Chemical Coordination and Integration

1. Endocrine System Overview

• Master chemical coordinators are hormones.
• Target cells have receptors specific for a particular hormone.
• Hormones regulate diverse processes like growth, development, reproduction, and metabolism.

2. Major Endocrine Glands and Hormones

• Pituitary Gland:

  • Location: In sella tursica.
  • Produces GH, TSH, Prolactin, ACTH, LH, FSH.
  • Regulates growth, metabolism, reproduction.

• Thyroid Gland:

  • Location: anterior neck.
  • Secretes Thyroxine and Triiodothyronine.
  • Essential for growth and metabolism.

• Parathyroid Glands:

  • Location: Embedded within the Thyroid gland.
  • Produces Parathyroid Hormone (PTH).
  • Regulates Calcium homeostasis.

• Adrenal Glands:

  • Location: On top each kidney.
  • Secretes Adrenaline, Noradrenaline, Cortisol, and Aldosterone.
  • Involved in stress responses, metabolism, electrolyte balance.

• Pancreas:

  • Role: both exocrine and endocrine.
  • Secretes Insulin and Glucagon.
  • Regulates blood glucose levels.

3. Mechanisms of Hormone Action

• Target Cells: specific cell types respond to a particular hormone.
• Binding to receptors triggers intracellular messengers like cAMP, IP3.
• Cellular responses like gene expression, metabolic regulation occur.

4. Regulation of Hormone Secretion

• Principle of feedback - maintains the body’s internal balance (homeostasis).
• Negative Feedback Loop: Hormone output decreases when desired effect is achieved.
• Positive Feedback Loop: Hormone output increases to enhance the effect further.

5. Hormonal Dysfunctions

• Hypopituitarism: decreased pituitary hormone output.
• Hyperpituitarism: excess hormone secretion.
• Thyroid Disorders: Hypo/Hyper secretions affect metabolism.
• Diabetes Mellitus: Type 1 and Type 2 related to insulin.
• Cushing’s and Addison’s: Adrenal hormone imbalances.
• Pheochromocytoma: Adrenal tumor causing high BP.