Download Ch 45 - Phillips Scientific Methods

Chapter 45
Endocrine System
Ch. 40 Review
1. What type of behavior in animals might be
triggered by cold temperatures?
2. What type of behaviors might be triggered in
hot temperatures?
3. List 2 examples of negative feedback. List 2
examples of positive feedback.
4. What is the main type of chemical messenger
in the endocrine system? The nervous
system?
Ch. 45 Warm-Up
1. Compare peptide hormones to steroids.
2. Explain how insulin and glucagon work to
regulate blood sugar levels.
3. Which glands and hormones respond when
your body is under stress?
Chapter 45
Hormones and the Endocrine System
A hormone called ecdysteroid regulates the timing of metamorphosis in this anise swallowtail butterfly.
You must know:
• Two ways hormones affect target organs.
• The secretion, target, action, and regulation of
at least 3 hormones.
• An illustration of both positive and negative
feedback in the regulation of homeostasis by
hormones.
Types of
Intercellular
Signaling
• Endocrine System = Hormone-secreting cells +
Tissues
• Endocrine glands: ductless, secrete hormones
directly into body fluids
• Hormones: chemical signals that cause a
response in target cells (receptor proteins for
specific hormones)
– Affects 1 tissue, a few, or most tissues in body
– Or affect other endocrine glands (tropic
hormones)
• Regulation by Positive & Negative Feedback
Pheromones
Hormones
Local
Regulators
Chemical signal
from 1 individual
to another
individual
Chemical signal
from endocrine
gland through
blood to target
cell
Chemical signal
from one cell to
an adjacent cell
Eg. cytokines,
Eg. ant trail; sex
Eg. peptide,
growth factors,
pheromones
steroid hormones
nitric oxide (NO)
DISCOVERY VIDEO: ENDOCRINE SYSTEM
Types of Hormones
Peptide
Steroid
• Water-soluble
• Bind to receptors on
plasma membrane &
triggers signal transduction
pathway
• Affects protein activity
already present in cell
• Rapid response
• Short-lived
• Eg. oxytocin, insulin,
epinephrine
• Lipid-soluble
• Enters cell & binds to
intracellular receptors
• Causes change in gene
expression (protein
synthesis)
• Slower response
• Longer life
• Eg. androgens
(testosterone), estrogen,
progesterone, cortisol
•
How do hormones act on target
cells
Lipid-based hormones
– hydrophobic & lipid-soluble
• diffuse across cell membrane & enter cells
• bind to receptor proteins in cytoplasm & nucleus
• bind to DNA as transcription factors
– turn on genes
• Protein-based hormones
– hydrophilic & not lipid soluble
•
•
•
•
can’t diffuse across cell membrane
bind to receptor proteins in cell membrane
trigger secondary messenger pathway
activate internal cellular response
– enzyme action, uptake or secretion of molecules…
Action of lipid (steroid) hormones
steroid hormone
target cell
S
S
cytoplasm
1
blood
S
protein
carrier
cross cell membrane
2
binds to receptor protein
becomes
transcription factor
5
S
3
mRNA read by ribosome
plasma membrane
4
DNA
mRNA
nucleus
6
protein
7
protein secreted
ex: secreted protein = growth factor (hair, bone, muscle, gametes)
signal-transduction pathway
Action of protein hormones
protein
hormone
1
P
signal
binds to receptor protein
plasma membrane
activates
G-protein
activates enzyme
cAMP
receptor
protein
activates
cytoplasmic
signal
cytoplasm
target cell
GTP
acts as 2° messenger
transduction
ATP
ATP
activates
enzyme
2
secondary
messenger
system
activates
enzyme
produces an action
3
response
cAMP
• cAMP = cyclic adenosine monophosphate
• GPCR  adenylyl cyclase (convert ATP  cAMP) 
activate protein kinase A
Ex: Action of epinephrine (adrenaline)
adrenal gland
signal
1
epinephrine
activates
G protein
receptor
protein
in cell
membrane
activates GTP
3
activates
adenylyl cyclase
cAMP
GDP
transduction
4
GTP
2
ATP activates
5
protein kinase-A
activates
phosphorylase kinase
cytoplasm
liver cell
released
to blood
activates
glycogen phosphorylase
glycogen
6
glucose
7
response
Epinephrine: one hormone  many effects
1.Liver cells break
2.Blood vessels to
down glycogen and
skeletal muscles
release glucose
dilate
3.Blood vessels
to intestines
constrict
Master Glands
Hypothalamus
Pituitary Gland
Master Glands
Hypothalamus
• Receives info from nerves and brain
• Initiates endocrine signals
Posterior pituitary gland:
• Oxytocin: contract uterine muscles, eject milk
in nursing
Pituitary Gland
• Antidiuretic Hormone (ADH): promote H2O
retention by kidneys
Anterior pituitary gland:
• Follicle-stimulating hormone (FSH):
development of ovarian follicles (eggs);
promote sperm production
• Luteinizing hormone (LH): trigger ovulation;
stimulate testosterone production in testes
Hypothalamus regulation of Posterior Pituitary gland
Hypothalamus regulation of Anterior Pituitary gland
Tropic- hormone affects
another endocrine gland;
Non-tropic- has direct
target
 Negative feedback systems:
• Thyroid hormones
• Blood Ca2+ levels
• Blood glucose levels
 Positive feedback system:
• Oxytocin (birthing process; release of
milk/suckling)
BIOFLIX: HOMEOSTASIS – BLOOD SUGAR
Control of Blood Glucose
High blood
glucose
Liver breaks down
glycogen and releases
glucose into blood
Insulin released from
pancreas
Body cells take up glucose
Liver stores glucose as
glycogen
Glucagon released
from pancreas
Blood glucose
drops
Diabetes Mellitus
• Type I diabetes (10%):deficiency of insulin
– Insulin-dependent
– Autoimmune disorder  beta cells of pancreas
destroyed
• Type II diabetes (90%): failure of target cells to
respond to insulin
– Non-insulin dependent
– Insulin produced  cells don’t respond (defect in
insulin receptor or response pathway)
– Risk factors: obesity, lack of exercise
Thyroid Gland
Hypothalamus
Graves’ Disease:
• Autoimmune disorder
• Antibodies bind to TSH
receptor
• Hyperthyroidism
• High temp, sweating,
weight loss, high BP
TRH
Anterior
pituitary
TSH
Thyroid
T3
T4
Stress and the Adrenal Gland
Anabolic-Androgenic Steroid (AAS) Use
• Legally prescribed to treat hormone deficiency, loss of
muscle mass (cancer, AIDS)
• Used to enhance performance and improve physical
appearance
Effects of AAS Abuse
Source: www.drugabuse.gov/infofacts/steroids.html
•
•
•
•
•
•
•
aggression
extreme mood swings
liver damage
jaundice
fluid retention
high blood pressure
increases in LDL (“bad”
cholesterol)
• decreases in HDL (“good”
cholesterol)
• renal failure
• severe acne
• For men—shrinking of the testicles,
reduced sperm count, infertility, baldness,
development of breasts, increased risk for
prostate cancer
• For women—growth of facial hair, malepattern baldness, changes in or cessation
of the menstrual cycle, enlargement of the
clitoris, deepened voice
• For adolescents—stunted growth due to
premature skeletal maturation and
accelerated puberty changes; risk of not
reaching expected height if AAS is taken
before the typical adolescent growth spurt
• In addition, people who inject AAS run the
added risk of contracting or transmitting
HIV/AIDS or hepatitis.