1. Hormones and the Endocrine System
Chapter 26
Hormones and the Endocrine System
Lecture by Edward J. Zalisko

2. Introduction: Gender Benders
Endocrine disruptors
Environmental pollutants
Interfere with the action of hormones
Some are estrogen mimics in the environment that may produce
Demasculinized male alligators
Bass with male and female characteristics
Decrease in size and functioning of polar bear genitalia
Copyright © 2009 Pearson Education, Inc.

3. Alligator.

4. Water runoff.

5. Polar bear.

6. THE NATURE OF CHEMICAL REGULATION
THE NATURE OF CHEMICAL REGULATION
Copyright © 2009 Pearson Education, Inc.

7. 26.1 Chemical signals coordinate body functions
Hormones
Chemical signals
Usually carried in the blood
Cause specific changes in target cells
Secreted by
Endocrine glands
Neurosecretory cells
For the BLAST Animation Signaling: Endocrine, go to Animation and Video Files.
Student Misconceptions and Concerns
1. Student comprehension of the two mechanisms by which hormones trigger changes in target cells relies upon a good understanding of cell membranes and basic cellular chemistry. If these subjects have not been taught recently in your course, consider giving students a brief refresher before distinguishing between these mechanisms.
2. Students might not appreciate the diverse ways in which coordination and communication are achieved between the body’s cells. Endocrine signals generally work like a radio transmitter, sending signals outward. Only target cells, like people with radios tuned to a particular frequency, will receive the signal. In contrast, the nervous system provides a direct, two-way connection between the sender and receiver, much more like a land-based telephone call.
Teaching Tips
1. The nervous and endocrine systems coordinate and regulate most other systems of the body. You might consider comparing the speed and duration of each system’s response. The nervous system generally responds faster but for a shorter duration than the endocrine system.
Copyright © 2009 Pearson Education, Inc.

8. Secretory vesicles Blood vessel Target cell Endocrine cell Hormone
Figure 26.1A Hormone from an endocrine cell.
Hormone
molecules

9. Blood vessel Neurosecretory cell Target cell Hormone molecules
Figure 26.1B Hormone from a neurosecretory cell.
Hormone
molecules

10. 26.1 Chemical signals coordinate body functions
The endocrine system
Consists of all hormone-secreting cells
Works with nervous system to regulate body activities
The nervous system also
Communicates
Regulates
Uses electrical signals via nerve cells
Student Misconceptions and Concerns
1. Student comprehension of the two mechanisms by which hormones trigger changes in target cells relies upon a good understanding of cell membranes and basic cellular chemistry. If these subjects have not been taught recently in your course, consider giving students a brief refresher before distinguishing between these mechanisms.
2. Students might not appreciate the diverse ways in which coordination and communication are achieved between the body’s cells. Endocrine signals generally work like a radio transmitter, sending signals outward. Only target cells, like people with radios tuned to a particular frequency, will receive the signal. In contrast, the nervous system provides a direct, two-way connection between the sender and receiver, much more like a land-based telephone call.
Teaching Tips
1. The nervous and endocrine systems coordinate and regulate most other systems of the body. You might consider comparing the speed and duration of each system’s response. The nervous system generally responds faster but for a shorter duration than the endocrine system.
Copyright © 2009 Pearson Education, Inc.

11. 26.1 Chemical signals coordinate body functions
Comparing the endocrine and nervous systems
Nervous system reacts faster
Endocrine system responses last longer
Student Misconceptions and Concerns
1. Student comprehension of the two mechanisms by which hormones trigger changes in target cells relies upon a good understanding of cell membranes and basic cellular chemistry. If these subjects have not been taught recently in your course, consider giving students a brief refresher before distinguishing between these mechanisms.
2. Students might not appreciate the diverse ways in which coordination and communication are achieved between the body’s cells. Endocrine signals generally work like a radio transmitter, sending signals outward. Only target cells, like people with radios tuned to a particular frequency, will receive the signal. In contrast, the nervous system provides a direct, two-way connection between the sender and receiver, much more like a land-based telephone call.
Teaching Tips
1. The nervous and endocrine systems coordinate and regulate most other systems of the body. You might consider comparing the speed and duration of each system’s response. The nervous system generally responds faster but for a shorter duration than the endocrine system.
Copyright © 2009 Pearson Education, Inc.

