Download Chapter 10: Endocrine System

Fig. 10.1
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Pituitary
Thyroid
Pineal
gland
Parathyroids
(posterior
part of
thyroid)
Thymus
Adrenals
Ovaries
(female)
Pancreas
(islets)
Testes
(male)
Table 10.1
Fig. 10.12
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Hypothalamus
Third
ventricle
Optic
chiasm
Infundibulum
Pituitary
gland
Sella turcica
of sphenoid
bone
Hypothalamic
nerve cell
Bone
Posterior
pituitary
Anterior
pituitary
Antidiuretic
hormone
(ADH)
Growth
hormone (GH)
Adrenocorticotropic
hormone (ACTH)
Kidney
tubules
Thyroidstimulating
hormone (TSH)
Oxytocin
Gonadotropic
hormones
Melanocyte- (FSH and LH)
Prolactin stimulating
hormone
Uterus
smooth
muscle
Adrenal
cortex
Thyroid
gland
Testis
Ovary
Mammary
glands
Mammary
glands
Skin
Fig. 10.13
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Stimuli from the
nervous system
1
2
3
4
Stimuli within the nervous system
regulate the secretion of releasing
hormones (green circles) and inhibiting
hormones (red circles) from neurons
of the hypothalamus.
Hypothalamic
neurons
1
Optic chiasm
Releasing hormones and inhibiting
hormones pass through the
hypothalamohypophysial portal
system to the anterior pituitary.
2
Artery
Hypothalamohypophysial portal
system
Anterior pituitary
Releasing hormones and inhibiting
hormones (green and red circles) leave
capillaries and stimulate or inhibit the
release of hormones (yellow squares)
from anterior pituitary cells.
Releasing
and
inhibiting
hormones
Anterior pituitary
endocrine cell
3
In response to releasing hormones,
anterior pituitary hormones (yellow squares)
travel in the blood to their target
tissues (green arrow), which in some cases,
are other endocrine glands.
Posterior
pituitary
Vein
4
Stimulatory
Target tissue
or endocrine gland
Fig. 10.14
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Stimuli from the nervous system
1
Stimuli within the nervous system
cause hypothalamic neurons to
either increase or decrease their
action potential frequency.
Hypothalamic
neurons in
supraoptic
nucleus
1
2
3
4
Action potentials are conducted by
axons of the hypothalamic neurons
through the hypothalamohypophysial
tract to the posterior pituitary. The
axon endings of neurons store
neurohormones in the posterior pituitary.
In the posterior pituitary gland,
action potentials cause the release
of neurohormones (blue circles) from
axon terminals into the circulatory
system.
The neurohormones pass through the
circulatory system and influence the
activity of their target tissues.
AP
Hypothalamohypophysial
tract
Optic
chiasm
2
Posterior
pituitary
Neurohormone
Anterior
pituitary
3
Vein
4
Target tissue
Fig. 10.1
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Pituitary
Thyroid
Pineal
gland
Parathyroids
(posterior
part of
thyroid)
Thymus
Adrenals
Ovaries
(female)
Pancreas
(islets)
Testes
(male)
Fig. 10.6
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Hormone 1
Hormone 2
Capillary
Circulating
blood
Hormone 2
cannot bind to
this receptor
Hormone 1
bound to
its receptor
Hormone 1
receptor
Target cell
for hormone 1
Fig. 10.7
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Water-soluble hormone
(glucagon, prolactin)
Lipid-soluble hormone
(thyroid or steroid)
Membrane-bound receptor
G protein
complex
Cellular
responses
ATP
cAMP
Protein
kinase
Nucleus
Hormone
DNA
(a)
Nuclear
receptor
Cellular responses
(b)
Adenylate
cyclase
Fig. 10.2
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
PTH
Ca2+
Endocrine cell
when blood
Ca2+ is too low
Osteoclast
No PTH secretion
Ca2+
Endocrine cell
when blood
Ca2+ is too high
Fig. 10.3
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Neuron
1
An action potential
(AP) in a neuron
innervating an
endocrine cell
stimulates secretion
of a stimulatory
neurotransmitter.
2 The endocrine cell
secretes its hormone
into the blood where it
will travel to its target.
AP
Stimulatory
neurotransmitter
Endocrine cell
Hormone
secreted
Capillary
Fig. 10.19
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
1
Stress, physical activity, and
low blood glucose levels act as
stimuli to the hypothalamus,
resulting in increased
sympathetic nervous system
activity.
1
• Physical activity
• Low blood glucose
• Other stressors
Hypothalamus
2
3
An increased frequency of
action potentials conducted
through the sympathetic
division of the autonomic
nervous system stimulates the
adrenal medulla to secrete
epinephrine and some
norepinephrine into the
circulatory system.
Epinephrine and
norepinephrine act on their
target tissues to produce
responses.
Spinal
cord
3
Sympathetic
nerve fiber
2
Adrenal medulla
Epinephrine and norepinephrine in the
target tissues:
• Increase the release of glucose
from the liver into the blood
• Increase the release of fatty acids
from adipose tissue into the blood
• Increase heart rate
• Decrease blood flow through blood
vessels of most internal organs
• Increase blood flow through blood
vessels of skeletal muscle and the
heart
• Increase blood pressure
• Decrease the function of visceral
organs
• Increase the metabolic rate of
skeletal muscles
Fig. 8.39
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Preganglionic neuron
Postganglionic neuron
Lacrimal gland
Ciliary ganglion
III
Eye
Pterygopalatine
ganglion
Nasal
mucosa
Sublingual and
submandibular
glands
Submandibular
ganglion
VII
IX
Parotid gland
Medulla
Otic ganglion
Sympathetic
nerves
Spinal
cord
X
Trachea
T1
Lung
Heart
Celiac
ganglion
Greater
splanchnic
nerve
Liver
Superior
mesenteric
ganglion
Stomach
Spleen
Adrenal
gland
Lesser
splanchnic
nerve
Pancreas
Small
intestine
L2
