SlideShare a Scribd company logo
1 of 13
Download to read offline
16 
The Endocrine System 
Endocrine System: Overview 
* Endocrine system – the body’s second great controlling system which 
influences metabolic activities of cells by means of hormones 
* Endocrine glands – pituitary, thyroid, parathyroid, adrenal, pineal, and 
thymus 
* The pancreas and gonads produce both hormones and exocrine 
products 
Endocrine System: Overview 
* The hypothalamus has both neural functions and releases hormones 
* Other tissues and organs that produce hormones – adipose cells, 
pockets of cells in the walls of the small intestine, stomach, kidneys, 
and heart 
Major Endocrine Organs 
Autocrines and Paracrines 
* Autocrines – chemicals that exert effects on the same cells that secrete 
them 
* Paracrines – locally acting chemicals that affect cells other than those 
that secrete them
* These are not considered hormones since hormones are long-distance 
chemical signals 
Hormones 
* Hormones – chemical substances secreted by cells into the 
extracellular fluids 
* Regulate the metabolic function of other cells 
* Have lag times ranging from seconds to hours 
* Tend to have prolonged effects 
* Are classified as amino acid-based hormones, or steroids 
* Eicosanoids – biologically active lipids with local hormone–like 
activity 
Types of Hormones 
* Amino acid based 
* Amines, thyroxine, peptide, and protein hormones 
* Steroids – gonadal and adrenocortical hormones 
* Eicosanoids – leukotrienes and prostaglandins 
Hormone Action 
* Hormones alter target cell activity by one of two mechanisms 
* Second messengers: 
* Regulatory G proteins 
* Amino acid–based hormones 
* Direct gene activation 
* Steroid hormones 
* The precise response depends on the type of the target cell
Mechanism of Hormone Action 
* Hormones produce one or more of the following cellular changes in 
target cells 
* Alter plasma membrane permeability 
* Stimulate protein synthesis 
* Activate or deactivate enzyme systems 
* Induce secretory activity 
* Stimulate mitosis 
Amino Acid-Based Hormone Action: 
cAMP Second Messenger 
* Hormone (first messenger) binds to its receptor, which then binds to a 
G protein 
* The G protein is then activated as it binds GTP, displacing GDP 
* Activated G protein activates the effector enzyme adenylate cyclase 
* Adenylate cyclase generates cAMP (second messenger) from ATP 
* cAMP activates protein kinases, which then cause cellular effects 
Amino Acid-Based Hormone Action: cAMP Second 
Messenger 
Amino Acid-Based Hormone Action: cAMP Second 
Messenger 
Amino Acid-Based Hormone Action: cAMP Second 
Messenger 
Amino Acid-Based Hormone Action: cAMP Second 
Messenger 
Amino Acid-Based Hormone Action: cAMP Second 
Messenger
Amino Acid-Based Hormone Action: cAMP Second 
Messenger 
Amino Acid-Based Hormone Action: cAMP Second 
Messenger 
Amino Acid-Based Hormone Action: cAMP Second 
Messenger 
Amino Acid-Based Hormone Action: cAMP Second 
Messenger 
Amino Acid-Based Hormone Action: cAMP Second 
Messenger 
Amino Acid-Based Hormone Action: cAMP Second 
Messenger 
Amino Acid-Based Hormone Action: cAMP Second 
Messenger 
Amino Acid-Based Hormone Action: 
PIP-Calcium 
* Hormone binds to the receptor and activates 
G protein 
* G protein binds and activates phospholipase 
* Phospholipase splits the phospholipid PIP2 into diacylglycerol (DAG) 
and IP3 (both act as second messengers) 
* DAG activates protein kinases; IP3 triggers release of Ca2+ stores 
* Ca2+ (third messenger) alters cellular responses 
Amino Acid-Based Hormone Action: 
PIP Mechanism 
Amino Acid-Based Hormone Action: 
PIP Mechanism
Amino Acid-Based Hormone Action: 
PIP Mechanism 
Amino Acid-Based Hormone Action: 
PIP Mechanism 
Amino Acid-Based Hormone Action: 
PIP Mechanism 
Amino Acid-Based Hormone Action: 
PIP Mechanism 
Amino Acid-Based Hormone Action: 
PIP Mechanism 
Amino Acid-Based Hormone Action: 
PIP Mechanism 
Steroid Hormones 
* This interaction prompts DNA transcription to produce mRNA 
* The mRNA is translated into proteins, which bring about a cellular 
effect 
Steroid Hormones 
* This interaction prompts DNA transcription to produce mRNA 
* The mRNA is translated into proteins, which bring about a cellular 
effect
Target Cell Specificity 
* Hormones circulate to all tissues but only activate cells referred to as 
target cells 
* Target cells must have specific receptors to which the hormone binds 
* These receptors may be intracellular or located on the plasma 
membrane 
Target Cell Specificity 
* Examples of hormone activity 
* ACTH receptors are only found on certain cells of the adrenal cortex 
* Thyroxin receptors are found on nearly all cells of the body 
Target Cell Activation 
* Target cell activation depends on three factors 
* Blood levels of the hormone 
* Relative number of receptors on the target cell 
* The affinity of those receptors for the hormone 
* Up-regulation – target cells form more receptors in response to the 
hormone 
* Down-regulation – target cells lose receptors in response to the 
hormone
Hormone Concentrations in the Blood 
* Hormones circulate in the blood in two forms – 
free or bound 
* Steroids and thyroid hormone are attached to plasma proteins 
* All others are unencumbered 
Hormone Concentrations in the Blood 
* Concentrations of circulating hormone reflect: 
* Rate of release 
* Speed of inactivation and removal from the body 
* Hormones are removed from the blood by: 
* Degrading enzymes 
* The kidneys 
* Liver enzyme systems 
Interaction of Hormones at Target Cells 
* Three types of hormone interaction 
* Permissiveness – one hormone cannot exert its effects without another 
hormone being present 
* Synergism – more than one hormone produces the same effects on a 
target cell 
* Antagonism – one or more hormones opposes the action of another 
hormone 
Control of Hormone Release 
* Blood levels of hormones: 
* Are controlled by negative feedback systems
* Vary only within a narrow desirable range 
* Hormones are synthesized and released in response to: 
* Humoral stimuli 
* Neural stimuli 
* Hormonal stimuli 