12. Nerve cell Nerve signals Neurotransmitter molecules Nerve cell
Figure 26.1C Neurotransmitter from a nerve cell.
Nerve
cell

13. 26.2 Hormones affect target cells by two main signaling mechanisms
Hormone signaling involves three key events
Reception
Signal Transduction
Response
Student Misconceptions and Concerns
1. Student comprehension of the two mechanisms by which hormones trigger changes in target cells relies upon a good understanding of cell membranes and basic cellular chemistry. If these subjects have not been taught recently in your course, consider giving students a brief refresher before distinguishing between these mechanisms.
2. Students might not appreciate the diverse ways in which coordination and communication are achieved between the body’s cells. Endocrine signals generally work like a radio transmitter, sending signals outward. Only target cells, like people with radios tuned to a particular frequency, will receive the signal. In contrast, the nervous system provides a direct, two-way connection between the sender and receiver, much more like a land-based telephone call.
Teaching Tips
1. The two mechanisms by which hormones trigger changes in target cells can be compared using this analogy. If a house is like a cell, ringing the doorbell and having someone answer it is like using a signal transduction pathway. Pushing the doorbell, like a hormone binding to plasma-membrane receptors, causes an internal change. Using steroid hormones, on the other hand, is like walking up to the house, opening the door, and walking inside to deliver a message. Here the signal passes through the surface and into the interior of the home/cell to directly communicate the message.
Copyright © 2009 Pearson Education, Inc.

14. 26.2 Hormones affect target cells by two main signaling mechanisms
Amino-acid-derived hormones
Are water-soluble
Include proteins, peptides, and amines
Bind to plasma-membrane receptors on target cells
Initiate a signal transduction pathway
For the BLAST Animation Signaling via Steroid Hormones, go to Animation and Video Files.
Student Misconceptions and Concerns
1. Student comprehension of the two mechanisms by which hormones trigger changes in target cells relies upon a good understanding of cell membranes and basic cellular chemistry. If these subjects have not been taught recently in your course, consider giving students a brief refresher before distinguishing between these mechanisms.
2. Students might not appreciate the diverse ways in which coordination and communication are achieved between the body’s cells. Endocrine signals generally work like a radio transmitter, sending signals outward. Only target cells, like people with radios tuned to a particular frequency, will receive the signal. In contrast, the nervous system provides a direct, two-way connection between the sender and receiver, much more like a land-based telephone call.
Teaching Tips
2. The two mechanisms by which hormones trigger changes in target cells can be compared using this analogy. If a house is like a cell, ringing the doorbell and having someone answer it is like using a signal transduction pathway. Pushing the doorbell, like a hormone binding to plasma-membrane receptors, causes an internal change. Using steroid hormones, on the other hand, is like walking up to the house, opening the door, and walking inside to deliver a message. Here the signal passes through the surface and into the interior of the home/cell to directly communicate the message.
Animation: Water-Soluble Hormone
Copyright © 2009 Pearson Education, Inc.

15. hormone (epinephrine) Receptor 1 protein Target cell Plasma membrane
Water-soluble
hormone
(epinephrine)
Receptor
protein 1
Target
cell
Plasma
membrane
Figure 26.2A A hormone that binds a plasma-membrane receptor.

16. hormone (epinephrine) Receptor 1 protein Target 2 cell Plasma membrane
Water-soluble
hormone
(epinephrine)
Receptor
protein 1
Target
cell 2
Plasma
membrane
Signal
transduction
pathway
Relay
molecules
Figure 26.2A A hormone that binds a plasma-membrane receptor.

17. (in this example, glycogen breakdown)
Water-soluble
hormone
(epinephrine)
Receptor
protein 1
Target
cell 2
Plasma
membrane
Signal
transduction
pathway
Relay
molecules 3
Figure 26.2A A hormone that binds a plasma-membrane receptor.
Glycogen
Glucose
Cellular response
(in this example, glycogen breakdown)

