Reproductive system
The hypothalamus regulates the release of sex
hormones that govern the development and
functioning of ovaries and testes (the gonads).
Oxytocin triggers uterine muscle contractions
during labor and (with prolactin) for milk release
for a nursing infant. Luteinizing hormone (LH) and
follicle-stimulating hormone (FSH) also have key
roles in reproduction.Digestive system
Insulin and GH support the delivery of nutrients to
all cells by stimulating cells to take up glucose from
the bloodstream.The Endocrine System
The endocrine system produces
hormones, signaling molecules that
travel in the bloodstream to nearly
all body cells. Each kind of hormone
influences the activity of its target
cells. Along with signals of the nervous
system, these changes adjust body
functions in ways that maintain
homeostasis in the body as whole.
In general, responses to hormones take
longer and last longer than responses
to nerve impulses. Hormones govern
long-term events such as bodily growth
and metabolism.The Endocrine System in Homeostasis
Skeletal system
Growth hormone stimulates the growth of bones.
Parathyroid hormone (PTH) is the main regulator of
blood calcium levels. Calcitonin stimulates uptake of
calcium from blood as needed to form bone tissue.Nervous system
Epinephrine supports the sympathetic nervous
system in the fight–flight response and helps the
CNS regulate blood pressure. Hormones that
regulate blood sugar ensure adequate fuel for
brain cells.Urinary system
Aldosterone and ANP support the urinary system’s
management of salt–water balance by promoting
or reducing the reabsorption of sodium.Muscular system
Growth hormone stimulates development of
skeletal muscle mass. PTH adjusts blood levels
of calcium and potassium, electrolytes that are
essential for muscle contraction.
Cardiovascular system and blood
Epinephrine adjusts heart rate and helps
maintain blood pressure. Erythropoietin from the
kidneys stimulates production of red blood cells.
Aldosterone indirectly (via the kidneys) helps
restore falling blood volume and pressure. PTH
adjusts blood levels of calcium needed for cardiac
muscle contraction.Unless otherwise indicated, all art on this page is © Cengage Learning.Immunity and the lymphatic system
Thymus hormones stimulate T cells to mature.
Cortisol from the adrenal cortex increases
blood levels of glucose, amino acids, and other
molecules used in tissue repair.15.12
connEcTionS
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