Humoral Stimuli 
* Humoral stimuli – secretion of hormones in direct response to 
changing blood levels of ions and nutrients 
* Example: concentration of calcium ions in the blood 
* Declining blood Ca2+ concentration stimulates the parathyroid glands to 
secrete PTH (parathyroid hormone) 
* PTH causes Ca2+ concentrations to rise and the stimulus is removed 
Humoral Stimuli 
Neural Stimuli 
* Neural stimuli – nerve fibers stimulate hormone release 
* Preganglionic sympathetic nervous system (SNS) fibers stimulate the 
adrenal medulla to secrete catecholamines 
Hormonal Stimuli 
* Hormonal stimuli – release of hormones in response to hormones 
produced by other endocrine organs 
* The hypothalamic hormones stimulate the anterior pituitary 
* In turn, pituitary hormones stimulate targets to secrete still more 
hormones 
Hormonal Stimuli 
Nervous System Modulation
* The nervous system modifies the stimulation of endocrine glands and 
their negative feedback mechanisms 
Nervous System Modulation 
* The nervous system can override normal endocrine controls 
* For example, control of blood glucose levels 
* Normally the endocrine system maintains blood glucose 
* Under stress, the body needs more glucose 
* The hypothalamus and the sympathetic nervous system are activated 
to supply ample glucose 
Major Endocrine Organs: Pituitary (Hypophysis) 
* Pituitary gland – two-lobed organ that secretes nine major hormones 
* Neurohypophysis – posterior lobe (neural tissue) and the 
infundibulum 
* Receives, stores, and releases hormones from the hypothalamus 
* Adenohypophysis – anterior lobe, made up of glandular tissue 
* Synthesizes and secretes a number of hormones 
Major Endocrine Organs: Pituitary (Hypophysis) 
Pituitary-Hypothalamic Relationships: 
Posterior Lobe 
* The posterior lobe is a downgrowth of hypothalamic neural tissue 
* Has a neural connection with the hypothalamus (hypothalamic-hypophyseal 
tract) 
* Nuclei of the hypothalamus synthesize oxytocin and antidiuretic 
hormone (ADH) 
* These hormones are transported to the posterior pituitary
Pituitary-Hypothalamic Relationships: 
Anterior Lobe 
* The anterior lobe of the pituitary is an outpocketing of the oral 
mucosa 
* There is no direct neural contact with the hypothalamus 
Pituitary-Hypothalamic Relationships: 
Anterior Lobe 
* There is a vascular connection, the hypophyseal portal system, 
consisting of: 
* The primary capillary plexus 
* The hypophyseal portal veins 
* The secondary capillary plexus 
Pituitary-Hypothalamic Relationships: 
Anterior Lobe 
Adenophypophyseal Hormones 
* The six hormones of the adenohypophysis: 
* Abbreviated as GH, TSH, ACTH, FSH, LH, and PRL 
* Regulate the activity of other endocrine glands 
* In addition, pro-opiomelanocortin (POMC): 
* Has been isolated from the pituitary 
* Is split into ACTH, opiates, and MSH 
Activity of the Adenophypophysis 
* The hypothalamus sends a chemical stimulus to the anterior pituitary 
* Releasing hormones stimulate the synthesis and release of hormones
* Inhibiting hormones shut off the synthesis and release of hormones 
Activity of the Adenophypophysis 
* The tropic hormones that are released are: 
* Thyroid-stimulating hormone (TSH) 
* Adrenocorticotropic hormone (ACTH) 
* Follicle-stimulating hormone (FSH) 
* Luteinizing hormone (LH) 
Growth Hormone (GH) 
* Produced by somatotropic cells of the anterior lobe that: 
* Stimulate most cells, but target bone and skeletal muscle 
* Promote protein synthesis and encourage the use of fats for fuel 
*Most effects are mediated indirectly by somatomedins 
Growth Hormone (GH) 
* Antagonistic hypothalamic hormones regulate GH 
* Growth hormone–releasing hormone (GHRH) stimulates GH release 
* Growth hormone–inhibiting hormone (GHIH) inhibits GH release 
Metabolic Action of Growth Hormone 
* GH stimulates liver, skeletal muscle, bone, and cartilage to produce 
insulin-like growth factors 
* Direct action promotes lipolysis and inhibits glucose uptake 
Metabolic Action of Growth Hormone (GH) 
Thyroid Stimulating Hormone (Thyrotropin)
* Stimulates the normal development and secretory activity of the 
thyroid 
* Triggered by hypothalamic peptide thyrotropin-releasing hormone 
(TRH) 
* Rising blood levels of thyroid hormones act on the pituitary and 
hypothalamus to block the release of TSH 
Adrenocorticotropic Hormone (Corticotropin) 
* Stimulates the adrenal cortex to release corticosteroids 
* Triggered by hypothalamic corticotropin-releasing hormone (CRH) in 
a daily rhythm 
* Internal and external factors such as fever, hypoglycemia, and 
stressors can trigger the release of CRH 
Gonadotropins 
* Gonadotropins – follicle-stimulating hormone (FSH) and luteinizing 
hormone (LH) 
* Regulate the function of the ovaries and testes 
* FSH stimulates gamete (egg or sperm) production 
* Absent from the blood in prepubertal boys and girls 
* Triggered by the hypothalamic gonadotropin-releasing hormone 
(GnRH) during and after puberty 
Functions of Gonadotropins 
* In females 
* LH works with FSH to cause maturation of the ovarian follicle 
* LH works alone to trigger ovulation (expulsion of the egg from the 
follicle) 
* LH promotes synthesis and release of estrogens and progesterone
Functions of Gonadotropins 
* In males 
* LH stimulates interstitial cells of the testes to produce testosterone 
* LH is also referred to as interstitial cell-stimulating hormone (ICSH) 
Prolactin (PRL) 
* In females, stimulates milk production by the breasts 
* Triggered by the hypothalamic prolactin-releasing hormone (PRH) 
* Inhibited by prolactin-inhibiting hormone (PIH) 
* Blood levels rise toward the end of pregnancy 
* Suckling stimulates PRH release and encourages continued milk 
production 
The Posterior Pituitary and Hypothalamic Hormones 
* Posterior pituitary – made of axons of hypothalamic neurons, stores 
antidiuretic hormone (ADH) and oxytocin 
* ADH and oxytocin are synthesized in the hypothalamus 
* ADH influences water balance 
* Oxytocin stimulates smooth muscle contraction in breasts and uterus 
* Both use PIP-calcium second-messenger mechanism

