Download Endocrine Notes 2

Adrenal Glands
Reference: pp. 381-382
The adrenal glands, located on top of each kidney, are made of two glands:
the inner adrenal medulla, and the outer adrenal cortex.
The adrenal medulla is under nervous control and releases epinephron (AKA
adrenaline) and norepinephron (AKA noradrenaline). The emotional stress of
anger, fear or depression causes the release of these “fight or flight”
hormones. They increase heart rate, blood flow to the brain, breathing rate,
pupil dilation, blood pressure, cell metabolism, and blood sugar levels. {For
short-term stresses only.}
The adrenal cortex is under the influence of ACTH from the pituitary. It
releases mineralocorticoids (e.g., aldosterone), glucocorticoids (e.g., cortisol),
and some sex hormones (e.g., androgens and some estrogens). {For long-term
stresses.}
✏Complete Lab Exercise 8.2.1 “The Effects of Hormones on Blood Sugar”,
p. 401.
HW: #4, 5, 6, 7 on page 383
Thyroid Gland
Reference: pp. 384-386
Located in the neck, the thyroid gland produces thyroxine (T4) and
tiiodothyronine (T3). These hormones control metabolic rate. It also
releases calcitonin, which lowers blood calcium levels.
Thyroxine is released when metabolic decreases signal the release of
thryoid-releasing factors (TRH), which stimulate the pituitary gland to release
thyroid-stimulating hormone (TSH), which stimulates the thyroid to release
thyroxine. When metabolic rates return to normal TSH is shut off.
When iodine is not present in foods the thyroid may have trouble producing
T3 and T4 hormones and the gland grows in size to compensate for the loss (it
is continually stimulated by TSH!). This causes swelling in the neck and is
called a goiter. (The disease = goiter)
Parathyroid Glands
The parathyroid glands are four small glands hidden within the thyroid gland.
Low levels of blood calcium signal the parathyroids to release parathyroid
hormone (PTH). PTH causes the kidneys and gut to retain calcium while
promoting calcium release from bone. PTH also activates vitamin D formation.
Reproductive Hormones
Reference: pp. 393-399
The sex hormones are produced by the ovaries and testes. These glands
secrete their hormones in response to signals from the pituitary and
hypothalamus.
Male Reproductive System
Testosterone
-produced in the interstitial cells of the testes
-stimulates spermatogenesis
-influences secondary sexual characteristics during puberty
-inhibits LH production
Gonadotropin-releasing Hormone (GnRH)
-released from hypothalamus
-stimulates the pituitary to release FSH and LH
Follicle-stimulating Hormone (FSH)
-stimulates production of sperm cells
-indirectly inhibits its own production
Luteinizing Hormone (LH)
-stimulates the interstitial cells to produce testosterone
Female Reproductive System
Estrogen
-produced in the follicle cells of the ovary
-causes thickening of the endometrium
-initiates secondary sexual characteristics
Progesterone
-produced by the corpus luteum in the ovary
-stimulates the endometrium to prepare for an embryo
-inhibits further ovulation and uterine contractions
-levels decline if fertilization/implantation does not occur
Follicle-stimulating Hormone (FSH)
-produced by the pituitary
-stimulates development of the follicle cells
-inhibited by estrogen and progesterone
Luteinizing Hormone (LH)
-produced by the pituitary in response to estrogen at mid-cycle
-stimulates ovulation and the corpus luteum
-inhibited by estrogen and progesterone
The Menstrual Cycle
Follicle develops.
↑Estrogen
↑FSH
Ovulation
Corpus luteum develops.
-Estrogen
↑LH
↑Progesterone
↓FSH, ↓LH
Flow Phase
1
Follicular Phase
5
Luteal Phase
14
28 Days
------------------------------------------↓-----------------------------------------➔
Ovulation
The maturing oocyte is surrounded by a layer of cells called the follicle.
After ovulation, the follicle transforms into the corpus luteum.
*Complete Lab Exercise 8.5.1 “Hormone Levels During the Menstrual Cycle”
pp. 404-405