Endocrine System

• The endocrine system, through the different glands, secrete hormones that control the growth and development of the body.
• Hormones travel throughout the body through the bloodstream.
• Hormones are directed toward a specific part of the body, which is called the target organ of the hormone.
• The Pituitary Gland is a gland located in the brain.
• The Pituitary Gland is often called the master gland because it controls the functions of other endocrine glands.
• A list of hormones secreted by the pituitary gland:

  • Human growth hormone (HGH)
  • Thyroid-stimulating hormone (TSH)
  • Follicle-stimulating hormone(FSH)
  • Luteinizing hormone(LH)
  • Prolactin
  • Adrenocorticotropic hormone(ACTH)
  • Oxytocin
  • Antidiuretic hormone (ADH)
• Human growth hormone promotes the release of insulin-like growth factors, which are responsible for the production of proteins in the body; maintains muscle and bone mass for growth; also helps in dealing injuries and repair of tissues.
• Thyroid-stimulating hormone helps in producing and secreting the thyroid hormones by the thyroid gland.
• Follicle-stimulating hormone targets the ovaries by initiating the development of the follicles in the ovary, which happens monthly.
• Luteinizing hormone initiates ovulation; also controls the secretion of progesterone.
• Progesterone is the female sex hormone.
• Prolactin affects the mammary glands by initiating and maintaining the production of milk especially during pregnancy.
• Adrenocorticotropic hormone is responsible for the production and secretion of glucocorticoids.
• Glucocorticoids are the hormones released by the adrenal gland.
• Oxytocin is activated during and after giving birth; targets the uterus to cause it to contract during giving birth; also controls milk secretion in the breast after giving birth.
• Antidiuretic hormone causes the kidneys to decrease urine production, which helps in conserving more body water; also known as vasopressin.
• The hypothalamus is the gland that is also located in the brain. It controls the function of the pituitary gland.
• Hormones secreted by the hypothalamus:

  • Thyrotropin-releasing hormone(TRH)
  • Gonadotropin-releasing hormone(GnRH)
  • Corticotropin-releasing hormone(CRH)
• The Thyrotropin-releasing hormone controls the secretion of the TSH
• Gonadotropin-releasing hormone stimulates the production of FSH and LH.
• Corticotropin-releasing hormone initiates the secretion of ACTH.
• The thyroid gland is located below the larynx (or the voice box).
• The thyroid gland is described as a butterfly-shaped gland that is composed of the right and left lobes.
• The thyroid gland secretes the hormones thyroxine (T4) and triiodothyronine (T3).
• Thyroid hormones are responsible for protein synthesis; regulation of oxygen use, metabolism, and growth; and the development of the body.
• Calcitonin is another hormone secreted by the thyroid gland, which is responsible for maintaining the calcium level in the body.
• The parathyroid glands can be found in the posterior surface of the thyroid gland.
• The parathyroid hormone is the hormone secreted by the parathyroid glands.
• The parathyroid hormone is the major regulator of calcium, magnesium, and phosphate levels in the blood.
• The pancreas is located in the duodenum of the small intestine. It secretes the hormones insulin and glucagon, which is responsible in regulating the blood sugar level.
• Insulin helps in lowering the amount of glucose in the blood when it is too high.
• Glucagon helps in increasing the level of glucose in the blood when it is too low.
• When the body has a high amount of glucose in the blood, the pancreas will secret insulin to lower the glucose by converting it into glycogen, which will be stored in the liver.
• Once the body's blood glucose level becomes low, the pancreas will then release glucagon and break down the glycogen in the liver to create glucose needed by the body.
• The adrenal glands are located on top of each kidney. Divided into the adrenal cortex and the adrenal medulla.
• The adrenal cortex secretes the following:

  • Mineralocorticoids
  • Glucocorticoids
  • Androgens
• Mineralocorticoids maintain the balance of minerals in the body such as sodium and potassium.
• Glucocorticoids break down proteins and triglycerides needed by the body, help in the formation of glucose, have anti-inflammatory effects, cause suppression of immune responses.
• Androgens secreted by both males and females, but it is an important hormone especially for females because these are converted into estrogen.
• The adrenal medulla secretes the epinephrine (adrenaline) and norepinephrine (noradrenaline), which are released during strenuous activities, such as exercise. These hormones control the heart rate, blood pressure, blood level, and breathing rate