Transcript Chapter 7, part A - El Camino College

POWERPOINT® LECTURE SLIDE PRESENTATION
by ZARA OAKES, MS, The University of Texas at Austin
UNIT 2
7
PART A
Introduction to the
Endocrine System
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
DEE UNGLAUB SILVERTHORN
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
FOURTH EDITION
About this Chapter
 Function and purpose of hormones
 Classification, structure, and synthesis of hormones
 Pathways of nervous to endocrine regulation
 Effects of hormone interactions
 Pathologies of the endocrine system
 Hormone evolution
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Anatomy Summary: Hormones
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Figure 7-2 (1 of 4)
Anatomy Summary: Hormones
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Figure 7-2 (2 of 4)
Anatomy Summary: Hormones
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Figure 7-2 (3 of 4)
Anatomy Summary: Hormones
PLAY Animation: Endocrine System: Endocrine System Review
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Figure 7-2 (4 of 4)
General Information on Hormones
Chemical Regulating Systems
 Hormones





Depend on cell to cell communication molecules
Made in gland(s) or cells
Transported by blood
Distant target tissue receptors
Activates physiological response
 Pheromones: organism to organism communication
Hormone Function
 Control rates of enzymatic reactions, transport of ions or
molecules across cell membranes, and gene expression and
protein synthesis
 Exert effects at very low concentrations
 Bind to target cell receptors
 Half-life indicates length of activity
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Hormones: Classification
 Peptide or protein hormones
 Molecular structure includes amino acid chains
 Water soluble and lipophobic = bind cell receptor
 short life-time but triggers rapid respondses
 Steroid hormones




