D4-3: The Endocrine System

You and Your Endocrine System  Endocrine System  A collection of glands and groups of cells that secrete hormones that regulate growth, development, and homeostasis.

I. Hormones as Chemical Signals  Our endocrine system is made up of glands, which are a group of cells that make special chemicals for the body.  The glands secrete hormones, which are substances that are made in one cell or tissue and that causes a change in another cell or tissue in a different part of the body.  Hormones are able to move very quickly, because of the bloodstream in our systematic circulation.

I. Hormones as Chemical Signals  The Adrenal Glands  These glands release a specific type of hormone called epinephrine, or adrenaline.  This chemical increases your heart rate and breathing.  This response is often called the “fight-or-flight” response.  When we get frightened, angry, or excited, this response prepares us to fight the approaching danger or “run for our lives!!”

I. Hormones as Chemical Signals

II. More Endocrine Glands  Your endocrine system is made up of several glands and organs including:  Pituitary gland  Thyroid gland  Parathyroid gland  Thymus gland  Adrenal glands  Pancreas  Ovaries and Testes

II. More Endocrine Glands  Pituitary Gland  Located in your brain  Stimulates skeletal growth  Assists in the function of the thyroid gland  Regulates the amount of water in blood  Stimulates the birth process in women

II. More Endocrine Glands  Thyroid Gland  Important for childhood  Control the secretion of growth hormones for normal body growth  Controls the growth of the CNS  Metabolism The sum of all the chemical processes that take place in an organism.

II. More Endocrine Glands  Parathyroid Glands  Regulates Calcium Levels in blood  Thymus  Immune System  Killer T cells grow and mature here  Assist by destroying or neutralizing substances that invade the body

II. More Endocrine Glands  Adrenal Glands  Produce epinephrine (adrenaline)  Help the body respond to danger  Pancreas  Regulate blood-glucose levels  Ovaries (in females)-Estrogen  Produce hormones needed for reproduction  Testes (in males)-Testosterone  Produce hormones needed for reproduction

III. Controlling the Endocrine Glands  These glands have similar feedback mechanisms that the nervous system has.  Your pancreas produce two different hormones that control the level of glucose in the blood.  Insulin Lowers blood-glucose levels by telling the liver to convert glucose into glucagon and store for future use.  Glucagon This hormone tells the liver to convert glucagon into glucose and to release it into the blood. (The opposite affect of Insulin)

III. Controlling the Endocrine Glands  Let’s take a look at Figure 3 on p.96 to see how this feedback mechanism works!

IV. Hormone Imbalances  An endocrine gland can sometimes make too much or not enough of a hormone, which causes the body to be unbalanced.  Diabetes mellitus  When a person’s body does not produce enough insulin must take daily injections of insulin to keep his or her blood- glucose level within safe limits.  If this person does not receive these shots, they can sometimes slip into a coma and dies of this condition.

IV. Hormone Imbalances  Pituitary Gland  Sometimes if a person’s pituitary gland does not produce enough of a growth hormone, their growth can often be stunted.  If this is detected early, growth hormones are prescribed by doctors and monitor his or her growth.  If this gland produces too much of the growth hormone, a child may grow taller than expected.

IV. Hormone Imbalances DIABETESPITUITARY GLAND IMBALANCE