医学英语课件：Endocrine System

1、Endocrine System,Ruan Lu ya Department of Endocrinology, The Second Affiliated Hospital of Wenzhou Medical University,New Words and Phrases,endocrine dwarf hormone growth hormone gland glandular reproduction cellular metabolism,New Words and Phrases,nutrient target tissue receptor hormonal steroid l

2、ipid protein proteinlike compound,New Words and Phrases,gonad cortex adrenal feedback kidney renin vitamin D calcium,New Words and Phrases,gastrointestinal pituitary thyroid parathyroid pancreas pineal sphenoid anterior lobe,New Words and Phrases,adenohypophysis posterior lobe neurohypophysis hypoth

3、alamus mammary antidiuretic oxytocin uterine(a),New Words and Phrases,throat larynx trachea isthmus thyroxine triiodothyronine calcitonin homeostasis,New Words and Phrases,medulla corticosteroids glucocorticoids cortisol mineralocorticoids aldosterone epinephrine norepinephrine,New Words and Phrases

4、,abdomen exocrine islets of Langerhans Insulin glucagon ovary Testes,Testis ovarian,New Words and Phrases,estradiol progesterone uterus(n) pregnancy testosterone melatonin puberty circadian rhythms,New Words and Phrases,thymus lymph gland lymphatic tissue lymphocyte thymosin,Lead-in,Why some people

5、reach excessive height and some are dwarfs? Most commonly it is due to abnormal secretion during childhood of a hormone called Growth Hormone by the pituitary gland.,Lead-in,Hormones are produced in small amount by endocrine glands, they affect the function of many vital organs.,Lead-in,This passage

6、 gives a brief description of the major endocrine glands, the hormones released by them, and the function of each.,Lead-in,The endocrine system consists of a widely distributed group of glands that release specific chemical substances called hormones. The endocrine glands secrete their hormones dire

7、ctly into the bloodstream.,Lead-in,Endocrine system is a network of glandular structures that function in close coordination with nervous system.,Lead-in,Processes under direct endocrine control include growth reproduction cellular metabolism the regulation of blood levels of many important nutrient

8、s.,Hormones,Despite the fact that hormones in the blood reach all of the tissues in the body, only certain ones respond. The tissue that is influenced by a specific hormone is called the target tissue.,Hormones,Hormones produce their effects by binding to receptors. The receptors initiate specific b

9、iological effects when the hormones bind to them. Each hormone has its own receptor, and binding of a receptor by a hormone is much like the interaction of a key and a lock.,Hormones,Hormones are generally secreted continuously. Endocrine regulation of target tissues occurs via increases or decrease

10、s in the rate of hormonal secretion, which in turn stimulate or inhibit cellular processes.,Hormones,Hormones are produced in extremely small amounts and are highly potent. By means of their actions on various target tissues, they affect growth, metabolism, reproductive activity, and behavior.,Hormo

11、nes,Chemically, hormones fall into two categories steroids, made from lipids proteins or proteinlike compounds Steroids are produced by the gonads and cortex of the adrenal glands. All the remaining endocrine glands produce protein hormones.,Hormones,The production of hormones is controlled mainly b

12、y feedback-a self regulating system. Production may also be controlled by nerve stimulation or by other hormones.,Hormones,Some hormones are produced by organs other than the internally secreting endocrine glands,for example: kidney secretes two hormones, renin and erythropoietin. Renin participates

13、 in the control of blood pressure. skin produces vitamin D, which is also considered a hormone. Vitamin D stimulates the absorption of calcium from the gastrointestinal tract and is necessary for the maintenance of proper amounts of calcium in the bones and in the bloodstream.,The Endocrine Glands,P

14、ituitary Gland Thyroid Gland Parathyroid Glands Adrenal Glands Pancreas Gonads Pineal Gland,Pituitary Gland,Pituitary gland is a pea-sized body located at the base of the brain in a saddle-like depression of the sphenoid bone.,Pituitary Gland,It is composed of two lobes: the anterior lobe or the ade

15、nohypophysis. the posterior lobe or the neurohypophysis. Both lobes are connected to the hypothalamus.,Pituitary Gland,Signals transmitted from the hypothalamus control the secretions by the pituitary gland.,Pituitary Gland,Pituitary Gland,The anterior lobe of the pituitary releases six hormones. Gr

16、owth hormone, which stimulates the growth of bones and acts on other tissues as well. The remainder regulate other glands, including the thyroid, adrenals, gonads, and mammary glands. These hormones are released in response to hormones (releasing hormones) that are sent to the anterior pituitary fro

17、m the hypothalamus.,Pituitary Gland,The posterior lobe of the pituitary releases two hormones antidiuretic hormone (ADH) oxytocin They are actually synthesized in the hypothalamus. They are stored in the posterior pituitary until nervous signals arrive from the hypothalamus to trigger their release.