Lumbar
splanchnic
nerves
Sacral
splanchnic
nerves
Inferior
mesenteric
ganglion
Kidney
Large
intestine
S2
S3
Pelvic
splanchnic
nerve
Hypogastric
ganglion
S4
Sympathetic
chain
Urinary
system
and genitalia
Sympathetic (thoracolumbar)
Preganglionic neuron
Postganglionic neuron
Parasympathetic (craniosacral)
Fig. 10.14
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Stimuli from the nervous system
1
Stimuli within the nervous system
cause hypothalamic neurons to
either increase or decrease their
action potential frequency.
Hypothalamic
neurons in
supraoptic
nucleus
1
2
3
4
Action potentials are conducted by
axons of the hypothalamic neurons
through the hypothalamohypophysial
tract to the posterior pituitary. The
axon endings of neurons store
neurohormones in the posterior pituitary.
In the posterior pituitary gland,
action potentials cause the release
of neurohormones (blue circles) from
axon terminals into the circulatory
system.
The neurohormones pass through the
circulatory system and influence the
activity of their target tissues.
AP
Hypothalamohypophysial
tract
Optic
chiasm
2
Posterior
pituitary
Neurohormone
Anterior
pituitary
3
Vein
4
Target tissue
Fig. 10.4
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Stimulatory
Hypothalamus
Releasing hormone
1
Anterior pituitary
Posterior pituitary
Hormone
2
Target
3
Target
endocrine
cell
Hormone
1 Neurons in the hypothalamus release stimulatory hormones, called
releasing hormones. Releasing hormones travel in the blood to the
anterior pituitary gland.
2 Releasing hormones stimulate the release of hormones from the anterior
pituitary, which travel in the blood to their target endocrine cell.
3 The target endocrine cell secretes its hormone into the blood, where
it travels to its target and produces a response.
Fig. 10.16
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Hypothermia
and other stressors
1
2
Stress and hypothermia cause TRH to
be released from neurons within the
hypothalamus. It passes through the
hypothalamohypophysial portal system
to the anterior pituitary.
Hypothalamus
TRH causes cells of the anterior pituitary
to secrete TSH, which passes through
the general circulation to the thyroid
gland.
3
TSH causes increased synthesis and
release of T3 and T4 into the general
circulation.
4
T3 and T4 act on target tissues to
produce a response.
5
TRH
1
Hypothalamohypophysial
portal system
Anterior
pituitary
TSH
2
T3 and T4 also have an inhibitory effect
on the secretion of TRH from the
hypothalamus and TSH from the anterior
pituitary.
Thyroid gland
5
3
T3 and T4
4
Stimulatory
Inhibitory
T3 and T4 in target tissues:
• Increase metabolism
• Increase body temperature
• Increase normal growth and
development
Fig. 10.21
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
1
Corticotropin-releasing hormone (CRH) is
released from hypothalamic neurons in
response to stress or low blood glucose
and passes, by way of the
hypothalamohypophysial portal system,
to the anterior pituitary.
2
In the anterior pituitary, CRH binds to and
stimulates cells that secrete
adrenocorticotropic hormone (ACTH).
3
ACTH binds to membrane-bound
receptors on cells of the adrenal cortex
and stimulates the secretion of
glucocorticoids, primarily cortisol.
4
Cortisol acts on target tissues, resulting
in increased lipid and protein breakdown,
increased glucose levels, and
anti-inflammatory effects.
5
Cortisol has a negative-feedback effect
because it inhibits CRH release from the
hypothalamus and ACTH secretion from
the anterior pituitary.
Low blood glucose and other stressors
CRH
1
Hypothalamus
Hypothalamohypophysial
portal system
5
Anterior
pituitary
ACTH
2
Cortisol
3
4
Stimulatory
Inhibitory
Cortisol in the target tissues:
• Increases lipid and protein breakdown
• Increases blood glucose
• Has anti-inflammatory effects
Adrenal cortex
(zona fasciculata)
Fig. 10.7
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Water-soluble hormone
(glucagon, prolactin)
Lipid-soluble hormone
(thyroid or steroid)
Membrane-bound receptor
G protein
complex
Cellular
responses
ATP
cAMP
Protein
kinase
Nucleus
Hormone
DNA
(a)
Nuclear
receptor
Cellular responses
(b)
Adenylate
cyclase
Fig. 10.8
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
1
Lipid-soluble hormones diffuse through
the plasma membrane.
Lipid-soluble
hormone
2
3
4
Plasma
membrane
Lipid-soluble hormones either bind to
cytoplasmic receptors and travel to the
nucleus or bind to nuclear receptors.
1
The hormone-receptor complex binds
to a hormone-response element on the
DNA, acting as a transcription factor.
Nuclear
membrane
Ribosome
The binding of the hormone-receptor
complex to DNA stimulates the
synthesis of messenger RNA (mRNA),
which codes for specific proteins.
2
3
5
The mRNA leaves the nucleus, passes
into the cytoplasm of the cell, and
binds to ribosomes, where it directs the
synthesis of specific proteins.
Hormone-receptor complex
mRNA
DNA
5
6
The newly synthesized proteins
produce the cell's response to the
lipid-soluble hormones—for example,
the secretion of a new protein.
Nuclear receptor
Hormoneresponse
element
mRNA synthesis
4
6
Proteins produced
mRNA
Nuclear pore
Fig. 10.7
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Water-soluble hormone
(glucagon, prolactin)
Lipid-soluble hormone
(thyroid or steroid)
Membrane-bound receptor
G protein
complex
Cellular
responses
ATP
cAMP
Protein
kinase
Nucleus
Hormone
DNA
(a)
Nuclear
receptor
Cellular responses
(b)
Adenylate
cyclase
Fig. 10.9
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Water-soluble hormone
binds to its receptor.
Water-soluble hormone
Receptor




