Anatomy of the Endocrine System PDF

Anatomy of the Endocrine System By: Dr. Khulood Al-Khater Department of Anatomy Wednesday, November 6, 2024 ...

Anatomy of the Endocrine System By: Dr. Khulood Al-Khater Department of Anatomy Wednesday, November 6, 2024  Learning Objectives By the end of this lecture, students should be able to understand: The definition of endocrine glands The location, relations, description, parts and blood supply of the major endocrine glands in the body Some clinical points related to these glands 2 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Endocrine Glands 3 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Endocrine Glands: Definition 4 Wednesday, November 6, 2024 Anatomy of the Endocrine System  The Pituitary Gland (hypophysis cerebri) 5 Wednesday, November 6, 2024 Anatomy of the Endocrine System  The Pituitary Gland ▪ A small, oval organ attached to the undersurface of the brain by the infundibulum. ▪ The gland is well protected by its location in the sella turcica of the sphenoid bone. ▪ Because the hormones produced by the gland influence the activities of many other endocrine glands, it is often referred to as the master endocrine gland. For this reason, it is vital to life Wednesday, November 6, 2024  The Pituitary Gland: Relations ▪ Anterior: Sphenoid sinus. ▪ Posterior: the basilar artery, and the pons ▪ Superior: Diaphragma sellae has a central aperture that allows the passage of the infundibulum and separates the anterior lobe from the optic chiasma. ▪ Inferior: Body of the sphenoid, with its sphenoid air sinuses. ▪ Lateral: Cavernous sinus and its contents. 7 Wednesday, November 6, 2024 Anatomy of the Endocrine System  The Pituitary Gland: Relations 8 Wednesday, November 6, 2024 Anatomy of the Endocrine System  The Pituitary Gland: Relations 9 Wednesday, November 6, 2024 Anatomy of the Endocrine System  The Pituitary Gland: Lobes The pituitary gland has two lobes: Anterior lobe (adenohypophysis) Posterior lobe (neurohypophysis) Adenohypophysis Neurohypophysis 10 Wednesday, November 6, 2024 Anatomy of the Endocrine System  The Pituitary Gland: Blood supply The superior and inferior hypophyseal arteries, branches of the internal carotid artery The veins drain into the intercavernous sinuses 11 Wednesday, November 6, 2024 Anatomy of the Endocrine System  The Pituitary Gland: Function ▪ The pituitary gland influences the activities of many other endocrine glands. ▪ The pituitary gland is itself controlled by the hypothalamus 12 Wednesday, November 6, 2024 Anatomy of the Endocrine System  The Pituitary Gland: Function 13 Wednesday, November 6, 2024 Anatomy of the Endocrine System  clinical application 14 Wednesday, November 6, 2024 Anatomy of the Endocrine System  clinical application ▪ Trans-sphenoidal surgery 15 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Pineal Gland The pineal gland is a small cone-shaped gland that projects posteriorly from the posterior end of the roof of the third ventricle of the brain 16 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Pineal Gland ▪ It influences the activities of the pituitary gland, the islets of Langerhans of the pancreas, the parathyroids, the adrenals, and the gonads ▪ Secretes melatonin ▪ Circadian rhythm (more active at night) Their actions are mainly inhibitory and either directly inhibit the production of hormones or indirectly inhibit the secretion of releasing factors by the hypothalamus 17 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Thyroid Gland The thyroid gland is anterior in the neck below and lateral to the thyroid cartilage 18 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Thyroid Gland: Lobes It consists of right and left lobes connected by a narrow isthmus 19 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Thyroid Gland: Lobes The isthmus extends across the midline in front of the second, third, and fourth tracheal rings. A pyramidal lobe is often present 20 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Thyroid Gland: Relations Posterolateral: Carotid sheath with the common carotid artery, the internal jugular vein, and the vagus nerve Medial: The larynx, the trachea, the pharynx, and the esophagus Posterior: Superior and inferior parathyroid glands 21 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Thyroid Gland: Blood supply The arteries to the thyroid gland are the superior thyroid artery, the inferior thyroid artery, and sometimes the thyroidea ima. The arteries anastomose profusely with one another over the surface of the gland. 