Hormones

"In the year 6565, ain't gonna need no husband, won't need no wife.
You'll pick your son, pick your daughter too
from the bottom of a long glass tube.
Woh - woh."
-Rick Evans (Zager and Evans), Zerland Music, 1969
In the Year 2525 (Exordium & Terminus)


Campbell and Reece Chapter 45 and part of 46

Metazoans (with more cells than protozoans) require systems of integration
INTEGRATION: Hormones, paracrine (local) & nervous system
"endocrine" - ductless, into blood stream
vs. exocrine (like digestive - saliva etc.)
hormones vs pheromones (intraspecific signalling molecules)
RELEASE - cells with blood vessels
Messenger, target cell
TRANSPARENCY from another book
(1) receptor molecule + second messenger (e.g. cAMP)
or (2) action on DNA steroids enter cell act on DNA

TRANSPARENCY Fig. 45.3 - your textbook's version of this same dichotomy of mechamisms
structures of steroids TRANSPARENCY Fig. 45.14
TRANSPARENCY (Fig. 4.8) [covered last semester]
TRANSPARENCY (Fig. 5-14) cholesterol
Steroid receptor (protein) TRANSPARENCY from another book - domains: gene activating, DNA binding and steroid binding

peptides protein, steroids

prostaglandins (mediators of inflammation) are derived from fatty acid (arachidonic acid, 20:4)
NSAIDS (non-steroidal anti-inflammtory drugs) aspirin, ibuprofen, Celebrex, Vioxx inhibit prostaglandin synthesis by inhibiting cyclooxygenase (COX-1, 2, 3)

TRANSPARENCY Fig. 45.6a Hypothalamus neurosecretion to posterior pituitary (peptides)
oxytocin (milk, delivery)
(synthetic to induce labor)
Fig. 44.24 from book to show ADH action on kidney
vasopressin (ADH), H2O and blood pressure
alcohol, caffein inhibit anti [diuresis] hormone

Master gland TRANSPARENCY (Fig. 45.5) to show glands controlled by pituitary (thyroid, adrenals, ovary, testes)
Some are not controlled by pituitary (pancreas, parathyroid)
TRANSPARENCY (back to Fig. 45.6b) to show portal system etc.
Hypothalamus to anterior pituitary through portal system (peptides)
releasing factors
inhibiting factors

PITUITARY

non-trophic hormones (not where pituitary acts as master gland to control other glands)
Anterior pituitary Fig. 45.7b
GH - 200 a.a. -bone, muscle, not fat, -> liver to make somatomedins
GH - gigantism (bones grow long if too much GH when young), dwarfism (if too little GH when young), acromegaly (bones grow too thick if too much GH when already grown up, danger of GH abuse)
abuse by body builders, dangers of extracts,
now available through recombinant DNA research

Prolactin - milk production, like GH (same ancestral gene)

Endorphins & Enkephalins (not trophic, thus here in outline, but covered more later)

So much for pituitary as its own gland
Now pituitary as master gland of the body

Trophic hormones (like gonadotropins) "Master Gland"
sex hormones from pituitary (more details later):
LH (female) = ICSH (male); (luteinizing) (interstitial cell)
FSH (follicle)
non-sex trophic hormones from pituitary:
TSH (thyroid)
ACTH (adrenal cortex)

Thyroid hormones TRANSPARENCY Fig. 45.8 to show negative feedback with pituitary
Hypothalamus -TRF-> + Ant. Pituit. -TSH->+ Thyroid -> thyroxine-
- neck thyroxin (T4), triiodothyroxine (T3) iodine, sea food (and iodized salt), goiter (thyroid overgrows if too little iodine in diet) SLIDE
TRANSPARENCY (Fig. 45.7) T4 and T3
cretinism if too little in infant, hypothyroid, hyperthyroid
change in salmon during salt to fresh water change, metamorphosis in frog
problem of radioactive iodine (like from reactor leaks) - helps to take large doses of non-radioactive iodine to compete

