Download How do they work? Intercellular Communication Endocrine Signaling

3/5/2017
The Body’s Long-Distance Regulators
• Hormones
How do they work?
Intercellular Communication
• Two criteria
– The type of secreting cell
• Communication
– The route taken by the signal in reaching its target
Endocrine Signaling
Blood
vessel
RESPONSE
(a) Endocrine signaling
Synapse
Neuron
RESPONSE
RESPONSE
(d) Synaptic signaling
(b) Paracrine signaling
Neurosecretory
cell
RESPONSE
(c) Autocrine signaling
Blood
vessel
RESPONSE
(e) Neuroendocrine signaling
1
3/5/2017
Paracrine and Autocrine Signaling
Synaptic and Neuroendocrine
Signaling
Signaling by Pheromones
Chemical Classes of Local Regulators
and Hormones
Classes of Local Regulators
2
3/5/2017
Classes of Hormones
Water-soluble (hydrophilic)
Lipid-soluble (hydrophobic)
Polypeptides
Steroids
0.8 nm
Insulin
Cortisol
Amines
Epinephrine
(a) Water-soluble hormone;
receptor in plasma
membrane
(b) Lipid-soluble hormone;
receptor in nucleus or
cytoplasm
SECRETORY
CELL
Cellular
Response
Pathways
SECRETORY
CELL
Thyroxine
Pathway for Water-Soluble Hormones
Lipidsoluble
hormone
Watersoluble
hormone
Blood
vessel
Blood
vessel
Transport
protein
Receptor protein
TARGET
CELL
TARGET
CELL
Cytoplasmic
response
OR
Receptor
protein
Gene
regulation
Cytoplasmic
response
Gene
regulation
NUCLEUS
NUCLEUS
EXTRACELLULAR FLUID
Pathway for Lipid-Soluble Hormones
Hormone (epinephrine)
Adenylyl
cyclase
G protein
GTP
G protein-coupled
receptor
ATP
cAMP Second
messenger
Inhibition of
glycogen synthesis
Promotion of
glycogen breakdown
Protein
kinase A
CYTOPLASM
3
3/5/2017
EXTRACELLULAR
FLUID
Hormone
(estradiol)
Estradiol
receptor
Plasma
membrane
Hormone-receptor
complex
NUCLEUS
CYTOPLASM
DNA
Vitellogenin
mRNA
for vitellogenin
Same receptors but different
intracellular proteins (not shown)
(a) Liver cell
Different receptors
(b) Smooth muscle cell
in wall of blood
vessel that supplies
skeletal muscle
Multiple Effects of Hormones
Fight or Flight!?!
1. What part of the brain initiates the fight-or-flight
signal?
2. What gland receives the signal from the brain? What
hormone is released by this gland?
3. List 3 effects when cortisol is released into the
bloodstream.
4. What are the effects of epinephrine
on:
a) The lungs?
b) The heart?
c) Muscle cells?
Endocrine Tissues and Organs
(c) Smooth muscle cell
in wall of blood
vessel that supplies
intestines
Epinephrine
Epinephrine
Epinephrine
β receptor
β receptor
α receptor
Glycogen
deposits
Glucose
Glycogen breaks down
and glucose is released
from cell.
Blood glucose level
increases.
Cell relaxes.
Cell contracts.
Blood vessel dilates,
increasing flow to
skeletal muscle.
Blood vessel
constricts, decreasing
flow to intestines.