18. 26.2 Hormones affect target cells by two main signaling mechanisms
Steroid hormones
Nonpolar lipids made from cholesterol
Can diffuse through plasma membranes
Bind to a receptor protein in the cytoplasm or nucleus
Hormone-receptor complex carries out the transduction of the hormonal signal
Student Misconceptions and Concerns
1. Student comprehension of the two mechanisms by which hormones trigger changes in target cells relies upon a good understanding of cell membranes and basic cellular chemistry. If these subjects have not been taught recently in your course, consider giving students a brief refresher before distinguishing between these mechanisms.
2. Students might not appreciate the diverse ways in which coordination and communication are achieved between the body’s cells. Endocrine signals generally work like a radio transmitter, sending signals outward. Only target cells, like people with radios tuned to a particular frequency, will receive the signal. In contrast, the nervous system provides a direct, two-way connection between the sender and receiver, much more like a land-based telephone call.
Teaching Tips
1. The two mechanisms by which hormones trigger changes in target cells can be compared using this analogy. If a house is like a cell, ringing the doorbell and having someone answer it is like using a signal transduction pathway. Pushing the doorbell, like a hormone binding to plasma-membrane receptors, causes an internal change. Using steroid hormones, on the other hand, is like walking up to the house, opening the door, and walking inside to deliver a message. Here the signal passes through the surface and into the interior of the home/cell to directly communicate the message.
Animation: Lipid-Soluble Hormone
Copyright © 2009 Pearson Education, Inc.

19. hormone (testosterone) 1 Target cell Nucleus Lipid-soluble
Figure 26.2B A hormone that binds an intracellular receptor.

20. hormone (testosterone) 1 Target cell 2 Receptor protein Nucleus
Lipid-soluble
hormone
(testosterone) 1
Target
cell 2
Receptor
protein
Nucleus
Figure 26.2B A hormone that binds an intracellular receptor.

21. hormone (testosterone) 1 Target cell 2 Receptor protein 3 Hormone-
Lipid-soluble
hormone
(testosterone) 1
Target
cell 2
Receptor
protein 3
Hormone-
receptor
complex
Nucleus
DNA
Figure 26.2B A hormone that binds an intracellular receptor.

22. activation of a gene and synthesis of new protein
Lipid-soluble
hormone
(testosterone) 1
Target
cell 2
Receptor
protein 3
Hormone-
receptor
complex
Nucleus
DNA 4
Transcription
mRNA
Figure 26.2B A hormone that binds an intracellular receptor.
New
protein
Cellular response:
activation of a gene and
synthesis of new protein

23. THE VERTEBRATE ENDOCRINE SYSTEM
THE VERTEBRATE ENDOCRINE SYSTEM
Copyright © 2009 Pearson Education, Inc.

24. 26.3 Overview: The vertebrate endocrine system consists of more than a dozen major glands
The vertebrate endocrine system
Consists of more than a dozen glands
Secretes more than 50 hormones
Student Misconceptions and Concerns
1. Appreciating the precise actions of hormones requires a thorough understanding of the specificity of target cells. The fact that only certain target cells will respond to a given hormonal signal allows hormones to be “broadcast” generally throughout the circulatory system without affecting every single cell.
Teaching Tips
1. Growth hormone levels typically decline as we age. Recent studies suggest that injections of engineered human growth hormone promote muscle growth and decrease body fat. However, additional research is necessary to fully appreciate the consequences of human growth hormone injections in the elderly.
Copyright © 2009 Pearson Education, Inc.

25. Hypothalamus Pineal gland Pituitary gland Thyroid gland Thymus
Parathyroid glands
Thymus
Adrenal glands
(atop kidneys)
Pancreas
Figure 26.3 The major endocrine glands in humans.
Ovary
(female)
Testes
(male)

26. 26.3 Overview: The vertebrate endocrine system consists of more than a dozen major glands
Hormones
Some have a very narrow range of targets and effects
Some have numerous effects on many kinds of target cells
Student Misconceptions and Concerns
1. Appreciating the precise actions of hormones requires a thorough understanding of the specificity of target cells. The fact that only certain target cells will respond to a given hormonal signal allows hormones to be “broadcast” generally throughout the circulatory system without affecting every single cell.
Teaching Tips
1. Growth hormone levels typically decline as we age. Recent studies suggest that injections of engineered human growth hormone promote muscle growth and decrease body fat. However, additional research is necessary to fully appreciate the consequences of human growth hormone injections in the elderly.
Copyright © 2009 Pearson Education, Inc.

