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The endocrine system, like the nevous system, is important in regulating organ
and cell function. It is these two systems that provide communication between
cells in an organized manner. The nervous system uses electrical signals (nervous
impulses) to communicate while the endocrine system uses hormones circulating
in blood to provide communication.
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I Gland structures
A. Exocrine glands produce oil, sweat, and digestive juices, transporting secretions
through tubes to exterior of body (includes digestive tube)
B. Endocrine glands have cells that produce hormones (production cells) , directly
into blood.
II Hormone actions
Hormones are signalling chemicals allowing communication between cells. Cells
that respond to hormones are called target cells. When the target cells respond
to the hormones that the hormone action has been achieved.
A. altered production of other hormones
B. altered production of chemicals
C. altered stimulation of cardiac and smooth muscular tissue
III. Hormone types
A. Protein based hormones (insulin, epinephrine)
B. Steroid (cholesterol) based hormones (estrogen, testosterone, cortisol
FOCUS ON: HORMONE PRODUCTION SITE (GLAND), HORMONE NAME, and HORMONE FUNCTION
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IV Endocrine Gland (production cells)
1. Hypothalamus
Major regulatory organ that produces hormones (releasing hormones) causing Pituitary
gland cells to release other hormones.
The pituitary gland is attached to the inferior side of the hypothalamus by
the infundibulum. It sits within the
sella turcica of the sphenoid bone.
2. Anterior Pituitary gland (Adenohypophysis) typical glandular tissue
a) human growth hormone (hGH) - promotes normal bone growth, muscle development,
use of fat
b) Follicle stimulating hormone (FSH) - promotes ova (eggs) and spermatozoa
(sperm)development
c) Leutinizing hormone (LH) - promotes ovulation in females, estrogen/progesterone
production in females...and testosterone production in males
d) prolactin - milk production
3. Posterior Pituitary (Neurohypophysis) nervous tissue .
-stores and releases two hormones produced by the hypothalamus (Posterior pituitary
is continuation of some of hypothalamic nervous tissue).
a) oxytocin (OT) - promote labor contractions, milk ejection
b) antidiuretic hormone (ADH) - targets the kidney tubules, promoting reabsorption
of water. Increased water means more blood therefore it increases blood volume
and pressure.
4. Thyroid Gland:
inferior to the larynx, attached to anterior side of trachea.
a) thyroid hormone (T3, T4 or Thyroxine) - major metabolic hormone raises
Basal Metabolic Rate, promotes
O2 and glucose use for making energy.
Promotes normal development of muscles,bones, and the nervous system. Produced
by
the follicle cells of thyroid
b) calcitonin - lowers blood calcium levels, adding into the bones. Produced
by the
parafollicular cells of thyroid
5. Parathyroids:
attached to the posterior side of the thyroid's lobes.
a) parathyroid hormone (PTH) - raises blood calcium levels, removing it from the bones, urine and dietary sources.
6. Adrenal cortex- the cortex is the outer part of the adrenal glands. Each
adrenal gland sits atop a kidney.
a) aldosterone - targets the kidney tubules, promoting sodium (Na+) reabsorption.
This action
will increase blood volume and thus pressure.
b) cortisol - increases glucose levels by using up carbohydrate energy storage,
promotes fat burning, protein burning. also immune suppresant, decreases inflammation
(long term stress hormones)
7. Adrenal medulla: the medulla is the mid-portion.
Actually nervous tissue.
a) epinephrine and norepinephrine-
Increases heart rate, respiratory rates, blood pressure. (Fight or flight short
term stress hormones)
8. Pancreas -
Islets of Langerhans: the islets are patches of endocrine cells (two types)
surrounded by
acini, the exocrine cells.
a) glucagon - produced by the alpha cells, raises blood levels.
b) insulin - produced by the beta cells, lowers blood glucose levels.
9. Thymus:
anterior and superior to the heart, posterior
to the sternum.
a) thymosin - makes T-cells/T lymphocytes immunocompetent (stimiulates immune
system cells)
Helpful
web link
Another helpful web link
A
web activity
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Professor Thomas M. Lancraft
Human Anatomy Courses
at St. Petersburg College
St. Petersburg/Gibbs Campus
11/2005