Download REGULATION

REGULATION
Part II
CHEMICAL REGULATION
(The Endocrine System)
Regulation
- includes the processes by which organisms respond to
stimuli within & around them.
It results in the coordination and control of life
processes.
Regulation is achieved by the integration of the
NERVOUS SYSTEM & the ENDOCRINE SYSTEM
I. SIMILARITIES between Nervous & Endocrine Systems
(Chemical vs. Nervous Regulation)
A. both maintain homeostasis
B. both secrete chemicals- such as:
Nervous System
Secretes neurotransmitters
Endocrine System
Secretes hormones
II. DIFFERENCES between Nervous & Endocrine Systems
A. Endocrine System response last longer
B. Nervous System response is faster
C. Nervous System impulses travel via neurons
D. Endocrine System hormones travel via
bloodstream
1. Associated with organs and tissues of the body that
collectively release substances known as hormones.
2. Known also as ductless glands because their
secretions are released directly into the bloodstream.
B. Glands- organs specialized for secretion
1. Exocrine glands- discharge secretions into ducts such
as digestive tract glands
ex.liver, pancreas, salivary, sweat
2. Endocrine glands- "ductless glands" discharge into
bloodstream
ex.) Pituitary, thyroid, thymus, pancreas, parathyroid, adrenal
glands
C. Hormones
“chemical messengers” secretions produced by the
endocrine system that target specific tissue
There are two types
1. Protein-type hormones [ex. insulin, thyomisin]
2. Steroid-type hormones [produced by the adrenals]
a. Anabolic Steroids- synthetic version of male hormone
testosterone which lead to increased muscle bulk & strength
in both males and females. Side effects are: acne, head aches,
sterility, stimulated growth, cancer & death.
REGULATION of HORMONE
1.POSITIVE FEEDBACK
reinforces original change [ex. poison ivy- first you get a
rash, then you scratch...then you have a larger rash,
then you scratch more....stop scratching]
2. NEGATIVE FEEDBACK
"self-regulation"
1. Mechanism by which hormone secretions are
regulated (works like a thermostat)
2. One hormone in the blood stimulates or inhibits the
production of another hormone
3. Opposes original change
ex.)[Estrogen & FSH] + [Thyroid Stimulating Hormone
(TSH) & thyroxin] +[Testosterone and Feedback
inhibition]
Negative feedback loops have been compared to a
thermostatically controlled temperature in a house,
where the internal temperature is monitored by a
temperature-sensitive gauge in the thermostat. If it is
cold outside, eventually the internal temperature of the
house drops, as cold air seeps in through the walls.
When the temperature drops below the point at which
the thermostat is set, the thermostat turns on the
furnace. As the temperature within the house rises, the
thermostat again senses this change and turns off the
furnace when the internal temperature reaches the preset point.
When you eat carbohydrates that include sugars (low density),
white flour, grains - all types, fruits and vegetables, your body
converts these to glucose that goes into your blood stream. The
hypothalamus gland senses a rise in blood sugar and sends
hormones to your pancreas to release insulin from the beta cells
(islets of langerham cells). Each cell in your body contains
insulin receptor sites. These receptor sites act like a lock on a
door to the cell. When insulin gets to the cell, it acts like a key
to open the cell door and allow glucose to enter the cell. The
glucose goes into the mitochondria where it goes through a
Krebs cycle that produces 2 units of energy for each 1 unit of
pyruvic acid that was formed from the glucose. This is how you
get energy from the glucose.
Now, when the glucose level in the blood is adequate, the hypothalamus
senses this and to stabilize the blood sugar, it sends a hormone to the
pancreas to produce glucagon. The glucagon is sent to the liver where the
glucose is now converted to glycogen and stored in the liver. If too much
sugar is eaten too quickly, the liver sends the glycogen to other parts of
the body. This overload of sugar does two other primary things, it causes
the insulin receptor sites to become fatigued because they start rejecting
the insulin and this is where diabetes type II insulin resistance can
happen. The next thing is the excess glucagon being produced drops the
blood sugar to a low point, and this triggers the body to think it is in a
major stress mode. This triggers the adrenal glands to fire and produce
CORTISOL, the stress hormone.
