Transcript The Endocrine System - Mr. Mazza's BioResource

The Endocrine System
Endocrine Glands
• Endocrine glands release hormones
• Hormones: chemicals that circulate
through the body to regulate the metabolic
functions of other cells in the body
• The cells affected by a hormone are
called its target cells
Target cells must have specific protein receptors
for the hormone so that the hormone can bind
and do its job
Process of hormone release and
action
Stimulus
Hormone is released
Hormone travels to
target cells
Desired effect is
achieved
Hormone binds to
receptor on target cell
Hormones we have mentioned in
class…
•
•
•
•
•
•
•
Calcitonin
Parathyroid hormone (PTH)
Growth hormone
Estrogen
Testosterone
Epinephrine (adrenalin)
Erythropoietin
Classes of Hormones
2 main types:
• Steroid (made from cholesterol) - bind
directly to DNA to exert their effects through
transcription and translation (ex.
Testosterone, estrogen, thyroxine)
• Amino acid based (made from amino acids)
- bind to a receptor on a cell’s membrane to
exert its effect via a 2nd messenger molecule
(ex. Growth hormone, epinephrine, insulin)
Endocrine Gland Stimuli
• Neural - nervous system stimulates
release of hormone
• Humoral - a substance in the blood
stimulates release of a hormone (ex.
PTH and blood calcium)
• Hormonal - a hormone is released for
the purpose of stimulating another gland
to release a hormone
Hormonal Blood Sugar
Regulation
• Insulin and glucagon
•
•
•
(both released from
pancreas) regulate blood
sugar
Insulin lowers blood
sugar if it is too high
Glucagon raises blood
sugar if it is too low
Carbohydrates stimulate
insulin release (fats and
proteins have little effect
on insulin)
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.