18、,Pituitary Gland,ADH acts on the kidneys to conserve water and also promotes constriction of blood vessels. Both these actions serve to raise blood pressure. Oxytocin stimulates uterine contractions and causes the production of milk from the mammary glands.,Thyroid Gland,Thyroid gland is a small, fl

19、at gland located in the front of the throat, just below the larynx. Thyroid consists of a right and a left lobe on either side of the trachea, connected by a narrow bridge of tissue called the isthmus, which stretches across the front of the trachea.,Thyroid Gland,-thyroid cartilage,Normal thyroid N

20、ormal thyroid during swallowing,Thyroid Gland,a normal thyroid an enlarged thyroid,Thyroid Gland,Anterior view of the thyroid gland,Thyroid Gland,Posterior view of trachea with two small paired parathyroid glands embedded in the connective tissue,Thyroid Gland,Thyroid gland regulates the overall sta

21、te of cellular metabolism in the body. Thyroid secretes a mixture of hormones, mainly thyroxine (T4) and triiodothyronine (T3). T4 is much more concentrated in the blood, whereas T3 is far more potent in affecting the metabolism of cells.,Thyroid Gland,T4 and T3 are necessary in the body to maintain

22、 a normal level of metabolism in all body cells and are essential for normal mental and physical development. Most thyroid hormone is bound to protein molecules as it travels in the bloodstream.,Thyroid Gland,Another hormone produced by the thyroid gland is called calcitonin(produced by parafollicul

23、ar cells of thyroid/C-cells). Calcitonin acts in conjunction with parathyroid hormone to regulate calcium balance in the blood.,Parathyroid Glands,The parathyroid glands are four to six tiny glands located on the posterior surface of the thyroid gland.,Parathyroid Glands,Posterior view of trachea wi

24、th two small paired parathyroid glands embedded in the connective tissue,Parathyroid Glands,Parathyroid hormone (PTH) secreted by the parathyroid glands affects calcium metabolism.,Parathyroid Glands,The adjustment of the level of calcium in the blood is a good example of the way hormones in general

25、 control the homeostasis of the body. If there is a decrease in the blood calcium,PTH is secreted in larger amounts to cause calcium to leave the bones and enter the bloodstream. Thus, blood calcium levels are brought back to normal. Conversely, any situation of increase in calcium in the bloodstrea

26、m, such as excess quantity of calcium or vitamin D in the diet, will lead to decreased PTH secretion, decreasing blood calcium, so that homeostasis is again achieved.,Adrenal Glands,The adrenal glands are a pair of triangular organs located on top of each kidney. Each adrenal gland consists of two d

27、istinct parts: adrenal cortex adrenal medulla,Adrenal Glands,Adrenal Glands,The adrenal cortex secretes three types of steroid hormones called corticosteroids. Glucocorticoids regulate the metabolism of complex molecules such as sugars, fats and proteins and have a powerful anti-inflammatory effects

28、. Cortisol is the most important glucocoticoids hormone. Mineralocorticoids regulate water balance and mineral levels in the body. aldosterone is the most important mineralocorticoids hormone. Adrenal cortex also produces small amounts of sex hormones. (androgen ),Adrenal Glands,The adrenal medulla

29、secrets two similar hormones epinephrine (Adrenaline) norepinephrine ( noradrenaline) These hormones are released in response to stress and work with the nervous system to help the body meet challenges.,Pancreas,Pancreas is located just below the stomach in the back of the abdomen.,Pancreas,Pancreas

30、,Pancreas acts as both an exocrine and endocrine organ. The specialized cells in the pancreas called the islets of Langerhans carry on its endocrine function.,Islets of Langerhans,In 1869, while looking down the microscope, the Berlin physician Paul Langerhans discovered small “islets” of cells scat

31、tered throughout the pancreas. These cells are responsible for the production of insulin.,Pancreas,The islets of Langerhans produces two hormones called insulin and glucagon. Both of these hormones regulate sugar metabolism in the body. Insulin increases cellular use of glucose, thus lowering sugar

32、levels in the blood. Glucagon has the opposite effect of raising blood sugar levels.,. Delta cells: somatostatin-regulates/stops alpha and beta cells .PP cells: pancreatic polypeptid,Gonads,Gonads are the organs of the reproductive system that are responsible for producing sex hormones. In females,

33、these organs are known as ovaries. In males, they are called the testis.,Ovary Testes,Gonads,Ovarian hormones are estradiol and progesterone. Estradiol is responsible for the development and maintenance of secondary sexual characteristics in the female. Progesterone is responsible for the preparation and maintenance of the uterus in