Download THE ENDOCRINE SYSTEM

HORMONES AND THE ENDOCRINE SYSTEM
Chapter 45
The glands of the endocrine system secrete hormones that send a stimulus to
another cell. The response that is elicited by the target cell helps bring the
organism back to homeostasis
I.
Overview of endocrine control
Primarily occurs by negative feedback control
General mechanism of action:
Stimulus (out of homeostasis) acts on
Endocrine gland
Negative Feedback
to
A response is
elicited
Secretes
hormone
Acts on target tissue
Purpose: to maintain homeostasis
ENDOCRINE GLANDS AND THEIR HORMONES
ENDOCRINE
HORMONE
TARGET TISSUE
GLAND
POSTERIOR
Antidiuretic
kidney
PITUITARY
hormone (ADH)
oxytocin
Uterus and
mammaries
ANTERIOR
PITUITARY
Growth hormone
(GH)
Thyroid
stimulating
hormone (TSH)
Leutinizing
hormone (LH)
Many organs
Stimulates water
reabsorption
Stimulates
contraction and
milk release
Growth
thyroid
Stimulates release
of thyroxine
Ovaries and testes
Stimulates
ovulation and
testosterone
secretion
Stimulates egg
maturation and
production od
sperm
Stimulates milk
production
Increases
metabolism
Lowers blood
calcium by
decreasing calcium
loss by bone
Raises blood
calcium levels by
stimulating bone
breakdown and
calcium
reabsorption
Lowers blood
sugar by
stimulating
conversion of
glucose to glycogen
Raises blood sugar
Follicle stimulating Ovaries and testes
hormone (FSH)
prolactin
mammaries
thyroxine
Many cells
calcitonin
bone
PARATHYROID
Parathyroid
hormone (PTH)
Bone, kidneys,
digestive tract
PANCREAS
insulin
Liver fat cells,
skeletal muscle
glucagon
Liver, fat cells
THYROID
RESPONSE
TESTES
testosterone
Testes and other
male parts and
other body parts
OVARIES
estradiol
Many body parts
progesterone
uterus
by stimulating
breakdown of
glycogen to glucose
Stimulates
secondary sex
characteristics and
spermatogenesis
Stimulates
secondary sex
characteristics
Prepares for
pregnancy
http://health.howstuffworks.com/human-body/systems/endocrine/adam200091.htm
II.
Endocrine control mechanisms
A. Blood calcium levels
Low Blood Calcium →stimulates parathyroid →to secrete PTH (parathyroid
hormone) → which stimulates calcium release from bones, increases calcium
uptake by intestines, increases calcium reabsorption by kidneys → which
increases blood calcium → which negatively feeds back on parathyroid
High Blood calcium →stimulates thyroid →to secrete calcitonin →which
increases calcium deposition in bone, decreases calcium uptake by kidneys and
intestines → which lowers blood calcium → which negatively feeds back on
thyroid
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C.
Blood sugar
Before a Meal:
Low blood glucose →stimulates pancreas → to secrete glucagon → which increases
breakdown of glycogen to glucose → which increases blood glucose → which
negatively feeds back on pancreas
After a Meal:
High blood glucose → stimulates pancreas → to secrete insulin → which stimulates
conversion of glucose to glycogen → which lowers blood sugar → which negatively
feeds back on pancreas
http://health.howstuffworks.com/human-body/systems/endocrine/adam200092.htm