Chapt. Object.

Figures & Tables

Trnspcy. Acetates

Masters

1

I. Introduction

A. Anatomy of the Gland

B. Hormones Secreted by the Gland

C. Target Tissues and Their Responses

D. Regulation of Secretion

E. Consequences of Hypersecretion and Hyposecretion

2

II. Pituitary Gland and Hypothalamus

A. Structure of the Pituitary Gland

Fig. 18.1, p.542;

TA-223

1. Infundibulum = Physical Connection to Hypothalamus

B. Posterior Pituitary, or Neurohypophysis

Fig. 18.2, p.543

TA-224

C. Anterior Pituitary, or Adenohypophysis

D. Relationship of the Pituitary to the Brain

4

1. Hypothalamohypophyseal Portal System

Fig. 18.3a, p.544

TA-225

a. System of Blood Vessels

b. Carries Blood from Capillaries in Hypothalamus to Capillaries in Adenohypophysis

c. Neurohormones from Hypothalamus Delivered to Target Cells in Adenohypophysis

Fig. 18.4, p.545; Table 18.1, p.546

TA-226

1). Releasing Hormones

2). Inhibiting Hormones

3

2. Hypothalamohypophyseal Tract

Fig. 18.3b, p.544

TA-225

a. Bodies of Neurosecretory Cells in Hypothalamus

b. Release of Neurohormones from Terminals in Neurohypophysis

Fig. 18.4, p.545; Predict Quest. 1

TA-226

III. Hormones of the Pituitary Gland

Table 18.2, p.546

3, 5

A. Posterior Pituitary Hormones

1. Antidiuretic Hormone (ADH or Vasopressin)

Fig. 18.5, p.547

TA-227

a. Secreted in Response to

1). Activity of Hypthalamic Osmoreceptors

2). Direct Osmotic Stim. of Neurosecretory Cells in Supraoptic Nuclei

3). Drop in systemic Blood Pressure

b. ADH Action = Increased Kidney Reabsorption of Water

Clinical Note, p.545

2. Oxytocin (discussed in Greater Detail in Chapter 29)

a. Synthesized by Neurosecretory Cells of Paraventricular Nuclei

b. Actions

1). Increases Smooth Muscle Contraction of Uterus

2). Causes Milk Ejection in Lactating Females

c. Stimuli

1). Stretch of Uterus or Uterine Cervix

2). Stimulation of Nipples during Infant Suckling

4, 5

B. Anterior Pituitary Hormones

Table 18.1, p.546

1. Growth Hormone (GH or Somatotropin)

Clinical Focus, p.549

a. Promotes Amino Acid Uptake and Protein Synthesis

b. Increases Availability of Fatty Acids as Energy Source = Glucose Sparing

c. Indirect Effects Through Somatomedins from Liver and Other Cells

1). Stimulate Cartilage and Bone Growth

2). Increase Protein synthesis in Skeletal Muscle

3). Insulin-Like Growth Factors I and II

d. Increased Secretion by

Fig. 18.6, p.548

TA-228

1). Growth Hormone-Releasing Hormone (GH-RH)

2). Low Blood Glucose

c). Stress

e. Decreased Secretion by Growth Hormone-Inhibiting Hormone (GH-IH)

f. Cyclic Secretion; Highest Levels During Deep Sleep

Predict Quest. 2

2. Thyroid-Stimulating Hormone (TSH) or Thyrotropin

3. Adrenocorticotropic Hormone and Related Substances

a. All Derived from Proopiomelanocortin

b. Adrenocorticotropic Hormone (ACTH)

1). Increases Cortisol Secretion

2). Acts on Adrenal cortex

c. Lipotropins

1). Acts on Adipose Cells

2). Causes Fat Breakdown and Release of Fatty Acids

d. Beta-Endorphins

1). Same Effects as Opiate Drugs, esp. Analgesia

2). Increase in Response to Stress and Exercise

e. Melanocyte-Stimulating Hormone (MSH) - Stimulates Melanin Deposition in Skin

4. Gonadotropins and Prolactin

a. Involved in Regulating Reproduction - Explained More Fully in Chapter 28

b. Luteinizing Hormone (LH) - Involved in Gamete Production

c. Follicle Stimulating Hormone (FSH) - Also Involved in Gamete Production

d. Both LH and FSH Secretion Regulated by Gonadotropin-Releasing Hormone (Gn-RH) [a.k.a. Luteinizing Hormone-Releasing Hormone (LH-RH)]

e. Prolactin

1). Involved in Milk Production

2). Permissive Effect for FSH and LH on Ovary

3). Enhances Progesterone Secretion by Ovary After Ovulation

4). Prolactin-Releasing Hormone (PRH)

5). Prolactin-Inhibiting Hormone (PIH)