More Related Content

What's hot

What's hot (19)

Introduction to hormones
Introduction to hormones Introduction to hormones
Introduction to hormones
 
Endocrine system
Endocrine systemEndocrine system
Endocrine system
 
Molecular endocrine2
Molecular endocrine2Molecular endocrine2
Molecular endocrine2
 
Endocrine online
Endocrine onlineEndocrine online
Endocrine online
 
Endocrinology
EndocrinologyEndocrinology
Endocrinology
 
Hormones and the endocrine system
Hormones and the endocrine system Hormones and the endocrine system
Hormones and the endocrine system
 
hormones and endocrine system
hormones and endocrine systemhormones and endocrine system
hormones and endocrine system
 
The Endocrine System/ The Autonomic Nervous System
The Endocrine System/ The Autonomic Nervous SystemThe Endocrine System/ The Autonomic Nervous System
The Endocrine System/ The Autonomic Nervous System
 
Hormones
HormonesHormones
Hormones
 
Presentation 19 - Chemical Signals In Animals
Presentation 19 - Chemical Signals In AnimalsPresentation 19 - Chemical Signals In Animals
Presentation 19 - Chemical Signals In Animals
 
B.sc. biochemistry sem 1 introduction to biochemistry unit 3.1 hormones
B.sc. biochemistry sem 1 introduction to biochemistry unit 3.1 hormonesB.sc. biochemistry sem 1 introduction to biochemistry unit 3.1 hormones
B.sc. biochemistry sem 1 introduction to biochemistry unit 3.1 hormones
 
Hormones
HormonesHormones
Hormones
 
Action of hormones
Action of hormonesAction of hormones
Action of hormones
 
\Endocrinesystem 1
\Endocrinesystem 1\Endocrinesystem 1
\Endocrinesystem 1
 
Endocrine system basic
Endocrine system basicEndocrine system basic
Endocrine system basic
 
Intoduction to endocrine
Intoduction to endocrineIntoduction to endocrine
Intoduction to endocrine
 
Biochemistry of hormones
Biochemistry of hormonesBiochemistry of hormones
Biochemistry of hormones
 
Molecular and Cell Biology of the Endocrine System
Molecular and Cell Biology of the Endocrine SystemMolecular and Cell Biology of the Endocrine System
Molecular and Cell Biology of the Endocrine System
 
Hormones gen. characterist., classific. i
Hormones gen. characterist., classific. iHormones gen. characterist., classific. i
Hormones gen. characterist., classific. i
 

Viewers also liked

The parts of speech
The parts of speechThe parts of speech
The parts of speechTheSlaps
 
Ch 12 lecture_outline_b
Ch 12 lecture_outline_bCh 12 lecture_outline_b
Ch 12 lecture_outline_bTheSlaps
 
22 b chapter
22   b chapter22   b chapter
22 b chapterTheSlaps
 
Ch04 b. summary
Ch04 b. summaryCh04 b. summary
Ch04 b. summaryTheSlaps
 
Ch06 a. summary
Ch06 a. summaryCh06 a. summary
Ch06 a. summaryTheSlaps
 
Ch 13 lecture_outline_d
Ch 13 lecture_outline_dCh 13 lecture_outline_d
Ch 13 lecture_outline_dTheSlaps
 
