1. Anatomy and Physiology Chapter 16 - Endocrine System
Martini’s Visual
Anatomy and Physiology
First Edition
Martini w Ober
Chapter 16 - Endocrine System
Lecture 14
50 min. (23 slides)

2. Midterm Grades
Your midterm grades (due March 29th) will be calculated as follows:
Lec 1 Exam points Lec 2 Exam points Lab 1 Exam points Laboratory Grade points (6 labs so far)
Total points possible so far points
Your grade… (Total points you have / 330) * 100
Notes:
1) Extra credit points you have earned so far will be included. 2) No grades will be dropped for calculation of midterm grade.

3. Mid-term Checkup
Based on the three (3) grades you have received so far, you should do a mid-term checkup.
To find your average so far total the following points: Lec Exam 1 + Lec Exam 2 + Lab Exam 1 + Lab points (6 labs)
Example: ( )  330 = 0.80 (80%)
Dropping the low grade: ( )  230 = 0.86 (86%)
To figure out what you need to AVERAGE for the next lecture and/or lab exam and the final COMBINED to get a particular grade:
Average grade needed on remaining exams*
Points desired (see syllabus) – Total points so far =
350 (if no grade dropped) or 450 (if low grade dropped)
*This formula assumes you will have 50 pts for lab and 6 XC pts at the end of the course

4. Points and Grades (from Syllabus) - Revised
Grade for Course
Grade as %
Points (of a possible 700)
Quality Points A
92-100
4.0 A-
90-91
3.7 B+
88-89
3.3 B
82-87
3.0 B-
80-81
2.7 C+
78-79
2.3 C
70-77
2.0 D+
68-69
1.0 D
60-67
0.7 F
less than 60
less than 420
0.0
Example 1: To get a grade of B for the course, using the example grades on previous slide, and not dropping lowest grade (50), and assuming 50 pts for lab and 6 XC points:
574 – ( ) = x; x = (79%) Average on upcoming exams
350
Example 2: To get a grade of B for the course, using the example grades on previous slide, and dropping lowest grade (67), and assuming 50 pts for lab and 4 XC points:
574 – ( ) = x; x = (76%) Average on upcoming exams
450

5. Lecture Overview Overview of the Endocrine System
Hormone Chemistry and Actions
Control of Hormone Secretion

6. Overview of the Endocrine System
The endocrine system consists of collections of cells located in tissues scattered throughout the body that produce substances released into the blood (hormones) to ultimately affect the activity and metabolism of target cells.
The endocrine system consists of collections of cells located in tissues scattered throughout the body that produce substances released into the blood (hormones) to ultimately affect the activity and metabolism of target cells.
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

7. Endocrine System Endocrine glands are ductless
Effects of hormones are INTRAcellular
Exocrine glands have ducts
Effects are EXTRAcellular
Figure from: Hole’s Human A&P, 12th edition, 2010

8. Endocrine Glands Endocrine glands release hormones
hormones travel throughout body in blood to targets
targets must have receptors to respond
Paracrine secretions
act locally
do not travel through blood
Autocrine secretions
affect only the secreting cell
Hormones regulate metabolic processes and change activity of cells
- Rates of biochemical reactions - Water/electrolyte balance - Blood pressure - Reproduction, development, and growth
Examples of paracrine factors: histamine and NO (smooth muscle of blood vessels), somatostatin in pancreas (inhib. Insulin/glucagon secrn), eicosanoids.

9. Comparison of Nervous and Endocrine Systems
Figure from: Hole’s Human A&P, 12th edition, 2010
Neurons release neurotransmitters into a synapse, affecting postsynaptic cells
Glands release hormones into the bloodstream
Only target of hormone responds

10. Classification of Hormones
Amino acids
Amino Acid Derivatives
Peptides
Proteins, glycoproteins
Hormones
Steroids (cholesterol-derived)
Lipid Derived
Hormones can be broadly grouped into steroid hormones, which are lipid-soluble and exert their actions by binding to intranuclear receptors, and amino acid-derived hormones, which are water soluble and exert their actions via second messengers.
Eicosanoids (cell membranes) (locally acting)

11. Chemistry of Hormones Steroid Hormones derived from cholesterol
sex hormones
adrenal cortex hormones
Eicosanoids
paracrine factors; secondary role as hormones
coordinate cellular activities; affect enzymatic processes
leukotrienes (from leukocytes)
prostaglandins (thromboxane, prostacyclin)
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

12. Eicosanoid Synthesis
Eicosanoids are important paracrine factors that mediate many processes in the body, including:
Inflammation - blood vessel constriction - blood clotting - smooth muscle contraction and relaxation

13. Chemistry of Hormones Amino Acid Derivatives - amines
- derivatives of the amino acids tyrosine and tryptophan
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

