Endocrine system overview - HS Anatomy and Physiology

24. Aug 2015

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Endocrine system overview - HS Anatomy and Physiology

  1. The Endocrine System
  2. Let’s watch a video about it first: o While we are watching the video record: 1. The 8 endocrine organs discussed in the video 2. At least one corresponding hormone to each gland
  3. 3 • The endocrine system is made up of a network of ductless glands. • These glands secrete hormones to regulate many internal bodily functions including growth and metabolism. • Simply put, the endocrine system is a network of glands that secrete chemicals called hormones to help your body function properly. • Hormones are chemical signals that coordinate a range of bodily functions. Overview of the Endocrine System
  4. 4 • Purely endocrine organs – Pituitary gland – Pineal gland – Thyroid gland – Parathyroid glands – Adrenal: 2 glands • Cortex • Medulla • Endocrine cells in other organs – Pancreas – Thymus – Gonads – Hypothalamus Endocrine Organs
  5. Not the EXOCRINE Glands • There are another category of bodily secretions that leave glands via tubes or ducts that travel to the surface of the body. These are called exocrine glands. • Examples: sweat glands secrete sweat and salivary glands secrete saliva. NOT the EXOCRINE System
  6. Hormones are messenger molecules • Circulate in the blood • Act on distant target cells • Target cells respond to the hormones for which they have receptors • The effects are dependent on the programmed response of the target cells • Hormones are just molecular triggers Basic categories of hormones • Amino acid based: modified amino acids (or amines), peptides (short chains of amino acids), and proteins (long chains of amino acids) • Steroids: lipid molecules derived from cholesterol What are Hormones?
  7. Role of the Pituitary • Called Master Gland because hormones of the pituitary gland help regulate the functions of other endocrine glands. • The pituitary gland has two parts—the anterior lobe and posterior lobe—that have two very separate functions. • The hypothalamus sends signals to the pituitary to release or inhibit pituitary hormone production.
  8. Role of the Pituitary (lobes) • The anterior lobe of the pituitary receives signals from the hypothalamus • Responds by sending out the appropriate hormone to other endocrine glands that causes them to act.  Adrenocorticotropic hormone (ACTH)  Growth hormone (GH)  Thyroid-stimulating hormone (TSH) • The posterior lobe uses the hormones oxytocin or antidiuretic hormone (ADH) from the hypothalamus, relays them to the body as necessary.
  9. Role of the Pineal • Small endocrine gland in the middle of brain shaped like a pinecone. • Produces melatonin, a serotonin derived hormone, which affects sleep patterns in both seasonal and circadian rhythms. What are circadian rhythms? Physical, mental and behavioral changes that follow a roughly 24- hour cycle, responding primarily to light and darkness in an organism's environment.
  10. • Two lobes connected in the middle to make a butterfly shape. Found in neck below thyroid cartilage. • Controls how quickly the body uses energy, makes proteins, and controls how sensitive the body is to other hormones. Role of the Thyroid • Produces and secretes thyroid hormones: triodothyronine, thyroxine and calcitonin to regulate the growth and rate of function of other systems in the body.
  11. • Small endocrine glands in the neck of that produce parathyroid hormone • Usually have four parathyroid glands, located on the back of the thyroid gland Role of the Parathyroid • Parathyroid hormone and calcitonin (made by the thyroid gland) regulate the amount of calcium in the blood and within the bones
  12. Role of the Adrenals • Two glands that sit on top of your kidneys that are made up of two distinct parts: • Adrenal cortex—the outer part of the gland—produces glucocorticoids hormones that are vital to life, such as cortisol and aldosterone. • Adrenal medulla—the inner part of the gland— produces nonessential (don’t need them to live) hormones, such as epinephrine and norepinephrine (which helps your body react to stress).
  13. Role of the Thymus • Located behind your sternum and between your lungs, is only active until puberty. • After puberty, the thymus starts to slowly shrink and become replaced by fat. • Thymosin is the hormone of the thymus, and it stimulates the development of disease-fighting T cells.
  14. Role of the Hypothalamus • The portion of the brain that maintains the body’s internal balance (homeostasis). • Monitors the body for temperature, pH, other conditions. • Hypothalamus signals pituitary gland if conditions need to be corrected. • Link between the endocrine and nervous systems. • The hypothalamus produces releasing and inhibiting hormones, which stop and start the production of other hormones throughout the body.
  15. Role of the Gonads • Ovaries maintain the health of the female reproductive system. • They secrete two main hormones—estrogen and progesterone. • These hormones promote the healthy development of female sex characteristics during puberty and to ensure fertility. • The testes secrete testosterone, which is necessary for proper physical development in boys. • In adulthood, testosterone maintains libido, muscle strength, and bone density.
  16. Role of the Pancreas • The pancreas maintains the body’s blood glucose (sugar) balance. • Primary hormones of the pancreas include insulin and glucagon, and both regulate blood glucose. • The pancreas is both an endocrine and exocrine gland—dual function of secreting hormones into blood (endocrine) and secreting enzymes through ducts (exocrine).
  17. Complete Lab 36: Procedure A – 1, 2, 3
  18. Finally…Exit Slip • In your own words, write a definition of the endocrine system in your science notebook.