16 b chapter
16   b chapter16   b chapter
16 b chapterTheSlaps
 
Ch 12 lecture_outline_c
Ch 12 lecture_outline_cCh 12 lecture_outline_c
Ch 12 lecture_outline_cTheSlaps
 
Subject verb agreement
Subject verb agreementSubject verb agreement
Subject verb agreementTheSlaps
 
Chap 1 intro and terminology
Chap 1   intro and terminologyChap 1   intro and terminology
Chap 1 intro and terminologyTheSlaps
 
Med Surg Chapter 018
Med Surg Chapter 018Med Surg Chapter 018
Med Surg Chapter 018TheSlaps
 
Ch 6 the mole 2 _1_
Ch 6 the mole  2  _1_Ch 6 the mole  2  _1_
Ch 6 the mole 2 _1_TheSlaps
 
Pathophysiology Chapter 37
Pathophysiology Chapter 37Pathophysiology Chapter 37
Pathophysiology Chapter 37TheSlaps
 
Pathophysiology Chapter 51
Pathophysiology Chapter 51Pathophysiology Chapter 51
Pathophysiology Chapter 51TheSlaps
 
22 a chapter
22   a chapter22   a chapter
22 a chapterTheSlaps
 
E configs2
E configs2E configs2
E configs2TheSlaps
 
Ch4 skin, martini
Ch4  skin, martiniCh4  skin, martini
Ch4 skin, martiniTheSlaps
 

Viewers also liked (20)

The parts of speech
The parts of speechThe parts of speech
The parts of speech
 
Hap7 28 a
Hap7 28 aHap7 28 a
Hap7 28 a
 
Hap7 22 a
Hap7 22 aHap7 22 a
Hap7 22 a
 
Ch 12 lecture_outline_b
Ch 12 lecture_outline_bCh 12 lecture_outline_b
Ch 12 lecture_outline_b
 
22 b chapter
22   b chapter22   b chapter
22 b chapter
 
C18 heart
C18   heartC18   heart
C18 heart
 
Ch04 b. summary
Ch04 b. summaryCh04 b. summary
Ch04 b. summary
 
Ch06 a. summary
Ch06 a. summaryCh06 a. summary
Ch06 a. summary
 
Ch 13 lecture_outline_d
Ch 13 lecture_outline_dCh 13 lecture_outline_d
Ch 13 lecture_outline_d
 
16 b chapter
16   b chapter16   b chapter
16 b chapter
 
Ch 12 lecture_outline_c
Ch 12 lecture_outline_cCh 12 lecture_outline_c
Ch 12 lecture_outline_c
 
Subject verb agreement
Subject verb agreementSubject verb agreement
Subject verb agreement
 
Chap 1 intro and terminology
Chap 1   intro and terminologyChap 1   intro and terminology
Chap 1 intro and terminology
 
Med Surg Chapter 018
Med Surg Chapter 018Med Surg Chapter 018
Med Surg Chapter 018
 
Ch 6 the mole 2 _1_
Ch 6 the mole  2  _1_Ch 6 the mole  2  _1_
Ch 6 the mole 2 _1_
 
Pathophysiology Chapter 37
Pathophysiology Chapter 37Pathophysiology Chapter 37
Pathophysiology Chapter 37
 
Pathophysiology Chapter 51
Pathophysiology Chapter 51Pathophysiology Chapter 51
Pathophysiology Chapter 51
 
22 a chapter
22   a chapter22   a chapter
22 a chapter
 
E configs2
E configs2E configs2
E configs2
 
Ch4 skin, martini
Ch4  skin, martiniCh4  skin, martini
Ch4 skin, martini
 

Similar to 16 a chapter

Hormones.ppt
Hormones.pptHormones.ppt
Hormones.pptbelaywube
 
Endocrine system
Endocrine systemEndocrine system
Endocrine systemtazuddin
 
12.0 The Endocrine System.pdf
12.0 The Endocrine System.pdf12.0 The Endocrine System.pdf
12.0 The Endocrine System.pdfRexBlancoNuez
 
Endocrine System
Endocrine SystemEndocrine System
Endocrine Systemthana123
 
INTRODUCTION TO ENDOCRINOLOGY.pptx
INTRODUCTION TO ENDOCRINOLOGY.pptxINTRODUCTION TO ENDOCRINOLOGY.pptx
INTRODUCTION TO ENDOCRINOLOGY.pptxFatimaSundus1
 
Endocrine new 1.pptx by omar moo 228 all
Endocrine new 1.pptx by omar moo 228 allEndocrine new 1.pptx by omar moo 228 all
Endocrine new 1.pptx by omar moo 228 allomarmoo7787
 
Hormonal regulation
Hormonal regulation Hormonal regulation
Hormonal regulation cutiepie39
 
Endocrine system
Endocrine systemEndocrine system
Endocrine systemReach Na
 
Hormonal biochemistry
Hormonal biochemistryHormonal biochemistry
Hormonal biochemistryAFiFi Faridz
 
Section 1, chapter 13: endocrine system
Section 1, chapter 13: endocrine systemSection 1, chapter 13: endocrine system
Section 1, chapter 13: endocrine systemMichael Walls
 