22 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Thyroid Gland: Blood supply The superior thyroid artery is a branch of the external carotid artery, descends to the upper pole of each lobe The inferior thyroid artery arises from the subclavian artery The thyroidea ima, if present, may arise from the brachiocephalic artery or the arch of the aorta 23 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Thyroid Gland Functions ▪ The thyroid hormones, thyroxine and triiodothyronine, increase the metabolic activity of most cells in the body. ▪ The parafollicular cells produce the hormone thyrocalcitonin, which lowers the level of blood calcium. Wednesday, November 6, 2024  clinical application Goiter a diffuse irregular enlargement of the thyroid gland 25 Wednesday, November 6, 2024 Anatomy of the Endocrine System  clinical application 26 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Parathyroid Glands The parathyroid glands are ovoid bodies measuring about 6 mm long in their greatest diameter. They are four in number and are closely related to the posterior border of the thyroid gland, lying within its fascial capsule 27 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Parathyroid Gland Functions ▪ The chief cells produce the parathyroid hormone, which stimulates osteoclastic activity in bones, thus mobilizing the bone calcium and increasing the calcium levels in the blood. ▪ The parathyroid hormone also stimulates the absorption of dietary calcium from the small intestine and the reabsorption of calcium in the proximal convoluted tubules of the kidney. ▪ The calcium levels in the blood control the secretion of the parathyroid hormone. Wednesday, November 6, 2024  ▪ The thymus is a flattened, Thymus Gland bilobed structure lying between the sternum and the pericardium in the anterior mediastinum. ▪ It reaches its largest size relative to the size of the body in the newborn infant ▪ The thymus continues to grow until puberty but thereafter undergoes involution. ▪ It has a pink, lobulated appearance and is the site for development of T (thymic) lymphocytes. Anatomy of the Endocrine System 29 Wednesday, November 6, 2024  Adrenal (suprarenal) Glands ▪ Location: on the upper pole of the kidneys ▪ Surrounded by renal fascia ▪ Shape: right is pyramidal left is crescentic 30 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Adrenal Glands: Inner structure ▪ Structure: outer cortex & inner medulla GFR 31 Wednesday, November 6, 2024 Anatomy of the Endocrine System Wednesday, November 6, 2024  Adrenal Glands: Blood supply ▪ Arterial blood supply: from 3 sources: Aorta Renal artery Inferior phrenic artery ▪ Venous drainage: to IVC on the right side and to renal vein on the left side 33 Wednesday, November 6, 2024 Anatomy of the Endocrine System  clinical application ▪ Cushing’s syndrome: results from cortical hyperplasia, adenoma or carcinoma increased ▪ Addison’s disease: pigmentation, adrenocortical muscular moon-shaped face, weakness, insufficiency weight loss, truncal obesity, abnormal hairiness ▪ Pheochromocytoma: and (hirsutism), and tumor of the medulla hypotension hypertension 34 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Islets of Langerhans in the pancreas ▪ α-cell: glucagon ▪ β-cell: insulin These play a key role in carbohydrate metabolism 35 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Gonads ▪ Ovary: estrogens→ proliferative phase progesterone→ secretory phase 36 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Gonads Testis: Interstitial cells of Leydig Produce androgens (testosterone) 37 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Placenta ▪ It is the organ that carries out respiration, excretion & nutrition of the embryo ▪ Flattened & circular with a diameter of ~20 cm and a thickness of ~2.5 cm and wt of ~500 g ▪ It secretes estrogens, progesterone, chorionic gonadotropin, and chorionic somatomamotropin. 38 Wednesday, November 6, 2024 Anatomy of the Endocrine System  Thank You 39 Wednesday, November 6, 2024 Anatomy of the Endocrine System