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AP Biology: Endocrine System
(Ch. 45 Campbell 6th Ed.)
-main job = homeostasis via hormones
-Endocrine vs. Exocrine (review)
-hormones released to whole system…only target organs effected…how?
-how is it determined when to release hormones?
-many endocrine glands controlled via autonomic nervous system
-what about hormonal disorders?…causes = # of hormones OR # of receptors
HORMONE TYPES / CATEGORIES
1. Lipid soluble hormones (usually steroid based hormones) (fig 45.3)
a. sex steroids (secreted via sex structures only)
b. corticosteroids (secreted via adrenal glands only)
-steroid hormones are lipid based..so, how do they interact with a cell?
2. Lipid insoluble hormones (usually amino acid based…often complexed with sugar = glycoprotein)
-many aminos are polar…so, how do they interact with the cell? (fig 45.3)
-G proteins
-2nd messengers…recognize them, don’t memorize except (cAMP, Ca2+)
-why is it necessary to have so many different 2 nd messengers?
Hormones: Lipid Insoluble (a) vs. Lipid Soluble (b)
SPECIFIC HORMONES
To see classification by gland…see table 45.1 in book…
ADH (antiduretic hormone) &. Aldosterone
-controls H2O/electrolyte balance primarily
-How did they discover? Bullet in brain
-alcohol inhibits ACH secretion….caffeine?
Calcitonin vs. PTH (parathyroid hormone)
-Ca2+ regulation…calcitonin lowers blood concentration of Ca2+, PTH raises it….
-low vitamin D = rickets, low vitamin C = scurvy
Alan Cotten, Fossil Ridge High School, Keller ISD – Endocrine System: Campbell 6th ed.
Insulin vs. Glucagon
-blood sugar (glucose) balance
-insulin removes glucose from blood to feed cells (or store excess as glycogen in the liver)
-glucagon removes glycogen from the liver to raise blood sugar level
-diabetes type I: insulin dependent…caused by autoimmune attack on pancreas…hence low
insulin production
-diabetes type II: insulin independent…usually caused by lack of receptors for insulin (linked to
genetics and obesity)…“adult onset” diabetes
GH (growth hormone)
-muscle & bone development…
-giants, acromegaly and epiphysial plates (growth plates)
ACTH (adrenocorticotropic hormone)
-Na+/K+ balance, fat metabolism, and oddly enough has some control of secondary sex characteristics in males
TSH (thyroid stimulating hormone) & Thyroxine
-metabolism (mitochondria ETC)…
-goiter
-“I have a thyroid problem, so I can’t lose weight.”
Cortisol -stress related, fat mobilization, glucose in blood
-stress kills, exercise “heals”
Epinephrine (aka norepinephrine or adrenaline)
-fight or flight (adrenaline rush)
-oddly epinephrine is also a neurotransmitter
MSH (melanocyte stimulating hormone)- function in humans debated somewhat…BUT lizards, etc.?
Melatonin -somewhat debated…biorhythms, biological/seasonal clock??
FEEDBACK INHIBITION
-control of hormones is often through negative feedback inhibition (remember glycolysis?)
-negative feedback inhibition maintains homeostasis (NO EXTREMES)!!
-usually this system works beautifully…sometimes, this system doesn’t work beautifully…
Example of a mess:
Step #1: my brain sends out TSH to stimulate my thyroid gland to make thyroxin
Step #2: iodine is needed to bind with thyroxin to activate it…
Step #3: if iodine is unavailable, thyroxin is not activated
Step #4: my brain perceives low thyroxin concentration in the blood (though we have plenty of thyroxin it’s
just inactive)
Step #5: my brain sends out more TSH…no change?...more TSH…no change?...goiter
Alan Cotten, Fossil Ridge High School, Keller ISD – Endocrine System: Campbell 6th ed.
Robert Wadlow stats…
http://www.altonweb.com/history/wadlow/#chart
GROWTH CHART
Age
Birth
6
1
mos.
1
1/2
5
8
9
10 12 14 16 18 20 21 22.4
Height N/R N/R N/R N/R
5'
4"
Weight
8.5
(lbs)
105 169 180 210 241 301 374 391 488 492 439
30
45
67
6'
6' 6' 6' 7' 7' 8' 8' 8' 8'
2" 5" 11" 5" 10" 4" 7" 8" 11.1"
"The Gentleman Giant" a biography of Robert P.Wadlow by Fredrick Fadner,
is now available from the Museum. Please see the Gift Shop Page for details.
Alan Cotten, Fossil Ridge High School, Keller ISD – Endocrine System: Campbell 6th ed.