1. Chapter 18: The Endocrine System

2. Homeostasis Regulate activity & growth of cells Regulates metabolism
Directs development
Regulates activity of smooth & cardiac muscles, & glands
Influences reproduction
Participates in circadian rhythm

3. Nervous vs Endocrine Neurotransmitters Act close Fast
Doesn’t last long
Hormones
Act far away
Slow
Longer lasting response

4. Figure 18-1 Organs and Tissues of the Endocrine System.
Hypothalamus
Pineal Gland
Production of ADH, OXT, and regulatory hormones
Melatonin
Parathyroid Glands
Pituitary Gland
(located on the posterior surface of the thyroid gland)
Anterior lobe
ACTH, TSH, GH, PRL, FSH, LH, and MSH
Parathyroid hormone (PTH)
Posterior lobe
Organs with Secondary Endocrine Functions
Release of oxytocin (OXT)
and antidiuretic hormone (ADH)
Heart
See Chapter 21
• Atrial natriuretic peptide (ANP)
Thyroid Gland
• Brain natriuretic peptide (BNP)
Thyroxine (T4) Triiodothyronine (T3)
Calcitonin (CT)
Thymus (Undergoes atrophy during adulthood)
See Chapter 22
• Thymosins
Adrenal Gland
Adipose Tissue
Medulla
• Leptin
Epinephrine (E) Norepinephrine (NE)
Digestive Tract
See Chapter 25
Cortex
Secretes numerous hormones involved in the coordination of system functions, glucose metabolism, and appetite
Cortisol, corticosterone, aldosterone, androgens
Pancreatic Islets
Kidneys
See Chapters 19 and 26
• Erythropoietin (EPO) • Calcitriol
Insulin, glucagon
Gonads
See Chapters 28 and 29
KEY TO PITUITARY HORMONES
Testes (male) Androgens (especially testosterone), inhibin
ACTH Adrenocorticotropic hormone
TSH Thyroid-stimulating hormone
Testis
GH Growth hormone
PRL Prolactin
FSH Follicle-stimulating hormone
Ovaries (female) Estrogens, progesterone, inhibin
LH Luteinizing hormone
Ovary
MSH Melanocyte-stimulating hormone

5. Hormone Receptors
Hormones can only affect cells that have receptors for the hormone
Receptors constantly synthesized & broken down
Down regulation
Number of receptors decreases
Cell becomes less sensitive
Up regulation
Number of receptors increases
Cell becomes more sensitive

6. Hormones Circulating hormones Paracrines Autocrines
Travel through blood
Paracrines
Act on neighboring cells
Autocrines
Acts on cell that secretes it

7. Table 18-1 Mechanisms of Intercellular Communication.

8. Figure 18-2 Structural Classification of Hormones.

9. Hormone Transport Water soluble Lipid soluble “free” in plasma
Bound to transport proteins

10. Figure 18-3 G Proteins and Second Messengers.

11. Figure 18-4 Effects of Intracellular Hormone Binding.
Steroid hormones diffuse through the plasma membrane and bind to receptors in the cytoplasm or nucleus. The complex then binds to DNA in the nucleus, activating specific genes. b
Thyroid hormones enter the cytoplasm and bind to receptors in the nucleus to activate specific genes. They also bind to receptors on mitochondria and accelerate ATP production. 1
Diffusion through membrane lipids 1
Transport across plasma membrane
Target cell response
Target cell response
Target cell response
CYTOPLASM
Increased
Alteration of cellular structure or activity
Alteration of cellular structure or activity
ATP
production
Receptor 6 6
Translation and protein synthesis
Translation and protein synthesis
Receptor 2 2
Binding of receptors at mitochondria and nucleus
Binding of hormone to cytoplasmic or nuclear receptors 5 5
Transcription and mRNA production
Transcription and mRNA production
Receptor
Receptor 4 4
Gene activation
Gene activation
Nuclear pore 3 3
Nuclear envelope
Binding of hormone–receptor complex to DNA
Binding of hormone–receptor complex to DNA

12. Hormone Interactions Permissive effect Synergistic effect
Requires simultaneous or recent exposure to 2nd hormone
Synergistic effect
2 hormones act together produces more powerful effect
Antagonistic effect
1 hormone opposes another

