Transcript parafollicular cell hormone

Pituitary Hormones
Growth Hormone (GH)
Also known as somatotropin
 Gland Source = Adenohypophysis
 Target = GH affects all cells, epiphyseal growth plate, skeletal
muscles
 Action = The three major ways it affects the body are:
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Increase cell growth, mitosis, protein production
Simulates the epiphyseal growth plate (bones) & repair and
maintenance of skeletal muscles
Encourage cells to use fats for fuel (gluconeogenesis: gluco=glucose;
neo=new; genesis=to create
Stimulus for release=Hypothalamus releases GRH (Growth
Release Hormone)
Inhibit=Hypothalamus will release GIH (Growth Inhibitory
Hormone)
Problems: Pituitary Dwarfism, Low GH levels in adults, Pituitary Gigantism,
And Acromegaly
Thyroid Stimulating Hormone
(TSH)
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Gland Source=Adenohypophysis
Target=Thyroid (makes sense…because the name of the
hormone gives it away )
Action=stimulates the thyroid to make and release thyroxin
Stimulus for release=Hypothalamus releases TRH (Thyroid
Release Hormone) when the level of thyroid hormones
decrease in the blood.
Inhibit-Negative Feedback Loop: When the hypothalamus
detects an increase or normal levels of thyroid hormone in
the blood, it will stop sending TRH.
Adrenocorticotropic Hormone
(ACTH)
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Gland Source=Adenohypophysis
Target=Adrenal cortex
Action=Stimulates the adrenal cortex to release
corticosteroid hormones (Cortisol is the main one) to help
the body resist stress.
Stimulus for release=Hypothalamus release CRH
(Corticotropic Release Hormone).
Inhibit=Negative Feedback: An increase in levels of
Cortisol in the blood causes the hypothalamus to decrease
and/or stop CRH
Follicle Stimulating Hormone (FSH)
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Gland source=Adenohypophysis
Target=Follicle egg maturation in the ovary; sperm
production in the tubes of the testes (the testes are made up
of 700 feet of seminiferous tubules!)
Action=This hormone’s primary function is to stimulate
gamete (egg and sperm) formation. It can also help with the
release of estrogen and testosterone from the gonads.
Stimulus for release=at the beginning of puberty and all
through out the reproductive years, the Hypothalamus will
release GnRH (Gonadotropin Releasing Hormone)
Inhibit= Negative Feedback: When the levels of estrogen
& testosterone rise, the Hypothalamus decreases its release
of GnRH.
Luteinizing Hormone (LH)
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Gland Source=Adenohypophysis
Target=ovaries and testes (the interstitial cells)
Action=stimulates ovulation in the ovary. The ovulation
process causes the release of progesterone (the other female
hormone); the testosterone production in the testes.
Stimulus for release= Hypothalamus releases GnRH
Inhibit=Negative Feedback: As the level of progesterone
and testosterone rise, the hypothalamus decreases its release
of GnRH.
Prolactin (PRL)
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Gland source=Adenohypophysis
Target=primary target is the mammary glands (breasts)
Action=stimulates the mammary glands (breasts) to produce milk
in females; in males, it enhances the effects of ICSH (LH)
Stimulus for release=Hypothalamus releases PRF (Prolactin Release
Factor). (Another Stimulus: when a mother is in the period of time
that she is breast feeding her child, an infants feeding causes more
milk to be made. As long as the infant breasts feed, the mother will
make milk.)
Inhibit=Hypothalamus releases PRIF (Prolactin Release-Inhibiting
Factor). It is not really understood what causes the hypothalamus
control of this hormone. Some women who do not wish to
continue or participate in breast-feeding, can ask their doctor for
the latest treatment to inhibit milk production.
Melanocyte Stimulating Hormone
(MSH)
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Gland source=Adenohypophysis
Target=Melanocyte
Action=Stimulates the production of melanin to protect the skin
from UV rays in fish, amphibians, reptiles, and other mammals. Its
levels are too low in a human to have a significant effect. There are
few times that MSH can affect humans:
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In pregnant women
During fetal development
In very young children
In young children
The reason some of these incidences occur is not understood.
Stimulus for release=Hypothalamus releases MRF (MSH-Releasing
Factor) This release is thought to be caused by sunlight on the
photosensitive receptors in the skin and eyes.
Inhibit=by the increase levels of dopamine (a hormone in the
brain)
Oxytocin
Gland source=Neurohypophysis
 Target=uterus wall (smooth muscle) and the breast area
around the nipple (there is no known normal function of
oxytocin in males.)
 Action=causes strong (and I mean STRONG) uterine
contractions [a.k.a labor contractions or labor pains] during
birth). Oxytocin also stimulates the area around the nipples
to eject milk. This really peaks after the birth of the child.