HUMAN ANATOMY AND PHYSIOLOGY: THE ENDOCRINE SYSTEM
HUMAN ANATOMY AND PHYSIOLOGY: THE ENDOCRINE SYSTEMHUMAN ANATOMY AND PHYSIOLOGY: THE ENDOCRINE SYSTEM
HUMAN ANATOMY AND PHYSIOLOGY: THE ENDOCRINE SYSTEMMeegsEstabillo2
 
1 introduction endocrinology
1 introduction endocrinology1 introduction endocrinology
1 introduction endocrinologyjehadms
 
Hormones- its chemistry, classification, types, functioning, physiology
Hormones- its chemistry, classification, types, functioning, physiologyHormones- its chemistry, classification, types, functioning, physiology
Hormones- its chemistry, classification, types, functioning, physiologyRoni Dudhwala
 
Endocrinology2003.ppt
Endocrinology2003.pptEndocrinology2003.ppt
Endocrinology2003.pptRAJParmar64
 
Ch 16_lecture pt a_sp2014
 Ch 16_lecture pt a_sp2014 Ch 16_lecture pt a_sp2014
Ch 16_lecture pt a_sp2014Ronaldo Paulino
 
Ch 16_lecture pt a_sp2014
 Ch 16_lecture pt a_sp2014 Ch 16_lecture pt a_sp2014
Ch 16_lecture pt a_sp2014robert owens
 

Similar to 16 a chapter (20)

Endocrine new.ppt
Endocrine new.pptEndocrine new.ppt
Endocrine new.ppt
 
Hormones.ppt
Hormones.pptHormones.ppt
Hormones.ppt
 
Endocrine system
Endocrine systemEndocrine system
Endocrine system
 
12.0 The Endocrine System.pdf
12.0 The Endocrine System.pdf12.0 The Endocrine System.pdf
12.0 The Endocrine System.pdf
 
Endocrine System
Endocrine SystemEndocrine System
Endocrine System
 
INTRODUCTION TO ENDOCRINOLOGY.pptx
INTRODUCTION TO ENDOCRINOLOGY.pptxINTRODUCTION TO ENDOCRINOLOGY.pptx
INTRODUCTION TO ENDOCRINOLOGY.pptx
 
Endocrine new 1.pptx by omar moo 228 all
Endocrine new 1.pptx by omar moo 228 allEndocrine new 1.pptx by omar moo 228 all
Endocrine new 1.pptx by omar moo 228 all
 
Hormonal regulation
Hormonal regulation Hormonal regulation
Hormonal regulation
 
Endocrine system
Endocrine systemEndocrine system
Endocrine system
 
Hormonal biochemistry
Hormonal biochemistryHormonal biochemistry
Hormonal biochemistry
 
Section 1, chapter 13: endocrine system
Section 1, chapter 13: endocrine systemSection 1, chapter 13: endocrine system
Section 1, chapter 13: endocrine system
 
HUMAN ANATOMY AND PHYSIOLOGY: THE ENDOCRINE SYSTEM
HUMAN ANATOMY AND PHYSIOLOGY: THE ENDOCRINE SYSTEMHUMAN ANATOMY AND PHYSIOLOGY: THE ENDOCRINE SYSTEM
HUMAN ANATOMY AND PHYSIOLOGY: THE ENDOCRINE SYSTEM
 
1 introduction endocrinology
1 introduction endocrinology1 introduction endocrinology
1 introduction endocrinology
 
15.1.pdf
15.1.pdf15.1.pdf
15.1.pdf
 
Hormones- its chemistry, classification, types, functioning, physiology
Hormones- its chemistry, classification, types, functioning, physiologyHormones- its chemistry, classification, types, functioning, physiology
Hormones- its chemistry, classification, types, functioning, physiology
 
Endocrinology2003.ppt
Endocrinology2003.pptEndocrinology2003.ppt
Endocrinology2003.ppt
 
Endocrine System.pptx
Endocrine System.pptxEndocrine System.pptx
Endocrine System.pptx
 
Endocrine system
Endocrine systemEndocrine system
Endocrine system
 
Ch 16_lecture pt a_sp2014
 Ch 16_lecture pt a_sp2014 Ch 16_lecture pt a_sp2014
Ch 16_lecture pt a_sp2014
 
Ch 16_lecture pt a_sp2014
 Ch 16_lecture pt a_sp2014 Ch 16_lecture pt a_sp2014
Ch 16_lecture pt a_sp2014
 

More from TheSlaps

Med Surg Chapter 020
Med Surg Chapter 020Med Surg Chapter 020
Med Surg Chapter 020TheSlaps
 
Med Surg Chapter 019
Med Surg Chapter 019Med Surg Chapter 019
Med Surg Chapter 019TheSlaps
 
Adams ch09 lecture
Adams ch09 lectureAdams ch09 lecture
Adams ch09 lectureTheSlaps
 
Adams ch08 lecture
Adams ch08 lectureAdams ch08 lecture
Adams ch08 lectureTheSlaps
 
Adams ch10 lecture
Adams ch10 lectureAdams ch10 lecture
Adams ch10 lectureTheSlaps
 
Adams ch05 lecture
Adams ch05 lectureAdams ch05 lecture
Adams ch05 lectureTheSlaps
 
Adams ch07 lecture
Adams ch07 lectureAdams ch07 lecture
Adams ch07 lectureTheSlaps
 
