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2 Communication Systems
The Nervous and Endocrine Systems
The Nervous system
• Tract system
• Quick signaling
Vertebrates
• CNS
• Peripheral NS
– Autonomic
• Sympathetic
• Parasympathetic
– Voluntary
• Motor
Chemical Signaling
• 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
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nerve impulse
Neuron
conducts
impulse
Neurotransmitter
released into
synapse
Postsynaptic
cell responds
(a)
Glandular
cells secrete
hormone into
bloodstream
(b)
Bloodstream
Target cells
(cells with hormone
receptors) respond
to hormone
Hormones have no
effect on other cells
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5
General Characteristics of the
Endocrine System
• Some hormones are produced by
small groups of specialized cells
• Other hormones are produced by
larger endocrine glands
• Pituitary gland
• Thyroid gland
• Parathyroid glands
• Adrenal glands
• Pancreas
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hypothalamus
Pituitary gland
Parathyroid gland
Pineal gland
Thyroid gland
Thymus
Adrenal gland
Kidney
Pancreas
Ovary
(in female)
Testis
(in male)
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General Characteristics of the
Endocrine System
• Some hormones are produced by
small groups of specialized cells
• Other hormones are produced by
larger endocrine glands
• Pituitary gland
• Thyroid gland
• Parathyroid glands
• Adrenal glands
• Pancreas
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hypothalamus
Pituitary gland
Parathyroid gland
Pineal gland
Thyroid gland
Thymus
Adrenal gland
Kidney
Pancreas
Ovary
(in female)
Testis
(in male)
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Hormone Action
• Hormones are released into the extracellular spaces
surrounding endocrine cells
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hypothalamus
Pituitary gland
Parathyroid gland
Pineal gland
Thyroid gland
Thymus
Adrenal gland
Kidney
Pancreas
Ovary
(in female)
Testis
(in male)
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Hormone Action
• Hormones are released into the extracellular
spaces surrounding endocrine cells
• Hormones then diffuse into the bloodstream
and are carried to all parts of the body
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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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Action of Hormones
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Steroid Hormones
Hormone molecule
Cell
membrane
1
Newly forming
protein molecule
Ribosome
mRNA
5
Nucleus
4
mRNA
2
DNA
3
Intracellular
receptor molecule
Hormone-receptor
complex
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Action of Hormones
• Non-steroid Hormones
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Binding site
Cell membrane
Membrane-bound
receptor molecule
1
Nonsteroid
hormone
molecule
2
Hormonereceptor
complex
G protein
Activity site
Adenylate
cyclase
3
4
Protein
kinases
(inactive)
ATP
cAMP
5
Protein
kinases
(active)
Cytoplasm
Substrate
(inactive)
Substrate
(active)
Nucleus
Cellular
changes
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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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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.
too high
Normal
hormone
levels
too low
Stimulus
Hormone levels drop or
controlled process
decreases.
Receptors
Hormone control
mechanism senses
change.
Response
Hormone levels
return toward
normal.
Effectors
Hormone secretion
increased.
Control center
Endocrine gland
stimulated.
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Control Sources
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
–
–
Hypothalamus
–
Nervous system
Changing level
of substance
in plasma
– Anterior pituitary gland
Peripheral
endocrine
gland
Endocrine
gland
Endocrine
gland
Target cells
Target cells
Target cells
Action
Action
Action
(a)
(c)
(b)
Thyroid Releasing
Hormone
T3&T4
Adrenal Medulla
Epinephrine
Pancreas
Insulin & Glucagon
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• Anterior Lobe Adenohypophysis
• Hypothalamic releasing hormones stimulate cells of
anterior lobe to release hormones
• Posterior Lobe Neurohypohysis
• Neurosecretory cells extending from hypothalamus
release hormones into the bloodstream of posterior lobe
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Third ventricle
Optic chiasma
Neurosecretory
cells that secrete
releasing hormones
Neurosecretory cells
that secrete posterior
pituitary hormones
Hypothalamus
Hypophyseal
portal veins
Superior hypophyseal
artery
Secretory cells
of anterior
pituitary gland
Capillary bed
Capillary bed
Inferior hypophyseal
artery
Hypophyseal veins
Sella turcica of
sphenoid bone
Anterior lobe of pituitary gland
Posterior lobe of pituitary gland
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
–
Hypothalamus
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
–
Releasing
hormone
(Hormone 1)
Secretory
cells
+
–
Anterior pituitary
Anterior pituitary
hormone
(Hormone 2)
+
Peripheral endocrine gland
© Michael Ross/Photo Researchers, Inc.
(Hormone 3)
Stimulation
+
Target cells
http://goo.gl/WbWJ3B
Inhibition
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