 Stimulus for release=stretch receptors in the vagina and
touch receptors around the nipples.
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 Oxytocin is a great example of a positive feedback loop during birth.
 As the baby is pushed down the vaginal canal (also known as the birth canal), there
is more and more stretching. This stretching causes more pain and stimulation to
the hypothalamus, which in return sends more oxytocin.
Oxytocin (cont.)
Stimulus=Another stimulus for oxytocin is milk ejection. The
ejection and flow of milk is known as lactation. This will
continue as breast-feeding continues.
 Inhibit=Once the stretching of the vaginal wall is finished, the
hypothalamus will stop the release of oxytocin to the uterus.
(Oxytocin will continue to the breast.) This takes a few days
to come down and end with a negative feedback.
 Problems: If a woman goes longer than expected in her
pregnancy, her pregnancy can be induced with the synthetic
form of oxytocin called Pitocin. Pitocin can also be used to
increase the intensity of the contractions when a woman’s
contractions are too weak or to control bleeding of the
uterus after birth.
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Endocrine Hormones
Antidiuretic Hormone
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Anti=against;
Diuretic=urine formation
◦ This hormone hinders urine formation.
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Gland source= Neurohypophysis
Target=kidney (more exactly, the distal end of the nephrons and
collecting tubes.)
Action=instructs kidney (nephrons) to pull water out and place it
into the blood (reabsorb). Instead of this water being a part of
urine and going to the bladder to be excreted, it is placed back into
the blood.
◦ This hormone rehydrates us!
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Stimulus for release=Dehydration
Inhibit=Hydrated (Hypothalamic osmoreceptors detect that the
thickness of blood is normal.)
Problems: Diabetes insipidus
Triiodothyronine (T3) and
Thyroxin (T4)
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FOLLICLE HORMONE
Gland source=Thyroid gland (follicles)
Target=All body cells
Action=Accelerates the rate of cellular metaboloism
(mitochondria breakdown of carbohydrates, rate of protein
synthesis, and lipid breakdown) in every body cell
Stimulus for release=Low levels of T3 & T4 in the blood trigger
the hypothalamus to release TRH, which causes TSH to be released
and stimulate the thyroid.
Inhibit=Negative feedback (normal blood levels of T3 & T4
Problems:
◦ Hypothyroidism
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Goiter
Cretinism
Myxedema
◦ Hyperthyroidism: Grave’s disease
Calcitonin
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PARAFOLLICULAR CELL HORMONE
Gland source=Thyroid gland (parafollicular cells)
Target= Osteoblasts and intestines
Action=Stimulates the osteoblasts to pull Ca++ from the
blood and deposits into the bone (make bone tissue!) and
causes a decrease in Ca++ absorption in the intestines. Job is
simple to lower the blood Ca++ levels.
Stimulus for release=(Humoral) High blood Ca++ levels
Inhibit=Negative feedback (normal or low blood Ca++
levels)
Problems: Tetany, Osteitis Fibrosa Cystica
Parathyroid Hormone (PTH)
Gland source=Parathyroid Glands
 Target=Three main targets:
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Osteoclasts are stimulated to break down bone matrix and place
Ca++ into the blood.
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Instruct the kidneys to retain Ca++ and not allow it to be excreted.
3.
Stimulate the skin to produce more Vitamin D to stimulate the
intestines to absorb Ca++.
Action=All three targets help raise the blood Ca++
levels!
Stimulus for release= (Humoral) Low blood Ca++ levels
stimulate production and release of PTH.
Inhibit=Normal (9-11mg/100ml of blood) levels of Ca++ or
high levels of Ca++ (Negative feedback).
Aldosterone
Gland source=Adrenal cortex (Zona Glomerulosa)
 Target= Kidney (distal tubule of the nephrons)
 Action=instructs the reabsorption of Na+ (Which also
causes water to be reabsorbed). This results in the not only
increase of Na+ but also increases blood pressure.
 Stimulus for release=Major regulation: ReninAngiostensin System
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◦ Other stimulators: Low Na+ and High K+ levels and ACTH is
released to increase blood pressure during times of stress.
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Inhibit=High Na+ and Low K+
◦ ANF (Atrial Natriuetic Factor) This hormone is released by the heart
when blood pressure goes to high. ANF inhibits Renin and Aldosterone.
Cortisol (Glucocorticoids)
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Gland source=Zona Fasciculata of the Adrenal Cortex
Target=Adipose Tissue and Liver (these are the main targets)
Action=Gluconeogenesis (Gluco=glucose; neo=new;
genesis=creation of something. “The creation of new sugar!”)
