The Endocrine System Controlling those Hormones And Maintaining Homeostasis

The Endocrine System Ductless glands that secrete hormones into the circulatory system. Hormones Chemical messengers relaying information to other, target, organs

Nervous System to Endocrine System The nervous system is in constant communication with the Endocrine system. Channeled through the Thalamus and Hypothalamus in the center of your brain.

The Endocrine System Negative feedback Increasing one hormone inhibits another to reduce the production of the second hormone Ex: insulin decreases sugar while glucagon increases sugar, together maintaining blood sugar levels

The Endocrine System The only job of this system is to maintain homeostasis by controlling hormone levels that control water balance, blood sugar levels, growth, reproduction, pigmentation, adrenalin, calcium levels, and metabolism. Two types of hormones: – Steroid hormones: lipid based from cholesterol, which can diffuse across a cell membrane. – Nonsteroid hormones: made up of amino acids, which cannot diffuse across a cell membrane, but attach directly to cell receptor protein which transports it into the cell; where it influences changes in DNA for protein production.

The Endocrine System Hypothalamus Portion of the brain that connects the nervous and endocrine system (pituitary g.) Pituitary gland (Master gland) Secretes 9 hormones that directly regulate the actions of several other endocrine glands Ex: Growth hormone is essential for normal growth & development

The Endocrine System Thyroid gland Has a major role in regulating the body’s metabolism Ex: Calcitonin regulates calcium levels in the blood

The Endocrine System Adrenal gland Plays a major role in preparing the body for stressful situations Ex: Epinephrine (adrenalin) is associated with the body’s fight or flight reactions

Negative Feedback Loop The endocrine system uses feedback loops to maintain homeostasis in the body. – Example: When your nerve receptors sense that you are cold, the hypothalamus is activated and releases a hormone into the blood called thyrotropin releasing hormone (TRH). This hormone targets the pituitary gland. Once activated, the pituitary gland releases a hormone into the blood called Thyroid-stimulating hormone (TSH). When the thyroid releases thyroxine into the blood stream, cells become active and the body temperature rises, until the temperature of 98.6 degrees Fahrenheit. Then the receptors tell the hypothalamus to stop releasing TRH, and in turn the other glands are turned off.

Hypothalamus TRH Pituitary THS Thyroid Set Point Reached STOP TRH production Thyroxine Production Level below set point

Diabetes Sometimes the feedback loops do not always operate properly. This is the case with Sugar Diabetes. Sugar diabetes is caused by a lack of production of insulin by the pancreas in order to maintain homeostasis. Insulin is needed by cells in order to absorb and utilize glucose. As insulin is released, glucose diffuses across the cell membrane through protein pores. Insulin also triggers the transfer of excess energy into glycogen to be stored in muscles and the liver, and also into triglycerides which are stored in fat tissue. As a result, blood sugar levels are lowered. Type I diabetes: person produces little or no insulin. Type II diabetes: person produces insulin, but bodies have developed a resistance to its effect. Since a person with diabetes body cells cannot access and adequate supply of energy problems develop such as blindness, kidney failure, heart attacks, and tissue death. Homeostasis can however be maintained through proper diet and health treatment of the diabetes with injections of insulin.