Friday, 16 September
Chapter 11 The Endocrine System
Wednesday 1QQ to be returned on Monday
Lab next week: Analyzing a research paper
Pick up your photocopy from the Piano, read it before lab!
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
Feedback (n=25) from Wednesday’s
Interactive Class: “Be the Hormone”
Cons
• Few/no notes
• Not all hormones were
introduced
• Covered less material
Pros
• Mental image of chemical
categories of hormones
and relative numbers
• Visualization of shared
properties
• Better able to answer
chapter questions
• More engaging
1QQ # 5 for 8:30
Each True/False Question counts 2 points. Answer all five.
1. Epinephrine is an amine hormone.
2. If you don’t know which category a hormone belongs to,
the best guess is “peptide.”
3. The thyroid hormones and steroid hormones have
intracellular receptors and affect gene expression and
have long-lasting effects in their target cells.
4. All amine and peptide hormones are transported in the
plasma in two forms: bound and free.
5. Thyroid hormones and steroid hormones are stored in
vesicles and secreted later.
1QQ # 5 for 9:30
Each True/False Question counts 2 points. Answer all five.
1. Dopamine is an amine hormone.
2. If you don’t know which category a hormone belongs to,
the best guess is “steroid.”
3. The thyroid hormones and steroid hormones have cellsurface receptors and usually have long-lasting effects
in their target cells.
4. T3 and T4 and peptide hormones are transported in the
plasma in two forms: bound and free.
5. Catecholamines and peptide hormones are stored in
vesicles and secreted later.
Endocrine Organs (Table 11-1)
•
•
•
•
•
•
•
•
•
•
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
Fig. 11.08
Permissive
effect
Thyroid hormone stimulates production of beta-adrenergic receptors,
Makes target cells more sensitive to EPI
3 Chemical Classes of
Hormones
• 1:
–
–
• 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
•
•
•
•
•
Hormone class
Major form in plasma
Location of receptors
Signal transduction mechanisms
Rate of excretion / metabolism
Questions so far?
Fig. 11.05
How do adrenal cortex cells
“know” which hormone to
synthesize from cholesterol?
Adrenal Glands
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
BV
&
BP
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
_______
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
Na+, K+, Ca++, Glucose, etc.
NE (sympathetic)
ACh (parasympathetic)
etc.
Integrator!
Recall example:
beta cells of Islets of Langerhans
Secretion is usually pulsative, may be diurnal.
Tropic
S1
Thyroid Gland
• TH =T3 and T4
Fenestrated Capillary
(typical of endocrine glands)
S2
Synthesis, Storage and Secretion of T3 and T4
Roles of TSH (Thyroid Stimulating Hormone)
Tropic: directs
controls, regulates
Trophic: growth
TH increases cell
metabolism & heat
production (BMR)
S3
Fig. 11.12a
Receives input
from many
regions of
brain; many factors
Affect its function
Homeostatsis center.
S4
Fig. 11.12b
Neurohypophysis
Adenohypophysis
6
Vasopressin (= Antidiuretic hormone)
Oxytocin
Tropic hormones control the function
S6
Trophic hormones promote survival and growth of targets
P P
P
P
A
P
Hypothalamo-hypophyseal portal system
P
P
S
P
P
P
A
Releasing Hormone
Release-inhibiting Hormone
P
S
Tropic hormones control the function
Trophic hormones promote survival and growth of targets
Short-loop Neg. Feed.
Long-loop negative feedback
Releasing Hormone
Release Inhibiting Hormone
S7