Endocrine System

Endocrine System

• The Endocrine System is a series of specialized cells and glands that secrete HORMONES.• HORMONES are substances the regulate the activity of other cells in

the body. Some regulate growth, development, behavior, etc.• ENDOCRINE GLANDS are organs that secrete the hormones, usually

into the bloodstream.• EXOCRINE GLANDS are similar to endocrine glands but can also

secrete hormones through ducts (tubes) to specific locations, like sweat glands, salivary glands, digestive glands.

Types of Hormones

Amino Acid Based

Steroid Hormones

Amino Acid Hormones/Nonsteriod Hormones•Water soluble•Composed of 1 to 200 amino acids (proteins)•Work on the cell membrane •Activate or deactivate enzymes•Cannot pass through the cell membrane of the target cell

Steroid Hormones

•Fat soluble•Work in the cytoplasm or nucleus•Activate or deactivate gene expression•Can cross the cell membrane and pass directly into the cell membrane

Endocrine Glands

• Endocrine glands are located throughout the body.• The

HYPOTHALAMUS and PITUITARY GLAND control the initial release of many hormones.

Control of the Endocrine System

•The endocrine system is regulated by feedback mechanisms that function to maintain homeostasis•When glands sense a hormone is too low, it will release more. If too much, it will stop releasing•Controlling metabolism, water levels, calcium levels are all controlled with hormones

Endocrine Coloring

HYPOTHALAMUS and PITUITARY GLAND• The HYPOTHALAMUS is An area of the brain that coordinates many

activities of the nervous and endocrine systems, including controlling the pituitary gland• It responds to information by sending instructions in the form of

hormones to the pituitary gland.• The PITUITARY GLAND is right below the hypothalamus and stores

hormones. • The Pituitary gland regulates most of the hormones released around

the body (nine that directly regulate body functions), including the growth hormone.

Thyroid Gland

• The thyroid gland is located near the larynx and secretes hormones which regulate heart rate, blood pressure, body temp, and also metabolic rates.•Abnormal thyroid activity can cause overactivity

(weightloss, high blood pressure and heart rate) or the opposite (weight gain, lethargy, low heart rate).

Adrenal Glands

•Located above each kidney•Produce epinephrine and norepinephrine (adrenaline and noradrenaline)•Fight-or-Flight •Fight or Flight example

Effects of Epinephrine and other hormones released under stress• Heart rate and blood pressure increase• Pupils dilate to take in as much light as possible• Veins in skin constrict to send more blood to major muscle groups (responsible for the "chill"

sometimes associated with fear -- less blood in the skin to keep it warm)• Blood-glucose level increases• Muscles tense up, energized by adrenaline and glucose (responsible for goose bumps -- when

tiny muscles attached to each hair on surface of skin tense up, the hairs are forced upright, pulling skin with them)

• Smooth muscle relaxes in order to allow more oxygen into the lungs• Nonessential systems (like digestion and immune system) shut down to allow more energy for

emergency functions• Trouble focusing on small tasks (brain is directed to focus only on big picture in order to

determine where threat is coming from)

Endocrine Response Activity!

Gonads

•Ovaries in females, Testes in males•Produce sex hormones which begin at puberty

Pancreas

•The PANCREAS is an organ that secretes hormones to regulate the level of sugar in the blood.• Insulin lowers the blood sugar level by stimulating cells and muscles to use it for energy•Lack of insulin or too much insulin= diabetes

Brain Pop! Endocrine System

Hormones Carry The Message Activity

Endocrine System—Body Booklet