Endocrine system

  • Endocrine system -is made up of glands that secrete substances into the blood stream.
  • Function- Maintains homeostasis through the secretion of hormones
  • hormones- are chemicals released from one part of the body and carried through the bloodstream to affect another part of the body.
  • Hormones are released in small quantities and are very specific!

Target cells have receptors for specific hormones.  If the hormones contact cells without these target cells, they will have no effect.

  • Most hormones released by endocrine glands are needed throughout a person’s life.
  • Some are only required during certain stages of development.
  • Improper functioning of an endocrine gland may cause:
    • Hyposecretion- not enough hormone is released
    • Hypersecretion too much hormone is released

Addison Disease aka hypocortisolism- adrenal gland produces too little hormone

Acromegaly-pituitary gland produces too much hormone

  • The pituitary gland is a small bulb found on the underside of the brain.

pituitary gland has 2 lobes: anterior pituitary and posterior pituitary.

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  • The hypothalamus is located just above the pituitary gland and is about the size of an almond.
  • Controls the pituitary and is often called the “master gland” because it has wide-reaching effects on the whole body.
  • Functions include:
    • Control of brain stem & spinal cord
    • Center of emotional response
    • Body temperature regulation
    • Regulation of food intake
    • Controls thirst
    • Regulates sleep &

wake cycles

  • Controls other glands

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  • The pineal is a tiny cone-shaped gland near the cerebellum.
  • The main secretion of the pineal gland is melatonin
  • The thyroid gland is located at the__base__ of the neck.
  • Two distinctive halves; shaped like a shaped like a butterfly

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Hyperthyroidism-too much thyroxine

  • Causes hyperactivity, high body temperature, and weight loss

Hypothyroidism-too little thyroxine

  • Causes lethargy, swelling of body tissues, and weight gain

  • Iodeon deficiency can cause a ”goiter” which is a enlarged malfunctioning thyroid gland

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  • The parathyroid glands are attached to the back of the_____thyroid____.
  • Produces parathyroid_, which is the opposite of calcitonin.

Parathyroid hormone brings____calcium_____ out of the bones and into the _bloodstream for use by cells.

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  • The adrenal glands sit atop each __kidney___

Each gland has an ____outer__ layer (adrenal cortex) and an inner layer (adrenal medulla) that have different functions

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  • Pancreas has both exocrine (using ducts) and endocrine (ductless) glands.
  • The endocrine part of the pancreas is made of groups of cells called the islets of Langerhans that look like tiny islands.

The islets of Langerhans produce insulin and glucagon_

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  • Insulin.

Glucagon does the opposite- stimulates fats____and ____glycogen_ to be broken down into glucose and released into the bloodstream.

The combination of these two hormones causes stabilizes the blood sugar in the body

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  • diabetes- is a disorder in which the body produces too litte_ insulin.
  • This keeps the blood glucose levels at a very high level and the kidneys excrete some excess glocouse in urine.
  • Instead of using the glucose, the body begins to break down fats for energy, eventually damaging nearly every cell in the body.
  • The two types of diabetes are Type 1 (juvenile-onset) or Type 2 (adult-onset)
  • Blood sugar monitoring and insulin injections can regulate or reduce the effects of the disease.

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  • Located near the sternum
  • Produces thymopoietisternumn, thymic factor, and thymosin, which is involved in the development of the immune system_.

——————————- \n Gonads=reproductive organs that produce sex cells and secrete sex hormones

  • Females- ovaries
  • Males- testes

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  • 2 major types of hormones:
    • Steroids- can pass directly through the target cell membrane, forming a hormone-receptor complex, which alters the actions of the cell

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  • Nonsteroids- Bind to receptors on the __outside of the target cell, which release chemicals that bind to other receptors inside the target cell.

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  • Control of hormone secretion is required to regulate the amount of hormones released into the body the body.
  • Often this control comes from feedback mechanisms.

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  • Example: The thyroid gland secretes the hormone thyroxine (T4).  It won’t secrete thyroxine, though, until it is stimulated by other hormones from the hypothalamus and anterior pituitary glands.

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If the level of thyroxine in the blood becomes ______too high__, the hypothalamus and pituitary will stop producing the stimulating hormones, thus slowing the thyroid from producing __thus lowing the thyroid function___. \n \n