principles of anatomy and physiology thirteenth edition chapter 18 the endocrine system copyright ©...
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Principles of Anatomy and Physiology
Thirteenth Edition
Chapter 18The Endocrine System
Copyright © 2012 by John Wiley & Sons, Inc.
Gerard J. Tortora • Bryan H. Derrickson
Thyroid gland
Trachea
PARATHYROIDGLANDS
PARATHYROID GLANDS(behind thyroid glands)
SKIN
Lung
ADRENALGLANDS
PANCREAS
SMALLINTESTINE
Scrotum
Male
TESTES
Female
OVARY
Uterus
KIDNEY
STOMACH
HEART
THYMUS
TracheaTHYROID GLAND
PITUITARY GLAND
HYPOTHALAMUS
PINEAL GLAND
LIVER
Hormonereceptor
Endocrinecell
Circulating hormone
Bloodcapillary
Distant target cells
(a) Circulating hormones
Paracrine receptor
AutocrinereceptorAutocrine
cell
(b) Local hormones (paracrines and autocrines)
Autocrine
Paracrine
Paracrine cell Nearby target cell
Aldosterone
Steroid hormones
Triiodothyronine (T3)
Thyroid hormones
Norepinephrine
Amines
Oxytocin
Peptides and proteins
A leukotriene (LTB4)
Eicosanoids
Nucleus
Cytosol
Receptor
DNA
mRNA
Ribosome
Newprotein
Activated receptor–hormonecomplex alters gene expression
NewlyFormed mRNAdirects synthesis of specific proteins on ribosomes
New proteins altercell's activity
Target cell
Lipid-soluble hormone diffuses into cell
Blood capillaryFree hormone
Transport protein
2
3
4
1
Activated protein kinases phosphorylatecellular proteins
4
Phosphodiesterase inactivates cAMP
6
Activated adenylatecyclase convertsATP to cAMP
2
Second messenger
Binding of hormone (first messenger) to its receptor activates G protein, which activates adenylate cyclase
1
Adenylate cyclase
Water-solublehormone
Receptor
G protein
ATP cAMP
Protein kinases
Activatedproteinkinases
cAMP serves as asecond messengerto activate proteinkinases
3
Protein
ATP
ADP
Protein - P
Millions of phosphorylatedproteins cause reactions thatproduce physiological responses
5
Blood capillary
Target cell
POSTERIORPITUITARY ANTERIOR
PITUITARY
Infundibulum
Sagittal section of pituitary gland
Hypothalamus
Pituitary gland
Primary plexus ofhypophyseal portal system
HYPOTHALAMUS
Median eminence
Superior hypophysealartery
Hypophyseal portal veins
Sphenoid bone
ANTERIOR PITUITARY
Secondary plexus ofhypophyseal portal system
Anterior hypophysealveins
ANTERIORPOSTERIOR
Inferior hypophyseal artery
(a) Relationship of hypothalamus to pituitary gland
Hypophysealfossa
Capillary plexus ofinfundibular process
POSTERIOR PITUITARY
Posterior hypophysealveins
Infundibulum
Hypophysealportal veins
Hypothalamicneurosecretorycell
(b) Path of releasing and inhibiting hormones
Primary plexus ofhypophyseal portal system
Corticotroph
(c) Histology of anterior pituitary
Lactotroph
Gonadotroph
ThyrotrophSomatotroph
LM all about 65x
Corticotropin-releasinghormone (CRH)
Elevated cortisolinhibits releaseof CRH byhypothalamicneurosecretorycells
Elevated cortisolinhibits releaseof corticotropinby anteriorpituitarycorticotrophs
Cortisol
Adrenalcortex
Corticotropin stimulates secretion of cortisol by adrenal cortex
Corticotropin(ACTH)
Anterior pituitary
CRH stimulates release of corticotropin (ACTH)
Hypothalamus
A low level of hGH andIGFs decreases the rateof glycogen breakdownin the liver and glucoseenters the blood moreslowly
1 6
2 7
3 8
4 9
5 10
hGH and IGFs speedup breakdown of liverglycogen into glucose,which enters the bloodmore rapidly
Blood glucose levelfalls to normal(about 90 mg/100 mL)
Blood glucose levelrises to normal(about 90 mg/100 mL)
If blood glucose continues to decrease,hypoglycemia inhibitsrelease of GHIH
If blood glucosecontinues to increase,hyperglycemia inhibitsrelease of GHRH
GHIH inhibitssecretion ofhGH bysomatotrophs
GHRH stimulatessecretionof hGH bysomatotrophs
hGH
Anteriorpituitary
GHRH GHIH
Low blood glucose (hypoglycemia)stimulates release of
High blood glucose(hyperglycemia)stimulates release of
Human growth hormone (hGH),also known as somatotropin
Liver (and other tissues)
Thyroid-stimulating hormone (TSH), also known as thyrotropin
Thyroid gland
Ovaries
Follicle-stimulating hormone (FSH)
Testes
Ovaries
Luteinizing hormone (LH)
