Endocrine Glands Study Documents

ENDOCRINE FUNCTION OF ENDOCRINE GLANDS In general, the functions of the endocrine glands can be stated as follows: 1. Secretes hormones that flow directly into the blood (without special channels/ ductless) that are needed by certain cells/tissues/organs of the body. 2. Acts to control the activity of the body's glands 3. Stimulates the activity of the body's glands 4. Stimulates tissue growth 5. Regulation of metabolism, oxidation processes, increasing glucose absorption in the small intestine 6. Affects the metabolism of fats, proteins, carbohydrates, vitamins, minerals and water. 7. Maintain the body's internal environment so that it remains optimal and homeostatic. ENDOCRINE GLANDS 1. Hypothalamus The hypothalamus is a vital area of the brain, which plays an important role in: a. Thermoregulation; b. Behavioral and emotional responses; c. Appetite regulation; d. Autonomic nervous system coordination; e. Produces various hormones that regulate the activity of endocrine glands. 2. Pituitary a. Anterior (front part). 1) Somatotropin hormone, which functions to stimulate protein and fat metabolism and stimulate bone and muscle growth. 2) Thyrotropin hormone, which functions to stimulate the growth and development of the goiter (thyroid gland) and also to stimulate thyroxine secretion. 3) Adenocorticotropin hormone (ACTH), which functions to control the development and growth of kidney skin activity and stimulates the adrenal glands to produce glucocorticoid hormones (hormones for carbohydrate metabolism). 4) Lactogenic hormone, which functions to maintain the corpus luteum (temporary endocrine gland in the ovaries) so that it can produce progesterone (primary development and growth hormone in women) and breast milk 5) Gonadotropin hormones, which function to stimulate the maturation of follicles in the ovaries (menstrual cycle), produce the hormone estrogen (secondary growth and development in women), and produce progesterone in women. Meanwhile, in men, the gonadotropin hormone functions to stimulate spermatogenesis (the sperm formation cycle in men) and stimulates testicular interstitial cells to produce androgen and testosterone hormones. b. Middle pituitary gland The middle pituitary gland produces only one hormone called Melanocyte Stimulating Hormone(MSH). This hormone is responsible for the coloring of human skin. The more melanocytes produced, the darker a person's skin. c. Posterior (back). The rear pituitary gland produces 2 types of hormones, namely: following. 1) Vasopressin Hormone or Diuretic Hormone (ADH), which functions to influence the process of urine reabsorption in the distal tubule of the kidney to prevent too much urine from coming out. 2) Oxytocin hormone, which functions to stimulate smooth muscles in the uterus (female reproductive organs). 3. Thyroid and Parathyroid The thyroid is a bilobed organ whose shape resembles a bow tie; usually weighs 25-30g and is located just below the larynx. The thyroid has two endocrine cells: a. Follicular cells – produce the iodine-containing hormones triiodothyronine (T3) and tetraiodothyronine (T4, also known as thyroxine), which regulate metabolism; b. Parafollicular cells – these produce the hormone calcitonin, which helps to regulate blood- calcium concentrations 4. Pancreas The pancreas is a vital organ in both the digestive and endocrine systems; is in the loop U-shaped part of the duodenum, usually 14-23cm long and weighing around 100g. The endocrine portion of the pancreas is known as the islets of Langerhans, which are small islands of glandular tissue found throughout the structure of the pancreas. The pancreatic islets contain several types of endocrine cells, including: a. Alpha cells, produce glucagon; b. Beta cells, produce insulin. These two hormones glucagon and insulin play a key role in regulating concentration blood glucose. 5. Adrenals There are two adrenal glands – one above each kidney. They are roughly triangular in shape shape, about 3cm wide and weighing 4-6g each m. The adrenal glands have two main regions: a. Adrenal cortex. Produces steroid hormones, including the long-acting stress hormone cortisol, aldosterone (which regulates sodium and potassium levels in the blood) and a group of testosterone-like hormones called androgens; b. Adrenal medulla. Produces adrenaline (epinephrine) and noradrenaline (norepinephrine). usually produced when someone is under threat, afraid or excited. Functions primarily to activate the sympathetic branch of the autonomic nervous system. 6. Ovaries and testicles Gonads are organs that produce gametes, sperm in men, and cells in women. Apart from its reproductive function, the gonads also secrete hormones. The ovaries secrete several steroid hormones including two estrogens (estradiol and estrone) and progesterone. Female sex hormones along with FSH and LH from the anterior pituitary regulate the menstrual cycle, maintain pregnancy and prepare the mammary glands for lactation. This hormone also causes breast enlargement and hip widening during puberty, and helps maintain female secondary sex characteristics. The ovaries also produce inhibin, a protein hormone that inhibits FSH secretion. During pregnancy the ovaries and placenta produce hormones called peptidesRelaxin(RLX) which increases the flexibility of the pubic symphysis during pregnancy and helps dilate the uterine cervix during labor. This action helps the baby to come out easily because the birth canal widens. Male gonads, testes, oval glands located in the scrotum. The main hormone produced and secreted by the testicles is testosterone, which is an androgen or male sex hormone. Testosterone stimulates the testicles before birth, regulates sperm production, and stimulates the development and maintenance of sex characteristics male secondary, such as beard growth and deepening of the voice. The testes also produce inhibin, which inhibits FSH secretion.