Download Lesson 2.3: Chemical Communication Preface While the nervous

Lesson 2.3: Chemical Communication
Preface
While the nervous system communicates using electrical signals, the body’s endocrine system
uses chemical signals, called hormones, to regulate body functioning. Hormones are proteins
involved in maintaining the body’s homeostasis. These chemical messengers carry signals from
one cell to another and regulate many of the body’s functions, including growth and development,
metabolism and reproduction.
Hormones are secreted by tissues in the body referred to as glands. Endocrine glands secrete
hormones directly into the bloodstream while exocrine glands secrete hormones into ducts, or
passageways, before they reach their target. Each hormone has a specific list of target tissues,
and in many cases these include other endocrine glands. This system of chemical communication,
the endocrine system, works with the nervous system to regulate and control all the actions of the
human machine.
In this lesson, students will examine chemical communication in the human body. Students will
investigate the components of the endocrine system, the mechanisms of hormone action and the
regulatory power of feedback. They will show, using a feedback loop, how the body uses
chemicals to maintain healthy blood sugar levels. Students will explore the many glands and
hormones of the endocrine system as they investigate a medical mystery. They will work as a
team and gather evidence to help diagnose an ailing patient. Along the way, students will be
asked to compare chemical communication with the system of electrical communication they
studied in the last lesson.
Students will not list and describe all of the endocrine organs and their associated hormones in
this lesson. Students will look at specific hormone pathways throughout the rest of the course, as
they relate to the topics such as water balance, calcium balance or the regulation of blood
pressure, and will continually show more glands, hormones and targets on their endocrine system
graphic organizer.
Essential Questions
1. What is a hormone?
2. How do hormones interact with target cells?
3. What are examples of endocrine glands and exocrine glands in the human body?
4. How do feedback loops help regulate the action of hormones?
5. How can too little or too much of a hormone lead to disease?
Key Terms
Endocrine Gland
Endocrine System
Exocrine Gland
Gland
Glucagon
Hormone
Hypothalamus
Insulin
Pituitary gland
A gland (as the thyroid or the pituitary) that produces an endocrine
secretion -- called also ductless gland, gland of internal secretion.
The glands and parts of glands that produce endocrine secretions, help
to integrate and control bodily metabolic activity, and include especially
the pituitary, thyroid, parathyroid, adrenals, islets of Langerhans,
ovaries, and testes.
A gland (as a sweat gland, a salivary gland, or a kidney) that releases a
secretion external to or at the surface of an organ by means of a canal
or duct.
A cell, group of cells, or organ of endothelial origin that selectively
removes materials from the blood, concentrates or alters them, and
secretes them for further use in the body or for elimination from the
body.
A protein hormone that is produced especially by the pancreatic islets of
Langerhans and that promotes an increase in the sugar content of the
blood by increasing the rate of breakdown of glycogen in the liver.
Any one of the many circulating chemical signals found in all
multicellular organisms that are formed in specialized cells, travel in
body fluids, and coordinate the various parts of the organism by
interacting with target cells.
The ventral part of the vertebrate forebrain; functions in maintaining
homeostasis, especially in coordinating the endocrine and nervous
systems; secretes hormones of the posterior pituitary and releasing
factors, which regulate the anterior pituitary.
A vertebrate hormone that lowers blood glucose levels by promoting the
uptake of glucose by most body cells and the synthesis and storage of
glycogen in the liver.
An endocrine gland at the base of the hypothalamus; consists of a
posterior lobe, which stores and releases two hormones produced by
the hypothalamus, and an anterior lobe, which produces and secretes
many hormones that regulate diverse body functions.