Testes
Mammary glands
Prolactin (PRL)
Adrenalcortex
Adrenocorticotropic hormone (ACTH), also known as corticotropin
Brain
Melanocyte-stimulating hormone (MSH)
Hypothalamus
Infundibulum
Pituitary gland
Neurosecretory cells
HYPOTHALAMUS
Opticchiasm
Capillary plexusof the posteriorpituitary
ANTERIORPITUITARY
Axons of neurosecretory cells
Axon terminal
POSTERIORPITUITARY
Target tissues
1 High blood osmotic pressure stimulates hypothalamic osmoreceptors
5 Low blood osmotic pressure inhibits hypothalamic osmoreceptors
Osmoreceptors2 Osmoreceptors
activate neurosecretorycells that synthesizeand release ADH
6 Inhibition of osmoreceptors reduces or stops ADH secretion
Hypothalamus
3 Nerve impulsesliberate ADH fromaxon terminals inposterior pituitary intobloodstream
ADH
Sudoriferous (sweat) glands decrease water loss by perspiration from skin
Arterioles constrict,which increasesblood pressure
Kidneys retainmore water,which decreasesurine output
4
Oxytocin (OT)
Uterus Mammary glands Kidneys Sudoriferous(sweat) glands
Arterioles
Antidiuretic hormone (ADH) or vasopressin
Hyoid bone
Superior thyroid artery
Superior thyroid vein
Thyroid cartilage of larynx
Internal jugular vein
LEFT LATERAL LOBEOF THYROID GLAND
Common carotid artery
ISTHMUS OF THYROIDGLAND
Vagus (X) nerve
Trachea
Inferior thyroid veins
Sternum
Pyramidal lobe ofthyroid gland
RIGHT LATERAL LOBEOF THYROID GLAND
Middle thyroid vein
Inferior thyroid artery
Subclavian artery
Thyroidgland
Trachea
(a) Anterior view of thyroid gland
Parafollicular (C) cell
Follicular cell
Thyroid follicle
Thyroglobulin (TGB)(colloid)
Basement membrane
500x
(b) Thyroid follicles
LM
LEFT LATERALLOBE
(c) Anterior view of thyroid gland
RIGHT LATERALLOBE
ISTHMUS
Thyroid cartilage of larynx
(d) Anterior view
Cricoid cartilage of larynxRIGHT LATERAL LOBE OF THYROID GLANDLEFT LATERAL LOBE OF THYROID GLANDISTHMUS OF THYROID GLAND
Trachea
Right lung
Arch of aorta
Portion of thyroid follicle
Follicularcell
Blood capillary
ColloidIodinationof tyrosine
4
Couplingof T1 and T2
5
Oxidationof iodide
3
Pinocytosisand digestionof colloid
6
Synthesisof TGB
2
Iodidetrapping
1Secretionof thyroidhormones
7
Transportin blood
8
TyrosineT1 T2
T4
T3Colloid
TGBI2
Secretoryvesicles Lysosome
Golgi complex T3
T4
T3 T4
Rough ER
I– I– I–
I– I– I–
I– I–
I–
I–
I– Bloodplasma
T3
T4
TBG
TBG
Blood capillary
Key:I– = Iodide; I2 = IodineTGB = thyroglobulinTBG = thyroxine-binding globulin
Elevated T3 inhibits release of TRH and TSH (negative feedback)
5
T3 and T4 released into blood by follicular cells
4
Anteriorpituitary
TSH
TRHHypothalamus
Low blood levels of T3 and T4 or low metabolic rate stimulates release of
1
TRH, carriedby hypophysealportal veins toanterior pituitary,stimulatesrelease of TSHby thyrotrophs
2
TSH released intoblood stimulatesthyroid follicular cells
3
Thyroidfollicle
T3 (triiodothyronine) and T4 (thyroxine) or thyroid hormones from follicular cells
Calcitonin (CT) from parafollicular cells
Thyroidfollicle
Follicularcells
Bloodvessel
Thyroidfollicle
Parafollicular cells
Parathyroidglands (behindthyroid gland)
Trachea
Right internal jugular vein
Right common carotid artery
Middle cervical sympathetic ganglion
Thyroid gland
RIGHT SUPERIORPARATHYROID GLAND
Inferior cervicalsympathetic ganglion
RIGHT INFERIORPARATHYROID GLAND
Vagus (X) nerve
Right brachiocephalic vein
Brachiocephalic trunk
Trachea
LEFT SUPERIORPARATHYROID GLAND
(a) Posterior view
Esophagus
LEFT INFERIORPARATHYROID GLAND
Left inferior thyroid artery
Left subclavian artery
Left subclavian vein
Left common carotid artery
Venule
Capillary
Arteriole
Chief cell
Oxyphil cell
240x(b) Parathyroid gland
LM
Blood vesselParafollicular cell
Follicular cellThyroid gland
(c) Portion of thyroid gland (left) and parathyroid gland (right)
Chief cell
Oxyphil cellParathyroid gland
Parathyroid
ThyroidCapsule
Thyroid gland
(d) Posterior view of parathyroid glands
PARATHYROIDGLAND
PARATHYROIDGLAND
PARATHYROID HORMONE (PTH)promotes release of Ca2+ frombone extracellular matrix intoblood and slows loss of Ca2+
in urine, thus increasing bloodCa2+ level.
