Download Human Endocrine System

Chapter 39
Human
Endocrine System
Endocrine System
 Consist of endocrine glands that
secrete hormones which regulate a
wide range of activities in humans
 Hormones- are secreted by glands
and diffuse directly into the
bloodstream
Note: Not
all of the
glands
listed in
this
diagram
are
endocrine
glands.
(1) Hypothalamus
Small region of the brain
It controls the release of hormones
by the pituitary gland
Considered to be a major link
between the nervous system and the
endocrine system
Location of the Hypothalamus and
Pituitary
(2) Pituitary Gland
Located at the base of the brain
Called the “master gland” because
it controls the activities of other
glands
Secretes these major hormones:
FSH, LH, ACTH, TSH,
Prolactin, Ignore, GH or FLAT PIG
Growth Hormone (GH)
This hormone controls the
growth of the body by
stimulating the elongation of
bones
Affects of Growth Hormone
What movie is the above
picture from?
The Princess Bride
André the Giant (May 19, 1946 – January 27, 1993)
was a professional wrestler and actor, born André
René Roussimoff in Coulomiers, France. He was at
least 208 cm (6 feet 10 in) tall and believed by many to
have been over 213 cm (7 feet) at his tallest. His great
size was a result of excessive growth hormone, a
condition known as pituitary gigantism, and led to him
being dubbed "The Eighth Wonder of the World[1][2]."
Thyroid Stimulating
Hormone (TSH)
Stimulates the thyroid gland to
produce its hormone thyroxin
When thyroxine (T4)
levels are too low, the
hypothalamus releases
more TRH, that in turn
stimulates the anterior to
produce more TSH,
causing the thyroid to
produce more thyroxine.
As the thyroxine levels
increase, a signal is sent
back to the hypothalamus,
causing it to release less
TRH. When a change
occurs that causes the
release of a chemical that
reverses the direction of
that change, this is known
as negative feedback.
Follicle Stimulating
Hormone (FSH)
Stimulates
the
activities of
the ovaries
and testes
Adrenocorticotropic Hormone (ACTH)
 ACTH stimulates the
cortex of the adrenal
glands to secrete
steroid hormones such
as cortisol, a hormone
involved in the
production of glucose
in the liver from
amino acid and lipid
sources.
(3) Thyroid Gland
 Located in the neck
below the larynx
and in front of the
trachea
 This gland secretes
thyroxin which
contains iodine
Thyroxin
 Regulates the rate of metabolism in the body and
is essential for normal physical and mental
development
 Secretion of thyroxin is regulated by TSH, which
is secreted by the pituitary gland
 Lack of iodine in the diet will lead to lack of
thyroxin secretion. This produces enlargement of
the thyroid gland and is called Goiter
 Goiter- is the result of iron deficiency in the diet
Goiter (enlargement of the thyroid
gland)
Thyroid with Goiter
(Cells are enlarged)
Normal Thyroid
An Individual with Goiter
(4) Parathyroid Gland
 Are tiny oval glands
embedded in the walls of
the thyroid gland
 Secretes parathormone
 Parathormone controls
calcium metabolism
 Calcium is necessary for
proper growth of teeth and
bones, blood clotting, and
nerve function
(5) Adrenal Gland
 Located on the top
of each kidney
 Each gland consists
of two layers:
Adrenal cortex
Adrenal medulla
Adrenal Cortex
Secrete steroid hormones that:
a) regulate water balance and blood
pressure by controlling the
reabsorption of sodium salt into the
blood from the kidneys
b) stimulate the conversion of fat
and protein into glucose
(gluconeogenesis)
Adrenal Medulla
Secretes adrenalin
(epinephrine)
Adrenalin increases the blood
sugar level and accelerates the
heart and breathing rate
Known as the “fight or flight”
hormone
(6)
Pancreas
 Both an exocrine gland and an endocrine gland
 The exocrine portion secretes digestive juices into
the small intestine
 The endocrine portion consists of small clusters
or “islands” of hormone-secreting cells called the
Islets of Langerhans
 The Islet of Langerhans secrete insulin and
glucagon
 The Islets of Langerhans secrete insulin and
glucagon
Location of Pancreas in Body
Stomach
Pancreas
Insulin
 Facilitates the entrance of glucose
into the cells
 Insulin lowers blood sugar levels by
promoting the movement of sugar out
of the blood and into the liver where
it is stored as glycogen
Glucagon
 Stimulates the release of sugar from
the liver and into the blood
 Therefore:
insulin  lowers sugar level in blood
glucagon  raises sugar level in blood
Diabetes
When the Islets of Langerhans fail
to produce enough insulin
As a result, glucose that enters the
cell decreases, and glucose levels
in the blood increases
(7)
Gonads
 Sex organs
1. Males- testes that secrete
testosterone which influences the
development of the male secondary
sex characteristics
2. Females- ovaries that secrete
estrogen which influences the
development of secondary sex
characteristics
Negative Feedback
 Is a type of self-regulation associated with
endocrine regulation
Functions like a thermostat. Only activated
when there is a need. Shuts off once that
need has been met.
Negative Feedback
 It operates on the principle that the level of
one hormone in the blood stimulates or
inhibits the production of another hormone
Ex: TSH regulates the secretion of thyroxin
by the thyroid gland