The three main patterns of hormone secretion are humoral,
hormonal, and neural stimuli and each are responsible for managing different
hormones. One of the responsibilities of the Humoral stimuli is managing the
changes within the blood levels of non-hormone chemicals. One example of this
is if the body suddenly spiked high levels of glucose it would trigger a
hormone release from the pancreas. This hormone is known as insulin. Insulin’s
job would be to bring the blood glucose levels down. The main function of
Hormonal stimuli is to release hormones when stimulated by other hormones from
the endocrine gland, such as the hypothalamus. For example, the hypothalamus
and the pituitary gland are known as the command center of the endocrine
system. The hypothalamus actually produces hormones that trigger other hormones
belonging to the anterior pituitary gland. Finally, the Neural stimuli responds
to nerve stimulation and will release hormones when triggered. For example, if
the body senses danger the Neural stimuli is triggered and will release
hormones call norepinephrine and epinephrine from the adrenal glands. These
hormones are responsible for the fight-in-flight stimulation.
The relationship, as explained above, between the hypothalamus and
is known as the command
center of the endocrine system. The hypothalamus is responsible for releasing hormones
that stimulate other hormones in the anterior pituitary gland. The hypothalamus
and the anterior pituitary gland are able to communicate through what is called
the hypophyseal portal system, and by releasing and inhibiting hormones. The
portal basically serves as a bridge between the hypothalamus and the anterior
side of the pituitary gland.
Hydrophilic hormones are amino acid based peptides and proteins.
They are water soluble in water and insoluble in lipids. Hydrophilic messengers
are also unable to cross the cell membrane and rely on a transduction system to
send signals across the cell membrane. Hydrophobic hormones on the other hand
are insoluble in water but soluble in lipids. They are made up of mostly
steroids and are able to cross the cell membrane.
Insulin and glucagon are hormones that are secreted from the
pancreas and are in charge of regulating glucose levels in the blood. When
glucose levels are to high the pancreas releases insulin. Insulin then
increases the liver’s storage of glycogen which brings blood sugar levels back
down. However, if glucose levels are too low, the pancreas releases glucagon
which breaks down glycogen in order to raise blood sugar levels back up.
Here are the following descriptions of the hormones thyroid,
parathyroid, adrenal glands, pineal gland and they thymus gland.
o The thyroid is located in the
neck, in front of the trachea, where it wraps around it. One hormone that the
thyroid releases is calcitonin. Calcitonin is released whenever there is a rise
in blood calcium levels. By releasing calcitonin, the hormone is able to reduce
the blood calcium levels. One way of doing this is by increasing calcium loss
through the urine.
o The Parathyroid is located on
the thyroid gland towards the back. Most period have four parathyroid glands.
Two on each side. The parathyroid releases the parathyroid hormone, also
referred to as PTH. PTH is responsible for regulating calcium levels.
o The Adrenal glands are
located on top of the kidneys. There are two glands total. One on each kidney.
They are responsible for regulating sodium and potassium ions through the
urine, sweat and saliva.
o The Pineal gland is located
inside the bran, just behind the third cerebral ventricle, not to far from the
thalamus. Not much is known about the pineal gland, except that it produces the
melatonin hormone which helps regulate sleep.
o The Thymus gland is located
in the upper anterior part of the chest, between the lungs. Not much is known
about the thymus gland, but what is known is that it plays a role in the immune
system. The thymus gland produces the hormone thymosin, which helps contribute
to the disease fighting T lymphocyte cells.