CALCITONIN inhibitsosteoclasts, thus decreasingblood Ca2+ level.
Low level of Ca2+ in blood stimulates parathyroid gland chief cells to release more PTH.
High level of Ca2+ in blood stimulates thyroid gland parafollicular cells to releasemore CT.
1 3
4 2
CALCITRIOL stimulatesincreased absorption ofCa2+ from foods, whichincreases blood Ca2+ level.
6
PTH also stimulatesthe kidneys to releaseCALCITRIOL.
5
Parathyroid hormone (PTH) from chief cells
Chief cell
Inferior phrenic arteries
Celiac trunkLEFT ADRENAL GLAND
Left middle suprarenal artery
Left inferior suprarenal artery
Left suprarenal vein
Left renal artery
Left renal vein
Right superiorsuprarenal arteries
RIGHT ADRENALGLAND
Right middlesuprarenal artery
Right inferiorsuprarenal artery
Right renal artery
Right renal vein
Kidney
Adrenalglands
Inferior vena cava Abdominal aorta
Superior mesenteric artery
(a) Anterior view
CAPSULE
ADRENALCORTEX
ADRENALMEDULLA
(b) Section through left adrenal gland
Kidney
ADRENAL GLAND
(c) Anterior view of adrenal gland and kidney
Zona glomerulosa secretes mineralocorticoids, mainly aldosterone
Capsule
(d) Subdivisions of adrenal gland
Adrenal cortex:
Zona fasciculata secretes glucocorticoids, mainly cortisol
Zona reticularis secretes androgens
Adrenal medulla chromaffin cells secrete epinephrine and norepinephrine (NE)
50xLM
Dehydration,Na+ deficiency,or hemorrhage
Decrease inblood volume
Decrease inblood volume
Angiotensinogen
Increased renin
Increasedangiotensin I
Increasedangiotensin II
Blood pressureincreases untilit returns to normal
Vasoconstrictionof arterioles
Increased bloodvolume
IncreasedK+ inextracellularfluid
In kidneys, increased Na+
and water reabsorptionand increased secretion ofK+ and H+ into urine
Increasedaldosterone
Juxtaglomerularcells of kidneys
Liver
ACEACE
Lungs (ACE = angiotensin converting enzyme)Lungs (ACE = angiotensin converting enzyme)
AdrenalcortexAdrenalcortex
1
2
3
6
8 7
9
5
4
15
10
11 12
16
13
14
Some stimulus disruptshomeostasis by
Decreasing
Glucocorticoid levelin blood
Neurosecretorycells inhypothalamus
Receptors
Input Increased CRH anddecreased cortisol
Corticotrophs inanterior pituitary
Control center
Return to homeostasiswhen response bringsglucocorticoid level inblood back to normal
Output Increased ACTH
Cells of zonafasciculata inadrenal cortexsecrete glucocorticoids
Effectors
Increased glucocorticoidlevel in blood
Androgens (mainly dehydroepiandrosterone, or DHEA) from zona reticularis cells
Epinephrine and norepinephrine from chromaffin cells
Adrenalcortex
Adrenalmedulla
Common hepatic artery
Abdominal aorta
Celiac trunk
Splenic artery
Spleen(elevated)
TAIL OF PANCREAS
BODY OF PANCREAS
Inferior pancreatic artery
Superior mesenteric artery
Inferior pancreaticoduodenal artery
Gastroduodenal artery
Dorsal pancreatic artery
Anterior pancreaticoduodenalarteryDuodenum of small intestine
HEAD OF PANCREAS
(a) Anterior view
PancreasKidney
Blood capillary
(b) Pancreatic islet and surrounding acini
Exocrine acini
Alpha cell(secretes glucagon)
Beta cell(secretes insulin)
Delta cell(secretes somatostatin)
F cell (secretespancreatic polypeptide)
Pancreaticislet
40xLM
200xLM
Exocrineacinus
Betacell
Alphacell
Pancreaticduct
(c) Pancreatic islet and surrounding acini
