The Endocrine System

By:

Imani Elston and Kristin Hildreth

Period 5

What is the Endocrine System?

• Bodily system comprised of glands and hormones

• Purpose: Regulate bodily functions– Maintain homeostasis– Regulate growth and development– Respond to external factors (outside of the

body)– Coordinate the production, use, and storage

of energy

What are Glands?

• A gland is a group of cells that produce and secrete hormones either directly into the bloodstream or extracellular fluid

 

The Hypothalamus and Pituitary Gland

• The hypothalamus links the activities of the nervous system and the endocrine system– Receives information about internal and external

conditions from other cerebral regions– Regulates bodily functions like body temperature– Issues instructions to the pituitary gland

• The pituitary gland secretes hormones that control other endocrine glands– Divided into two lobes: anterior and posterior– Aids in bodily functions, like the development of

gametes

The Thyroid and Parathyroid Glands

• The thyroid gland makes and releases thyroid hormones– Regulates metabolism and promote the

growth of bones, muscles, and the brain during childhood

– Maintains mental alertness in adults and affects reproductive functions

• The parathyroid gland produces the parathyroid hormone– Raises the body's calcium levels

The Adrenal Glands

• Two almond-sized glands, one on top of each kidney

• Adrenal medulla is a warning system in time of stress by releasing "fight-or-flight" hormones (epinephrine and norepinephrine)– Prepare the body for action in emergencies

• Adrenal cortex produces hormones that give a slower, long-term response to stress– Cortisol: Makes more energy available to the body– Aldosterone: Reabsorbs sodium ions from kidney

filtrate

What are Hormones?

• A hormone is a chemical compound that is secreted by cells to regulate the activity of other cells (chemical messengers)– Two types:

• Amino-acid-based: Hormones made of amino acids (water-soluble)

• Steroid: Lipid hormones made from cholesterol (fat-soluble)

• Hormones bind and act on target cells– Specific cell with certain receptors on surface or in

cytoplasm of cell– Proteins are shaped to allow only one hormone to fit

 

 

Insulin and Adrenaline

• Insulin is a hormone that is secreted from the pancreas– Lowers glucose levels in the blood by promoting the

accumulation of glycogen, a polysaccharide, in the liver

– Stimulates muscle cells to convert glucose into glycogen

• Adrenaline (epinephrine) is a hormone made in the adrenal glands– Increases heart rate, blood pressure, cardiac output,

and metabolism

Calcitonin and Human Growth Hormone

• Calcitonin is a hormone secreted from the thyroid gland– Is involved in the regulation of calcium levels in

animals by stopping the loss of calcium from bone to the blood

• Growth Hormone is produced in the pituitary gland– Stimulates protein synthesis as well as bone and

muscle growth– Encourages cell division

Estrogen and Testosterone(Sex Hormones)

• The ovaries produce estrogen in females– Estrogen is used to develop and maintain female sex

characteristics– Prepares the uterus for fertilization of an egg

• Testosterone is produced in the testes in males– The sex hormone that stimulates the development of

male sex organs, sexual traits, and sperm

Other Organs and Diseases

• Other organs and glands produce hormones, they include:– Stomach, small intestine, kidney, liver, pancreas

Diseases/Disorders:• Overproduction of thyroid hormones (hypothyroidism)

can cause nervousness, sleep disorders, and an irregular heart rate– Daily use of synthetic thyroid hormone levothyroxine (Restores

hormone levels)• Diabetes mellitus causes cells to be unable to obtain

glucose from the blood– Result: High glucose levels– Solution: Insulin injections, proper dieting and exercising

Bibliography

• Dowshen, Steven, MD. "Endocrine System: Body Basics." Kidshealth.org. The Nemours Foundations, Mar. 2012. Web. 12 May 2013. <http://kidshealth.org/teen/your_body/body_basics/endocrine.html>.

• Johnson, George B., Ph.D., and Peter H. Raven, Ph.D. Biology. Austin: Holt, Rinehart and Winston, 2007. Print. (textbook)

• Rogers, Kirsteen, Verinder Bhachu, and Joanne Kirkby. The Usborne Science Encyclopedia. London: Usborne, 2009. Print.