27. Table 26.3 Major Human Endocrine Glands and Some of Their Hormones.

28. Table 26.3 Major Human Endocrine Glands and Some of Their Hormones.

29. 26.4 The hypothalamus, which is closely tied to the pituitary, connects the nervous and endocrine systems
The hypothalamus
Blurs the distinction between endocrine and nervous systems
Receives input from nerves about body conditions
Responds by sending out appropriate nervous or endocrine signals
Uses the pituitary gland to exert master control over the endocrine system
Student Misconceptions and Concerns
1. The abuse of growth hormones and steroids is of great concern in the world of professional and amateur sports. Although this is mentioned briefly in the text, consider emphasizing further the potential negative consequences of the abuse of these powerful hormones. The National Institutes of Health provide additional details on its website at
Teaching Tips
1. Morphine and other opiates bind to the same cell receptors that naturally bind endorphins, producing powerful pain-killing effects.
Copyright © 2009 Pearson Education, Inc.

30. 26.4 The hypothalamus, which is closely tied to the pituitary, connects the nervous and endocrine systems
The pituitary gland consists of two parts
Posterior pituitary
Composed of nervous tissue
Stores and secretes oxytocin and ADH
Student Misconceptions and Concerns
1. The abuse of growth hormones and steroids is of great concern in the world of professional and amateur sports. Although this is mentioned briefly in the text, consider emphasizing further the potential negative consequences of the abuse of these powerful hormones. The National Institutes of Health provide additional details on its website at
Teaching Tips
1. Morphine and other opiates bind to the same cell receptors that naturally bind endorphins, producing powerful pain-killing effects.
Copyright © 2009 Pearson Education, Inc.

31. Brain Hypothalamus Posterior pituitary Anterior pituitary (Bone)
Figure 26.4A Location of the hypothalamus and pituitary.
Anterior pituitary
(Bone)

32. Uterine muscles Mammary glands
Hypothalamus
Hormone
Neurosecretory
cell
Posterior
pituitary
Anterior
pituitary
Blood
vessel
Figure 26.4B Hormones of the posterior pituitary.
Oxytocin
ADH
Uterine muscles
Mammary glands
Kidney tubules

33. 26.4 The hypothalamus, which is closely tied to the pituitary, connects the nervous and endocrine systems
Anterior pituitary
Synthesizes and secretes hormones that control the activity of other glands
Is controlled by the hypothalamus
Releasing hormones stimulate the anterior pituitary
Inhibiting hormones inhibit the anterior pituitary
Morphine and other opiates bind to the same cell receptors that naturally bind endorphins, producing powerful pain-killing effects.
Student Misconceptions and Concerns
1. The abuse of growth hormones and steroids is of great concern in the world of professional and amateur sports. Although this is mentioned briefly in the text, consider emphasizing further the potential negative consequences of the abuse of these powerful hormones. The National Institutes of Health provide additional details on its website at
Teaching Tips
1. Morphine and other opiates bind to the same cell receptors that naturally bind endorphins, producing powerful pain-killing effects.
Copyright © 2009 Pearson Education, Inc.

34. the anterior pituitary
Neurosecretory
cell
Blood
vessel
Releasing hormones
from hypothalamus
Endocrine cells of
the anterior pituitary
Figure 26.4C Hormones of the anterior pituitary.
Pituitary hormones
TSH
ACTH
FSH
and LH
Prolactin
(PRL)
Growth
hormone
(GH)
Endorphins
Thyroid
Adrenal
cortex
Testes or
ovaries
Mammary
glands
(in mammals)
Entire
body
Pain
receptors
in the brain

35. Inhibition Anterior pituitary Inhibition Thyroid Thyroxine
Hypothalamus
Inhibition
TRH
Anterior
pituitary
Inhibition
TSH
Figure 26.4D Control of thyroxine secretion.
Thyroid
Thyroxine

36. HORMONES AND HOMEOSTASIS
HORMONES AND HOMEOSTASIS
Copyright © 2009 Pearson Education, Inc.

37. 26.5 The thyroid regulates development and metabolism
Thyroid gland hormones
Thyroxine (T4) and triiodothyronine (T3)
Regulate
Metabolism
Development
Negative feedback
Maintain homeostatic levels of T4 and T3 in the blood
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. Hypothyroidism produces symptoms that are like turning down a furnace during a cold winter. When thyroid levels are low, cells produce ATP and heat at a slower rate, and the person feels colder and is more lethargic than others in the same room. This reminds students that aerobic respiration produces heat and ATP. Hyperthyroidism is just the opposite, with an overproduction of heat as the consequence.
Copyright © 2009 Pearson Education, Inc.

