Download The term endocrine comes from the Greek The term endocrine

Th Human
The
Endocrine System
The term endocrine comes from the Greek
Endon meaning within, and
k i i meaning
krinein
i to separate or secrete.
HORMONES
ARE A SECRETION OF AN
ENDOCRINE GLAND THAT
PASS DIRECTLY INTO THE
BLOOD STREAM
zMAY STIMULATE OR REPRESS THE
ACTIVITY OF THE TARGET ORGAN
zARE "CHEMICAL MESSENGERS"
TARGET ORGANS
zONCE IN THE BLOOD, HORMONES
AFFECT ONLY SPECIFIC "TARGET
TARGET
ORGANS"
EX The
EX:
Th adrenal
d
l gland
l d secretes the
h h
hormone
epinephrine, which affects the liver (the target
organ)) by
b causing
i it
i to change
h
glycogen
l
to
glucose.
TARGET CELLS
TARGET CELLS
Glands
zAre organs that produce and release a
substance (secretion)
zExocrine glands release their secretions
through
g ducts (sweat,
(
tears, digestive
g
juices)
zEndocrine glands release their secretions
(hormones) directly into the bloodstream
Hormones
zSteroid
zN
zNonsteroid
id
Steroid Hormones
zProduced from the lipid cholesterol
zCan pass directly across a cell membrane
zBinds to steroid receptor protein (found
only
l in
i target cells)
ll ) to form
f
a hormoneh
receptor complex
zHormone-receptor complex enters nucleus
of cell and binds to a DNA control
sequence
Steroid Hormones (cont’d)
(cont d)
zBinding initiates transcription of specific
genes to mRNA
zThe mRNA moves into cytoplasm and
directs p
protein synthesis
y
zExamples: testosterone, estradiol
zS
zSecreted
d by
b the
h gonads,
d adrenal
d
l cortex and
d
placenta
Nonsteroid Hormones
zInclude proteins
proteins, small peptides,
peptides and
modified amino acids
zGenerally cannot pass through the cell
membrane of their target cells (water
soluble)
zBinds to receptors on the cell
membrane
Nonsteroid Hormones (cont’d)
(cont d)
zThis enzyme activates secondary
messengers that carry the message of the
hormone inside the cell
zOnce released, the second messengers can
activate
ti t orr inhibit a wide
id range
r n off other
th r cellll
activities
zExamples: FSH, GH, Oxytocin,
epinephrine (adrenal medulla)
Prostaglandins
zFirst identified in the male prostate gland,
gland
hence, the name
zAll cells (except RBC) have been shown to
produce small amounts of hormonelike
p
substances called prostaglandins
zAre modified fatty acids
Prostaglandins (cont’d)
(cont d)
zGenerally affect only nearby cells and
tissues “local hormones”
zCan cause smooth muscle contractions (ex.
uterus, bronchioles, blood vessels))
zAspirin helps to stop the pain of a
headache because it inhibits the synthesis
of these prostaglandins
Control of the Endocrine System
Regulated by feedback mechanisms that
function to maintain homeostasis
zNegative feedback
zPositive feedback
zComplimentary hormone action
(two hormones with opposite
effects))
Human Endocrine System
Pituitary Gland
zLocated under the brain.
zThe gland produces hormones that control
many other glands .
zS
zSome
off its
i hormones
h
include:
i l d
{Growth Stimulating Hormone: controls the growth of the
long bones of the body.
body
{Thyroid-Stimulating Hormone (TSH): stimulates the
thyroid to produce thyroxin.
{Follicle-Stimulating Hormone (FSH): affects the ovary in
females. It stimulates the maturation and release of eggs at
maturity.
y
Pituitary Gland
Hypothalamus
zA tiny gland in the brain attached to the
posterior pituitary.
pituitary
zProduces and secretes hormones that affect the
pituitary
i i
gland.
l d
zIt is the connection between the nervous and
endocrine systems.
Hypothalamus
Thyroid Gland
zLocated in the neck region, it surrounds the
trachea.
zProduces a hormone called thyroxin that
regulates your metabolic rate.
