Endocrine system

General Infomation Connected to the nervous system via the Hypothalamus. Often in this system, the sensor and control center are the same.

Component 1: Glands Endocrine glands release hormones directly into the blood. (They may release other secretions, too) Master Gland: Pituitary Gland –Produces “tropic hormones”, which regulate hormone production –Anterior section & Posterior section Anterior: produces 11 hormones! Posterior: stores ADH & oxytocin

Other Glands…

Hormones Chemical messengers Carry instructions to target organs. Very potent! Released in small quantities. I’m stressed. I’m hungy. I’m sleepy.

Two Types of Hormones: Steroid Made from cholesterol (hydrophobic) In the blood they combine with protein carriers until they reach the target cell. Fat soluble, so they pass through the target cell membrane easily. Once inside, they form a hormone-receptor complex in the cytoplasm, which enters the nucleus and activates transcription of specific gene(s). (see handout)

Two Types of Hormones: Non- Steroid Made from amino acids (hydrophillic) Cannot pass directly through the cell membrane Target cells have receptors on their surface for this type of hormone. When activated, they trigger a chain of chemical reactions within the cytoplasm, where ATP is dephosphorylated to create cyclic AMP, which activates the required pathway. (see handout)

How The Endocrine System Works Two possibilities… –Antagonistic hormones constantly work against each other to maintain a constant environment. –Hormones that act through negative feedback will activate one response and inhibit their own release at the same time.

Flowcharts: Antagonistic Gland, Component Hormone Effector(s) Action Effector Action Dropping Stimulates Increases Raising Stimulates Decreases

Patient! Symptoms: –Fatigue –Tingling in hands and feet –Have passed out a few times –Frequent urination –Very thirsty

Diabetes Canadians Banting & Best discovered that insulin was responsible for diabetes Won Nobel Prize. 3 types: –Type I: Born with an immune system that attacks pancreatic cells. –Type II: Cells stop responding to insulin. Usually due to poor diet and lack of exercise. –Gestational: Diabetes during pregnancy. Usually clear up after birth of baby.

The Pancreas: Blood Sugar After you’ve eaten, your blood sugar increases. –Beta cells in the pancreas release insulin, which stimulates receptors on the liver cells, muscle and other organs to store glucose in the form of glycogen. This lowers blood sugar. In between meals, your blood sugar decreases –Alpha cells in the pancreas release glucagon, which stimulates receptors on liver cells, muscle and other organs to break down glycogen and release it. This raises blood sugar.

Questions What type of hormone are insulin and glucagon? What type of homeostatic control is portrayed?

Flowcharts: Negative Feedback Event Gland Hormone Effector Hormone Gland Inhibits Stimulates Releases Action