Adrenal gland TRANSPARENCY (Fig. 45.14)
Adrenal cortex - Glucocorticoids stimulate metabolism, inhibits inflamation
JFKennedy had too little glucocorticoids (needed replacement therapy) which would create a situation of no feedback Addison's - too much ACTH (darkens skin like MSH)
pro-opiomelanocortin - big peptide cleaved to ACTH, MSH, endorphins, enkephalins
Emphasize regulation, negative feedback
Mineralocorticoids Aldosterone
to retain salt
adrenalectomy - salt appetite gatorade salt in cystic fibrosis

now we get off of the topic of hormones regulated by the pituitary

while on the topic of the adrenal gland,
Adrenal medulla (vs cortex under pituitary control)- Epinephrine, adrenalin - activates body
Autonomic vs voluntary motor control sympathetic parasympathetic
sympathetic n.s. norepinephrine
sympathetic - "fight or flight"
helps in metabolism to release glucose to blood stream
muscles activity up, peripheral circulation and digestion inhibited
heart rate goes up

TRANSPARENCY Fig. 45.10
In pancreas, which is largely a digestive exocrine gland, there are also islets of Langerhans (as shown in this picture from our histology course) which are the endocrine glands where the beta cells make insulin and the alpha cells make glucagon
Pancreas Insulin- sugar uptake into cells (blood sugar down), make glycogen in liver
2 peptides clipped from one chain held by disulfide bonds

Diabetes mellitus
Type 1 autoimmune disease beta cells are destroyed, young people, insulin dependent
inject insulin. protein, must inject
(vs steroid like "the pill" which can be taken orally)
Type 2, older people, genetic, correlated with overweight, non-insulin dependent
sugar in urine- can't pump back
Eye problems (too many new blood vessels - angiogenesis) and cardiovascular problems
Brain is not insulin-dependent - coma from too much insulin because no glucose for brain
Glucagon mobilize sugar to blood like adrenalin
sugar regulates insulin and glucagon

TRANSPARENCY (Fig. 45.9) (see also Fig. 45.1)
Thyroid 2 glands (pituit - thyroxine TSH) vs:
Thyroid - thyrocalcitonin - blood Ca2+ down
Parathyroid - parathormone - blood Ca2+ up (from bones)
near thyroid gland in neck
Vitamin D sunlight, rickets, fish oil, hormone, absorption from gut
Osteoporosis - bone deterioration with age especially in women
Ca2+ very important, muscle (later), nerve (later)

Insect hormones TRANSPARENCY Fig. 45.2
Brain hormone via corpus cardiacum causes prothoracic gland to release ecdysone
Corpus allatum releases juvenile hormone

The sex hormones

Female reproductive cycle good example of Regulation, Negative feedback
CHAULKBOARD DIAGRAM (simultaneously show TRANSPARENCY Fig. 46.15
Hypothalamus - RF's (peptides)
(chaulkboard diagram is also here, peptides in black, steroids in red)
Pituitary makes peptide hormones "gonado-trophic hormones" (gonadotropins, FSH and LH)
gonads (ovaries) make steroid hormones (estrogen and progesterone)
Feedback system plus effects on endometrium (lining of uterus)

FSH (follicle stimulating hormone) stimulates estrogen release from follicle
estrogen inhibits FSH
estrogen turns on LH (lutenizing hormone) release
estrogen begins buildup of endometrium
surge of LH causes ovulation
then follicle becomes corpus luteum that puts out progesterone
progesterone inhibits LH and FSH
progesterone also stimulates buildup of endometrium
to finish cycle, low FSH & LH which lets estrogen and progesterone go down
(corpus luteum starts to go away)
with low estrogen and progesterone, endometrium breaks down (menstruation)
with low estrogen and progesterone, pituitary is not inhibited so FSH starts
(if pregnant, HCG [human corionic gonadotropin] maintains corpus luteum
progesterone (from maintained corpus luteum) maintains endometrium
Here is a primary follicle, a growing follicle, the mature follicle, and the corpus luteum from our histology course.

Human corionic gonadotropin
Menstruation in primates
Estrus cycle - dogs heat 2x/yr, cats 3x/yr
Rabbits reflex ovulators
Pill Progesterone and Estrogen inhibit ovulation
28 day pill 7 duds: 1st 4 days, last 3
"combination pill"
Weight gain, circulation problems
lower proportion of estrogen
Rhythm - sperm viable 48 hr, ovum 15 hr: 3-4 day abstinance

The male pattern TRANSPARENCY Fig. 46.14
FSH for spermatogenesis
LH (ICSH) to stimulate interstitial cells to release testosterone

The Biology department's primary expert on endocrinology is Dr. Asa who is director of research at the St. Louis Zoo. As an adjunct Professor in SLU's Biology department, she teaches the popular course, "Introductory Endocrinology" BL A450-01

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this page was last updated 2/20/03