GDP


GTP
GTP replaces
GDP on  subunit.
1
Before the hormone binds to its receptor, the G protein consists of
three subunits, with GDP attached to the  subunit, and freely floats
in the plasma membrane.
3
Water-soluble hormone
bound to its receptor.
GDP
After the hormone binds to its membrane-bound receptor, the receptor
changes shape, and the G protein binds to it. GTP replaces GDP on the
 subunit of the G protein.
Water-soluble hormone
separates from its receptor.
Receptor




GTP
G protein
separates
from receptor.
Phosphate (Pi)
is removed from
GTP on  subunit.
 subunit separates
from other subunits.
2 The G protein separates from the receptor. The GTP-linked
 subunit activates cellular responses, which vary among
target cells.


GDP
Pi
4
When the hormone separates from the receptor, additional G proteins are
no longer activated. Inactivation of the  subunit occurs when phosphate (Pi)
is removed from the GTP, leaving GDP bound to the subunit.
Fig. 10.10
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
1
After a water-soluble hormone binds to its
receptor, the G protein is activated.
2
The activated  subunit, with GTP bound to it,
binds to and activates an adenylate
cyclase enzyme so that it converts ATP
to cAMP.
3
The cAMP can activate protein kinase enzymes,
which phosphorylate specific enzymes activating
them. The chemical reactions catalyzed by the
activated enzymes produce the cell's response.
Water-soluble hormone
bound to its receptor.
1



GTP
Adenylate cyclase
2
4
Phosphodiesterase enzymes inactivate cAMP
by converting cAMP to AMP.
ATP
cAMP
3
Protein
kinase
cAMP is an
intracellular mediator
that activates protein
kinases.
Cellular responses
Phosphodiesterase
inactivates cAMP.
4
AMP
(inactive)
Fig. 10.11
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Receptor
Hormone
Activated
G proteins
Activated
adenylate
cyclase
cAMP
Activated protein
kinase enzymes
Table 10.2a
Table 10.2b