38. No inhibition No inhibition No iodine Thyroid grows to form goiter
Hypothalamus
TRH
No inhibition
Anterior
pituitary
TSH
Insufficient
T4 and T3
produced
No iodine
Thyroid
Figure 26.5B How iodine deficiency causes goiter.
Thyroid grows
to form goiter

39. 26.5 The thyroid regulates development and metabolism
Thyroid imbalance can cause disease
Hyperthyroidism
Too much T4 and T3 in the blood
Leads to high blood pressure, loss of weight, overheating, and irritability
Produces Graves’ disease
Hypothyroidism
Too little T4 and T3 in the blood
Leads to low blood pressure, overweight, often cold, lethargy
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. Hypothyroidism produces symptoms that are like turning down a furnace during a cold winter. When thyroid levels are low, cells produce ATP and heat at a slower rate, and the person feels colder and is more lethargic than others in the same room. This reminds students that aerobic respiration produces heat and ATP. Hyperthyroidism is just the opposite, with an overproduction of heat as the consequence.
Copyright © 2009 Pearson Education, Inc.

40. Graves’ disease, a form of hyperthyroidism.
Figure 26.5A Graves’ disease, a form of hyperthyroidism.

41. 26.6 Hormones from the thyroid and parathyroids maintain calcium homeostasis
Blood calcium level is regulated by a tightly balanced antagonism between
Calcitonin from the thyroid
Parathyroid hormone (PTH) from the parathyroid glands
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. The use of calcitonin and parathyroid hormone to hold blood calcium levels steady is similar to the use of a heater and chiller on a fish tank or a laboratory incubator to hold temperatures steady. The same analogy can be applied to the contrasting functions of insulin and glucagon.
Copyright © 2009 Pearson Education, Inc.

42. Homeostasis: Normal blood calcium level (about 10 mg/100 mL)8 7
Calcitonin
Thyroid
gland
releases
calcitonin
Stimulates
Ca2+ deposition
in bones
Reduces
Ca2+ uptake
in kidneys 9 6
Blood Ca2+ falls
Stimulus:
Rising
blood Ca2+
level
(imbalance)
Ca2+
level
Homeostasis: Normal blood
calcium level (about 10 mg/100 mL)
Stimulus:
Falling
blood Ca2+
level
(imbalance)
Ca2+
level 1
Blood Ca2+ rises 5
Parathyroid
glands
release parathyroid
hormone (PTH)
Figure 26.6 Calcium homeostasis.
Stimulates
Ca2+ release
from bones 2 3
Parathyroid
gland
PTH
Increases
Ca2+ uptake
in kidneys
Active
vitamin D
Increases
Ca2+ uptake
in intestines 4

43. Homeostasis: Normal blood calcium level (about 10 mg/100 mL)
Stimulus:
Falling
blood Ca2+
level
(imbalance)
Ca2+
level 1
Blood Ca2+ rises 5
Parathyroid
glands
release parathyroid
hormone (PTH)
Stimulates
Ca2+ release
from bones
Figure 26.6 Calcium homeostasis. 2
Parathyroid
gland 3
PTH
Increases
Ca2+ uptake
in kidneys
Active
vitamin D
Increases
Ca2+ uptake
in intestines 4

44. Homeostasis: Normal blood calcium level (about 10 mg/100 mL)8 7
Calcitonin
Thyroid
gland
releases
calcitonin
Stimulates
Ca2+ deposition
in bones
Reduces
Ca2+ uptake
in kidneys 9 6
Stimulus:
Rising
blood Ca2+
level
(imbalance)
Blood Ca2+ falls
Ca2+
level
Figure 26.6 Calcium homeostasis.
Homeostasis: Normal blood
calcium level (about 10 mg/100 mL)
Ca2+
level

45. 26.7 Pancreatic hormones regulate blood glucose levels
The pancreas secretes two hormones that control blood glucose
Insulin—signals cells to use and store glucose
Glucagon—causes cells to release stored glucose into the blood
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. The use of calcitonin and parathyroid hormone to hold blood calcium levels steady is similar to the use of a heater and chiller on a fish tank or a laboratory incubator to hold temperatures steady. The same analogy can be applied to the contrasting functions of insulin and glucagon.
2. Scientists are exploring the use of pancreatic cell transplants into patients with type 1 diabetes as a new source of insulin. Pancreatic cells may be derived from donors and/or modified from other cells using stem cell technology. One website devoted to this subject is
Copyright © 2009 Pearson Education, Inc.

