Overview of the Endocrine System & Hormones; Major Endocrine Glands and their Functions; Hormonal Regulation: Feedback Loops & HPA Axis; Endocrine Disorders & Environmental Disruptors; Future Directions and Ethical Considerations

The Endocrine System

Biology

The Endocrine System

Glands, hormones, and their vital roles in human physiology.

Agenda

• Overview of the Endocrine System & Hormones

• Major Endocrine Glands and their Functions

• Hormonal Regulation: Feedback Loops & HPA Axis

• Endocrine Disorders & Environmental Disruptors

• Future Directions and Ethical Considerations

The Endocrine System: Overview

The endocrine system comprises a complex network of glands that produce and secrete hormones directly into the bloodstream. These chemical messengers regulate diverse physiological processes, from metabolism and growth to mood and reproduction. This intricate system is essential for maintaining internal homeostasis, exemplified by the adrenal glands' stress response or the pancreas's glucose regulation.

Diagram of the human endocrine system and its glands.

Hormones: Chemical Messengers

Hormones are potent chemical signaling molecules secreted by endocrine glands that regulate diverse physiological processes. They are categorized by chemical structure, such as steroid hormones like testosterone, peptide hormones like insulin, or amine hormones like epinephrine. These molecules specifically interact with target cells via specialized receptors, triggering precise biological responses.

Hand-drawn hormones: Dopamine, Serotonin, Testosterone, and more.

Diagram of the human endocrine system and its major glands.

Key Endocrine Glands

• Hypothalamus, Pituitary: Neuroendocrine control, hormone secretion.

• Pineal gland: Melatonin, circadian rhythm regulation.

• Thyroid, Parathyroid: Metabolism, calcium homeostasis via hormones.

• Adrenal, Pancreas, Gonads: Stress, glucose, reproductive functions.

Hypothalamus-Pituitary Axis

The Hypothalamic-Pituitary Axis (HPA) is the neuroendocrine hub, integrating nervous and endocrine signals. The hypothalamus releases specific hormones, like GnRH, directly regulating anterior pituitary function. This control, exemplified by GnRH stimulating LH and FSH for reproduction, orchestrates systemic endocrine responses.

HPA axis: Hypothalamus, pituitary, and adrenal glands regulate cortisol.

Thyroid &amp; Parathyroid Functions

Diagram of the human body's stress response system.

Adrenal Glands: Stress Response

• Cortisol (cortex): manages chronic stress, glucose metabolism, immune suppression.

• Aldosterone (cortex): regulates Na+/K+ balance, blood pressure.

• Epinephrine/Norepinephrine (medulla): acute 'fight-or-flight' response.

Pancreas: Glucose Regulation

The pancreatic islets of Langerhans are central to glucose homeostasis, secreting antagonistic hormones: insulin and glucagon. Beta cells release insulin, lowering blood glucose by promoting cellular uptake and glycogenesis, while alpha cells secrete glucagon, raising levels via glycogenolysis and gluconeogenesis. This precise, negative feedback system is vital for cellular energy and preventing metabolic disorders like diabetes mellitus.

The Endocrine System

Overview of the Endocrine System & Hormones; Major Endocrine Glands and their Functions; Hormonal Regulation: Feedback Loops & HPA Axis; Endocrine Disorders & Environmental Disruptors; Future Directions and Ethical Considerations

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