, weight gain, and slower mental and physical growth.
Hyperthyroidism: Excess thyroxine causing weight loss, fast heartbeat, and nervousness.
Importance of iodine: Without iodine, the thyroid cannot produce sufficient thyroxine. Hence, iodized salt is essential to prevent goitre and hypothyroidism, ensuring normal metabolic functioning and growth.
Q4. Explain how the pancreas maintains blood sugar levels using insulin and glucagon. What happens in diabetes mellitus?
Answer:
The pancreas, located behind the stomach, releases two key hormones:
Insulin: Lowers blood sugar by helping body cells absorb glucose for energy or storage.
Glucagon: Raises blood sugar by prompting the liver to release stored glucose, especially during fasting.
After a meal rich in sweets, insulin prevents blood sugar from rising too high by pushing glucose into cells.
During long gaps between meals, glucagon prevents low blood sugar by increasing glucose release into the blood.
In Diabetes Mellitus, the pancreas does not produce enough insulin or the body does not use it well. This causes high blood sugar, leading to thirst, frequent urination, and weakness. Some patients may need insulin injections and lifestyle changes.
The pancreas is both an endocrine (hormones) and exocrine (digestive juices) gland, showing its dual role in the body.
Q5. Describe the roles of the adrenal glands in stress and survival. Explain the actions of adrenaline, cortisol, and aldosterone with examples.
Answer:
The adrenal glands sit on top of each kidney. They help the body face danger and stress.
Key hormones:
Adrenaline (epinephrine): Triggers the fight or flight response—raises heart rate, breathing, moves more blood to muscles, and increases alertness. Example: Before an exam or when frightened by a loud sound, you may sweat and feel your heart race.
Cortisol: Helps manage long-term stress by keeping energy steady over time, like during exam weeks or long sports training.
Aldosterone: Controls salt and water balance, helping regulate blood pressure and body fluids.
Together, these hormones make the body react quickly to emergencies and cope with ongoing stress. The adrenal glands are essential for survival, ensuring the body has energy, oxygen, and fluid balance when needed.
High Complexity (Analytical & Scenario-Based)
Q6. A teenager reports tiredness, weight gain, and a visible neck swelling. Analyze the likely endocrine cause, connect it to hormone functions, and suggest simple measures.
Answer:
These symptoms point to the thyroid gland and suggest hypothyroidism with goitre. The swelling indicates the thyroid is working harder, possibly due to iodine deficiency, while low thyroxine explains tiredness and weight gain.
The pituitary releases TSH to push the thyroid to make thyroxine. If iodine is low, thyroxine stays low despite high effort, leading to goitre.
Effects of low thyroxine include slow metabolism, low energy, and sluggish growth and brain function if persistent.
Simple steps: Use iodized salt, eat iodine-rich foods (as advised locally), and maintain a balanced diet. Medical evaluation can confirm the condition and guide treatment.
Understanding the pituitary–thyroid link and the role of iodine helps explain why neck swelling and fatigue occur together in such cases.
Q7. Before a stage performance, a student feels shaky, sweaty, and the heart is pounding. Link these to adrenal hormones and suggest practical, science-based coping steps.
Answer:
These signs match the fight or flight effect of adrenaline from the adrenal glands. Adrenaline increases heart rate, breathing, and alertness to prepare the body for quick action.
It pushes more oxygen and glucose to muscles, explaining the shakiness and energy surge. Mild sweating and dilated pupils are also common.
For coping:
Practice slow, deep breathing to calm the heart and reduce adrenaline’s impact.
Do a brief warm-up or light jogging before going on stage to use the extra energy constructively.
Use positive self-talk to turn stress into focus.
Hydrate and avoid heavy sweets just before, to prevent sudden blood sugar swings.
Understanding that these are normal hormonal responses helps reduce fear and improves performance using the body’s natural stress tools.
Q8. Predict what happens if the pituitary does not release enough TSH. How will this affect the thyroid’s hormone, metabolism, and visible signs compared to iodine deficiency?
Answer:
Low TSH from the pituitary means the thyroid does not receive enough stimulation to make thyroxine. As a result, thyroxine levels fall, leading to slow metabolism, tiredness, and weight gain—typical of hypothyroidism.
Visible signs: Because the thyroid is not being pushed by TSH, neck swelling (goitre) may be less prominent than in iodine deficiency. In iodine deficiency, the thyroid tries to work harder but cannot make enough thyroxine, leading to a more noticeable swelling.
Common outcomes in both cases include low energy, cold intolerance, and slowed growth if prolonged.
Thus, both low TSH and low iodine reduce thyroxine, but the reasons differ: one is due to less pituitary stimulation, the other due to lack of raw material (iodine), often with a bigger goitre in the latter.
Q9. Evaluate how sex hormones guide puberty in boys and girls. Discuss what may happen if these hormones are imbalanced during adolescence.
Answer:
In boys, testosterone from the testes causes deeper voice, facial hair, muscle growth, and maturation of male reproductive organs. In girls, estrogen and progesterone from the ovaries lead to breast development, wider hips, start and regulation of the menstrual cycle, and growth of female reproductive organs.
If these hormones are imbalanced:
Boys may have delayed or limited facial hair, voice changes, or slower growth if testosterone is low.
Girls may have irregular periods, delayed breast development, or other puberty delays if estrogen/progesterone are low.
Balanced sex hormones ensure healthy growth, body shape, and reproductive health. Understanding these changes removes confusion and promotes body confidence during a normal life phase called puberty.
Q10. Design and analyze a simple school activity to observe the effects of adrenaline on the body. Include steps, observations, and scientific explanation.