46. Homeostasis: Normal blood glucose level
Body
cells
take up more
glucose
Insulin 3 2
Beta cells of pancreas stimulated
to release insulin into
the blood 4
Blood glucose level
declines to a set point;
stimulus for insulin
release diminishes
Liver takes
up glucose
and stores it as
glycogen 1
High blood
glucose level
Stimulus:
Rising blood glucose
level (e.g., after eating
a carbohydrate-rich
meal)
Glucose
level
Homeostasis: Normal blood glucose level
(about 90 mg/100 mL)
Stimulus:
Declining blood
glucose level
(e.g., after
skipping a meal)
Glucose
level
Figure 26.7 Glucose homeostasis. 5
Low blood
glucose level
Blood glucose level
rises to set point;
stimulus for glucagon
release diminishes 6
Alpha
cells of
pancreas stimulated
to release glucagon
into the blood 8
Liver
breaks down
glycogen and
releases glucose
to the blood 7
Glucagon

47. Homeostasis: Normal blood glucose level
Body
cells
take up more
glucose
Insulin 3 2
Beta cells of pancreas stimulated
to release insulin into
the blood 4
Blood glucose level
declines to a set point;
stimulus for insulin
release diminishes
Liver takes
up glucose
and stores it as
glycogen 1
High blood
glucose level
Stimulus:
Rising blood glucose
level (e.g., after eating
a carbohydrate-rich
meal)
Figure 26.7 Glucose homeostasis.
Glucose
level
Homeostasis: Normal blood glucose level
(about 90 mg/100 mL)
Glucose
level

48. Homeostasis: Normal blood glucose level
(about 90 mg/100 mL)
Stimulus:
Declining blood
glucose level
(e.g., after
skipping a meal)
Glucose
level 5
Low blood
glucose
level
Blood glucose level
rises to set point;
stimulus for glucagon
release diminishes 6
Alpha
cells of
pancreas stimulated
to release glucagon
into the blood
Figure 26.7 Glucose homeostasis. 8
Liver
breaks down
glycogen and
releases glucose
to the blood 7
Glucagon

49. 26.8 CONNECTION: Diabetes is a common endocrine disorder
Diabetes mellitus
Results from
A lack of insulin or
A failure of cells to respond to it
Affects about 21 million Americans
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. The use of calcitonin and parathyroid hormone to hold blood calcium levels steady is similar to the use of a heater and chiller on a fish tank or a laboratory incubator to hold temperatures steady. The same analogy can be applied to the contrasting functions of insulin and glucagon.
2. Scientists are exploring the use of pancreatic cell transplants into patients with type 1 diabetes as a new source of insulin. Pancreatic cells may be derived from donors and/or modified from other cells using stem cell technology. One website devoted to this subject is
Copyright © 2009 Pearson Education, Inc.

50. 26.8 CONNECTION: Diabetes is a common endocrine disorder
Two common types of diabetes mellitus
Type 1 (insulin-dependent)
Autoimmune disease
Insulin-producing cells destroyed
Type 2 (non-insulin-dependent)
Deficiency of insulin
More commonly, reduced response to insulin
More than 90% of diabetics are type 2
Associated with being overweight and underactive
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. Scientists are exploring the use of pancreatic cell transplants into patients with type 1 diabetes as a new source of insulin. Pancreatic cells may be derived from donors and/or modified from other cells using stem cell technology. One website devoted to this subject is
Copyright © 2009 Pearson Education, Inc.

51. Results of glucose tolerance tests
400
350
300
Diabetic
250
Blood glucose (mg/100 mL)
200
150
Normal
100
Figure 26.8 Results of glucose tolerance tests. 50 1 1 2 3 4 5 2
Hours after glucose ingestion

52. 26.9 The adrenal glands mobilize responses to stress
Hormones from the adrenal glands help maintain homeostasis when the body is stressed
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. Students may not have carefully considered the benefits of pain. Consider emphasizing the adaptive nature of pain to your class. The authors note the risks of stopping pain in an injured part of the body. Based on this, challenge students to propose explanations as to why endorphins nonetheless evolved.
Copyright © 2009 Pearson Education, Inc.