14. Chemistry of Hormones Amino Acid Derivatives peptides and proteins
glycoproteins
most hormones
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

15. Types of Hormones
Figure from: Hole’s Human A&P, 12th edition, 2010

16. Steroid Hormones Composed of rings of C and H
Steroid hormones are hydrophobic, i.e., lipid soluble
What does this mean for
- Blood (plasma) solubility?
- Cell membrane solubility?
Cholesterol - Cyclopentanoperhydrophenanthrene

17. Actions of Steroid Hormones
hormone crosses membranes
Figure from: Hole’s Human A&P, 12th edition, 2010
hormone combines with receptor in nucleus or cytoplasm
synthesis of mRNA activated
mRNA enters cytoplasm to direct synthesis of protein, e.g., aldosterone->Na/K Pump
Example of this: aldosterone. Binding of aldosterone to nuclear receptors triggers the cell to make Na-K ATPase pump, the sodium pump that exchanges K+ for Na+
(Thyroid hormone has a similar mechanism of action, even though it is a tyrosine derivative)
Magnitude of cellular response proportional to the number of hormone-receptor complexes formed

18. Amino Acid-Derived Hormones
Figure from: Hole’s Human A&P, 12th edition, 2010
Water soluble (hydrophilic)
What does this imply about their solubility in blood and the cell membrane?

19. Actions of Amino Acid-Derived Hormones
Figure from: Hole’s Human A&P, 12th edition, 2010
hormone (first messenger) binds to receptor on cell membrane
adenylate cyclase activated
ATP converted to cAMP
cAMP (second messenger) promotes a series of reactions leading to cellular changes
Example: TSH stimulates the synthesis of the thyroid hormone, thyroxine. Binding of GH activates anabolic reactions in which aa are made into proteins.
Magnitude of response is not directly proportional to the number of hormone-receptor complexes – it’s amplified

20. Other Second Messengers
Other second messengers include:
- Diacylglycerol (DAG)
- Inositol triphosphate (IP3)
- cGMP
DAG
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

21. Target Cell Activation by Hormones
Target cells must have specific receptors to be activated by hormones
Target cell activation depends upon
Blood levels of the hormone
Rate of release from producing organ
Rate of degradation (target cells, kidney, liver)
Half-life
Relative numbers of receptors for the hormone
Cellular receptors can be up- or down-regulated
Affinity (strength) of binding of the hormone to its receptor

22. Negative Feedback for Hormone Regulation
Figure from: Hole’s Human A&P, 12th edition, 2010
Recall that homeostasis is the maintenance of STABLE (not constant) internal conditions
**Slide moved

23. Control of Hormone Secretion
Ca2+
Blood plasma
Ca2+
Endocrine organ #1
Ca2+
Ca2+
Ca2+
Ca2+
2) Humoral control
3) Hormonal control
(Hormone)
Ca2+
1) Neural control
Endocrine organ
Endocrine organ #2
Endocrine organ
Hormone secretion

24. Control of Hormonal Secretions
Figure from: Hole’s Human A&P, 12th edition, 2010
primarily controlled by negative feedback mechanism
Humoral example: Ca blood levels and PTH, glucose levels and insulin/glucagon secretion
Neural example: SNS stimulation of adrenal medulla, dopaminergic control of prolactin release by hypothalamus, milk letdown, sympath control of endocrine pancreas
Hormonal example: TSH, ACTH, somatostatin inhibition of growth hormone release.
Humoral
Hormonal
Neural
Control mechanisms for hormone release

25. Review The endocrine system consists of…
Tissues scattered throughout the body that secrete…
Hormones, which are chemical messengers,
Into the blood to circulate throughout the body
And affect metabolism/activity of target cells
A major control system of the body
Regulates many body functions
Rates of reactions
Transport of substances
Water and electrolyte balance
Blood pressure
Reproduction, development, and growth

26. Review Hormones can be divided chemically into Amino acid derivatives
Peptides, proteins, glycoproteins, amines
Water soluble (cannot cross cell membranes)
Use membrane-based receptors
Response can be amplified by intracellular cascades
Use second messengers (cAMP, cGMP, DAG, IP3)
Examples: norepinephrine, insulin, ADH, TSH
Steroid hormones
Composed of rings of C and H
Lipid soluble (can cross cell membranes)
Response is proportional to number of intracellular hormone-receptor complexes
Examples: Sex hormones, aldosterone, cortisol

27. Review Hormone release is controlled by
Humoral factors, e.g., blood [Ca2+], [glucose]
Neural mechanisms, e.g., SNS stimulation of adrenal medulla
Hormonal mechanisms, e.g., hypothalamus-pituitary
Control of hormone secretion is mostly accomplished by negative feedback