Download hormones - Lemon Bay High School

Chapter 9
The Endocrine System and
Hormone Activity
Overview
• Coordinates and
directs the activity of
cells.
• Interacts with the
nervous system
• Uses chemical
messengers called
hormones released by
organs and tissues
called GLANDS.
• Controls
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Reproduction
Growth and development
Immune Defense
Balance of fluids and
electrolytes
Mechanism of Action
• Hormones only affect certain tissues
or organs:
• Hormones bind to specific sites on
the plasma membrane:
Receptors
• The hormone becomes active once
the hormone is bound to its receptor.
Classification of Hormones
Amine
• Chemical bases are the amino acids tyrosine and
tryptophan.
• Acts through a Second Messenger System
– Binds and activates a cell through receptor-binding on the
target cell membrane.
• Does NOT enter the cell; remains on the outside of
the cell membrane.
Peptide
• Chemical base is a chain of amino acids.
• Acts through a Second Messenger System
– Binds and activates a cell through receptor-binding on the
target cell membrane.
• Does NOT enter the cell; remains on the outside of
the cell membrane.
Classification of Hormones
Lipid/Steroid
• Chemical base is cholesterol.
• Acts by Direct Gene Activation
– Targets specific gene sequences within the genetic
instructions that maintain cellular homeostasis.
• DOES enter both the cell membrane and the nuclear
membrane of the target cell because it is lipidsoluble.
Hormone Action
Once a hormone has activated its target, what
impact does the hormone have on cell function/
action?
Examples…
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Change in membrane permeability
Change in membrane electrical state.
Initiate the synthesis of molecules by the cell.
Activation/Inactivation of enzymes.
Stimulating or impeding mitosis
It all depends on the need(s) of the cell/organism.
Control of Hormone Release
What determines when, where, why a hormone
is released by a gland?
3 categories of stimuli/control
1. Hormonal stimuli: hormones stimulate hormones.
2. Humoral stimuli: blood levels of ions and nutrients
stimulate hormones.
3. Neural stimuli: nerve fibers stimulate hormones.
Pituitary Gland
“The Master Gland”
• 2 Functional Lobes
– Anterior Lobe
– Posterior Lobe
• Interacts closely with
the Nervous System
through the
Hypothalamus.
Sphenoid Bone
Anterior Pituitary
• Regulated through hormonal
stimuli from the hypothalamus.
• Many of the hormones released
are Trophic/Tropic Hormones:
–A hormone that stimulates other
endocrine glands to secrete their
hormones.
Anterior Pituitary Hormones
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Growth Hormone (GH)
Thyroid Stimulating Hormone (TSH)
Adrenocorticotropin Hormone (ACTH)
Follicle Stimulating Hormone (FSH)
Luteinizing Hormone (LH)
Melanocyte Stimulating Hormone (MSH)
Hypersecretion
of GH
Acromegaly is caused by too
much growth hormone AFTER
puberty has completed.
Gigantism is caused by too much growth
hormone during adolescence and
puberty.
Posterior Pituitary
• Regulated through neural stimuli
from the hypothalamus.
• Produces 2 hormones in response to
nervous system stimulation.
• Antidiuretic Hormone (ADH)
• Oxytocin
Thyroid Gland
• Located in the
anterior portion of
the neck, just below
the throat.
• Releases 2
hormones that act on
the metabolic rate.
*T4: thyroxine
*T3: triiodothyronine
• Also produces the
calcitonin.
Parathyroid Gland
• Located on the
posterior surface of
the thyroid gland.
• Secretes
parathyroid
hormone: most
important regulator
of blood calcium
levels.
Adrenal Glands
• Located on the
superior aspect of
each kidney.
• 2 functional parts
*Cortex
*Medulla
Each part secretes a
specific type of
hormone.
Adrenal Gland Divisions
CORTEX
• Produces
hormones that
control fluid and
electrolyte
balance.
• Produces sex
hormones.
MEDULLA
• Produces
hormones for
sympathetic/
parasympathetic
nervous system.
Pancreas
• Located in
abdominal cavity
close to stomach.
• Produces
hormones for the
effective use and
storage of
glucose.
*insulin
*glucagon
Pineal Gland
• Pea-sized; found on
roof of 3rd ventricle in
the brain.
• Cells of pineal gland
closely associated
with optic tracts in the
brain.
• Produces hormone
(melatonin) that
activates sleep-wake
cycles.
Thymus Gland
• Located behind the
sternum.
• Decrease in size as
you age.
• Produces hormone
(thymosin) needed for
the production of Tlymphocytes.
T-cells are active in
immune protection
against viral
infections.
Ovaries and Testes
• Hormone producing glands of the female and
male reproductive systems.
• Controls fertility, reproduction, and gestation.
•
Ovaries produce
and release
estrogen and
progesterone
•
Testes produce
testosterone and
androgens
Other Hormone-Producing
Organs
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Placenta
Stomach
Intestines
Heart
Striated muscles
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Skin
Adipose/Fat
Liver
Kidneys
Uterus