Endocrine System Lecture Notes PDF

Centro Escolar University - Makati School of Science and Technology Biological Sciences Department Human Anatomy and Physiology Lecture: Endocrine System Table of Contents: Introduction to Endocrin...

Centro Escolar University - Makati School of Science and Technology Biological Sciences Department Human Anatomy and Physiology Lecture: Endocrine System Table of Contents: Introduction to Endocrine System Different Organs Involved in Endocrine System Disorders associated with Endocrine System Presentation by: Montuya, John Gilbert A. Introduction to Endocrine System: The endocrine system is a complex regulatory network that regulates feedback mechanisms in the human body. It is the main gland or organ that is associated with the homeostasis of any physiological responses of our body. It consists of the following organs: Hypothalamus (nervous system) Pineal Gland Pituitary Gland (Anterior and Posterior) Testis and Ovaries Adrenal Gland (Medulla and Cortex) Thymus Gland Thyroid Gland Parathyroid Gland Pancreas Introduction to Endocrine System: Introduction to Endocrine Endocrine System: System Target Cells Endocrine System: Hormone Classes Endocrine System: Overview Anterior Pituitary Gland (Adenohypophysis) Hormones produced by the anterior pituitary: 1. Thyroid-stimulating hormone (TSH) stimulates the thyroid to produce thyroid hormones. 2. Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex to produce cortisol. 3. Gonadotropic hormones stimulate gonads to produce sex cells and hormones. Anterior Pituitary Gland (Adenohypophysis) 4. Prolactin (PRL) stimulates mammary glands to develop and produce milk only after childbirth. 5. Melanocyte-stimulating hormone (MSH) causes skin-color changes in many fishes, amphibians, and reptiles having melanophores, special skin cells that produce color variations. 6. Growth hormone (GH) promotes skeletal and muscular growth. Anterior Pituitary Gland (Adenohypophysis)  Posterior Pituitary Gland (Neurohypophysis) Stores antidiuretic hormone (ADH) and oxytocin that are produced by the hypothalamus – ADH (vasopressin) regulates water balance by reabsorbing water into the bloodstream. – Oxytocin causes uterine contractions during childbirth and allows milk to be released during nursing. Thyroid Gland: T3 and T4 Hormones It is a large gland located below the larynx. Iodine is needed in the diet to allow the thyroid gland to produce its hormones. It produces: thyroid hormone (TH) which regulates metabolism. calcitonin which helps lower blood Ca2+ levels by stimulating the deposition of calcium in the bones. The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3). Thyroid Gland: T3 and T4 Hormones Simple goiter – thyroid enlarges due to lack of iodine in the diet Hypothyroidism – low blood levels of thyroid hormones A. Congenital hypothyroidism: thyroid does not develop properly and is characterized by a short, stocky person who may have mental retardation B. Myxedema: hypothyroidism in adults characterized by lethargy, weight gain, loss of hair, cold intolerance, and thick, puffy skin Thyroid 3. Gland: Thyroid Gland:T3 and T4 Hormones Hyperthyroidism – excess thyroid hormones in the blood A. Exophthalmic goiter: characterized by enlargement of the thyroid gland, protrusion of the eyes, hyperactivity, and insomnia B. Thyroid tumor: can also cause hyperthyroidism Parathyroid Gland: PTH Small glands embedded in the surface of the thyroid gland Produces parathyroid hormone (PTH) – Causes blood Ca2+ level to increase by promoting osteoclast activity – Promotes reabsorption of Ca2+ by the kidneys Adrenal Gland: Medullar Cavity Hypothalamus initiates stimulation of hormone secretion in the adrenal medulla Produces hormones that allow a short-term response to stress (“fight or flight” response) – Epinephrine (adrenaline) – Norepinephrine (noradrenaline) Adrenal Gland: Cortex Region Produces hormones that provide a long-term response to stress Two major types of hormones – Glucocorticoids regulate carbohydrate, protein, and fat metabolism. suppress the body’s inflammatory response. e.g., cortisol and cortisone – Mineralocorticoids regulate salt and water balance. e.g., aldosterone (targets the kidney) Pancreas: Exocrine and Endocrine Gland Composed of two tissues: A. Exocrine: produces and secretes digestive juices B. Endocrine (islets of Langerhans): produces and secretes hormones 1. Insulin – secreted when blood glucose is high; stimulates the uptake of glucose by cells (muscle and liver) 2. Glucagon – secreted when blood glucose is low; stimulates the breakdown of glycogen in the liver Pancreas: Diabetes Disorder General symptoms include – frequent urination. – unusual hunger and/or thirst. – unexplained change in weight. – blurred vision. – sores that heal slowly or not at all. – excessive fatigue. It is the inability to control blood glucose levels. Normal Blood Sugar Level: 140 mg/L (7.8 mmol/L) There are two types: type 1 and type 2. 25.8 million people in the US have diabetes. Long-term effects are blindness, loss of limbs, nerve deterioration, kidney, and cardiovascular disease. Pancreas: Diabetes mellitus (Type 1) Type 1 (Hyperglycemia – Type 1) – It is normally early-onset. – Type 1 is an autoimmune disorder that tends to run in families. – Pancreatic cells are attacked and cannot produce insulin. – Need insulin injections are needed. Pancreas: Diabetes mellitus (Type 2) Type 2 (Hyperglycemia – Type 2) – Type 2 is normally adult-onset and is the most common type. – It tends to occur in obese, sedentary people. – Cells do not respond to insulin. – Diet and exercise are important for controlling this and may even prevent this. Pineal Gland: Circadian Rhythm Secretes melatonin that regulates the sleep/wake cycle (circadian rhythm) May also regulate sexual development Thymus Gland: Lymphocyte Maturation The thymus lies beneath the sternum. This gland is largest and most active during childhood. T lymphocytes mature here. It secretes hormones called thymosins that aid in differentiation of lymphocytes. Gonads: 9. GonadsReproduction-Related (Sex Glands) Glands Testis (Leydig Cells) - produces androgens (e.g., testosterone) – Stimulates growth of the penis and testes – Responsible for male sex characteristics such as facial, underarm, and pubic hair – Prompts the larynx and vocal cords to enlarge, resulting in a lower voice – Promotes muscular strength Gonads: Reproduction-Related Glands Ovaries - produces estrogen and progesterone – Stimulate the growth of the vagina and uterus – Responsible for secondary sex characteristics such as female body hair, fat distribution, and breast development – Responsible for egg maturation CamScanner CamScanner