Download Chapter 45

Chapter 45: Hormones and the Endocrine System
1. What is the difference between paracrine & endocrine?
- Paracrine – local signaling between neighboring cells
- Endocrine – distance signaling thereby using the circulatory system
- Review Ch 11: Cell communication
- Reception
- G protein-linked receptors
- Tyrosine kinase receptors
Membrane bound
- Ion channel receptors
- Steroid hormone receptors – intracellular
- Transduction
- 2nd messengers – Ca+2 ions, cAMP, IP3 & DAG
- Phosphorylation cascades – protein kinases
- Response
- Gene activation aka transcription
- Enzyme activation
- Cell division
}
Figure 45.3 Mechanisms of hormonal signaling: a review
SECRETORY
CELL
SECRETORY
CELL
Hormone
molecule
Hormone
molecule
VIA
BLOOD
VIA
BLOOD
Signal receptor
TARGET
CELL
Signal
transduction
pathway
Cytoplasmic
response
OR
TARGET
CELL
Signal
receptor
DNA
Signal
transduction
and response
mRNA
DNA
NUCLEUS
Nuclear
response
NUCLEUS
(a) Receptor in plasma membrane
Synthesis of
specific proteins
(b) Receptor in cell nucleus
Chapter 45: Hormones and the Endocrine System
1. What is the difference between paracrine & endocrine?
2. What are the 3 general types of signaling pathways?
- Simple endocrine
- Simple neurohormone
- Simple neuroendocrine
Figure 45.2 Basic patterns of simple hormonal control pathways
Pathway
Example
Low blood
glucose
Stimulus
Receptor
protein
Pancreas
secretes
glucagon ( )
Endocrine
cell
Blood
vessel
Target
effectors
Response
Pathway
Stimulus
Example
Example
Pathway
Suckling
Hypothalamic
neurohormone
released in
response to
Sensory
neural and
neuron
hormonal
signals
Hypothalamus
Sensory
neuron
Hypothalamus/
posterior pituitary
Neurosecretory
cell
Posterior pituitary
secretes oxytocin
Blood ( )
vessel
Stimulus
Neurosecretory
cell
Hypothalamus
secretes prolactinBlood
releasing
vessel
hormone ( )
Liver
Glycogen
breakdown,
glucose release
into blood
(a) Simple endocrine pathway
Target
effectors
Response
Smooth muscle
in breast
Milk release
Anterior
pituitary
secretes
Endocrine prolactin ( )
cell
Blood
vessel
(b) Simple neurohormone pathway
Target
effectors
Response
Mammary glands
Milk production
(c) Simple neuroendocrine pathway
Chapter 45: Hormones and the Endocrine System
1. What is the difference between paracrine & endocrine?
2. What are the 3 general types of signaling pathways?
3. How can 1 ligand cause different effects?
- Different receptor types on different cells
- Different intracellular signal molecules (relay proteins)
Figure 45.4 One chemical signal, different effects
Different receptors
different cell responses
Epinephrine
Epinephrine
Epinephrine
a receptor
b receptor
b receptor
Glycogen
deposits
Vessel
constricts
(a) Intestinal blood
vessel
Vessel
dilates
(b) Skeletal muscle
blood vessel
Different intracellular proteins
Glycogen
breaks down
and glucose
is released
from cell
(c) Liver cell
different cell responses
Figure 45.6 Human endocrine glands surveyed in this chapter
Hypothalamus
Pineal gland
Pituitary gland
Thyroid gland
Parathyroid glands
Adrenal glands
Pancreas
Ovary
(female)
Testis
(male)
Chapter 45: Hormones and the Endocrine System
1.
2.
3.
4.
5.
What is the difference between paracrine & endocrine?
What are the 3 general types of signaling pathways?
How can 1 ligand cause different effects?
What are some common endocrine glands?
How does the hypothalamus control the anterior & posterior pituitary
differently?
- posterior – directly via neurohormones
- anterior – indirectly via releasing hormones (tropic hormones)
 tropic hormones = hormones that influence other glands to release
other hormones
Figure 45.7 Production and release of posterior pituitary hormones
Hypothalamus
Neurosecretory
cells of the
hypothalamus
Axon
Posterior
pituitary
HORMONE
TARGET
Anterior
pituitary
ADH
Kidney tubules
Oxytocin
Mammary glands,
uterine muscles
Figure 44.16 Hormonal control of the kidney by negative feedback
circuits
ALCOHOL =
Inhibits ADH release 
decreased H2O reabsorption 
increased H2O release 
dehydration 
hangover!
Figure 45.8 Production and release of anterior pituitary hormones
Tropic Effects Only
FSH, follicle-stimulating hormone
LH, luteinizing hormone
TSH, thyroid-stimulating hormone
ACTH, adrenocorticotropic hormone
Neurosecretory cells
of the hypothalamus
Nontropic Effects Only
Prolactin
MSH, melanocyte-stimulating hormone
Endorphin
Portal vessels
Nontropic and Tropic Effects
Growth hormone
Hypothalamic
releasing
hormones
(red dots)
HORMONE
TARGET
FSH and LH
Testes or
ovaries
TSH
Thyroid
Endocrine cells of the
anterior pituitary
Pituitary hormones
(blue dots)
ACTH
Prolactin
MSH
Endorphin
Adrenal
cortex
Mammary
glands
Melanocytes
Pain receptors
in the brain
Growth hormone
Liver
Bones
Chapter 45: Hormones and the Endocrine System
1.
