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Monday, 19 September
Chapter 11 The Endocrine System
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Classes of hormones
The adrenal gland
Fates of hormones
Renin-Angiotensin-Aldosterone System
Control of hormone secretion
Hormone interactions (permissive effects)
1QQ # 6
1. Stress leads to the secretion of epinephrine which alters
the metabolism of many cell types. Describe the effects
of EPI on two different cell types and explain how these
effects are beneficial to the person.
2. Starting with the arrival of carbohydrates in the stomach
list the sequence of events, cell types, and hormone(s)
that comprise a feedforward mechanism. What is the
purpose of this feedforward mechanism?
3. Beginning with the ingestion of a large amount of sugar,
list the sequence of events in a reactive hypoglycemic
person that ultimately leads to a headache, fast heart
rate, and cold, clammy skin.
Endocrine Organs (Table 11-1)
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Hormone
Pituitary Gland
Paracrine agent
Thyroid Gland
Autocrine agent
Pancreas
Neurotransmitter
Gonads
Neuromodulator
Gastrointestinal Tract
Heart
Hormone: chemical messengers
carried by blood to target cells
Kidney
upon which they act.
Hypothalamus
Liver
Only those cells having receptors
Etc.
Can respond to a given hormone
Analogy: SSNs and receptors
3 Chemical Classes of
Hormones
• 1:
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–
• 2:
• 3:
Amine hormones (from amino acid tyrosine)
Thyroid hormones
Adrenal medullary hormones (catecholamines)
Peptide hormones (peptides & proteins)
Steroid Hormones (derivatives of cholesterol)
Why does the chemical class matter?
Amine
Hormones
Fig. 11.01
Thyroid
Hormones
Not soluble
in plasma,
bound & free
Adrenal
medulla
NT
Catecholamines
soluble in
plasma
NT
Steroid hormones
Fig. 11.03
not soluble in plasma, not storable in vesicles
Bound & Free
Target cells have intracellular receptors.
Changes is gene expression.
Timecourse?
Peptide Hormones
Fig. 11.02
Soluble in plasma
e.g.
Beta cell
Guess peptide!
Cell surface receptors on target cells
Examples of
Peptide Hormones:
Insulin,
glucagon
prolactin,
erythropoietin,
parathyroid
hormone,
gastrin,
leptin,
growth hormone,
oxytocin,
vasopressin,
FSH,
LH,
GHRH, and
many more!
Know Table 11-2 p 323
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Hormone class
Major form in plasma
Location of receptors
Signal transduction mechanisms
Rate of excretion / metabolism
Questions so far?
Fig. 11.05
Hormones of the Adrenal Cortex
Adrenal Gland
Part of Sympathetic Nervous System
Hormones of the Adrenal Cortex
Androgens
DHEA
“Andro”
Glucocorticoids
Mineralicorticoid
What regulates the secretion of cortisol and aldosterone?
Fig.
Gonadal Steroids
11.06
(not adrenal cortex)
Estrogens
King DS, Sharp RL, Vukovich MD, Brown GA, Reifenrath TA, Uhl NL,
Parsons KA . Effect of oral androstenedione on serum testosterone and
adaptations to resistance training in young men: a randomized controlled
trial. JAMA 1999; 281(21):2020-8
What happens to hormones once released?
Be able to give
Examples.
Ex: Renin
Fast if free
Slow if bound
T4 to T3 and Testosterone to Estradiol
Renin-angiotensin-aldosterone
Renin is an enzyme released from kidney cells
into bloodstream, its “substrate” is a plasma
protein called Angiotensinogen.
Renin
Angiotensinogen
from liver, an
ever-present plasma protein
Angiotensin I
Angiotensin converting enzyme
(ACE)
Angiotensin II
Zona Glomerulosa of Adrenal Cortex
Aldosterone
Thirst
Arterial smooth muscle …
vasoconstriction…increase blood
pressure
Promotes Na+ retention in Kidney
Blood Pressure
(-)
Renin from
Juxtaglomerular
cells in Kidney
Multi-step process involving
Angiotensin I and II
Angiotensin II
thirst
Aldosterone
Na+ reabsorption in kidney
Drink
Plasma volume
vasoconstriction
Blood pressure
K+ in plasma
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What happens to hormones once released?
Be able to give
Examples.
Ex: Renin
Fast if free
Slow if bound
T4 to T3 and Testosterone to Estradiol
Factors that affect hormone secretion
Integrator!
Recall example:
beta cells of Islets of Langerhans
Secretion is usually pulsative, may be diurnal.
Fig. 11.08
Permissive
effect
Thyroid hormone stimulates production of beta-adrenergic receptors