BIO 202 ASU A&P Chapter 17 - Endocrine System
Endocrine System - glands, tissues and cells that secrete hormones
Endocrine glands - organs that are sources of hormones
Differences between Endocrine (Enter) versus Exocrine (Exit)
Endocrine: NO ducts, easy uptakes of hormones into bloodstream, internal
secretions. Direct.
Exocrine: HAVE ducts, carries secretion to epithelial surface, external
secretions.
Differences between nervous versus exocrine
Speed - Nervous: reacts quickly/stops quickly.
Endocrine: reacts slowly, effects may lasts days
Adaption - Nervous: response declines (adapts quickly)
Endocrine: responses persist (adapts slowly)
Area of effect - Nervous: target and specific
Endocrine: general and widespread
The Anatomy
Hypothalamus: regulates functions from water balance and thermoregulation to
sex drive and childbirth. Many carried out by pituitary gland. It produces
hormones that tells the gland what to do.
Pituitary gland: has anterior and posterior portion.
ANTERIOR PITUITARY (adenohypophysis)
Controlled by the blood vessels and makes up about ¾ of the gland.
It has a special blood vessel highway called the hypophyseal portal system
connecting the hypothalamus to the pituitary gland. Makes and releases its own
hormones.
, (ex: release more thyroid stimulating hormone -> travels through portal to
anterior pituitary)
Anterior = Blood
POSTERIOR PITUITARY (Neurohypophysis)
Controlled by neurons/nerves and makes up about ¼ of gland.
Does not make its own hormones but is a storage and release area for hormones
made by hypothalamus.
It has a special nerve pathway called hypothalamo hypophyseal tract.
Hypothalamus > Nerve fibers > posterior pituitary
● The suckling of infants also triggered by neuroendocrine reflexes
THE 8 HORMONES
6 controls the anterior pituitary and 2 are stored/released by the posterior.
6 that regulate anterior:
- Gonadotropin (reproductive system)-releasing hormone (GnRH): Tells
the anterior to release FSH and LH
- Thyrotropin-releasing hormone (TRH): Tells anterior to release thyroid
stimulating hormones (TSH) and then travels to thyroid gland and
produces its hormones.
- Corticotropin-releasing hormone (CRH): Tells anterior to release ACTH
(adrenal) then travels to the adrenal cortex which produces cortisol,
important for the body's stress response.
- Prolactin-inhibiting hormone (PIH): It says don't release prolactin, so
PIH decreases prolactin (milk production)
- Growth hormone-releasing hormone (GHRH): Tells anterior to release
growth hormones. Induces the liver to produce growth stimulants.
- Somatostatin: Tells anterior to slow down and don’t release so much. So it
inhibits GH and TSH
2 stored posterior pituitary hormones:
- Oxytocin (OT): causes the uterus to contract during childbirth and causes
milk to be released from the mammary gland during breastfeeding.
Endocrine System - glands, tissues and cells that secrete hormones
Endocrine glands - organs that are sources of hormones
Differences between Endocrine (Enter) versus Exocrine (Exit)
Endocrine: NO ducts, easy uptakes of hormones into bloodstream, internal
secretions. Direct.
Exocrine: HAVE ducts, carries secretion to epithelial surface, external
secretions.
Differences between nervous versus exocrine
Speed - Nervous: reacts quickly/stops quickly.
Endocrine: reacts slowly, effects may lasts days
Adaption - Nervous: response declines (adapts quickly)
Endocrine: responses persist (adapts slowly)
Area of effect - Nervous: target and specific
Endocrine: general and widespread
The Anatomy
Hypothalamus: regulates functions from water balance and thermoregulation to
sex drive and childbirth. Many carried out by pituitary gland. It produces
hormones that tells the gland what to do.
Pituitary gland: has anterior and posterior portion.
ANTERIOR PITUITARY (adenohypophysis)
Controlled by the blood vessels and makes up about ¾ of the gland.
It has a special blood vessel highway called the hypophyseal portal system
connecting the hypothalamus to the pituitary gland. Makes and releases its own
hormones.
, (ex: release more thyroid stimulating hormone -> travels through portal to
anterior pituitary)
Anterior = Blood
POSTERIOR PITUITARY (Neurohypophysis)
Controlled by neurons/nerves and makes up about ¼ of gland.
Does not make its own hormones but is a storage and release area for hormones
made by hypothalamus.
It has a special nerve pathway called hypothalamo hypophyseal tract.
Hypothalamus > Nerve fibers > posterior pituitary
● The suckling of infants also triggered by neuroendocrine reflexes
THE 8 HORMONES
6 controls the anterior pituitary and 2 are stored/released by the posterior.
6 that regulate anterior:
- Gonadotropin (reproductive system)-releasing hormone (GnRH): Tells
the anterior to release FSH and LH
- Thyrotropin-releasing hormone (TRH): Tells anterior to release thyroid
stimulating hormones (TSH) and then travels to thyroid gland and
produces its hormones.
- Corticotropin-releasing hormone (CRH): Tells anterior to release ACTH
(adrenal) then travels to the adrenal cortex which produces cortisol,
important for the body's stress response.
- Prolactin-inhibiting hormone (PIH): It says don't release prolactin, so
PIH decreases prolactin (milk production)
- Growth hormone-releasing hormone (GHRH): Tells anterior to release
growth hormones. Induces the liver to produce growth stimulants.
- Somatostatin: Tells anterior to slow down and don’t release so much. So it
inhibits GH and TSH
2 stored posterior pituitary hormones:
- Oxytocin (OT): causes the uterus to contract during childbirth and causes
milk to be released from the mammary gland during breastfeeding.