6

IV. Thyroid Gland

A. Histology

Fig. 18.7, p.550

1. Follicles

a. Follicular Cells

b. Lumen Filled with Thyrogobulin - Precursor to Thyroid Hormones

2. Parafollicular Cells

a. Between Follicles

b. Secrete Calcitonin

7

B. Thyroid Hormones

Table 18.3, p.551

1. Secretory Products = Triiodothyronine (T₃) 10% and Tetraiodothyronine (T₄) 90%

2. Thyroid Hormone Synthesis (and Secretion -TSH Must be Present, Activates cAMP Second Messenger System)

Fig. 18.8, p.552

TA-229

a. Active Absorption of I^- Ions

b. Synthesis of Thyroglobulins by Follicle Cells

c. Tyrosine Residues Iodinated

d. Iodinated Thryroglobulin Moved by Exocytosis to Lumen of Follicle

e. Iodinated Tyrosines Combined to Form Iodinated Thyronine

1). Two Diiodotyrosines form Tetraiodothyronine

2). One Diiodotyrosine and one Mono-iodotyrosine Form Triiodothyronine

3). Both Stored as Part of Thyroglobulin in Lumen

4). Two-week Supply Kept

f. Thryoglobulin Taken into Follicle Cell by Endocytosis

1). Lysosomes Fuse Wtih Endocytotic Vesicles

2). T₃ , T₄, and Free Amino Acids Released

g. T₃ and T₄ diffuse out of Follicle Cell into Interstitial Spaces then Blood, Amino Acids Reused within Follicle Cells

3. Transport in the Blood

a. Combined with Plasma Proteins - 10-75% Bound to Thyroxine-Binding Globulin (TBG)

b. 33-40% of T₄ Converted to T₃ (the More Active Form) in Body Tissues

4. Mechanism of Action of Thyroid Hormones

a. Readily Diffuse through Membranes

b. Nuclear Receptor Molecules

c. Initiate New Protein Synthesis

d. Increase ATP and Heat Production by Mitochondria

5. Effects of Thyroid Hormones

Table 18.4, p.553

a. Increased Metabolism of Glucose, Fat and Protein

b. Increased Body Temperature

c. Normal Growth Patterns Require Presence of Thyroid Hormones - Permissive Effect on Growth Hormone

d. Hypothyroidism During Development and Cretinism

6. Regulation of Thyroid Hormone Secretion

Fig. 18.9, p.554; Table 18.5, p.554; Predict Quest. 3

TA-230

a. TSH

b. TRH

c. Negative Feedback Inhibition of TSH & TRH by T₃ and T₄

8

C. Calcitonin

1. Secretion by Parafollicular Cells

2. Target Cells in Bone

3. Secretion Associated with High Blood Calcium

4. Lowers Blood Calcium and Phosphate

a. Inhibits Osteoclasts

b. Stimulates bone Deposition

5. Calcitonin secretion Decreases with Age - Osteoporosis Increases with Age

V. Parathyroid Glands

A. Location and Structure

Fig. 18.10, p.555

9

B. Parathyroid Hormone (PTH)

Table 18.3, p.551

1. Secretion Stimulated by Low Blood Calcium, Inhibited by High Plasma Calcium

Fig. 18.11, p.556

TM-59

2. PTH Raises Blood Calcium

a. Stimulates Osteoclasts Possibly Acting through Local Factor Produced By Osteoblasts in Response to PTH

b. Promotes Calcium Reabsorption at Kidney

c. Promotes Activation of Vitamin D at Kidney

10

1). Vit. D Increases Calcium Absorption at Intestine

2). Vit. D Increases Phosphate Absorption at Intestine

3. PTH Produces Net Lowering of Phosphate Levels by Increasing Kidney Excretion of Phosphate

4. Hypo- and Hyperparathyroidism

Table 18.6, p.557

Predict Quest. 4, 5

VI. Adrenal (Suprarenal) Glands

Fig. 18.12a, p.557

11

A. Histology

Fig. 18.12b, p.557

1. Medulla

a. Embryologically from Neural Crest Cells

b. Functions as Part of Sympathetic Nervous System

2. Cortex Has Layers

Fig. 18.12b, p.557

a. Zona Glomerulosa (Outermost)

b. Zona Fasciculata

c. Zona Reticularis

B. Hormones of the Adrenal Medulla

Table 18.7, p.558

1. Hormones

a. Epinephrine 80%

b. Norepinephrine 20%

2. Hormone Action

a. Increase Blood Glucose via cAMP Second Messenger Systems

b. Increase Heart Rate and Force of Contraction

c. Constrict Blood Vessels to Skin and Viscera

d. Dilate Blood Vessels to Skeletal and Cardiac Muscle

12

C. Regulation (Release is Primarily a Response to Sympathetic Stimulation)

Fig. 18-13, p.582; Clinical Note, p.558

TA-231

D. Hormones of the Adrenal Cortex

Table 18.7, p.558; Clinical Focus, p.560; Clinical Focus (Stress), p.568

1. Mineralocorticoids - Aldosterone

a. From Zona Glomerulosa

b. Help Regulate Blood Levels of Na⁺, K⁺, and H⁺

Predict Quest. 6

c. Effects and Controls Discussed in Detail with the Kidney (Chpts. 26 &27) and Circulatory System (Chpt. 21)