53. 26.9 The adrenal glands mobilize responses to stress
Nerve signals from the hypothalamus stimulate the adrenal medulla to secrete
Epinephrine
Norepinephrine
These hormones quickly trigger the fight-or-flight responses
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. Students may not have carefully considered the benefits of pain. Consider emphasizing the adaptive nature of pain to your class. The authors note the risks of stopping pain in an injured part of the body. Based on this, challenge students to propose explanations as to why endorphins nonetheless evolved.
Copyright © 2009 Pearson Education, Inc.

54. 26.9 The adrenal glands mobilize responses to stress
Adrenocorticotropic hormone (ACTH) from the pituitary causes the adrenal cortex to secrete
Glucocorticoids
Mineralocorticoids
These hormones
Boost blood pressure
Boost energy in response to long-term stress
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. Students may not have carefully considered the benefits of pain. Consider emphasizing the adaptive nature of pain to your class. The authors note the risks of stopping pain in an injured part of the body. Based on this, challenge students to propose explanations as to why endorphins nonetheless evolved.
Copyright © 2009 Pearson Education, Inc.

55. Figure 26.9 How the adrenal glands control our responses to stress.
medulla
Adrenal
gland
Nerve
signals 1
Adrenal
cortex
Hypothalamus 3
Kidney
Releasing hormone
Spinal cord
(cross section)
Nerve
cell
Anterior pituitary
Blood vessel 4
Nerve cell
ACTH 5
Adrenal medulla
Adrenal cortex
ACTH 2
Epinephrine and
norepinephrine
Mineralocorticoids
Glucocorticoids
Figure 26.9 How the adrenal glands control our responses to stress.
Short-term stress response
Long-term stress response
1. Glycogen broken down to glucose;
increased blood glucose
2. Increased blood pressure
3. Increased breathing rate
4. Increased metabolic rate
5. Change in blood-flow patterns,
leading to increased alertness and
decreased digestive and kidney activity
Mineralocorticoids
Glucocorticoids
1. Retention of
sodium ions and
water by kidneys
1. Proteins and fats
broken down and
converted to glucose,
leading to increased
blood glucose
2. Increased blood
volume and blood
pressure
2. Immune system may
be suppressed

56. Short-term stress response Long-term stress response
Adrenal
medulla
Adrenal
gland
Adrenal
cortex
Kidney
Stress
Nerve
signals 1
Hypothalamus 3
Releasing hormone
Spinal cord
(cross section)
Nerve
cell
Anterior pituitary
Blood vessel 4
Nerve cell
ACTH
Figure 26.9 How the adrenal glands control our responses to stress. 5
Adrenal medulla
Adrenal cortex
ACTH 2
Epinephrine and
norepinephrine
Mineralocorticoids
Glucocorticoids
Short-term stress response
Long-term stress response

57. Short-term stress response
1. Glycogen broken down to glucose;
increased blood glucose
2. Increased blood pressure
3. Increased breathing rate
4. Increased metabolic rate
5. Change in blood-flow patterns,
leading to increased alertness and
decreased digestive and kidney activity
Figure 26.9 How the adrenal glands control our responses to stress.

58. Long-term stress response
Mineralocorticoids
Glucocorticoids
1. Retention of
sodium ions and
water by kidneys
1. Proteins and fats
broken down and
converted to glucose,
leading to increased
blood glucose
2. Increased blood
volume and blood
pressure
Figure 26.9 How the adrenal glands control our responses to stress.
2. Immune system may
be suppressed

59. 26.10 The gonads secrete sex hormones
Steroid sex hormones
Include estrogens, progestins, and androgens
Produced by the gonads in response to signals from
Hypothalamus
Pituitary
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. There seems to be no equivalent of menopause in human males. Although men experience a steady decline in testosterone production as they age, they can retain the ability to father offspring through at least 80 years of age.
2. The North American Menopause Society is a scientific nonprofit organization that may be a useful reference for related questions. Their website is
Copyright © 2009 Pearson Education, Inc.

