Endocrine System
Control of Our Bodies Homeostasis
Explain
Section 39-2
The Endocrine
System
regulates
Metabolism
Calcium
and glucose
levels
Response
to stress
by means
of the
by means
of the
by means
of the
by means
of the
Testes
Thyroid
Growth
Water
balance
Reproduction
by means
of the
by means
of the
Pituitary
Ovaries
Pancreas
Parathyroids
Adrenals
Exocrine or Endocrine
• Exocrine – release products
(enzymes) into ducts
– Ex) Sweat, tears, digestive juices
• Endocrine – directly to bloodstream;
NO DUCTS
– Ex) Hormones
Endocrine System
• Glands – release products to
bloodstream directly.
• Horomones – products deliver
messages to body
• Target cells – have specific
receptors for specific hormones
Endocrine Glands
Section 39-1
Hypothalamus
The hypothalamus makes
hormones that control the
pituitary gland. In addition, it
makes hormones that are stored
in the pituitary gland.
Pituitary gland
The pituitary gland produces
hormones that regulate many of the
other endocrine glands.
Parathyroid glands
These four glands release
parathyroid hormone, which
regulate the level of calcium
in the blood.
Thymus
During childhood, the thymus
releases thymosin, which
stimulates Tcell development.
Adrenal glands
The adrenal glands release
epinephrine and nonepinephrine,
which help the body deal with stress.
Pineal gland
The pineal gland releases melatonin, which
is involved in rhythmic activities, such as
daily sleep-wake cycles.
Thyroid
The thyroid produces thyroxine, which
regulates metabolism.
Pancreas
The pancreas produces insulin and glucagon, which
regulate the level of glucose in the blood.
Ovary
The ovaries produce estrogen and progesterone.
Estrogen is required for the development of secondary
sex characteristics and for the development of eggs.
Progesterone prepares the uterus for a fertilized egg.
Testis
The testes produce testosterone,
which is responsible for sperm
production and the development of
male secondary sex characteristics
Pituitary Gland
• Master gland
– Controls the other
endocrine glands
• Growth Hormone (GH)
– Too much –
gigantism
– Too little – dwarfism
• Antidiuretic (ADH)
– Stimulates kidneys
to keep water
Hypothalamus
• Part of brain and attached to
pituitary
• Controls pituitary secretions
Thyroid
THYROID GLAND
• Regulates
– Metabolism and energy balance
Thyroid Hormones
• Thyroxine
– Regulates body energy usage
• Calcitonin
– One hormones that regulates calcium
and phosphate in blood
Parathyroid
Calcium Regulation
PARAthyroid Glands
• PTH-Parathyroid hormones
• Increases calcium, phosphate, and
magnesium absorption in intestines.
• Causes bones to release calcium and
phosphate
• Causes removal of calcium and magnesium
from urine by kidneys
• Increases the making of Vitamin D in body
Negative Feedback
Mechanism
• Our body uses feedback mechanism
to maintain homeostasis within our
body.
• Regulation of calcium is one example
of this process.
• Can you think of another one? Hint:
Role Play Activity
Adrenal Gland
• Releases hormones to deal with stress
Adrenal Gland Cont.
• Cortex
– Produces more than
2 dozen steroid
hormones
– corticosteriods
• Medulla
– “fight or flight”
– Epinephrine and
norepinephrine
Glucose Regulation
Two Ways:
1. Eating Regularly
2. Hormone Adjustments
Pancreas:
Endocrine and Exocrine
• What did the pancreas do in digestion?
Secreted Enzymes
Pancreas also secretes hormones
Endocrine glands
- ductless organ that releases hormones
DIRECTLY into the bloodstream.
Blood Glucose Level
• Pancreatic Hormones regulate blood
sugar level before and after meals.
• Islets; clusters of cells in pancreas
– Alphasecrete glucagon – increases sugar
– Beta secrete insulin – decreases sugar
What Happens?
• Between meals
Blood glucose lowPancreas secretes
glucagonLiver changes glycogen to
glucoseglucose sent to target tissues
• After a meal
Blood glucose highPancreas secretes
insulinGlucose goes to the Liver(Glygogen) and
goes to Target tissues
Diabetes
• Diabetes
– High sugar levels in blood
– Do not produce enough insulin to control
blood sugar
– Some take insulin injections to regulate
Reproductive Glands
•
•
•
•
Production of gametes
Secretion of sex hormones
Female – Ovaries - Estrogen
Males – Testes - Testosterone