The Endocrine System

T. Zack Crawford

What is the Endocrine System?

• A collection of glands that produce hormones to regulate the body’s growth, metabolism, and sexual development

• These hormones are released into the bloodstream for transport throughout the body.

• In general, the Endocrine system is in charge of maintaining homeostasis, the property of a stable body in terms of things like temperature and pH

Example Hormone Functions

• Oxytocin – Released during and after childbirth. Important for lactation and other maternal behaviors.

• Dopamine – Important for social behavior, controls reward, punishment, mood, cognition, motivation, etc.

• Thyronines – Simulate body heat production, bone growth, and metabolism.

• Thymosin – controls immune mechanisms, matures T and B-cells.

Example Hormone Functions

• Insulin – regulates fat/carbohydrate metabolism• Adrenaline – Controls “fight of flight” response, can

suppress non emergency processes, boost oxygen and glucose supply, etc.

• Testosterone – developing male reproductive tissues as well as promoting muscular and bone growth.

• Progesterone – Involved in female menstrual cycle and pregnancy, etc. Can inhibit immune response to embryo, inhibit onset of labor, increase core temperature during ovulation, etc.

An example negative feedback mechanism of the endocrine system

An example if a negative feedback mechanism is the blood calcium levels. Calcium receptors on parathyroid cells activate in the absence of calcium. This activation leads to the release of the parathyroid hormone which will then release calcium into the blood from various locations on the body such as reservoirs in the bones. The increase in calcium concentration in the blood will then turn off the calcium receptors and inhibit the release of the parathyroid hormone.

Insulin and Glucose Uptake

After eating food, glucose is released into the blood. High concentrations of glucose will cause the beta cells of the pancreas to release insulin into the blood. Insulin will bind to the cell membrane proteins to facilitate flow of glucose into cells.

Diabetes

• Diabetes refers to a chronic disease where a person has high blood sugar but the pancreas does not produce enough insulin(Type I) or cells cannot respond to the insulin produced by the pancreas (Type II)

• Symptoms include weight loss. Frequent urination, increased hunger/thirst, sometimes blurred vision or skin rashes. Type I Diabetes usually onsets more quickly than Type II

Diabetes

• An estimated 285 million people have diabetes, 90% of which are Type II. Both types of diabetes is more common in the western world.

• No cure currently existing. Management includes measuring and maintaining insulin levels, insulin injections (especially in those with Type I), and medications to combat insulin resistance in those with Type II diabetes.

Cushing’s Syndrome

• Cushing’s Syndrome refers to the symptoms caused by abnormally high exposure to the hormone cortisol. It can be onset by medicine or a tumor on the pituitary gland (Cushing’s disease)

• Symptoms include weight gain, moodiness, weakness in the muscles, osteoporosis, diabetes, hypertension, etc.

Cushing’s Syndrome

• Cushing’s syndrome is a relatively common condition, it is usually caused as a side effect of a steroid medication.

• The easiest treatment for Cushing’s is tapering off of the causing medicine, or in the case of Cushing’s Disease, removal of the causing pituitary tumor.

Sources• http://www.ama-assn.org/ama/pub/physician-resources/patient-education-materials/atlas-of-human-body/endocrine-

system.page• http://en.wikipedia.org/wiki/Endocrine_system• http://en.wikipedia.org/wiki/Homeostasis

• http://www.anewlife.co.uk/hormones_endocrine_glands.html• http://en.wikipedia.org/wiki/Oxytocin• http://en.wikipedia.org/wiki/Dopamine• http://en.wikipedia.org/wiki/Melatonin• http://en.wikipedia.org/wiki/Thyroxine• http://en.wikipedia.org/wiki/Insulin• http://en.wikipedia.org/wiki/Adrenaline• http://en.wikipedia.org/wiki/Testosterone• http://en.wikipedia.org/wiki/Progesterone

• http://en.wikipedia.org/wiki/Parathyroid_hormone

• http://www.livestrong.com/article/27924-insulin-signal-cell-glucose-blood/• http://en.wikipedia.org/wiki/Diabetes

• http://en.wikipedia.org/wiki/Cushing%27s_syndrome• http://en.wikipedia.org/wiki/Cushing%27s_disease