Chapter 13 Endocrine System

Hole's Anatomy and Physiology

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Chapter 13
Lecture
PowerPoint

2. 2
2401
Anatomy and Physiology I
Chapter 13
Susan Gossett
[email protected]
Department of Biology
Paris Junior College

3. 3
Hole’s Human Anatomy
and Physiology
Twelfth Edition
Shier  Butler  Lewis
Chapter
13
Endocrine System
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4. 4
13.1: Introduction
• The endocrine system assists the nervous system with
communication and control of the body
• The cells, tissues, and organs are called endocrine glands
• They are ductless
• They use the bloodstream
• They secrete hormones
• There are also similar glands called paracrine and
autocrine glands that are quasi-endocrine
• Other glands that secrete substances are the exocrine glands
• They have ducts
• They deliver their products directly to a specific site

5. 5
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Hormone secretion
(a)
(b)
Blood flow
Skin
Duct
Thyroid
gland
Endocrine
gland
Endocrine
cell
Exocrine gland
(sweat gland)
Exocrine
cells

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13.2: General Characteristics
of the Endocrine System
• The endocrine and nervous systems communicate using
chemical signals
• Neurons release neurotransmitters into a synapse
affecting postsynaptic cells
• Endocrine glands release hormones into the
bloodstream to specific target cell receptors

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(a)
(b)
Nerve impulse
Bloodstream
Neuron
transmits
nerve
impulse
Glandular
cells secrete
hormone into
bloodstream
Neurotransmitter
released into
synapse
Post-
synaptic
cell responds
Target cells
(cells with hormone
receptors) respond
to hormone
Hormones have no
effect on other cells
7

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13.3: Hormone Action
• Hormones are released into the extracellular spaces
surrounding endocrine cells
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Hypothalamus
Pituitary gland
Thyroid gland
Thymus
Adrenal gland
Pancreas
Parathyroid gland
Pineal gland
Kidney
Testis
(in male)
Ovary
(in female)

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Chemistry of Hormones
• Chemically, hormones are either:
• Steroid or steroid-like hormones such as:
• Sex hormones
• Adrenal cortex hormones
• Non-steroid hormones such as:
• Amines
• Proteins
• Peptides
• Glycoproteins

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O
H
3
C
(a) Cortisol
(d) Oxytocin
OH
HO C
HO
(b) Norepinephrine
HH
OHH
CNH
2
C
H
H
C C
H
H
C
H
H
C
H
H
H
HH
H
C
CCC
C
(e) Prostaglandin PGE
2
H
OHH
HHOH
C
H
H
H
H
C
H
C
C
H
H
C C
H
H
C
O
OH
HH
HH
C
HO
H
3C
CO
C
O
C
Ala
Val
AspHis SerArgGlyArgArgAspSerGluProArgAspAla
SerGluGluPheIleGlyAsp HisHisSerLeuLeu
Met
Ala
ProProAlaAlaGluGluLeuAspSerGlyGlu GluGlu
Arg
Gly
Cys
Cys
Asp
Glu
Ile
Pro Leu Gly
HisIleuMetGluSerPheAla LeuGlu
SerAspIleLeuLeuLeuAspGluLeu GlyGlu
S
S
CH
2
OH
Val LysLys
Lys
LysVal
LysLysLys
Val LysTyr ValVal Lys
LysLys Try Val
Tyr
(c) Parathyroid ho rm one (PTH)

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13. 13

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Action of Hormones
• Steroid Hormones
Hormone molecule
Ribosome
Nucleus
1
2
3
5
4
Newly forming
protein molecule
Cell
membrane
Hormone-receptor
complex
Intracellular
receptor molecule
mRNA
mRNA
DNA
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Action of Hormones
• Non-steroid Hormones
Cell membrane
G protein
Cytoplasm
Nucleus
ATP
cAMP
1
2
3
5
4
Membrane-bound
receptor molecule
Nonsteroid
hormone
molecule
Hormone-
receptor
complex
Adenylate
cyclase
Protein
kinases
(inactive)
Substrate
(inactive)
Protein
kinases
(active)
Substrate
(active)
Cellular
changes
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13.1 Clinical Application
Using Hormones to Improve
Athletic Performance

