Download endocrine system

ENDOCRINE SYSTEM
ENDOCRINE GLANDS
• Are ductless and secrete
hormones directly into the
bloodstream
• Target Cells – the cells that a
hormone directly affects;
if a cell does not have
receptors or the receptors
don’t respond, the hormone
has no effect.
Human
Endocrine
Glands
• Most hormones operate by a
negative feedback system –
an excess of a hormone will
cause the gland to stop
producing it
THE PITUITARY GLAND
• Often called the “master
gland” because it secretes
so many hormones (9 total!)
• Has two parts: Anterior
Pituitary and Posterior
Pituitary
• The pituitary sits just below
the hypothalamus
• The hypothalamus regulates
the anterior pituitary by
secreting neurosecretory
hormones that can stimulate
or inhibit the actions of it
Hormones of the hypothalamus and pituitary
glands
Nerve cells that
release hormones
into the blood
Remember the acronym:
“MAP TO FLAG”
to remember the nine pituitary
hormones
ANTERIOR PITUITARY
• Secretes six hormones:
–Growth Hormone (GH) –
stimulates bone and
muscle growth
–Adrenocorticotropic
Hormone (ACTH)
stimulates the adrenal
cortex to secrete
hormones (corticosteroids)
Anterior Pituitary Gland:
Thyroid-Stimulating Hormone
(TSH)
• Stimulates the thyroid to secrete
thyroxine
Follicle-Stimulating Hormone
• Stimulates the follicle to grow in
females, oogenesis, and
spermatogenesis
Anterior Pituitary Gland:
Luteinizing Hormone
• Causes the release of the
ovum during the menstrual
cycle in females and
testosterone production in
males
Anterior Pituitary Gland:
Prolactin
• Stimulates the mammary
glands to produce milk
Anterior Pituitary Gland
Melanocyte-Stimulating Hormone:
Regulates skin color in lower
vertebrates, although its function
In humans is unknown
Posterior Pituitary Gland:
• Secretes Two Hormones: (made by
hypothalamus)
• Antidiuretic Hormone (ADH) –
acts on the kidneys, increasing
water retention and thus
decreasing urine volume.
Posterior Pituitary Gland
•Oxytocin – is secreted by the
stimulation of the nipples
during breast feeding and
sexual intercourse; it also
stimulates uterine
contractions during labor
ADRENAL GLANDS
• Adrenal Medulla – secretes
epinephrine (adrenaline) and
norepinephrine(noradrenaline)
“fight-or-flight” response –
increase HR, BP, metabolism,
etc
ADRENAL CORTEX
• ACTH – causes the
adrenal cortex to produce
its different hormones
•Glucocorticoids –
target the liver and
promote the release of
glucose
Adrenal Cortex:
• Mineralcorticoids – target the
kidney and promote the
retention of water
• Ex: Aldosterone – increases
recovery of Na and increases
excretion of K and H ions into
the urine
THYROID GLAND
• Located in the neck, is the
target gland of thyroidstimulating hormone (TSH)
• When the thyroid is stimulated
by TSH it releases the
hormones Triiodothyronine (T3)
and Thyroxine (T4), which
regulates the metabolic rate of
your body tissues
• The thyroid also increases
the concentration of
calcitonin which decreases
the blood’s concentration of
calcium
PARATHYROID GLANDS
• These are four pea-shaped
organs that rest on the
thyroid They secrete
parathyroid hormone which
increases blood calcium
levels – the opposite effect
of what calcitonin does
An example of how feedback regulation
maintains homeostasis
THE PANCREAS
• Glucagon – stimulates the
liver to convert glycogen
into glucose and to release
that glucose into the blood
• Insulin – has the opposite
effect of glucagon
Major Vertebrate Endocrine Glands and Some of
Their Hormones
Major Vertebrate Endocrine Glands and
Some of Their Hormones (Pancreas–Thymus)
Glucose homeostasis maintained by insulin
and glucagon
Feedback control loops regulating the
secretion of thyroid hormones T3 and T4