13. Figure 18-5 Three Mechanisms of Hypothalamic Control over Endocrine Function.2 3
Production of antidiuretic hormone (ADH) and oxytocin (OXT)
Secretion of regulatory hormones to control activity of the anterior lobe of pituitary gland
Control of sympathetic output to adrenal medullae
HYPOTHALAMUS
Preganglionic motor fibers
Infundibulum
Adrenal cortex
Adrenal medulla
Posterior lobe of pituitary gland
Anterior lobe of pituitary gland
Adrenal gland
Hormones secreted by the anterior pituitary control other endocrine organs
Release of antidiuretic hormone (ADH) and oxytocin (OXT)
Secretion of epinephrine (E) and norepinephrine (NE)

14. Figure 18-6 The Anatomy and Orientation of the Pituitary Gland.
Anterior pituitary lobe
Posterior pituitary
lobe
Pars distalis
Pars intermedia
Third ventricle
Mammillary body
Hypothalamus
Optic chiasm
Infundibulum
Sellar diaphragm
Anterior pituitary lobe
Pars tuberalis
Pars distalis
Posterior pituitary
lobe
Pars intermedia
Secretes other pituitary hormones
Secretes MSH
Releases ADH and OXT
Sphenoid (sella turcica)
Pituitary gland
LM × 77 a
Relationship of the pituitary gland to the hypothalamus b
Histology of the pituitary gland showing the anterior and posterior lobes

15. Paraventricular nuclei Neurosecretory neurons
Figure 18-7 The Hypophyseal Portal System and the Blood Supply to the Pituitary Gland.
Supraoptic nuclei
Paraventricular nuclei
Neurosecretory neurons
Mammillary body
Median eminence
Optic chiasm
The superior hypophyseal artery delivers blood to the capillary network in the median eminence
Capillary network in the median eminence
The portal vessels deliver blood containing regulatory factors to the capillary network within the anterior lobe of the pituitary gland
Infundibulum
Anterior lobe of the pituitary gland
Capillary network in the anterior lobe
The inferior hypophyseal artery delivers blood to the posterior lobe of the pituitary gland
Posterior lobe of the pituitary gland
Endocrine cells
Hypophyseal veins carry blood containing the pituitary hormones to the cardiovascular system for delivery to the rest of the body

16. Anterior Pituitary Cells
Somatotrophs
hGH
Thyrotrophs
TSH
Gonadotrophs
FSH LH
Lactotrophs
Prolactin
Corticotrophs
ACTH

17. Figure 18-8 Feedback Control of Endocrine Secretion.

18. Figure 18-9 Pituitary Hormones and Their Targets.
Hypothalamus
KEY TO PITUITARY HORMONES:
Direct Control by Nervous System
Indirect Control through Release of Regulatory Hormones
Direct Release of Hormones
ACTH
Adrenocorticotropic hormone
TSH
Thyroid-stimulating hormone
Regulatory hormones are released into the hypophyseal portal system for delivery to the anterior lobe of the pituitary gland
Sensory stimulation
Osmoreceptor stimulation GH
Growth hormone
PRL
Prolactin
FSH
Follicle-stimulating hormone LH
Luteinizing hormone
MSH
Melanocyte-stimulating hormone
ADH
Antidiuretic hormone
OXT
Oxytocin
Posterior lobe of pituitary gland
Anterior lobe of pituitary gland
Adrenal medulla
ADH
Adrenal gland
ACTH
Adrenal cortex GH
TSH
Kidneys
OXT
Males: Smooth muscle in ductus deferens and
prostate gland
Epinephrine and norepinephrine
Liver
MSH
Thyroid
gland
PRL
FSH LH
Somatomedins
Females: Uterine smooth muscle and mammary glands
Glucocorticoids (cortisol, corticosterone)
Melanocytes (uncertain significance in healthy adults)
Bone, muscle, other tissues
Ovaries of female
Testes of male
Mammary glands
Thyroid hormones (T3, T4)
Inhibin
Testosterone
Estrogen
Progesterone
Inhibin

19. Human Growth Hormone
Promotes synthesis & secretion of insulin-like growth factors (IGFs)
IGFs function
Cause cells to grow & multiply
Enhances lipolysis
Decreases glucose uptake