2. Glucocorticoids - Cortisol

Table 18.8, p.550

a. From Zona Fasciculata

b. Numerous Targets and Responses

1). Increases Fat and Protein Metabolism

2). Increases Blood Glucose Levels

3). Increases Glycogen Stores in Cells

12

c. Regulation

Fig. 18.14, p.561; Predict Quest. 7

TA-232

1). ACTH (From Anterior Pituitary) Stimulates Cortisol Secretion

2). Central Stress and Hypoglycemia Cause Increased CRH Secretion by Hypothalamus

3. Adrenal Androgens - Androstenedione

a. Stimulate Axillary and Pubic Hair Growth in Females

b. Negligible Effects in Males Compared to Testosterone

13

VII. Pancreas

A. Histology

Fig. 18.15, p.562

1. Exocrine Portion, Ducts and Acini and Pancreatic Juice (Chapter 24)

2. Endocrine Portion = Pancreatic Islets

Table 18-10, p.586

a. Alpha Cells and Glucagon

b. Beta Cells and Insulin

c. Delta Cells and Somatostatin

14

B. Effects Insulin and Glucagon on Their Target Tissues

Table 18.10 & Table 18.11, p.563

1. Insulin

a. Targets; Liver, Adipose, Muscle and Satiety Center

b. Effects; Increase Glucose and Amino Acid Uptake

2. Glucagon

a. Target; Liver

b. Effects; Increase Breakdown of Glycogen and Fats

C. Regulation of Pancreatic Hormone Secretion

1. Insulin

a. Secretion

1). Increased Blood Glucose

2). Parasympathetic Stimulation

3). Gastrointestinal Hormones (Chapter 24)

b. Inhibition; Somatostatin

2. Glucagon

a. Secretion

1). Low Blood Glucose

2). Sympathetic Stimulation

b. Inhibition; Somatostatin

Fig. 18-16, p.565; Predict Quest. 8, 9

Clinical Focus (Diabetes Mellitus), p.568

TM-60

14

VIII. Hormonal Regulation of Nutrients

A. Following a Meal

Fig. 18.17a, p.566

TA-233

1. Increased Blood Levels of Nutrients

2. Increased Parasympathetic Stimulation

3. Increased Insulin Secretion

4. Most Cells Take Up Glucose, Amino Acids and Fatty Acids - Excesses Put into Storage Forms (Glycogen and Fat)

5. Inhibition of Glucagon, Cortisol, GH and Epinephrine Secretion

B. Several Hours After Last Meal

Fig. 18.17b, p.566

TA-233

1. Decreased Blood Levels of Nutrients

2. Increased Sympathetic Stimulation

3. Decreased Insulin and Increased Glucagon Secretion

4. Most Cells Decrease Glucose Uptake and Switch to Other Fuels

a. Increased Gluconeogenesis, Glygogenolysis

b. Increased Lipolysis

c. Increased Proteolysis

5. Increased Levels of Epinephrine, GH, and Cortisol

C. Regulation of Blood Nutrient Levels During Exercise

Fig. 18.18, p.567

TM-61

1. Skeletal Muscle Cells Switch to Fat Metabolism (Increased Protein Catabolism with Prolonged Exercise)

a. Increased Sympathetic Stimulation

b. Increased Circulating Levels of

1). Epinephrine

2). Glucagon

3). GH (Prolonged Exercise)

4). Cortisol (Prolonged Exercise)

c. Decreaed Insulin

2. Increased Glycogenolysis (Liver and Skeletal Muscle) and Gluconeogenesis (Liver) to Keep Blood Glucose Available to Nerual Tissue

Predict Quest. 10

IX. Reproductive Hormones - Discussed in Chapter 28

Table 18.12, p. 569

X. Hormones of the Pineal Body, Thymus Gland, and Others

Table 18.13, p.569

15

A. Pineal Body

1. Names - Melatonin, Arginine Vasotocin

2. Associated with Photoperiod and Seasonal Behavior in Animals

Fig. 18.19, p.570

TA-234

B. Thymus Gland - Thymosin and Immune System Funcitons (Chapter 22)

C. Gastrointestinal Tract - Several Hormones of Local Action (Chapter 24)

XI. Hormonelike Substances

A. Paracrine Regulatory Substances

1. Release Near Target Cells

2. Diffuse Without Entering Blood

3. Produce Local Effects

4. Short Half-Lives

B. Prostaglandins

1. Role in Inflammation (Chapter 22)

2. Many Other Local Effects

a. Stimulate Pain Receptors

b. Vasodilation Associated With Headaches

3. Synthesis Inhibited by Aspirin and Other Antiinflammatory Drugs

C. Endorphins, Enkephalins and Dynorphins

1. Endogenous Analgesics (Morphine Binds to Endorphin Receptors)

2. Moderate Sensitivity to Pain

3. Stress and Exercise Seem to Increase Secretion of Endorphins

XII. Systems Pathology

Systems Interactions, p.572; Predict Quest. 11