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ICSE Class 10 · Biology · Chapter 13

Endocrine Glands

9 topics · 15 questions

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Everything you need, in order

Introduction to Endocrine System

  • Endocrine System: System of ductless glands that secrete hormones directly into bloodstream.
  • Hormones: Chemical messengers. Produced in small quantities. Transported by blood. Act on target organs.
  • Difference from Nervous System: Nervous system - fast, electrical impulses; Endocrine system - slow, chemical messengers.
  • Exocrine vs Endocrine: Exocrine glands have ducts (salivary glands), Endocrine glands are ductless (thyroid, pituitary).
  • Functions: (1) Regulation of metabolism, (2) Growth and development, (3) Reproduction, (4) Homeostasis, (5) Stress response.
  • Diagram Importance: Diagram showing location of endocrine glands in human body is essential for ICSE.

Pituitary Gland - Master Gland

  • Pituitary Gland: Small pea-sized gland. Located at base of brain in sella turcica.
  • Structure: Two lobes - Anterior (adenohypophysis) and Posterior (neurohypophysis).
  • Anterior Pituitary Hormones: (1) Growth Hormone (GH) - promotes growth, (2) TSH - stimulates thyroid, (3) ACTH - stimulates adrenal cortex, (4) FSH - follicle development, (5) LH - ovulation and testosterone production, (6) Prolactin - milk production.
  • Posterior Pituitary Hormones: (1) ADH (vasopressin) - water reabsorption, (2) Oxytocin - uterine contraction and milk ejection.
  • Disorders: (1) Gigantism (excess GH in childhood), (2) Dwarfism (GH deficiency), (3) Diabetes insipidus (ADH deficiency).
  • Regulation: Controlled by hypothalamus via releasing hormones.

Thyroid Gland

  • Thyroid Gland: Butterfly-shaped gland. Located in neck, in front of trachea.
  • Hormones: (1) Thyroxine (T4) - regulates metabolism, (2) Triiodothyronine (T3) - active form of T4, (3) Calcitonin - lowers blood calcium.
  • Functions: (1) Controls metabolic rate, (2) Growth and development, (3) Calcium homeostasis.
  • Iodine: Essential for thyroid hormone synthesis. Deficiency causes goiter.
  • Disorders: (1) Hypothyroidism (cretinism in children, myxedema in adults), (2) Hyperthyroidism (Graves' disease, exophthalmia).
  • Diagram Importance: Labeled diagram of thyroid gland showing follicles is important.

Parathyroid Glands

  • Parathyroid Glands: Four small glands. Located behind thyroid gland.
  • Hormone: Parathyroid hormone (PTH) - increases blood calcium.
  • Functions: (1) Increases calcium absorption from intestines, (2) Releases calcium from bones, (3) Reduces calcium excretion by kidneys.
  • Regulation: Works with calcitonin from thyroid to maintain calcium balance.
  • Disorders: (1) Hypoparathyroidism - low calcium, tetany, (2) Hyperparathyroidism - high calcium, kidney stones.

Adrenal Glands

  • Adrenal Glands: Two glands. Located on top of kidneys.
  • Structure: Outer cortex and inner medulla.
  • Adrenal Cortex Hormones: (1) Mineralocorticoids (aldosterone) - sodium and water balance, (2) Glucocorticoids (cortisol) - stress response, metabolism, (3) Sex hormones (androgens).
  • Adrenal Medulla Hormones: (1) Adrenaline (epinephrine) - fight or flight response, (2) Noradrenaline (norepinephrine) - increases heart rate and blood pressure.
  • Functions: Stress response, blood pressure regulation, metabolism.
  • Disorders: (1) Addison's disease (cortisol deficiency), (2) Cushing's syndrome (cortisol excess).

Pancreas - Islets of Langerhans

  • Pancreas: Mixed gland. Located behind stomach. Has exocrine (digestive enzymes) and endocrine (hormones) functions.
  • Islets of Langerhans: Endocrine part. Alpha cells and beta cells.
  • Hormones: (1) Insulin (beta cells) - lowers blood glucose, (2) Glucagon (alpha cells) - raises blood glucose.
  • Functions: Regulates blood sugar levels. Insulin promotes glucose uptake by cells.
  • Diabetes Mellitus: (1) Type 1 - insulin deficiency, (2) Type 2 - insulin resistance.
  • Regulation: Maintains glucose homeostasis.

Other Endocrine Glands

  • Testes: Produce testosterone - male secondary sexual characteristics, spermatogenesis.
  • Ovaries: Produce estrogen and progesterone - female secondary sexual characteristics, menstrual cycle.
  • Pineal Gland: Produces melatonin - regulates sleep-wake cycle.
  • Thymus Gland: Produces thymosin - immune system development (active in childhood).
  • Hypothalamus: Produces releasing hormones that control pituitary gland.

Feedback Mechanisms

  • Negative Feedback: Hormone secretion stops when level reaches optimum. Example: TSH secretion decreases when thyroid hormone increases.
  • Positive Feedback: Hormone secretion continues until process completes. Example: Oxytocin during childbirth.
  • Importance: Maintains hormone balance and homeostasis.
  • Diagram Importance: Diagram showing feedback mechanism in hormone regulation is crucial.

Disorders of Endocrine System

  • Diabetes Mellitus: High blood sugar. Type 1 (autoimmune), Type 2 (lifestyle). Symptoms: frequent urination, thirst, weight loss.
  • Goiter: Thyroid enlargement due to iodine deficiency. Prevented by iodized salt.
  • Gigantism and Acromegaly: Excess GH. Gigantism in children, acromegaly in adults.
  • Dwarfism: GH deficiency in childhood. Short stature but normal intelligence.
  • Addison's Disease: Adrenal insufficiency. Symptoms: fatigue, low blood pressure.
  • Cushing's Syndrome: Excess cortisol. Symptoms: moon face, buffalo hump.
  • Prevention: Balanced diet, regular exercise, stress management.

Quiz

Test your knowledge

Multiple choice

  1. Question 1 of 15Knowledge
    The master gland of endocrine system is:
  2. Question 2 of 15Knowledge
    Growth hormone is secreted by:
  3. Question 3 of 15Knowledge
    The hormone that regulates blood sugar level is:
  4. Question 4 of 15Knowledge
    Thyroxine hormone contains:
  5. Question 5 of 15Knowledge
    The gland located on top of kidneys is:
  6. Question 6 of 15Knowledge
    ADH is secreted by:
  7. Question 7 of 15Comprehension
    The hormone that prepares body for fight or flight is:
  8. Question 8 of 15Knowledge
    Diabetes mellitus is caused by deficiency of:
  9. Question 9 of 15Assertion-Reasoning
    Assertion (A): Endocrine glands are ductless. Reason (R): They secrete hormones directly into blood.
  10. Question 10 of 15Knowledge
    The hormone that regulates calcium level is:
  11. Question 11 of 15Application
    Gigantism is caused by:
  12. Question 12 of 15Knowledge
    The islets of Langerhans are located in:
  13. Question 13 of 15Knowledge
    The hormone melatonin is secreted by:
  14. Question 14 of 15Knowledge
    The condition of low blood calcium is called:
  15. Question 15 of 15Comprehension
    The feedback mechanism that stops hormone secretion is:

0 of 15 answered