◦ Cortisol causes glucose to be formed from the breakdown of fats and
protein during tomes of long-term stress. This process helps keep the
glucose level in the normal range during times of long term stress such as
loosing a job, loved one, divorce, illness, and others
◦ During a daily cycle, Cortisol is higher in the morning than in the evening.
Handling stress in the morning seems to be much easier than later in the
day.
◦ High levels of cortisol (Glucocorticoids) can be used to act as an antiinflammatory and Anti-histamine.
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Stimulus for release=Stress
Inhibit=Negative feedback (no CRH from the Hypothalamus
because stress level is low)
Problems: Cushing’s Disease, Addison’s Disease
Gonadocorticoids (Androgens)
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Androgens develop mainly into male hormones and a very small
amount into female hormones.
Gland source= Adrenal Cortex (Zona Reticularis)
Target=High levels occur mostly in the fetus and in early puberty,
after this time has past, the gonads take over.
Action=Increases cell metabolism, red blood cell production in
infants. In adult females, may play a role in the level of sex drive
(libido) and provide some female hormones during menopause. In
males, androgens may more or less effect amounts of body hair
upon onset of puberty.
Stimulus for release=ACTH
Inhibit=Negative Feedback
Problems=In young men, a high amount of androgens can result in
rapid sex characteristics and a very high sex drive. In young women,
high levels of androgens can result in facial hair, and a male pattern
of body hair distribution In some cases, the clitoris can grow to
look like a small penis.
Epinephrine and Norepinephrine
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Gland source=Adrenal Medulla
Target= Heart, blood vessels, respiratory system, liver, and skeletal
muscles
Action=Increases blood sugar, blood pressure, heart arte,
and blood flow to brain, heart, and skeletal muscles (vasodilation
in these areas). Vasoconstriction to the skin and GI(gut) in
order to redirect blood to the systems that can get you out of
danger. Bronchi and bronchiole dilation to increase air
exchange during the event.
All this produces the “FIGHT OR FLIGHT” response!
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Stimulus for release=Signals from the brain to the hypothalamus
trigger the Sympathetic Nervous System, to activate the adrenal
medulla.
Inhibit=Neural stimulation end and the liver and kidneys quickly
remove these hormones from the body. This is a short term effect
on the body.
Glucagon
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Gland Source=Pancreas (Alpha Cells of Islet of Langerhans)
Target=Liver and Adipose tissue (fat)
Action= Instructs the Liver to change Glycogen into glucose
(Glycogenolysis) [1 Glycogen molecule= 1,000,000
molecules of glucose; -olysis=break down]
Glycogenolysis=breaking glycogen down in to glucose
Glucagon causes glucose to be formed from the breakdown
of fats and protein to raise blood sugar into the normal
range.
Stimulus for release= low blood sugar (humoral response)
Inhibit=high blood sugar (negative feedback)
Insulin
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Gland source= Pancreas (Beta Cells of Islet of Langerhans)
Target=all body cells (liver, kidney, and brain does not need insulin)
Action=Insulin stimulates the cells:
1. Respiration of glucose into ATP
2. Excess glucose is turned into glycofen (Glycogenesis)
3. When the glycogen storage is full, excess glucose is turned into fat
4. Amino acids are taken in for protein synthesis (repair & growth)
5. Free fatty acids (tails of the triglyceride) are covered into lipids
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Stimulus for release=high blood sugar (glucose), amino acids, and
fatty acids (humoral control)
Inhibit=negative feedback (low blood sugar, amino acids, and fatty
acids
Problems: Diabetes mellitus
Estrogen
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Gland source=ovaries
Target=Most body cells and the female’s reproductive organs.
Action=Development of secondary sex characteristics
(female), supports the egg (oocyte) maturation, and works
with progesterone for breast development and the menstrual
cycle.
Stimulus for release=FSH and LH
Inhibit=Negative feedback
Progesterone
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Gland Source=ovaries (corpus luteum)
Target=uterus and breast (mammary glands)
Action=Prepares the lining (endometrium) or the uterus for
a fertilized egg and causes swelling in the breasts (PRL works
here with progesterone)
Stimulus for release=LH
Inhibit=Negative feedback
Testosterone
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Gland source=Testes (interstitial cells)
Target=Most body cells and seminiferous tubules
Action=Stimulates the production of sperm (spermatogenesis),
secondary male sex characteristics, promotes protein synthesis in
skeletal muscle (repair and maintained of the muscle).
Stimulus for release=LH
Inhibit=Negative feedback
Problems=There are many major health problems with the use of
this ‘extra’ testosterone: the negative feedback to the testes causes
them to stop producing their own testosterone, which can lead to
testicular atrophy. Testosterone is an aggressive hormone and
adding more of this hormone to the body can cause extreme
aggressive behavior. This hormone causes major internal organs to
enlarge, and other major problems that can lead to a lifethreatening situation.