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)

Midterm Grades Your midterm grades (due March 29th) will be calculated as follows: Lec 1 Exam 100 points Lec 2 Exam 100 points Lab 1 Exam 100 points Laboratory Grade 30 points (6 labs so far) Total points possible so far...330 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.

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: (83 + 67 + 90 + 26)  330 = 0.80 (80%) Dropping the low grade: (83 + 90 + 26)  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

Points and Grades (from Syllabus) - Revised Grade for Course Grade as % Points (of a possible 700) Quality Points A 92-100 644-700 4.0 A- 90-91 630-643 3.7 B+ 88-89 616-629 3.3 B 82-87 574-615 3.0 B- 80-81 560-573 2.7 C+ 78-79 546-559 2.3 C 70-77 490-545 2.0 D+ 68-69 476-489 1.0 D 60-67 420-475 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 – (83 + 67 + 90 + 50 + 6) = x; x = 0.79 (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 – (83 + 90 + 50 + 6) = x; x = 0.76 (76%) Average on upcoming exams 450

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

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

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

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.

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

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)

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

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

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

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

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

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

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

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?

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

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

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

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

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

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

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

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

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