20. Figure 18-9 Pituitary Hormones and Their Targets.
Hypothalamus
KEY TO PITUITARY HORMONES:
Direct Control by Nervous System
Indirect Control through Release of Regulatory Hormones
Direct Release of Hormones
ACTH
Adrenocorticotropic hormone
TSH
Thyroid-stimulating hormone
Regulatory hormones are released into the hypophyseal portal system for delivery to the anterior lobe of the pituitary gland
Sensory stimulation
Osmoreceptor stimulation GH
Growth hormone
PRL
Prolactin
FSH
Follicle-stimulating hormone LH
Luteinizing hormone
MSH
Melanocyte-stimulating hormone
ADH
Antidiuretic hormone
OXT
Oxytocin
Posterior lobe of pituitary gland
Anterior lobe of pituitary gland
Adrenal medulla
ADH
Adrenal gland
ACTH
Adrenal cortex GH
TSH
Kidneys
OXT
Males: Smooth muscle in ductus deferens and
prostate gland
Epinephrine and norepinephrine
Liver
MSH
Thyroid
gland
PRL
FSH LH
Somatomedins
Females: Uterine smooth muscle and mammary glands
Glucocorticoids (cortisol, corticosterone)
Melanocytes (uncertain significance in healthy adults)
Bone, muscle, other tissues
Ovaries of female
Testes of male
Mammary glands
Thyroid hormones (T3, T4)
Inhibin
Testosterone
Estrogen
Progesterone
Inhibin

21. Table 18-2 The Pituitary Hormones (Part 1 of 2).

22. Posterior Pituitary
Doesn’t produce any hormones but stores & secretes 2 of them
Oxytocin
Acts on smooth muscle to increase strength of contraction
Secreted when uterus stretched
Antidiuretic hormone (ADH)
Causes kidneys to conserve water
Weak vasoconstrictor
Stimulated when osmoreceptors are stimulated by high osmotic pressure

23. Table 18-2 The Pituitary Hormones (Part 2 of 2).

24. Figure 18-10 The Thyroid Gland.
Hyoid bone
Thyroid follicles
Superior
thyroid artery
Thyroid cartilage
of larynx
Internal
jugular vein
Superior
thyroid vein
Cricoid cartilage
of larynx
Common
carotid artery
Left lobe of
thyroid gland
Right lobe of
thyroid gland
Isthmus of
thyroid gland
Middle thyroid vein
Inferior
thyroid artery
Thyrocervical trunk
Inferior
thyroid
veins
Trachea
Outline of clavicle
Outline of sternum
The thyroid gland
LM × 122 a
Location and anatomy of the thyroid gland b
Histological organization
of the thyroid
Capillary
Capsule
C cell
Cuboidal
epithelium
of follicle
Follicle
cavities
Thyroid
follicle
Thyroid
follicle
Thyroglobulin
stored in colloid
of follicle
C cell
Follicles of the thyroid gland
LM × 260 c
Histological details of the thyroid gland showing thyroid follicles and both cell types in the follicular epithelium
ATLAS: Plate 18c

25. Figure 18-11 The Thyroid Follicles.
Follicle cavity
Hypothalamus releases TRH 3
Thyroglobulin (contains T3 and T4)
FOLLICLE CAVITY
Homeostasis Disturbed
Decreased T3 and T4 concentrations in blood or low body temperature 4
TRH
Endocytosis
Thyroglobulin 2
Anterior lobe
Iodine atoms (I0) 5
Lysosomal digestion
Other amino acids
Pituitary gland
Tyrosine T4
HOMEOSTASIS T3
Normal T3 and T4 concentrations, normal body temperature
Anterior lobe
Diffusion
TSH
Diffusion
TSH- sensitive ion pump 6
FOLLICLE CELL 1
Homeostasis Restored 7
Increased T3 and T4 concentrations in blood
CAPILLARY
Thyroid gland
Iodide ions (I−)
Thyroid follicles release T3 and T4
TBG, transthyretin, or albumin
T4 & T3 a
The synthesis, storage, and secretion of thyroid hormones. The numbered events are explained in the text. b
The regulation of thyroid secretion.