60. 26.10 The gonads secrete sex hormones
Estrogens and progestins
Stimulate the development of female characteristics
Maintain the female reproductive system
Androgens
Such as testosterone
Trigger the development of male characteristics
Androgens
Such as testosterone
Trigger the development of male characteristics
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. There seems to be no equivalent of menopause in human males. Although men experience a steady decline in testosterone production as they age, they can retain the ability to father offspring through at least 80 years of age.
2. The North American Menopause Society is a scientific nonprofit organization that may be a useful reference for related questions. Their website is
Copyright © 2009 Pearson Education, Inc.

61. Male elephant seals in combat
Figure Male elephant seals in combat.

62. 26.11 EVOLUTION CONNECTION: A single hormone can perform a variety of functions in different animals
Prolactin in humans
Stimulates mammary glands to grow and produce milk during late pregnancy
Suckling by a newborn stimulates further release of prolactin
High prolactin during nursing inhibits ovulation
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. The shifting functions of prolactin reflect the kind of “remodeling” frequently found in evolution. Typically, new structures and functions result from modifications of ancestral structures and functions. In this case, as reproductive strategies evolved, the functional significance of prolactin was remodeled.
Copyright © 2009 Pearson Education, Inc.

63. Figure 26.11 Suckling promotes prolactin production.

64. 26.11 EVOLUTION CONNECTION: A single hormone can perform a variety of functions in different animals
Prolactin
Nonhuman mammals—stimulates nest building
Birds—regulates fat metabolism and reproduction
Amphibians—movement to water
Fish—migration between salt and fresh water
The shifting functions of prolactin reflect the remodeling nature of evolution. Typically, new structures and functions result from modifications of ancestral structures and functions. As reproductive strategies evolved, the functional significance of prolactin was remodeled.
Student Misconceptions and Concerns
1. Many students struggle to remember the basic structures, functions, and locations of the major vertebrate organs. Understanding and remembering the specific control mechanisms are typically beyond their background knowledge entering a general biology college course. Students will appreciate any reminders or reference materials that help them to organize this information.
2. As the section title indicates, a central theme of endocrine function is the maintenance of homeostasis. Repeatedly framing the details of hormonal and glandular function in the context of homeostasis can increase levels of student comprehension.
Teaching Tips
1. The shifting functions of prolactin reflect the kind of “remodeling” frequently found in evolution. Typically, new structures and functions result from modifications of ancestral structures and functions. In this case, as reproductive strategies evolved, the functional significance of prolactin was remodeled.
Copyright © 2009 Pearson Education, Inc.

65. To Review… Water- Lipid- soluble soluble hormone hormone Receptor
protein
Receptor
protein
Hormone-
receptor
complex
Signal
transduction
pathway
DNA
mRNA
To Review…
Cellular response
New protein

66. To Review… Brain Hypothalamus: Master control center of the
endocrine system
Anterior pituitary:
Composed of
endocrine tissue;
controlled by
hypothalamus;
produces and
secretes its
own hormones
Posterior pituitary:
Composed of nervous tissue;
stores and secretes hormones
made by hypothalamus
To Review…

67. 1. thyroxine
2. epinephrine
3. androgens
4. insulin
5. melatonin
6. FSH
7. PTH
8. ADH
Pineal gland
Testes
Parathyroid gland
Adrenal medulla
Pancreas
Hypothalamus
Anterior pituitary
Thyroid gland
a. lowers blood glucose
b. stimulates ovaries
c. triggers fight-or-flight
d. promotes male traits
e. regulates metabolism
f. related to daily rhythm
g. raises blood calcium levels
h. boosts water retention

68. You should now be able to
Explain how endocrine disruptors are causing environmental problems
Compare the mechanisms and functions of the endocrine and nervous systems
Distinguish between the two major classes of vertebrate hormones
Describe the different types and functions of vertebrate endocrine organs
Copyright © 2009 Pearson Education, Inc.

69. You should now be able to
Describe the interrelationships between the hypothalamus and pituitary glands
Describe the functions of the thyroid and parathyroid glands
Explain how insulin and glucagon manage blood glucose levels
Describe the causes and symptoms of types 1 and 2 diabetes
Copyright © 2009 Pearson Education, Inc.

70. You should now be able to
Compare the functions of the adrenal gland hormones
Describe the three major types of sex hormones and their functions
Describe the diverse functions of prolactin in vertebrate groups
Copyright © 2009 Pearson Education, Inc.