Endocrine System and Hormones Lecture

The endocrine system consists of a complex network of ductless glands that secrete hormones directly into the bloodstream, allowing for communication between different parts of the body over long distances. This system plays a crucial role in regulating a wide variety of physiological processes, including metabolism, growth, reproduction, and response to environmental changes or stressors.

Major endocrine glands include:

• Pineal gland: Secretes melatonin which regulates sleep cycles and circadian rhythms.

• Hypothalamus: Serves as a major link between the endocrine and nervous systems, controlling the pituitary gland and regulating numerous autonomic functions.

• Pituitary gland: Often referred to as the "master gland," it regulates other endocrine glands and releases hormones that affect growth, metabolism, and reproductive functions.

• Thyroid gland: Produces thyroid hormones (T3 and T4) which are vital for metabolism, energy production, and maintaining normal bodily functions.

• Thymus: Plays a key role in the immune system by producing thymosin, which is involved in the maturation of T-cells.

• Adrenal glands: Composed of the adrenal cortex and adrenal medulla, these glands produce hormones such as cortisol, which regulates stress responses, and epinephrine, which is crucial for the fight-or-flight response.

• Pancreas: Functions both as an endocrine gland, secreting insulin and glucagon to control blood sugar levels, and as an exocrine gland for digestion.

• Gonads: Ovaries in females produce estrogen and progesterone, crucial for reproductive health, while testes in males produce testosterone, which influences male characteristics and reproduction.