Molecular structure includes a cholesterol molecule.
Made only in few organs (adrenal gland, gonads, placenta)
Not water soluble, lipophobic
Enters the nucleus, affects transcription= genomic effect
 Amine hormones
 Small hormone derived from tryptophan and tyrosine
 Catecholamines- epinephrine, norepinephrine, and dopamine are
neurohormones that are lipophobic
 Thyroid hormones – T3, T4, Thyroxine, are lipophilic and bind
intracellular receptors
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Hormones: Peptides or Proteins
 Preprohormone
 Large, inactive- before being processed they may have
multiple copies of a peptide hormone
 Prohormone
 Post-translational modification - inactive
prehormones are cleaved by proteolytic enzymes
 Peptide hormone-receptor complex
 Signal transduction system -
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Peptide Hormone Synthesis,
Packaging, and Release
1 Messenger RNA on the 2 Enzymes in the 3 The prohormone 4 Secretory vesicles containing 5 The secretory 6 The hormone
ribosomes binds amino
acids into a peptide chain
called a preprohormone.
The chain is directed into
the ER lumen by a signal
sequence of amino acids.
ER chop off the
signal sequence,
creating an
inactive
prohormone.
passes from the
ER through the
Golgi complex.
enzymes and prohormone
bud off the Golgi. The enzymes
chop the prohormone into one
or more active peptides plus
additional peptide fragments.
vesicle releases
its contents by
exocytosis into
the extracellular
space.
moves into the
circulation for
transport to its
target.
Golgi complex
Endoplasmic reticulum (ER)
To target
Ribosome
Active hormone
Transport
vesicle
Peptide
fragment
3
4
Prohormone
6
Secretory
5
vesicle
Release
signal
Capillary
endothelium
2
1
mRNA
Signal
sequence
Cytoplasm ECF
Plasma
Preprohormone
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Figure 7-3
Peptide Hormone-Receptor Complex
Membrane receptors and signal
transduction for peptide hormones
Surface receptor
Hormone binds
Enzyme activation
Open channels
Second messenger
systems
Cellular response
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Figure 7-5
Steroid Hormones: Features
 Cholesterol-derived- made only in a few organs,
synthesized as needed, not stored.
 Lipophilic and can enter target cell -
 Cytoplasmic or nuclear receptors (mostly) – binds
receptors intracellularly
 Activate DNA for protein synthesis – receptorhormone complexes act as transcription factors.
 Slower acting, longer half-life – because of it’s slow
rate of activation they do not mediate reflex
pathways.
 Examples Cortisol, estrogen, and testosterone
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Steroid Hormones: Structure
Steroid hormones are derived from cholesterol
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Figure 7-6
Steroid Hormones: Action
1 Most hydrophobic
steroids are bound
to plasma protein
carriers. Only
unbound hormones
can diffuse into the
target cell.
2 Steroid hormone
receptors are
typically in the
cytoplasm or
nucleus.
2a Some steroid
hormones also
bind to membrane receptors
that use second
messenger
systems to
create rapid
cellular
responses.
3 The receptorhormone complex
binds to DNA
and activates or
represses one or
more genes.
Blood
vessel
Steroid
hormone
Cell surface receptor
2a
Rapid responses
1
2
Protein
carrier
Nucleus
Cytoplasmic
receptor
Nuclear
receptor
DNA
Interstitial
fluid
Cell
membrane
3
Endoplasmic
reticulum
Transcription
produces mRNA
5
4
New
proteins
4 Activated genes create new
mRNA that moves into the
cytoplasm.
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Translation
5 Translation produces new
proteins for cell processes.
Figure 7-7
Steroid Hormones: Action
1 Most hydrophobic
steroids are bound
to plasma protein
carriers. Only
unbound hormones
can diffuse into the
target cell.
2 Steroid hormone
receptors are
typically in the
cytoplasm or
nucleus.
2a Some steroid
hormones also
bind to membrane receptors
that use second
messenger
systems to
create rapid
cellular
responses.
Blood
vessel
Steroid
hormone
Cell surface receptor
2a
Rapid responses
1
2
Protein
carrier
Nucleus
Cytoplasmic
receptor
Nuclear
receptor
Interstitial
fluid
Cell
membrane
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Figure 7-7, steps 1–2a
Steroid Hormones: Action
1 Most hydrophobic
steroids are bound
to plasma protein
carriers. Only
unbound hormones
can diffuse into the
target cell.
2 Steroid hormone
receptors are
typically in the
cytoplasm or
nucleus.
2a Some steroid
hormones also
bind to membrane receptors
that use second
messenger
systems to
create rapid
cellular
responses.
3 The receptorhormone complex
binds to DNA
and activates or
represses one or
more genes.
Blood
vessel
Steroid
hormone
Cell surface receptor
2a
Rapid responses
1
2
Protein
carrier
Nucleus
Cytoplasmic
receptor
Nuclear
receptor
DNA
Interstitial
fluid
3
Transcription
produces mRNA
Cell
membrane
4
4 Activated genes create new
mRNA that moves into the
cytoplasm.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-7, steps 1–4
Steroid Hormones: Action
1 Most hydrophobic
steroids are bound
to plasma protein
carriers. Only
unbound hormones
can diffuse into the
target cell.
2 Steroid hormone
receptors are
typically in the
cytoplasm or
nucleus.
2a Some steroid
hormones also
bind to membrane receptors
that use second
messenger
systems to
create rapid
cellular
responses.
3 The receptorhormone complex
binds to DNA
and activates or
represses one or
more genes.
Blood
vessel
Steroid
hormone
Cell surface receptor
2a
Rapid responses
1
2
Protein
carrier
Nucleus
Cytoplasmic
receptor
Nuclear
receptor
DNA
Interstitial
fluid
Cell
membrane
3
Endoplasmic
reticulum
Transcription
produces mRNA
5
4
New
proteins
4 Activated genes create new
mRNA that moves into the
cytoplasm.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Translation
5 Translation produces new
proteins for cell processes.
Figure 7-7, steps 1–5
Amine Hormones: Features
 Derived from one of two
amino acids
 Tryptophan – double ring
amino acid
 Tyrosine-single ring amino
acid
 Ring structure Thyroid hormones- bind
intracellular receptors.
 Catecholaminesneurohormones that bind
cell membrane receptors
 Epinephrine  Norepinephrine  Dopamine Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Endocrine Reflex Pathways
 Stimulus
Hormones may have multiple stimuli
for their release and endocrine
cells act as the receptor
 Afferent signal
input signal
 Integration
The cells that make the hormone
must interpret the various signals
and decide how much to produce.
 Efferent signal
Out put signal=hormone
 Physiological action
 Negative feedback
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The Pituitary Gland Anatomy
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Figure 7-11
The Pituitary Gland: Two Fused
Posterior
pituitary
produces
1.
Vasopressin
(also called
ADH)
2. Oxytocin
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Figure 7-12
The Hypothalamic-Hypophyseal Portal System
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Figure 7-16
The Pituitary Gland: Two Fused
Hormones of the hypothalamic-anterior pituitary
pathway
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Figure 7-13
Endocrine Control
 Three levels
 Hypothalamic
stimulation—from CNS
 Pituitary stimulation—
from hypothalamic trophic
hormones
 Endocrine gland
stimulation—from
pituitary trophic hormones
 Long-loop feedback
 Short-loop feedback
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Comparing two control Pathways
Two types of Neuro
hormones:
1. Adrenal medulla
Catecholamines
2. Hypothalamus
Anterior
pituitary
Posterior
pituitary
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Figure 7-15
Hormone Interactions
 Synergism
 Multiple stimuli—more
than additive
 Permissiveness
 Need second hormone to
get full expression
 Antagonism
 Glucagons opposes insulin
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Endocrine Pathologies
 Hormone disease is caused by an imbalance due to either excess or deficiency or
abnormal responsiveness
 Hypersecretion: excess hormone causes exaggerated effects
 Tumors (benign or cancerous) of glandular tissues
 Exogenous sources- most sources are medications or suppliments, can cause
gland atrophy
 Grave’s disease—high secretion of thyroxin Hyposecretion: deficient hormone
 Most often low levels cause increased tropic hormone levels
 Goiter— low secretion of thyroxin
 Diabetes—low secretion of insulin
 Abnormalities related to hormone response
 Target tissues do not respond to the hormone correctly
 Downregulation- high hormone levels may result in a decrease of receptors as it
happens in Hyperinsulinemia
 Receptor abnormalities- the receptors may not function due to a genetic
mutation as it happens in Testicular feminization syndrome
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Endocrine Pathologies
 Exogenous
medication
 Replaces and
exceeds normal
 Cause atrophy
of gland
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Figure 7-19
Primary and Secondary Pathologies
Primary and
Secondary
hypersecreti
ons are
caused by
abnormalitie
s of different
glands
along the
hormone
release path
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Figure 7-20
Pineal Gland and Melatonin
 Influences body clock- sets sleep-wake cycles
 Antioxidant activity- neutralizes free radicals
 Other roles need research
 SAAD - seasonal affective depressive disorder
 sexual behavior- sexual function and the onset of
puberty
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Pineal Gland and Melatonin
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Figure 7-22 (1 of 3)