Pineal gland
Hypothalamus
Pituitary gland
Thyroid gland
Parathyroid glands
Adrenal glands
Pancreas
Ovaries (female)
Testes (male)
4
3/5/2017
Feedback regulation and coordination
with the nervous system
Simple endocrine pathway
Simple Hormone Pathways
Simple
Pathways
STIMULUS
Negative feedback
Endocrine
cell
Hormone
Target
cells
RESPONSE
Simple neuroendocrine pathway
Simple
Pathways
STIMULUS
Example: secretin signaling
Low pH in
duodenum
S cells of duodenum
Secretin (•)
Pancreatic cells
Bicarbonate release
Example: oxytocin signaling
Suckling
Feedback Regulation
Sensory neuron
Positive feedback
Hypothalamus/
posterior pituitary
Neurosecretory
cell
Neurohormone
Target
cells
RESPONSE
Oxytocin (▪ )
Smooth muscle in
mammary glands
Milk release
5
3/5/2017
Coordination of Endocrine and
Nervous Systems
Vertebrates
• hypothalamus
• pituitary gland
Cerebrum
Pineal
gland
Thalamus
Hypothalamus
Cerebellum
• posterior pituitary
Pituitary
gland
Spinal cord
• anterior pituitary
Hypothalamus
Posterior
pituitary
Anterior
pituitary
Hypothalamus
Posterior Pituitary Hormones
Neurosecretory
cells of the
hypothalamus
Axons
Neurohormone
Posterior
pituitary
Anterior
pituitary
HORMONE
ADH
Oxytocin
TARGET
Kidney tubules
Mammary glands,
uterine muscles
6
3/5/2017
Neurosecretory cells
of the hypothalamus
Anterior Pituitary Hormones
Hypothalamic
releasing and
inhibiting
hormones
Portal vessels
Endocrine cells of
the anterior pituitary
Anterior pituitary
hormones
HORMONE
Posterior
pituitary
TARGET
FSH and LH
Testes or
ovaries
TSH
ACTH
Prolactin
MSH
GH
Thyroid
Adrenal
cortex
Mammary
glands
Melanocytes
Liver, bones,
other tissues
Tropic effects only
Nontropic effects only
STIMULUS
Thyroid Regulation: A Hormone
Cascade Pathway
1 Thyroid hormone
levels drop.
Sensory
neuron
Hypothalamus
Negative feedback
Tropic and
nontropic effects
Neurosecretory
cell
TRH
2 The hypothalamus secretes
TRH ●into the blood. Portal
vessels carry TRH to anterior
pituitary.
3 TRH causes anterior pituitary
to secrete TSH ▲ .
TSH
Anterior
pituitary
Circulation
throughout
body via blood
Thyroid
gland
4 TSH stimulates endocrine
cells in thyroid gland to
secrete T3 and T4 ■.
Thyroid
hormone
6 Thyroid hormone blocks TRH
release and TSH release
preventing overproduction
of thyroid hormone.
Circulation
throughout
body via blood
RESPONSE
Disorders of Thyroid Function and
Regulation
5 Thyroid hormone levels
return to normal range.
Hormonal Regulation of Growth
7
3/5/2017
Parathyroid Hormone and Vitamin D:
Control of Blood Calcium
NORMAL BLOOD
Ca2+ LEVEL
(about 10 mg/100 mL)
Adrenal Hormones: Response to Stress
Blood Ca2+
level rises.
Blood Ca2+ level falls.
Active vitamin D
increases Ca2+.
PTH stimulates Ca2+
uptake and promotes
activation of vitamin D.
PTH
Parathyroid
glands
release PTH.
PTH stimulates
Ca2+ release.
Catecholamines from the Adrenal
Medulla
(a) Short-term stress response and the adrenal medulla
(b) Long-term stress response and the adrenal cortex
Hypothalamus
Stress
Nerve
impulses
Spinal cord
(cross section)
Releasing
hormone
Neuron
Anterior pituitary
Blood vessel
Adrenal
medulla
Neuron
Adrenal
gland
ACTH
Adrenal
cortex
Kidney
Effects of epinephrine and norepinephrine:
• Glycogen broken down to glucose;
increased blood glucose
• Increased blood pressure
• Increased breathing rate
• Increased metabolic rate
• Change in blood flow patterns, leading to
increased alertness and decreased digestive,
excretory, and reproductive system activity
Effects of
mineralocorticoids:
Effects of
glucocorticoids:
• Retention of sodium • Proteins and fats broken
ions and water by
down and converted to
kidneys
glucose, leading to
increased blood glucose
• Increased blood
volume and blood
pressure
• Partial suppression of
immune system
8
3/5/2017
Steroid Hormones from the Adrenal
Cortex
• Epinephrine and norepinephrine
Sex Hormones
Bipotential gonad
Male duct
(Wolffian)
Female duct
(Müllerian)
Embryo (XY or XX)
Absence of male
hormones
Testosterone
AMH
Ovary
Testis
Uterus
Vas
deferens
Oviduct
Bladder
Bladder
Seminal
vesicle
Male (XY) fetus
Endocrine Disruptors
Female (XX) fetus
Hormones and Biological Rhythms
9
3/5/2017
Evolution of Hormone Function
10