The%20Endocrine%20System

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The Endocrine System

• By Nathan Aleynick
• AP Biology
• Period 1
• Ms. Straubel

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What is the Endocrine System?

• The endocrine system in charge of producing and
  distributing hormones through out the body.
• Hormones are used by the body to bring about long
  term changes (Ex. Puberty, Ovulation) by bonding
  to their target cells.
• Hormones are responsible for long distance
  communication within the body.

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How does the Endocrine System work?

• The endocrine system works with the nervous
  system to keep the body in homeostasis.
• Balance is maintained using feedback loops.
• Feedback loops come in two forms
• Negative Most prevalent of the two. The nervous
  system indicates an imbalance in the body, and
  the endocrine works to reverse the problem to
  maintain balance (Ex. High blood sugar is
  reversed with insulin).
• Positive Less prevalent of the two. The nervous
  system indicates that a change is beneficial and
  the endocrine system works to enhance the change
  (Ex. Uterine contractions are enhanced by the
  release of oxytocin).

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Hormones

• There are three different kinds of molecules that
  could be hormones
• Protein/Peptide hormones
• Anime (derived from amino acids)
• hormones
• Steroid hormones
• Hormones are secreted
• by a gland, enter the
• bloodstream and then bind to
• their target cells.
• Once the hormone is bonded to their
• target cell, a response is triggered.

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Local Regulators

• Local regulators work similarly to hormones
  except that they travel between neighboring cells
  rather than long distance.
• Local regulators convey messages through what is
  called paracrine signaling.
• Ex. Nitric oxide is released by endothelial cells
  when O2 levels are low, causing other endothelial
  cells to relax and increase blood flow.

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Endocrine Glands
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Posterior Pituitary Gland

• No hormones are produced by the posterior
  pituitary gland.
• Rather, it stores and secretes the hormones
  produced by the hypothalamus.

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Hypothalamus

• The hypothalamus produces hormones for the
  posterior pituitary gland.
• Oxytocin A peptide hormone that stimulates the
  contraction of the uterus and mammary glands.
• Antidiuretic hormone (ADH) A peptide hormone
  that signals the kidneys to retain water.

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Anterior Pituitary Gland

• Growth hormone (GH) A protein hormone that
  stimulates growth and metabolic functions.
• Prolactin (PRL) A protein hormone that
  stimulates the production and secretion of milk.
• Follicle-stimulating hormone (FSH) A
  glycoprotein that stimulates the production of
  sperm and ova.

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Anterior Pituitary Gland Cont

• Luteinizing hormone (LH) A glycoprotein that
  stimulates the ovaries and the testes.
• Thyroid-stimulating hormone (TSH) A glycoprotein
  that stimulates the thyroid gland to release its
  hormones.
• Adrenocorticotropic hormone (ACTH) A peptide
  hormone that stimulates the adrenal cortex to
  secrete glucocorticoids.

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Thyroid Gland

• Triiodothyronine (T3) and Thyroxine (T4) Amine
  hormones that stimulate and maintain metabolic
  processes.
• Calcitonin A peptide hormone that lowers the
  level of calcium in the blood.

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Parathyroid Glands

• Parathyroid hormone (PTH) A peptide hormone that
  raises the level of calcium in the blood.

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Pancreas

• Insulin A protein hormone that lowers the blood
  glucose level.
• Glucagon A protein hormone that raises the blood
  glucose level.

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Adrenal Medulla

• Epinephrine/Norepinephrine An amine hormone that
  raises the blood glucose level, increases the
  bodys metabolic activities and constricts
  certain blood vessels.

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Adrenal Cortex

• Glucocorticoids A steroid hormone that raises
  the blood glucose level.
• Mineralocorticoids A steroid hormone that
  increases the absorption of Na and increase the
  excretion of K from the kidneys.

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Testes

• Androgens A steroid hormone that aids in the
  production of sperm and helps develop secondary
  male sex characteristics.

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Ovaries

• Estrogens Steroid hormones that stimulate the
  development of the uterine lining and helps
  develop secondary female sex characteristics.
• Progesterone A steroid hormone that promotes the
  growth of the uterine lining.

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Pineal Gland

• Melatonin An amine hormone that helps control
  biological rhythms (Ex. Sleep cycle).

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