Transcript Endocrine System

Now for a little recap..
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?
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,
phermones
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
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
 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
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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.
OK, Now….
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?