Duodenum(cut open)
Pancreas
(d) Anterior view of pancreas dissected to reveal pancreatic duct
Low blood glucose(hypoglycemia) stimulates alpha cells to secrete
1 High blood glucose (hyperglycemia) stimulates
beta cells to secrete
5
Glucagon acts on hepatocytes (liver cells) to:
2
Glucose released by hepatocytes raises blood glucose level to normal
3
If blood glucosecontinues to rise, hyperglycemia inhibitsrelease of glucagon
4
• convert glycogen into glucose (glycogenolysis)• form glucose from lactic acid and certain amino acids (gluconeogenesis)
Insulin acts on various body cells to:
• accelerate facilitated diffusion of glucose into cells• speed conversion of glucose into glycogen (glycogenesis)• increase uptake of amino acids and increase protein synthesis• speed synthesis of fatty acids (lipogenesis)• slow glycogenolysis• slow gluconeogenesis
Blood glucose level falls
If blood glucose continuesto fall, hypoglycemiainhibits release of insulin
6
7
8
INSULINGLUCAGON
Glucagon from alphacells of pancreatic islets
Insulin from beta cellsof pancreatic islets
Pancreatic polypeptide fromF cells of pancreatic islets
Somatostatin from deltacells of pancreatic islets
Alpha cell
Delta cell
Beta cell
F cell
Estrogens and progesterone
Ovaries
Testosterone
Testes
STRESS RESPONSES
1. Increased heart rate and force of beat
2. Constriction of blood vessels of most viscera and skin
3. Dilation of blood vessels of heart, lungs, brain, and skeletal muscles
4. Contraction of spleen 5. Conversion of glycogen
into glucose in liver 6. Sweating 7. Dilation of airways 8. Decrease in digestive
activities 9. Water retention and
elevated blood pressure
STRESSORSstimulate
HypothalamusCRHGHRHTRH
Nerveimpulses
Sympathetic centersin spinal cord Anterior
pituitary
Sympathetic nerves
TSHhGHACTH
Adrenalmedulla
Epinephrine andnorepinephrine
Visceral effectors
ACTH hGH TSH
Cortisol IGFsThyroid hormones
(T3 and T4)
STRESS RESPONSESLipolysisGluconeogenesisProtein catabolismSensitized blood vesselsReduced inflammation
STRESS RESPONSESLipolysisGlycogenolysis
STRESS RESPONSESIncreased useof glucose toproduce ATP
Adrenalcortex
Liver Thyroidgland
Supplementand prolong“fight-or-flight”responses
(a) Fight-or-flight responses (b) Resistance reaction
Key:CRH = Corticotropin-releasing hormoneACTH = Adrenocorticotropic hormoneGHRH = Growth hormone–releasing hormonehGH = Human growth hormoneTRH = Thyrotropin-releasing hormoneTSH = Thyroid-stimulating hormone
Stomodeum
Hypophyseal(Rathke’s) pouch
Neurohypophyseal bud
Hypothalamus
Thyroid diverticulumRespiratory diverticulum
Esophagus
Pharyngeal pouches
4 3 2 1
(a) Location of neurohypophyseal bud, hypophyseal (Rathke’s) pouch, thyroid diverticulum, and pharyngeal pouches in 28-day embryo
Neurohypophyseal bud
Mouth cavity
Hypophyseal(Rathke’s)
pouch
Infundibulum Infundibulum
Pars intermedia
Hypothalamus
Infundibulum
Anteriorpituitary
Posterior pituitaryMesenchyme
(b) Development of pituitary gland between 5 and 16 weeks
(a) A 22-year-old man with pituitary giantism shown beside his identical twin
(b) Acromegaly (excess hGH during adulthood)
(c) Goiter (enlargement of thyroid gland)
(d) Exophthalmos (excess thyroid hormones, as in Graves’ disease)
(e) Cushing’s syndrome (excess glucocorticoids)