39-1 The Endocrine System Control of the Body by Feedback Control of Hormones

Control of the Body The body is controlled by two systems: * These two systems work together Nervous system Endocrine System

Analogy from the textbook: If your nervous system is like a telephone then your endocrine system sends out messages like _________ waves.

Endocrine System Series of endocrine glands that release chemicals, called hormones, directly into the blood stream. Because the hormone needs to travel through the blood stream, the response by the body is usually not immediate. Only target cells, cells that have protein receptors specific to the hormone, respond.

Hypothalamus - controls the pituitary Pituitary gland - master gland… has an effect on many other glands Parathyroid glands - regulates calcium levels in the blood Thymus - stimulates “T” cell development Adrenal glands -produce epinepharine and norepinepharine which accelerate the metabolism by promoting the breakdown of glucose to make ATP Thyroid -Produces thyroxine which increases metabolism Pancreas -Produces insulin and glucagon which control blood glucose levels Ovary -produces estrogen and progesterone… which prepares the uterus for the egg Testis -produces testosterone Endocrine Gland Locations (Fig. 39-2) Pineal Gland - releases melatonin which regulates sleep cycles

Hormone Action There are two basic types of hormones. A.Steroid Hormones- Made out of Lipids B.Amino Acid Hormones- Made out of Protein

What is feedback control? How does it control the action of hormones?

Here is a non-biological example of feedback control.

This is a picture of my wife and I. I love vacation!

She likes to shop! This is our bank. Shopping makes me happy!

Shopping vs. Money in the Bank Relative Quantity Time

No more Money! No more shopping!

Negative Feedback Control No money No Shopping Not Happy!

How about a biological example? Regulation of Blood Glucose levels

Blood Sugar Levels are Regulated by the Pancreas When you have high blood sugar, the pancreas produces insulin which allows the cells to absorb the sugar and your liver to remove sugar from the circulatory system. When you have low blood sugar, the pancreas produces glucagon, which causes the liver to increase the blood sugar by breaking glycogen down into glucose and releasing it into the circulatory system.

Blood Glucose levels Hours 8:00 9:00 insulinglucagon Regulation of blood glucose levels 10:00

Levels of insulin and glucogon during exercise Time Exercising Hormone levels in the blood insulin glucogon

Which disease effects this regulatory system and how common is it in the U.S.? Diabetes This disease effects over 15 million Americans, which is about 6% of the population. Experts say that 1/3 of those people with diabetes do not even know that they have it.

Blood-Glucose Regulation Activity LiverPancreas Path of glucose through the tissue GlucoseInsulin Glucogon

Hypothalamus Pituitary gland Parathyroid glands Thymus Adrenal glands Thyroid Pancreas Ovary Testis Endocrine Gland Locations (Fig. 39-2) Pineal Gland