Adams ch06 lecture
Adams ch06 lectureAdams ch06 lecture
Adams ch06 lectureTheSlaps
 
Adams ch04 lecture
Adams ch04 lectureAdams ch04 lecture
Adams ch04 lectureTheSlaps
 
Adams ch02 lecture
Adams ch02 lectureAdams ch02 lecture
Adams ch02 lectureTheSlaps
 
Adams ch01 lecture
Adams ch01 lectureAdams ch01 lecture
Adams ch01 lectureTheSlaps
 
Adams ch03 lecture
Adams ch03 lectureAdams ch03 lecture
Adams ch03 lectureTheSlaps
 
Pathophysiology Chapter 52
Pathophysiology Chapter 52Pathophysiology Chapter 52
Pathophysiology Chapter 52TheSlaps
 
Pathophysiology Chapter 47
Pathophysiology Chapter 47Pathophysiology Chapter 47
Pathophysiology Chapter 47TheSlaps
 
Pathophysiology Chapter 45
Pathophysiology Chapter 45Pathophysiology Chapter 45
Pathophysiology Chapter 45TheSlaps
 
Pathophysiology Chapter 44
Pathophysiology Chapter 44Pathophysiology Chapter 44
Pathophysiology Chapter 44TheSlaps
 
Pathophysiology Chapter 36
Pathophysiology Chapter 36Pathophysiology Chapter 36
Pathophysiology Chapter 36TheSlaps
 
Pathophysiology Chapter 38
Pathophysiology Chapter 38Pathophysiology Chapter 38
Pathophysiology Chapter 38TheSlaps
 
Pathophysiology Chapter 041
Pathophysiology Chapter 041Pathophysiology Chapter 041
Pathophysiology Chapter 041TheSlaps
 
PathoPhysiology Chapter 4
PathoPhysiology Chapter 4PathoPhysiology Chapter 4
PathoPhysiology Chapter 4TheSlaps
 

More from TheSlaps (20)

Med Surg Chapter 020
Med Surg Chapter 020Med Surg Chapter 020
Med Surg Chapter 020
 
Med Surg Chapter 019
Med Surg Chapter 019Med Surg Chapter 019
Med Surg Chapter 019
 
Adams ch09 lecture
Adams ch09 lectureAdams ch09 lecture
Adams ch09 lecture
 
Adams ch08 lecture
Adams ch08 lectureAdams ch08 lecture
Adams ch08 lecture
 
Adams ch10 lecture
Adams ch10 lectureAdams ch10 lecture
Adams ch10 lecture
 
Adams ch05 lecture
Adams ch05 lectureAdams ch05 lecture
Adams ch05 lecture
 
Adams ch07 lecture
Adams ch07 lectureAdams ch07 lecture
Adams ch07 lecture
 
Adams ch06 lecture
Adams ch06 lectureAdams ch06 lecture
Adams ch06 lecture
 
Adams ch04 lecture
Adams ch04 lectureAdams ch04 lecture
Adams ch04 lecture
 
Adams ch02 lecture
Adams ch02 lectureAdams ch02 lecture
Adams ch02 lecture
 
Adams ch01 lecture
Adams ch01 lectureAdams ch01 lecture
Adams ch01 lecture
 
Adams ch03 lecture
Adams ch03 lectureAdams ch03 lecture
Adams ch03 lecture
 
Pathophysiology Chapter 52
Pathophysiology Chapter 52Pathophysiology Chapter 52
Pathophysiology Chapter 52
 
Pathophysiology Chapter 47
Pathophysiology Chapter 47Pathophysiology Chapter 47
Pathophysiology Chapter 47
 
Pathophysiology Chapter 45
Pathophysiology Chapter 45Pathophysiology Chapter 45
Pathophysiology Chapter 45
 
Pathophysiology Chapter 44
Pathophysiology Chapter 44Pathophysiology Chapter 44
Pathophysiology Chapter 44
 
Pathophysiology Chapter 36
Pathophysiology Chapter 36Pathophysiology Chapter 36
Pathophysiology Chapter 36
 
Pathophysiology Chapter 38
Pathophysiology Chapter 38Pathophysiology Chapter 38
Pathophysiology Chapter 38
 
Pathophysiology Chapter 041
Pathophysiology Chapter 041Pathophysiology Chapter 041
Pathophysiology Chapter 041
 
PathoPhysiology Chapter 4
PathoPhysiology Chapter 4PathoPhysiology Chapter 4
PathoPhysiology Chapter 4
 

