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 levelsOvary-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 ActionThere 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

insulin glucagon

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

Glucose Insulin Glucogon

Hypothalamus

Pituitary gland

Parathyroid glands

Thymus

Adrenal glands

Thyroid

Pancreas

Ovary

Testis

Endocrine Gland Locations (Fig. 39-2)Pineal Gland