26. Actions of Thyroid Hormones
Increases BMR
Synthesis of Na+ K+ pumps
Stimulates protein synthesis
Enhances some of the actions of catecholamines

27. Table 18-3 Effects of Thyroid Hormones on Peripheral Tissues.

28. Calcitonin
From parafollicular cells
Decrease in calcium in blood

29. Table 18-4 Hormones of the Thyroid Gland and Parathyroid Glands.

30. Figure 18-12 The Parathyroid Glands.
Blood vessel
Connective tissue capsule of parathyroid gland
Thyroid follicle
Parathyroid gland
LM × 94 b
Both parathyroid and thyroid tissues.
Left lobe of thyroid gland
Parathyroid (chief) cells
Parathyroid glands a
Thyroid gland, posterior view. The location of the parathyroid glands on the posterior surface of the thyroid lobes. (The thyroid lobes are located anterior to the trachea.)
Oxyphil cells
Parathyroid cells and oxyphil cells
LM × 600 c
Parathyroid gland cells.

31. Parathyroid Hormone
Increases blood calcium

32. Figure 18-13 The Homeostatic Regulation of Calcium Ion Concentrations.
Increased excretion of calcium by kidneys
Thyroid gland produces calcitonin
Calcium deposition in bone
HOMEOSTASIS RESTORED
HOMEOSTASIS DISTURBED
Increasing levels of blood calcium
Blood calcium levels decrease
Increasing calcium levels in blood
HOMEOSTASIS
Normal blood calcium levels (8.5–11 mg/dL)
Decreasing levels of blood calcium
HOMEOSTASIS DISTURBED
HOMEOSTASIS RESTORED
Decreasing calcium levels in blood
Blood calcium levels increase
Increased reabsorption of calcium by kidneys
Parathyroid glands secrete parathyroid hormone (PTH)
Calcium release from bone
Increased calcitriol production causes Ca2+ absorption by digestive tract

33. Figure 18-19a Endocrine Functions of the Kidneys.
Sunlight
Digestive tract
Cholesterol
Epidermis
Cholecalciferol
Dietary cholecalciferol
Liver
Parathyroid glands
Intermediate form
Stimulation of calcium and phosphate ion absorption
PTH
Calcitriol
Kidney a
The production of calcitriol

34. Table 18-4 Hormones of the Thyroid Gland and Parathyroid Glands.

35. Figure 18-14a The Adrenal Gland.
Right superior adrenal arteries
Right and left inferior phrenic arteries
Celiac trunk
Right adrenal gland
Left adrenal gland
Right middle adrenal artery
Left middle adrenal artery
Right inferior adrenal artery
Left inferior adrenal arteries
Left adrenal vein
Right renal artery
Left renal artery
Left renal vein
Right renal vein
Superior mesenteric artery
Abdominal aorta
Inferior vena cava a
A superficial view of the kidneys and adrenal glands

36. Figure 18-14bc The Adrenal Gland.
Capsule
Cortex
Medulla b
An adrenal gland in section
The Adrenal Hormones
Region/Zone Hormones Primary Target Hormonal Effects Regulatory Control
ADRENAL CAPSULE
ADRENAL CORTEX
Increase renal reabsorption of Na+ and water (especially in the presence of ADH), and accelerate urinary loss of K+
Stimulated by angiotensin II, elevated blood K+ or fall in blood Na+; inhibited by ANP and BNP
Zona glomerulosa
Mineralocorticoids, primarily aldosterone
Kidneys
Zona fasciculata
Glucocorticoids (cortisol [hydrocortisone], corticosterone)
Most cells
Increase rates of glucose and glycogen formation by the liver; release of amino acids from skeletal muscles, and lipids from adipose tissues; promote peripheral utilization of lipids; anti-inflammatory effects
Stimulated by ACTH from the anterior lobe of the pituitary gland
Zona reticularis
Adrenal androgens stimulate the development of pubic hair in boys and girls before puberty.
Androgens
Most cells
Androgen secretion is stimulated by ACTH.
ADRENAL MEDULLA
Epinephrine (E), norepinephrine (NE)
Most cells
Increases cardiac activity, blood pressure, glycogen breakdown, blood glucose levels; releases lipids by adipose tissue
Stimulated by sympathetic preganglionic fibers
Adrenal gland
LM × 140 c
The major regions and zones of an adrenal gland and the hormones they produce