When you don’t get enough iodine your thyroid doesn’t
work correctly. This is what can happen:
IV. The Human Endocrine System
A. Hypothalamus
-controls body temperature, blood pressure, sleep & emotions
1. Produces secretions that stimulates the pituitary
B. Pituitary Gland-"master gland"
1. Secretes hormones that control the activity of other
endocrine glands and regulate
various biological processes.
The pituitary gland is influenced both neurally
and hormonally by the hypothalamus.
2. Pituitary Secretions include:
1. growth hormone GH
(stimulates cellular activity in bone, cartilage, and other structural
tissue) disorders for GH include giantism (hypersecretion) &
dwarfism (hyposecretion)
2. thyroid stimulating hormone TSH
(causes the thyroid to release thyroxin)
3. follicle stimulating hormone FSH
(stimulates activity in the ovaries & testes)
4. lutenizing hormone LH
(causes the release of egg cells from ovaries & controls sex
hormones in males + females)
5. antidiuretic hormone ADH
vasopressin (which causes the nephrons of the kidney to excrete less
water in the urine) ALCOHOL STOPS THE RELEASE OF ADH;
therefore, IT CONTRIBUTES TO A HANGOVER
C. Thyroid Gland
produces thyroxin that is made of iodine
1. located in the neck
2. thyroxin regulates the rate of metabolism
D. Parathyroid Glands
produces parathormone, located within the thyroid
1. parathormone controls metabolism of calcium which is
necessary for growth, health of bones & teeth, *BLOOD
CLOTTING*, nerve functions + muscle contraction
E. Adrenal Glands
- secrete adrenaline causes "Flight or Fight" action
adrenaline causes blood vessels to constrict, heartbeat,
blood pressure, clotting
adrenaline also increases rate of metabolism and release of
glucose by liver [example: slows flow of digestive juices]
F. Pancreas- ISLETS of LANGERHANS (cells found
within pancreas)
-is both exocrine & endocrine gland
secrete hormones such as glucagon & insulin
Insulincauses absorption of sugar into body cells which results
in lowering blood sugar levels.
The cells of the body need glucose as a source of
energy.
This sugar simply doesn't pass into the body cells.
INSULIN MUST BE PRESENT.
Also, insulin turns glucose into glycogen for
storage of energy.
Glucagon- cause discharge of sugar from liver into blood which results
in raising blood sugar levels glycogen into glucose.
(opposite of insulin)
G. Gonads- sex glands (two each)
1. in females OVARIES secrete many hormones one is
estrogen which causes development of female
REPRODUCTIVE system & sex characteristics
2. TESTES in males secrete testosterone which causes
development of male sex characteristics
V. Disorders of the Endocrine System
A. Goiter
- enlargement of the thyroid gland usually resulting from the
gland’s inability to make thyroxin. It is associated with iodine
deficiency in diet.
B. Diabetic Mellitus -(form of diabetic coma)disorder characterized by an
INSULIN deficiency (hypoglycemia) that results in an
elevated blood sugar level.
C. Diabetes Insipidus,
rare disease caused by deficiency of vasopressin, one of the
hormones of the posterior pituitary gland, which controls the
amount of urine secreted by the kidneys. The symptoms of
diabetes insipidus are marked thirst and the excretion of large
quantities of urine, as much as 4 to 10 liters a day. This urine
has a low specific gravity and contains no excess sugar. In
many cases, injection or nasal inhalation of vasopressin
controls the symptoms of the disease.
D. Diabetic Shockhypersecretion of insulin. Glucose level in blood drops, leads
to death, unconsciousness or convulsions.