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Prostaglandins
• Prostaglandins:
• Are paracrine substances
• Are very potent in small amounts
• Are not stored in cells but synthesized just before release
• Rapidly inactivate
• Regulate cellular responses to hormones
• Can activate or inhibit adenylate cyclase
• Controls cAMP production
• Alters a cells response to hormones
• Has a wide variety of effects

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13.4: Control of
Hormonal Secretions
• Primarily controlled by negative feedback mechanism
• Hormones can be short-lived or may last for days
• Hormone secretions are precisely regulated

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Control Sources
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too high
too low
Control center
Endocrine gland
inhibited.
Receptors
Hormone control
mechanism senses
change.
Effectors
Hormone secretion
decreased.
Stimulus
Hormone levels rise or
controlled process
increases.
Response
Hormone levels
return toward
normal.
Normal
hormone
levels
Stimulus
Hormone levels drop or
controlled process
decreases.
Response
Hormone levels
return toward
normal.
Receptors
Hormone control
mechanism senses
change.
Effectors
Hormone secretion
increased.
Control center
Endocrine gland
stimulated.

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Control Sources
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Nervous system
(a) (b) (c)
Target cells
Action
Target cells
Action
–
– – –
Anterior pituitary gland
Action
Hypothalamus
Peripheral
endocrine
gland
Target cells
Endocrine
gland
Changing level
of substance
in plasma
Endocrine
gland

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13.5: Pituitary Gland
• Lies at the base of the brain in the sella turcica
• Consists of two distinct portions:
• Anterior pituitary (adenohypophysis)
• Posterior pituitary (neurohypophysis)

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Optic nerve
Sphenoid bone
Hypothalamus
Optic chiasma
Sella turcica
Third ventricle
Trochlear nerve
Basilar artery
Anterior cerebral
artery
Pituitary stalk
(Infundibulum)
Anterior lobe
of pituitary gland
Sphenoidal
sinus
Posterior lobe
of pituitary
gland
Oculomotor
nerve
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Anterior Pituitary Hormones
• Hypothalamic releasing hormones stimulate cells of anterior
pituitary to release hormones
• Nerve impulses from hypothalamus stimulate nerve endings
in the posterior pituitary gland to release hormones
Hypophyseal veins
Optic chiasma
Capillary bed
Posterior lobe of pituitary gland
Third ventricle
Hypothalamus
Anterior lobe of pituitary gland
Capillary bed
Hypophyseal
portal veins
Secretory cells
of anterior
pituitary gland
Neurosecretory
cells that secrete
releasing hormones
Superior hypophyseal
artery
Neurosecretory cells
that secrete posterior
pituitary hormones
Inferior hypophyseal
artery
Sella turcica of
sphenoid bone
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Anterior pituitary
Peripheral endocrine gland
Hypothalamus
Target cells
(Hormone 3)
+
––
–
+
+ Inhibition
Stimulation
Releasing
hormone
(Hormone 1)
Anterior pituitary
hormone
(Hormone 2)
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Secretory
cells
© Michael Ross/Photo Researchers, Inc.

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ThyroidMammary gland Ovary TestisBoneMuscle
Hormones fromAnterior Pituitary
Hormones from Hypothalamus
GHRH
Growth
hormone-
releasing
hormone
SS
Somatostatin
PRF
Prolactin-
releasing
factor
PIH
Prolactin-
release
inhibiting
hormone
TRH
Thyrotropin-
releasing
hormone
CRH
Corticotropin-
releasing
hormone
GnRH
Gonadotropin-
releasing
hormone
GH
Growth
hormone
PRL
Prolactin
TSH
Thyroid-
stimulating
hormone
ACTH
Adrenocorticotropic
hormone
LH
Luteinizing
hormone
FSH
Follicle-
stimulating
hormone
Adipose
tissue
Adrenal
cortex

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13.2 Clinical Application
Growth Hormone Ups and Downs

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Posterior Pituitary Hormones
• Structurally consists of nerve fibers and neuroglia v.
glandular epithelial cells of the anterior pituitary gland
• The nerve fibers originate in the hypothalamus
• Two hormones are produced:
• Antidiuretic hormone (vasopressin)
• Oxytocin