{When a person
{Wh
p
is
i nott getting
tti enough
h iodine
i di they
th may
develop a condition called goiter where the thyroid is
not producing thyroxin and the gland swells (associated
with hypothyroidism.
hypothyroidism
{When an excessive amount of thyroid hormones are
secreted a condition known as hyperthyroidism
develops Its most noticeable symptom is the
develops.
protrusion of the eyeballs, but can lead to nervousness,
high blood pressure, weight loss and elevated body
temperature
Iodized Salt
Thyroid Gland
Thyroid Gland
GOITER
GOITER
GOITER
Grave’ss Disease
Grave
Parathyroids
zFour tiny glands within the thyroid gland.
gland
zSecrete a hormone called parathomone.
zRegulates the metabolism of calcium.
{Calcium is necessary for
zconduction of nerve impulses
zblood clotting
zbones and teeth
Parathyroids
Adrenal Glands
zLocated on kidneys, there are two main
parts off the
h adrenal
d
l glands:
l d
{Cortex (outer region – produces
corticosteroid hormones)
{Medulla ((inner region)
g )
zsecretes epinephrine a.k.a. adrenaline when a
person is frightened
p
g
(p
(powered byy sympathetic
y p
nervous system)
zAdrenaline increases metabolic rate, heart rate,
and breathing rate
Adrenal Glands
Cortex of Adrenal Gland
zSecretes corticosteroid hormones
zRegulates water balance in blood (blood
pressure)
{done by controlling salt reabsorption in
kidneys
kid
zStimulates the conversion of complex stored
foods, such as fat and protein to glucose.
Pancreas
zFunctions as an exocrine gland for the
digestive system
zFunctions as an endocrine gland by
releasingg hormones directlyy into the blood
zReleases insulin and glucagon to help keep
the level of glucose in the blood stable
Islets of Langerhans
g
zSmall ggroups
p of gglandular tissue in
pancreas.
zP d
zProduce
i li andd glucagon
insulin
l
zInsulin: promotes the storage of
excess blood glucose as glycogen or
fat.
Glucagon: stimulates the conversion
zGlucagon:
of glycogen back into glucose
Islets of Langerhans
Feedback Inhibition
zThe process by which the product of a
system shuts down the system or limits
its operation.
*Negative
Negative Feedback
Feedback*
Using Blood Sugar level as an example
zBlood Sugar Levels are high so insulin is
released and glucagon is not produced
zInsulin converts sugar into glycogen or fat so
blood sugar level drops and the production of
glucagon increases as insulin production
decreases.
zAs glucagon levels increases so does the blood
g level and we’re back to the beginning
g
g
sugar
Diabetes Mellitus
z Malfunction of the endocrine system
y
z Occurs primarily when not enough insulin is produced
by the Islets of Langerhans in the pancreas (Type
I/Juvenile
/
Onset generally occurs b
before
f
the age off 15.)
z In Type II diabetics (adult-onset,) cells are unable to
respond to the hormone because the interaction of the
insulin receptors and the insulin is inefficient.
Generally occurs in adults over 40.
z The result is an inability of the body to remove glucose
from blood and store it as glycogen.
Understanding
U
de sta d g Type
ype I & II Diabetes
abetes
zhttp://www.youtube.com/watch?v=jHRfDTqPzj
zhttp://www.youtube.com/watch?v
jHRfDTqPzj
4&feature=em-share_video_user
z8 minutes
Gonads (sex glands)
z Differ in men and women
zWomen have ovaries that secrete estrogen
{estrogen is responsible for secondary sex characteristics
zbroad hips
zBreast development
zMen have testes that secrete testosterone
{testosterone is responsible for secondary sex
characteristics
zbroad shoulders
zfacial hair
ENDOCRINE VS. EXOCRINE
GLANDS
GLAND
SECRETION METHOD OF WHERE
TRANSPORT SECRETION
FUNCTIONS
LIQUID,
EXOCRINE OFTEN
(DUCT
GLAND)
DUCT
CONTAINING
ENZYMES
ENDOCRINE HORMONE BLOOD
BLOOD(DUCTLESS
STREAM
GLAND)
ORGAN
NEAR
GLAND
ORGAN
DISTANT
FROM
GLAND
EXAMPLES OF ENDOCRINE AND
EXOCRINE SECRETIONS
EXOCRINE:
z SALIVA
z SWEAT
z BILE
z TEARS
ENDOCRINE:
z INSULIN
z ADRENALINE
z THYROXIN
z HUMAN GROWTH
HORMONE (HGH)
(
)
z ESTROGEN
z TESTOSTERONE
Review with Hank – Crash Course
zhttp://www.yout
zhttp://www
yout
ube.com/watch?v
=WVrlHH14q3o
& eatu e e
&feature=emshare_video_user