37. Renin-Angiotensin-Aldosterone Pathway
Decrease in blood volume
Decrease in BP
Renin released from kidney
Converts angiotensinogen to angiotensin I
ACE in lungs converts angiotensin I to angiotensin II
Stimulates adrenal cortex to secrete aldosterone

38. Figure 18-19b Endocrine Functions of the Kidneys.
HOMEOSTASIS
Normal blood pressure and volume
HOMEOSTASIS DISTURBED
HOMEOSTASIS RESTORED
Falling blood pressure and volume
Rising blood pressure and volume
Kidney
Falling renal blood flow and O2
Increased fluid intake and retention
Increased red blood cell production
Erythropoietin released
Aldosterone secreted
ADH secreted
Renin released
Stimulation of thirst
ACE
Angiotensin II
Angiotensinogen
Angiotensin I b
The release of renin and erythropoietin, and an overview of the renin- angiotensin-aldosterone system beginning with the activation of angiotensinogen by renin

39. Figure 18-14bc The Adrenal Gland.
Capsule
Cortex
Medulla b
An adrenal gland in section
The Adrenal Hormones
Region/Zone Hormones Primary Target Hormonal Effects Regulatory Control
ADRENAL CAPSULE
ADRENAL CORTEX
Increase renal reabsorption of Na+ and water (especially in the presence of ADH), and accelerate urinary loss of K+
Stimulated by angiotensin II, elevated blood K+ or fall in blood Na+; inhibited by ANP and BNP
Zona glomerulosa
Mineralocorticoids, primarily aldosterone
Kidneys
Zona fasciculata
Glucocorticoids (cortisol [hydrocortisone], corticosterone)
Most cells
Increase rates of glucose and glycogen formation by the liver; release of amino acids from skeletal muscles, and lipids from adipose tissues; promote peripheral utilization of lipids; anti-inflammatory effects
Stimulated by ACTH from the anterior lobe of the pituitary gland
Zona reticularis
Adrenal androgens stimulate the development of pubic hair in boys and girls before puberty.
Androgens
Most cells
Androgen secretion is stimulated by ACTH.
ADRENAL MEDULLA
Epinephrine (E), norepinephrine (NE)
Most cells
Increases cardiac activity, blood pressure, glycogen breakdown, blood glucose levels; releases lipids by adipose tissue
Stimulated by sympathetic preganglionic fibers
Adrenal gland
LM × 140 c
The major regions and zones of an adrenal gland and the hormones they produce

40. Functions of Glucocorticoids
Increases rate of protein breakdown
Glucose from gluconeogenesis
Stimulates lipolysis
Provides resistance to stress
Has anti-inflammatory effects
Depresses immune responses

41. Figure 18-14bc The Adrenal Gland.
Capsule
Cortex
Medulla b
An adrenal gland in section
The Adrenal Hormones
Region/Zone Hormones Primary Target Hormonal Effects Regulatory Control
ADRENAL CAPSULE
ADRENAL CORTEX
Increase renal reabsorption of Na+ and water (especially in the presence of ADH), and accelerate urinary loss of K+
Stimulated by angiotensin II, elevated blood K+ or fall in blood Na+; inhibited by ANP and BNP
Zona glomerulosa
Mineralocorticoids, primarily aldosterone
Kidneys
Zona fasciculata
Glucocorticoids (cortisol [hydrocortisone], corticosterone)
Most cells
Increase rates of glucose and glycogen formation by the liver; release of amino acids from skeletal muscles, and lipids from adipose tissues; promote peripheral utilization of lipids; anti-inflammatory effects
Stimulated by ACTH from the anterior lobe of the pituitary gland
Zona reticularis
Adrenal androgens stimulate the development of pubic hair in boys and girls before puberty.
Androgens
Most cells
Androgen secretion is stimulated by ACTH.
ADRENAL MEDULLA
Epinephrine (E), norepinephrine (NE)
Most cells
Increases cardiac activity, blood pressure, glycogen breakdown, blood glucose levels; releases lipids by adipose tissue
Stimulated by sympathetic preganglionic fibers
Adrenal gland
LM × 140 c
The major regions and zones of an adrenal gland and the hormones they produce

