Overview of Endocrine Glands PDF

Overview of endocrine glands Dr. Adel Mohamed Aboregela Assistant professor of Human Anatomy and Embryology FAIMER fellowship of Medical Education, ASU MENA-FRI, Philadelphia, USA Faculty of Medicine, University of Bisha...

Overview of endocrine glands Dr. Adel Mohamed Aboregela Assistant professor of Human Anatomy and Embryology FAIMER fellowship of Medical Education, ASU MENA-FRI, Philadelphia, USA Faculty of Medicine, University of Bisha [email protected] 00966505163578 Date: October 10, 2024 1 Endocrine glands In the head and neck: 1. Pituitary (Hypophysis Cerebri) 2. Pineal 3. Thyroid 4. Parathyroid In the Abdomen and Pelvis 1. Suprarenal 2. Islets of Langerhans of the pancreas 3. Interstitial cells of testis 4. Ovary 6 Pituitary gland (the master endocrine gland) It is vital to life A small, oval structure attached to the undersurface of the brain by the infundibulum The gland is well protected by its location in the sella turcica. It is divided into an anterior lobe (adenohypophysis) [subdivided into pars anterior, pars intermedia and pars tuberalis] and a posterior lobe (neurohypophysis) 7 8 Blood Supply Superior and inferior hypophyseal arteries, branches of the internal carotid artery. Functions of the Pituitary Gland The pituitary gland influences the activities of many other endocrine glands. The pituitary gland is itself controlled by the hypothalamus and the activities of the hypothalamus are modified by the central nervous system and by the plasma levels of the circulating electrolytes and hormones. 9 10 Pineal gland A small cone-shaped body that projects posteriorly from the brain with rich blood supply. Functions of the Pineal Gland It can influence the pituitary gland, the islets of Langerhans of the pancreas, the parathyroids, the adrenals, and the gonads. The pineal secretions, reach their target organs via the bloodstream or through the cerebrospinal fluid. Their actions are mainly inhibitory and either directly inhibit the production of hormones or indirectly inhibit the secretion of releasing factors by the hypothalamus 11 12 Thyroid Gland The thyroid gland consists of right and left lobes connected by a narrow isthmus. Each lobe is pear shaped, with its apex directed upward; its base down to the level of the fourth or fifth tracheal ring. The isthmus extends across the midline in front of the second, third, and fourth tracheal rings. A pyramidal lobe is often project upward from the isthmus, usually to the left of the midline. It attaches to the larynx and the trachea by strong facia. 13 Blood Supply Superior thyroid artery, the inferior thyroid artery, and sometimes the thyroidea ima. The superior thyroid artery, a branch of the external carotid artery, reaches the upper pole of each lobe, accompanied by the external laryngeal nerve The inferior thyroid artery, a branch of thyrocervical trunk, reaches the gland with recurrent laryngeal nerve. The thyroidea ima, from the brachiocephalic artery or the arch 14 of the aorta. In front of the trachea to the isthmus Functions of the thyroid gland Thyroxine and triiodothyronine, increase the metabolic activity of most cells in the body. The parafollicular cells produce calcitonin, which lowers the level of blood 15 calcium. Parathyroid Glands Four ovoid bodies measuring about 6 mm long related to the posterior border of the thyroid gland The two superior glands lie at the middle of the posterior border of the thyroid gland. The two inferior glands lie close to the inferior poles of the thyroid gland. Supplied by superior and inferior thyroid arteries. The chief cells produce the parathyroid hormone, which controls bone-blood calcium levels. 16 Suprarenal gland Two yellowish retroperitoneal organs that lie on the upper poles of the kidneys, surrounded by renal fascia. Each gland has a yellow cortex and a dark brown medulla. The right suprarenal gland is pyramid shaped and caps the upper pole of the right kidney. The left suprarenal gland is crescentic in shape and extends along the medial border of the left kidney from the upper pole to the hilus. 17 Function The cortex of the suprarenal glands secretes mineral corticoids (control of fluid and electrolyte balance), glucocorticoids (control of the metabolism of carbohydrates, fats and proteins) and small amounts of sex hormones (probably play a role in the prepubertal development of the sex organs). The medulla of the suprarenal glands secretes the catecholamines (epinephrine and norepinephrine). 18 Pancreas The pancreas is both an exocrine and endocrine gland. The exocrine portion of the gland produces a secretion that contains enzymes capable of hydrolyzing proteins, fats and carbohydrates. The endocrine portion of the gland, the pancreatic islets (islets of Langerhans), produces the hormones insulin and glucagon, which play a key role in carbohydrate metabolism. 20 21 Ovary Each ovary is oval shaped, lies against the lateral wall of the pelvis in a depression (ovarian fossa) Surrounded by a thin fibrous capsule (tunica albuginea) The ovaries are responsible for the production of the female germ cells (the ova) and the female sex hormones (estrogen and progesterone) in the sexually mature female. The ovarian artery arises from the abdominal aorta The ovarian vein drains into the IVC on the right side and 22 into the left renal vein on the left side. Testis Firm, mobile organ within the scrotum (the left is lower) Surrounded by a tough fibrous capsule (tunica albuginea) Fibrous septa divide the organ into lobules with 1:3 coiled seminiferous tubules in each lobule. Each lobule contains connective tissue with endocrine interstitial cells (Leydig cells) secreting testosterone The testicular artery arises from the abdominal aorta The testicular vein drains into the IVC on the right side and 24 into the left renal vein on the left side.