Online College Courses for Credit

Endocrine System

Endocrine System

Author: Meg O'Mahony

In order to demonstrate an understanding of the the organs and functions of the Endocrine System, you need to be able to:

  1. define hormone, endocrine gland and target organ.
  2. describe the overall pattern of the physiology of the endocrine system in terms of the endocrine gland, its hormone and the target organ of the hormone.
  3. list, and identify on a diagram or fetal pig, the eight major human endocrine glands
  4. compile and display data for the:
    • major mammalian glands,
    • major hormones produced by each gland,
    • stimulus for hormone production,
    • target organ
    • action and nature of hormone
    • related disorders.
  5. describe the mechanism by which the nervous system exerts control over the endocrine gland activity.
  6. describe how  blood sugar levels are regulated when blood sugar level is a) high, b) low.  Include the impact/effect or the liver, pancreas, adrenal glands, muscles and the blood stream.
  7. describe the cause, effects and treatment of diabetes mellitus.


The endocrine system works in cooperation with the nervous system.  It adjusts for long ter m processes such as growth and sexual maturation.  It works more slowly than the nervous system and provides long term homeostatic controls.  The blood is the usual medium of transmission of the message - not nerve tissue.                           

The functional units of the endocrine system are the endocrine glands.  These produce hormones directly into the blood stream.  They do not have ducts or tubes.  Specific endocrine glands produce minute amounts of specific hormones in response to a stimulus from another part of the body.  These hormones are then transported to another part of the body called a target organ.

To be a hormone, the molecule must meet four criteria:

  1. it must be produced by a specialized gland or organized group of cells and be released directly into the  blood,
  2. it must produce an effect on a part of the body other than where it was produced.  This affected part is called the target,
  3. it is required in very small amounts,
  4. it must operate by regulating the rate of metabolism of a metabolic pathway.
See More
Fast, Free College Credit

Developing Effective Teams

Let's Ride
*No strings attached. This college course is 100% free and is worth 1 semester credit.

37 Sophia partners guarantee credit transfer.

299 Institutions have accepted or given pre-approval for credit transfer.

* The American Council on Education's College Credit Recommendation Service (ACE Credit®) has evaluated and recommended college credit for 32 of Sophia’s online courses. Many different colleges and universities consider ACE CREDIT recommendations in determining the applicability to their course and degree programs.


The Endocrine System

Hormones often work together with the Nervous System - as with the Fight or Flight Response. They also control many of the activities of the body. Hormonal responses are slower - and longer lasting than Nervous activity which has its benefits. Again, the control is through Negative Feedback.

Source: M. O'Mahony, open source images

The Endocrine System Part II

Source: M. O'Mahony, open source images

Student Notes Template

Template for students to take notes from tutorial video. Includes the various figures.


Source: M. O'Mahony, open source images

Glucose Metabolism

This site from WISC-Online goes into detail about all 7 hormones that help with blood glucose regulation. It has a quiz at the end.

As typical for WISC activities, it is well put together.  You will be responsible for knowing the interacting roles of insulin and glucagon.  However, this virtual tutorial provides excellent context and "big picture" understanding.

Source: WISC-Online (Wisconsin's Technical College, maintained by Fox Valley Technical College)

The Diabetic Dog Game

Source: Nobel

HHMI: The Human Suprachiasmatic Nucleus

An animation and information about how the suprachiasmatic nucleus  - the target organ of melatonin which is part of the hypothalamus - is affected by light:


Source: HHMI Holiday Lectures 2000 "Clockwork Genes: Discoveries in Biological Time"