42. Adrenal Medulla Hormones secreted from chromaffin cells
Epinephrine & norepinephrine

43. The gross anatomy of the pancreas
Figure The Pancreas.
Pancreatic duct
Body of pancreas
Lobule
Tail
Common bile duct
Pancreatic acini (clusters of exocrine cells)
Accessory pancreatic duct
Head of pancreas
Pancreatic islet (islet of Langerhans)
Capillary
Small intestine (duodenum)
LM × 400
Pancreatic islet a
The gross anatomy of the pancreas b
A pancreatic islet surrounded by exocrine cells

44. Table 18-5 Hormones Produced by the Pancreatic Islets.

45. Figure 18-17 The Regulation of Blood Glucose Concentrations.
Increased rate of glucose transport into target cells
Increased rate of glucose utilization and ATP generation
Increased conversion of glucose to glycogen
Increased amino acid absorption and protein synthesis
Beta cells secrete insulin
Increased triglyceride synthesis in adipose tissue
HOMEOSTASIS RESTORED
Increasing blood glucose levels
HOMEOSTASIS DISTURBED
Blood glucose levels decrease
Increasing blood glucose levels
HOMEOSTASIS
Normal blood glucose levels (70–110 mg/dL)
HOMEOSTASIS DISTURBED
Decreasing blood glucose levels
HOMEOSTASIS RESTORED
Decreasing blood glucose levels
Blood glucose levels increase
Alpha cells secrete glucagon
Increased breakdown of glycogen to glucose (in liver, skeletal muscle)
Increased breakdown of fat to fatty acids (in adipose tissue)
Increased synthesis and release of glucose (by the liver)

46. Table 18-7 Hormones of the Reproductive System.

47. Figure 18-15 The Pineal Gland.
Pinealocytes
Pineal gland
LM × 400

48. Table 18-6 Representative Hormones Produced by Organs of Other Systems.

49. Figure 18-20 The General Adaptation Syndrome.

50. Figure 18-18 Diabetes Mellitus.

51. Figure diagrams the functional relationships between the endocrine system and other body systems we have studied so far.
SYSTEM INTEGRATOR
Body System
Endocrine System
Endocrine System
Body System
Protects superficial endocrine
organs; epidermis synthesizes
vitamin D
Sex hormones stimulate sebaceous gland activity,
influence hair growth, fat distribution, and apocrine
sweat gland activity; PRL stimulates development of
mammary glands; adrenal hormones alter dermal
blood flow; MSH stimulates melanocyte activity
Integumentary
Integumentary
Page 174
Protects endocrine organs, especially
in brain, chest, and pelvic cavity
Skeletal growth regulated by several hormones;
calcium mobilization regulated by parathyroid
hormone and calcitonin; sex hormones speed
growth and closure of epiphyseal cartilages at
puberty and help maintain bone mass in adults
Skeletal
Skeletal
Page 285
Skeletal muscles provide protection
for some endocrine organs
Hormones adjust muscle metabolism,
energy production, and growth;
regulate calcium and phosphate levels
in body fluids; speed skeletal muscle
growth
Muscular
Muscular
Page 380
Hypothalamic hormones directly
control pituitary secretions and
indirectly control secretions of other
endocrine organs; controls adrenal
medullae; secretes ADH and OXT
Several hormones affect neural metabolism
and brain development; hormones help
regulate fluid and electrolyte balance;
reproductive hormones influence CNS
development and behaviors
Nervous
Nervous
Page 558
The ENDOCRINE System
The endocrine system provides
long-term regulation and
adjustments of homeostatic
mechanisms that affect
many body functions. For
example, the endocrine
system regulates fluid and
electrolyte balance, cell
and tissue metabolism, growth and development, and reproductive functions. It also works with the nervous system in responding to stressful stimuli through the general adaptation syndrome.
Cardiovascular
Page 776
Lymphatic
Page 824
Respiratory
Page 874
Gonads—ovaries in females and testes in males—are organs that produce gametes (sex cells). LH and FSH, hormones secreted by the anterior lobe of the pituitary gland, affect these organs. The ovaries and testes are discussed further in Chapter 28.
Digestive
Page 929
Urinary
Page 1010
Reproductive
Page 1090

52. Table 18-8 Clinical Implications of Endocrine Malfunctions (Part 1 of 2).

53. Table 18-8 Clinical Implications of Endocrine Malfunctions (Part 2 of 2).