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Ch. 40 Warm-Up
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.
Hormones
• Why are hormones needed?
– chemical messages from one body part to cells
in other parts of body
– communication needed
to coordinate whole body
– maintaining homeostasis
•
•
•
•
•
energy production
growth
development
maturation
reproduction
growth hormones
Endocrine System
• Endocrine system releases hormones
– glands which secrete
chemical signals into blood
• chemicals cause changes
in other parts of body
• slow, long-lasting response
– growth hormones
– sex hormones
– response hormones
– metabolism hormones
– and more….
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)
Glands
• Pineal
– melatonin
• Pituitary
– many hormones:
master gland
• Thyroid
– thyroxine
• Adrenal
– adrenaline
• Pancreas
– insulin, glucagon
• Ovary
– estrogen
• Testes
– testosterone
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
Maintaining homeostasis
hormone 1
lowers
body condition
gland
high
specific body condition
low
raises
body condition
gland
hormone 2
Negative Feedback
• Response to changed body condition
– every time body is high or low from normal level
a signal tells the body to make changes that will
bring body back to normal level
– once body is back
hormone 1
to normal level,
signal is
lowers
gland
turned off
body condition
high
specific body condition
Nervous System Control
Controlling Body Temperature
nerve signals
brain
sweat
high
body temperature
low
brain
constricts surface shiver
blood vessels
nerve signals
dilates surface
blood vessels
Endocrine System Control
Regulation of Blood Sugar
insulin
liver stores
sugar
body
cells take
up sugar
from blood
pancreas
high
liver
blood sugar level
(90mg/100ml)
low
triggers
hunger
liver
releases
sugar
liver
pancreas
glucagon
reduces
appetite
 Negative feedback systems:
• Thyroid hormones
• Blood Ca2+ levels
• Blood glucose levels
 Positive feedback system:
• Oxytocin (birthing process; release of
milk/suckling)
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
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