2.
3.
4.
5.
What is the difference between paracrine & endocrine?
What are the 3 general types of signaling pathways?
How can 1 ligand cause different effects?
What are some common endocrine glands?
How does the hypothalamus control the anterior & posterior pituitary
differently?
6. How is the thyroid regulated?
- Regulates metabolism
- T3 & T4 hormones
- Triiodothyronine (T3) & thyroxine (T4) have 3 or 4 iodine atoms
Figure 45.9 Feedback regulation of T3 and T4 secretion from the
thyroid gland
Hypothalamus
TRH
Anterior
pituitary
TSH
Thyroid
T3 + T4
What happens with a lack of iodine in the diet?
Pg 33
Chapter 45: Hormones and the Endocrine System
1.
2.
3.
4.
5.
What is the difference between paracrine & endocrine?
What are the 3 general types of signaling pathways?
How can 1 ligand cause different effects?
What are some common endocrine glands?
How does the hypothalamus control the anterior & posterior pituitary
differently?
6. How is the thyroid regulated?
7. How is homeostasis of blood calcium achieved?
- Thyroid & parathyroid glands
- Calcitonin & PTH
Figure 45.11 Hormonal control of calcium homeostasis in mammals
Thyroid gland
releases
calcitonin.
Calcitonin
Reduces
Ca2+ uptake
in kidneys
Stimulates
Ca2+ deposition
in bones
Blood Ca2+
level declines
to set point
STIMULUS:
Rising blood
Ca2+ level
Homeostasis:
Blood Ca2+ level
(about 10 mg/100 mL)
STIMULUS:
Falling blood
Ca2+ level
Blood Ca2+
level rises
to set point
Stimulates
Ca2+ release
from bones
Parathyroid
gland
PTH
Increases
Ca2+ uptake
in intestines
Active
vitamin D
Stimulates Ca2+
uptake in kidneys
Chapter 45: Hormones and the Endocrine System
1.
2.
3.
4.
5.
What is the difference between paracrine & endocrine?
What are the 3 general types of signaling pathways?
How can 1 ligand cause different effects?
What are some common endocrine glands?
How does the hypothalamus control the anterior & posterior pituitary
differently?
6. How is the thyroid regulated?
7. How is homeostasis of blood calcium achieved?
8. How is homeostasis of blood glucose achieved?
- Pancreas
- Insulin and glucagon
Figure 45.12 Maintenance of glucose homeostasis by insulin and
glucagon
Body cells
take up more
glucose.
Insulin
Beta cells of
pancreas are stimulated
to release insulin
into the blood.
Liver takes
up glucose
and stores it
as glycogen.
STIMULUS:
Rising blood glucose
level (for instance, after
eating a carbohydraterich meal)
Blood glucose level
declines to set point;
stimulus for insulin
release diminishes.
Homeostasis:
Blood glucose level
(about 90 mg/100 mL)
Blood glucose level
rises to set point;
stimulus for glucagon
release diminishes.
STIMULUS:
Dropping blood glucose
level (for instance, after
skipping a meal)
Alpha cells of pancreas
are stimulated to release
glucagon into the blood.
Liver breaks
down glycogen
and releases
glucose into
blood.
Glucagon
Chapter 45: Hormones and the Endocrine System
1.
2.
3.
4.
5.
6.
7.
8.
9.
What is the difference between paracrine & endocrine?
What are the 3 general types of signaling pathways?
How can 1 ligand cause different effects?
What are some common endocrine glands?
How does the hypothalamus control the anterior & posterior pituitary
differently?
How is the thyroid regulated?
How is homeostasis of blood calcium achieved?
How is homeostasis of blood glucose achieved?
How does the body respond to short-term stress, ie fight or flight?
- epinephrine & norepinephrine
Figure 45.13 Stress and the adrenal gland
Stress
Nerve
Spinal cord
signals
(cross section)
Hypothalamus
Releasing
hormone
Nerve
cell
Anterior pituitary
Blood vessel
Adrenal medulla
secretes epinephrine
and norepinephrine.
Nerve cell
Adrenal cortex
secretes
mineralocorticoids
and glucocorticoids.
ACTH
Adrenal
gland
Kidney
(a) Short-term stress response
(b) Long-term stress response
Effects of epinephrine and norepinephrine:
Effects of
mineralocorticoids:
Effects of
glucocorticoids:
1. Retention of sodium
ions and water by
kidneys
1. Proteins and fats
broken down and
converted to glucose,
leading to increased
blood glucose
1. Glycogen broken down to glucose; increased
blood glucose
2. Increased blood pressure
3. Increased breathing rate
4. Increased metabolic rate
5. Change in blood flow patterns, leading to
increased alertness and decreased digestive
and kidney activity
2. Increased blood
volume and blood
pressure
2. Immune system may
be suppressed
Table 45.1 Major Human Endocrine Glands and Some of Their Hormones
Table 45.1