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13.6: Thyroid Gland
• The thyroid gland has two lateral lobes and lies just below
the larynx
• It produces three hormones:
• T3 (thyroxine)
• T4 (triiodothyronine)
• Calcitonin

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Structure of the Gland
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Follicular cells
Colloid
Extrafollicular
cells
© Fred Hossler/Visuals Unlimited
Larynx
Colloid
Isthmus
(a)
(b)
Thyroid
gland
Follicular
cell
Extrafollicular
cell
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31. Thyroid Hormones
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OH
O
I I
CH
2
I I
OH
O
I
CH
2
I I
NH
2
CHCOOH NH
2
CHCOOH
Thyroxine (T
4
) Triiodothyronine (T
3
)
31

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© Mediscan/Visuals Unlimited © Mediscan/Visuals Unlimited © Mediscan/Visuals Unlimited
32

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13.7: Parathyroid Glands
• The parathyroid glands are on the posterior surface of the
thyroid gland
• There are typically four parathyroid glands
• It secretes one hormone:
• PTH (parathyroid hormone or parathormone)

34. Posterior view
Esophagus
Pharynx
Thyroid
gland
Parathyroid
glands
Trachea
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34
Structure of the Glands
Secretory cells
Capillaries
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© R. Calentine/Visuals Unlimited

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Parathyroid Hormone
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Liver
Intestinal enzymes
Ultraviolet light in skin
Kidney Stimulated by PTH
Hydroxycholecalciferol
Foods
Ca
+2
Ca
+2
Ca
+2
Cholesterol
Provitamin D
Vitamin D
(Cholecalciferol)
Also obtained directly
from foods
Dihydroxycholecalciferol
(active form of vitamin D)
Controls absorption of
calcium in intestine

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PTH
Ca
+2
+
PTH
PTH
Ca
+2
+
Ca
+2
Bloodstream
–
Stimulation
Inhibition
Release into
bloodstream
Parathyroid glands (on
posterior of thyroid gland)
Decreased blood calcium
stimulates parathyroid
hormone secretion
Increased blood
calcium inhibits
PTH secretion
Kidneys
conserve Ca
+2 and
activate Vitamin D
Bone
releases Ca
+2
Intestine
absorbs Ca
+2
Active
Vitamin D
36

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13.8: Adrenal Glands
• The adrenal glands are closely associated with the kidneys
• The gland sits like a cap on each kidney
• Hormones are secreted from two different areas of the
gland, the adrenal cortex and the adrenal medulla
• Numerous hormones are secreted by the adrenal glands

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Structure of the Glands
Cortex
Medulla
Capsule
Zona
glomerulosa
Zona
fasciculata
Zona
reticularis
Chromaffin
cells
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© Ed Reschke
Adrenal gland
Kidney
Adrenal cortex
(a)
Zona
lomerulosa
Connective
tissue capsule
(b)
Zona
fasciculata
Zona
reticularis
Adrenal
medulla
Adrenal
cortex
Adrenal
medulla
Surface of
adrenal gland
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Hormones of the Adrenal Medulla

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Hormones of the Adrenal Cortex

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13.3 Clinical Application
Disorders of the Adrenal Cortex

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13.1 From Science to Technology
Treating Diabetes

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13.9: Pancreas
• The pancreas has two major types of secretory tissue
• This is why it is a dual functioning organ as both an
exocrine gland and endocrine gland
• Three hormones are secreted from the islet cells:
• Alpha cells secrete glucagon
• Beta cells insulin
• Delta cells secrete somatostatin

45. Structure of the Gland
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Pancreatic islet (Islet of Langerhans)
From Kent M. Van De Graaff and Stuart Ira Fox, Concepts of Human Anatomy and
Physiology, 2nd ed. ©1989 Wm. C. Brown Publishers, Dubuque, Iowa. All Rights
Reserved. Reprinted with permission
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Gallbladder Common bile duct
Pancreatic duct
PancreasDuct
Capillary
Small
intestine
Digestive enzyme-
secreting cells
Pancreatic islet
(Islet of Langerhans)
Hormone-secreting
islet cells
45

