The Entire Endocrine System in 45 minutes

🌐 Website: https://taimtalksmed.com/ 🫀 Help keep this content free:    / @taimtalksmed   🔬 Get 10% off anatomy models (code: TAIMTALKSMED): https://anatomywarehouse.com?aff=34 📲 Instagram:   / taimtalksmed   Content: 00:00 Introduction 00:33 Content 01:33 What is a hormone? 04:54 Peptide and Protein Hormones 06:05 Steroid Hormones 06:49 Amino Acid-Derived Hormones 08:05 How Hormones Communicate with Cells 08:29 Cell Surface Receptors 11:35 Intracellular Receptors 13:38 Clinical Relevance of Receptor Location 14:22 Major Endocrine Glands 14:46 Hypothalamus and Pituitary 15:40 Anterior Pituitary (Adenohypophysis) 19:20 Posterior Pituitary (Neurohypophysis) 21:44 Thyroid Gland 26:26 Parathyroid Glands 28:26 Adrenal Glands 28:49 Adrenal Cortex 32:57 Adrenal Medulla 34:35 Pancreas 38:43 Male Gonads (Testes) 39:19 Female Gonads (Ovaries) 40:20 Pineal Gland 41:22 How the Endocrine System is Balances 41:35 Negative Feedback 43:47 Positive Feedback 44:37 Hormonal Rhythms 45:16 Pulsatile Secretion 46:16 Ending What Is a Hormone & Endocrine Signaling Hormone: chemical messenger released directly into bloodstream acting on distant target cells Endocrine vs exocrine glands: ductless secretion vs duct-based secretion Endocrine signaling: systemic, blood-borne communication Paracrine signaling: local signaling to nearby cells Autocrine signaling: self-targeting signaling Receptor specificity: lock-and-key principle Hormone potency: low concentrations with signal amplification Hormone Classes Peptide & protein hormones: water-soluble, cell-surface receptors Steroid hormones: cholesterol-derived, intracellular receptors Amino acid derivatives: Thyroid hormones (T3, T4): tyrosine-derived, lipid-soluble Catecholamines (epinephrine, norepinephrine): tyrosine-derived, water-soluble Melatonin: tryptophan-derived Hormone Receptors & Signal Transduction Cell surface receptors: G-protein-coupled receptors (Gs, Gi, Gq) Second messengers: cAMP, IP3, DAG, Ca²⁺ Receptor tyrosine kinases: insulin receptor Intracellular receptors: steroid & thyroid hormone receptors Fast, short-acting signaling vs slow, long-lasting gene transcription effects Hypothalamus & Pituitary Hypothalamus: releasing and inhibiting hormones Pituitary gland (hypophysis): located in sella turcica, connected via infundibulum Anterior pituitary (adenohypophysis): Growth hormone (GH) → IGF-1 Prolactin ACTH → adrenal cortex TSH → thyroid gland FSH & LH → gonads Hypothalamic-hypophyseal portal system Posterior pituitary (neurohypophysis): ADH (vasopressin): water reabsorption via aquaporin-2 Oxytocin: labor contractions & milk ejection Supraoptic & paraventricular nuclei Clinical notes: Diabetes insipidus SIADH Thyroid Gland Location: anterior neck, two lobes + isthmus Follicular cells & thyroid follicles Colloid & thyroglobulin Sodium-iodide symporter Thyroid peroxidase (TPO) MIT, DIT → T3 & T4 synthesis Peripheral T4 → T3 conversion Calcitonin from parafollicular (C) cells Clinical correlations: Hyperthyroidism (Graves’ disease) Hypothyroidism (Hashimoto’s thyroiditis, iodine deficiency) Parathyroid Glands Parathyroid hormone (PTH): primary calcium regulator Bone resorption (osteoclast activation) Renal calcium reabsorption & phosphate excretion Vitamin D activation (calcitriol) Intestinal calcium absorption Clinical signs: Hyperparathyroidism Hypoparathyroidism Chvostek’s sign Trousseau’s sign Adrenal Glands Adrenal cortex (GFR): Zona glomerulosa → aldosterone (RAAS, potassium) Zona fasciculata → cortisol Zona reticularis → DHEA, androstenedione Cortisol effects: Gluconeogenesis Lipolysis Protein catabolism Anti-inflammatory & immunosuppressive actions Clinical: Cushing syndrome Addison disease Adrenal medulla: Epinephrine & norepinephrine Alpha & beta adrenergic receptors Fight-or-flight response Pheochromocytoma Pancreas Exocrine pancreas: acinar cells, digestive enzymes Endocrine pancreas: islets of Langerhans Beta cells → insulin (GLUT4 translocation) Alpha cells → glucagon Delta cells → somatostatin Clinical: Type 1 diabetes mellitus Type 2 diabetes mellitus Diabetic ketoacidosis Gonads Testes: Leydig cells → testosterone Sertoli cells → spermatogenesis, inhibin Ovaries: Estrogen (follicular phase) Progesterone (corpus luteum) Ovulation & menstrual cycle regulation Pineal Gland Location: epithalamus Melatonin secretion Suprachiasmatic nucleus Retinohypothalamic tract Circadian rhythm regulation Endocrine Regulation Negative feedback Positive feedback Circadian rhythms Pulsatile secretion Sources Memorix Anatomy StatPearls / NCBI Bookshelf – Endocrinology & Cortisol Williams Textbook of Endocrinology Boron & Boulpaep – Medical Physiology Programs Used: Complete Anatomy, Biorender, PowerPoint