16 a chapter

  • 1. 16 The Endocrine System Endocrine System: Overview * Endocrine system – the body’s second great controlling system which influences metabolic activities of cells by means of hormones * Endocrine glands – pituitary, thyroid, parathyroid, adrenal, pineal, and thymus * The pancreas and gonads produce both hormones and exocrine products Endocrine System: Overview * The hypothalamus has both neural functions and releases hormones * Other tissues and organs that produce hormones – adipose cells, pockets of cells in the walls of the small intestine, stomach, kidneys, and heart Major Endocrine Organs Autocrines and Paracrines * Autocrines – chemicals that exert effects on the same cells that secrete them * Paracrines – locally acting chemicals that affect cells other than those that secrete them
  • 2. * These are not considered hormones since hormones are long-distance chemical signals Hormones * Hormones – chemical substances secreted by cells into the extracellular fluids * Regulate the metabolic function of other cells * Have lag times ranging from seconds to hours * Tend to have prolonged effects * Are classified as amino acid-based hormones, or steroids * Eicosanoids – biologically active lipids with local hormone–like activity Types of Hormones * Amino acid based * Amines, thyroxine, peptide, and protein hormones * Steroids – gonadal and adrenocortical hormones * Eicosanoids – leukotrienes and prostaglandins Hormone Action * Hormones alter target cell activity by one of two mechanisms * Second messengers: * Regulatory G proteins * Amino acid–based hormones * Direct gene activation * Steroid hormones * The precise response depends on the type of the target cell
  • 3. Mechanism of Hormone Action * Hormones produce one or more of the following cellular changes in target cells * Alter plasma membrane permeability * Stimulate protein synthesis * Activate or deactivate enzyme systems * Induce secretory activity * Stimulate mitosis Amino Acid-Based Hormone Action: cAMP Second Messenger * Hormone (first messenger) binds to its receptor, which then binds to a G protein * The G protein is then activated as it binds GTP, displacing GDP * Activated G protein activates the effector enzyme adenylate cyclase * Adenylate cyclase generates cAMP (second messenger) from ATP * cAMP activates protein kinases, which then cause cellular effects Amino Acid-Based Hormone Action: cAMP Second Messenger Amino Acid-Based Hormone Action: cAMP Second Messenger Amino Acid-Based Hormone Action: cAMP Second Messenger Amino Acid-Based Hormone Action: cAMP Second Messenger Amino Acid-Based Hormone Action: cAMP Second Messenger
  • 4. Amino Acid-Based Hormone Action: cAMP Second Messenger Amino Acid-Based Hormone Action: cAMP Second Messenger Amino Acid-Based Hormone Action: cAMP Second Messenger Amino Acid-Based Hormone Action: cAMP Second Messenger Amino Acid-Based Hormone Action: cAMP Second Messenger Amino Acid-Based Hormone Action: cAMP Second Messenger Amino Acid-Based Hormone Action: cAMP Second Messenger Amino Acid-Based Hormone Action: PIP-Calcium * Hormone binds to the receptor and activates G protein * G protein binds and activates phospholipase * Phospholipase splits the phospholipid PIP2 into diacylglycerol (DAG) and IP3 (both act as second messengers) * DAG activates protein kinases; IP3 triggers release of Ca2+ stores * Ca2+ (third messenger) alters cellular responses Amino Acid-Based Hormone Action: PIP Mechanism Amino Acid-Based Hormone Action: PIP Mechanism
  • 5. Amino Acid-Based Hormone Action: PIP Mechanism Amino Acid-Based Hormone Action: PIP Mechanism Amino Acid-Based Hormone Action: PIP Mechanism Amino Acid-Based Hormone Action: PIP Mechanism Amino Acid-Based Hormone Action: PIP Mechanism Amino Acid-Based Hormone Action: PIP Mechanism Steroid Hormones * This interaction prompts DNA transcription to produce mRNA * The mRNA is translated into proteins, which bring about a cellular effect Steroid Hormones * This interaction prompts DNA transcription to produce mRNA * The mRNA is translated into proteins, which bring about a cellular effect
  • 6. Target Cell Specificity * Hormones circulate to all tissues but only activate cells referred to as target cells * Target cells must have specific receptors to which the hormone binds * These receptors may be intracellular or located on the plasma membrane Target Cell Specificity * Examples of hormone activity * ACTH receptors are only found on certain cells of the adrenal cortex * Thyroxin receptors are found on nearly all cells of the body Target Cell Activation * Target cell activation depends on three factors * Blood levels of the hormone * Relative number of receptors on the target cell * The affinity of those receptors for the hormone * Up-regulation – target cells form more receptors in response to the hormone * Down-regulation – target cells lose receptors in response to the hormone
  • 7. Hormone Concentrations in the Blood * Hormones circulate in the blood in two forms – free or bound * Steroids and thyroid hormone are attached to plasma proteins * All others are unencumbered Hormone Concentrations in the Blood * Concentrations of circulating hormone reflect: * Rate of release * Speed of inactivation and removal from the body * Hormones are removed from the blood by: * Degrading enzymes * The kidneys * Liver enzyme systems Interaction of Hormones at Target Cells * Three types of hormone interaction * Permissiveness – one hormone cannot exert its effects without another hormone being present * Synergism – more than one hormone produces the same effects on a target cell * Antagonism – one or more hormones opposes the action of another hormone Control of Hormone Release * Blood levels of hormones: * Are controlled by negative feedback systems