46. 46
Hormones of the Pancreatic Islets

47. 47
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too high
too low
Control center
Beta cells secrete
insulin
Receptors
Beta cells detect a rise
in blood glucose
Effectors
Insulin
• Promotes movement of glucose into
certain cells
• Stimulates formation of glycogen from
glucose
Stimulus
Rise in blood glucose
Response
Blood glucose drops toward
normal (and inhibits insulin
secretion)
Normal
blood glucose
concentration
Stimulus
Drop in blood glucose
Response
Blood glucose rises toward
normal (and inhibits glucagon
secretion)
Receptors
Alpha cells detect a drop
in blood glucose
Effectors
Glucagon
• Stimulates cells to break down glycogen
into glucose
• Stimulates cells to convert
noncarbohydrates into glucose
Control center
Alpha cells secrete
glucagon

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13.4 Clinical Application
Diabetes Mellitus

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13.10: Other Endocrine Glands
Pineal Gland
• Secretes melatonin
• Regulates circadian rhythms
Thymus Gland
• Secretes thymosins
• Promotes development of certain lymphocytes
• Important in role of immunity
Reproductive Organs
• Ovaries produce estrogens and progesterone
• Testes produce testosterone
• Placenta produces estrogens, progesterone, and
gonadotropin
Other organs: digestive glands, heart, and kidney

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13.11: Stress and Its Effects
• Survival depends on maintaining homeostasis
• Factors that change the internal environment are
potentially life-threatening
• Sensing such dangers directs nerve impulses to the
hypothalamus
• This can trigger a loss of homeostasis

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Types of Stress
• Two types of stress:
• Physical stress
• Psychological stress

52. 52
Responses to Stress
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Sympathetic impulses
CRH released
ACTH released
Cortisol released
Long-term adjustment or resistance stage
• Increase in blood concentration of amino acids.
• Increased release of fatty acids.
• Blood glucose increases.
• Blood glycerol and fatty acids increase.
• Heart rate increases.
• Blood pressure rises.
• Breathing rate increases.
•Air passages dilate.
• Pupils dilate.
Anterior pituitary
Hypothalamus
Adrenal cortex
Adrenal medulla
Neural signals
Hormonal signals
Stress results from changes
in the external environment
Signals from
sensory receptors
Epinephrine and
norepinephrine
released
Norepinephrine
released
Short-term “fight or flight” or alarm stage.
• Blood flow redistributes.
• Increased glucose formed from
noncarbohydrates—amino acids (from
proteins) and glycerol (from fats).

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13.12: Lifespan Changes
• Endocrine glands decrease in size
• Muscular strength decreases as GH levels decrease
• ADH levels increase due to slower break down in liver
and kidneys
• Calcitonin levels decrease; increase risk of osteoporosis
• PTH level changes contribute to risk of osteoporosis
• Insulin resistance may develop
• Changes in melatonin secretion affect the body clock
• Thymosin production declines increasing risk of
infections

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Important Points in Chapter 13:
Outcomes to be Assessed
13.1: Introduction
 Define hormone.
 Distinguish between endocrine and exocrine glands.
13.2: General Characteristics of the Endocrine System
 Explain what makes a cell a target cell for a hormone.
 List some important functions of hormones.
13.3: Hormone Action
 Describe how hormones can be classified according to their chemical
composition.
 Explain how steroid and non-steroid hormones affect their target
cells.

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Important Points in Chapter 13:
Outcomes to be Assessed
13.4: Control of Hormone Secretion
 Discuss how negative feedback mechanisms regulate hormone
secretion.
 Explain how the nervous system controls hormone secretion.
13.5-13.10: Pituitary Gland – Other Endocrine Glands
 Name and describe the locations of the major endocrine glands and
list the hormones that they secrete.
 Describe the actions of the various hormones and their contributions
to homeostasis.
 Explain how the secretion of each hormone is regulated.

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Important Points in Chapter 13:
Outcomes to be Assessed
13.11: Stress and Its Effects
 Distinguish between physical and psychological stress.
 Describe the general stress response.
13.12: Lifespan Changes
 Describe some of the changes associated with aging of the endocrine
system.

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Quiz 13
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