  • 8. * Vary only within a narrow desirable range * Hormones are synthesized and released in response to: * Humoral stimuli * Neural stimuli * Hormonal stimuli Humoral Stimuli * Humoral stimuli – secretion of hormones in direct response to changing blood levels of ions and nutrients * Example: concentration of calcium ions in the blood * Declining blood Ca2+ concentration stimulates the parathyroid glands to secrete PTH (parathyroid hormone) * PTH causes Ca2+ concentrations to rise and the stimulus is removed Humoral Stimuli Neural Stimuli * Neural stimuli – nerve fibers stimulate hormone release * Preganglionic sympathetic nervous system (SNS) fibers stimulate the adrenal medulla to secrete catecholamines Hormonal Stimuli * Hormonal stimuli – release of hormones in response to hormones produced by other endocrine organs * The hypothalamic hormones stimulate the anterior pituitary * In turn, pituitary hormones stimulate targets to secrete still more hormones Hormonal Stimuli Nervous System Modulation
  • 9. * The nervous system modifies the stimulation of endocrine glands and their negative feedback mechanisms Nervous System Modulation * The nervous system can override normal endocrine controls * For example, control of blood glucose levels * Normally the endocrine system maintains blood glucose * Under stress, the body needs more glucose * The hypothalamus and the sympathetic nervous system are activated to supply ample glucose Major Endocrine Organs: Pituitary (Hypophysis) * Pituitary gland – two-lobed organ that secretes nine major hormones * Neurohypophysis – posterior lobe (neural tissue) and the infundibulum * Receives, stores, and releases hormones from the hypothalamus * Adenohypophysis – anterior lobe, made up of glandular tissue * Synthesizes and secretes a number of hormones Major Endocrine Organs: Pituitary (Hypophysis) Pituitary-Hypothalamic Relationships: Posterior Lobe * The posterior lobe is a downgrowth of hypothalamic neural tissue * Has a neural connection with the hypothalamus (hypothalamic-hypophyseal tract) * Nuclei of the hypothalamus synthesize oxytocin and antidiuretic hormone (ADH) * These hormones are transported to the posterior pituitary
  • 10. Pituitary-Hypothalamic Relationships: Anterior Lobe * The anterior lobe of the pituitary is an outpocketing of the oral mucosa * There is no direct neural contact with the hypothalamus Pituitary-Hypothalamic Relationships: Anterior Lobe * There is a vascular connection, the hypophyseal portal system, consisting of: * The primary capillary plexus * The hypophyseal portal veins * The secondary capillary plexus Pituitary-Hypothalamic Relationships: Anterior Lobe Adenophypophyseal Hormones * The six hormones of the adenohypophysis: * Abbreviated as GH, TSH, ACTH, FSH, LH, and PRL * Regulate the activity of other endocrine glands * In addition, pro-opiomelanocortin (POMC): * Has been isolated from the pituitary * Is split into ACTH, opiates, and MSH Activity of the Adenophypophysis * The hypothalamus sends a chemical stimulus to the anterior pituitary * Releasing hormones stimulate the synthesis and release of hormones
  • 11. * Inhibiting hormones shut off the synthesis and release of hormones Activity of the Adenophypophysis * The tropic hormones that are released are: * Thyroid-stimulating hormone (TSH) * Adrenocorticotropic hormone (ACTH) * Follicle-stimulating hormone (FSH) * Luteinizing hormone (LH) Growth Hormone (GH) * Produced by somatotropic cells of the anterior lobe that: * Stimulate most cells, but target bone and skeletal muscle * Promote protein synthesis and encourage the use of fats for fuel *Most effects are mediated indirectly by somatomedins Growth Hormone (GH) * Antagonistic hypothalamic hormones regulate GH * Growth hormone–releasing hormone (GHRH) stimulates GH release * Growth hormone–inhibiting hormone (GHIH) inhibits GH release Metabolic Action of Growth Hormone * GH stimulates liver, skeletal muscle, bone, and cartilage to produce insulin-like growth factors * Direct action promotes lipolysis and inhibits glucose uptake Metabolic Action of Growth Hormone (GH) Thyroid Stimulating Hormone (Thyrotropin)
  • 12. * Stimulates the normal development and secretory activity of the thyroid * Triggered by hypothalamic peptide thyrotropin-releasing hormone (TRH) * Rising blood levels of thyroid hormones act on the pituitary and hypothalamus to block the release of TSH Adrenocorticotropic Hormone (Corticotropin) * Stimulates the adrenal cortex to release corticosteroids * Triggered by hypothalamic corticotropin-releasing hormone (CRH) in a daily rhythm * Internal and external factors such as fever, hypoglycemia, and stressors can trigger the release of CRH Gonadotropins * Gonadotropins – follicle-stimulating hormone (FSH) and luteinizing hormone (LH) * Regulate the function of the ovaries and testes * FSH stimulates gamete (egg or sperm) production * Absent from the blood in prepubertal boys and girls * Triggered by the hypothalamic gonadotropin-releasing hormone (GnRH) during and after puberty Functions of Gonadotropins * In females * LH works with FSH to cause maturation of the ovarian follicle * LH works alone to trigger ovulation (expulsion of the egg from the follicle) * LH promotes synthesis and release of estrogens and progesterone
  • 13. Functions of Gonadotropins * In males * LH stimulates interstitial cells of the testes to produce testosterone * LH is also referred to as interstitial cell-stimulating hormone (ICSH) Prolactin (PRL) * In females, stimulates milk production by the breasts * Triggered by the hypothalamic prolactin-releasing hormone (PRH) * Inhibited by prolactin-inhibiting hormone (PIH) * Blood levels rise toward the end of pregnancy * Suckling stimulates PRH release and encourages continued milk production The Posterior Pituitary and Hypothalamic Hormones * Posterior pituitary – made of axons of hypothalamic neurons, stores antidiuretic hormone (ADH) and oxytocin * ADH and oxytocin are synthesized in the hypothalamus * ADH influences water balance * Oxytocin stimulates smooth muscle contraction in breasts and uterus * Both use PIP-calcium second-messenger mechanism