Download Thyroid Gland

Why you should enter the
Endocrinology Field
By Charles Chen, Aleem Malik, &
Danny Yang
WHAT DO ENDOCRINOLOGISTS DO?
 Most endocrinologists are specialized
internists, OB/GYN’s, or pediatricians
 They make diagnoses of a wide variety of
symptoms and variations and deal with
disorders related to deficiency or excess
of hormones.
 They diagnose a variety of diseases
Different parts of the Endocrine System
 Pituitary Gland
• Located inferior to the hypothalamus ;
looks like a pea on a stalk
• Secretes at least 9 hormones
• Posterior lobe releases neurohormones
• Anterior lobe releases adenohypophysis
Adenohypophyseal Hormones
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• Melanocyte- stimulating hormone (MSH) CNS Neurotransmitter that controls
appetite
• POMC- Source of two natural opiates
• Growth Hormones- targets mainly bones and muscle
• Thyroid-stimulating hormone (TSH)- Stimulates normal development and
secretory activity of the thyroid gland
• Adrenocorticotropic Hormone (ACTH)- stimulates the adrenal cortex to
release corticosteroid hormones
• Gonadotropins- Follicle-stimulating hormone (FSH) and luteinizing hormone
(LH)
o FSH stimulates gamete production
o LH promotes production of gonadal hormones; trigger ovulation
• Prolactin (PRL)- protein hormone
o Produced by lactotrophs; stimulates milk production in breasts
o Estrogen stimulates prolactin (breast swelling during menstrual period)
• Oxytocin- Released during childbirth, allows stretching of uterus
o Hormonal trigger for milk ejection
• Antidiueretic Hormone (ADH)- Prevents urine formation; helps the body avoid
dehydration
o Releases when solute concentration in blood is too high
o Alcohol inhibits ADH secretion
Thyroid Gland
•
• Largest pure endocrine
• Located in the anterior neck on the trachea just
inferior to the larynx
• Thyroid Hormone (TH)- thyroxine(T4) and
triiodothyronine (T3)
o Affects virtually every cell in the body
Stimulates enzymes with glucose oxidation,
increases basal metabolic rate and body heat
production (calorigenic effect)
• Calcitonin- Produced in C cells of the thyroid
gland
o Inhibits osteoclast activity
o Only important in childhood
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Parathyroid Gland
• Parathyroid hormone (PTH) is the single most important hormone controlling
the calcium balance of the blood.
o PTH is released by falling blood Ca2+ levels and inhibited by hypercalcemia
o Precise control of Ca2+ is critical for nerve impulses, muscle contraction and
blood clotting
Adrenal (Suprarenal) Glands
• Sits on top of kidneys
• Corticosteroids
• Mineralocorticoids
o Aldosterone- maintain sodium ion balance
• Glucocorticoids
o Influence the energy metabolism of most body cells and help us to resist
stressors
o Maintain blood glucose levels
• Gonadocorticoids (Sex hormones)
o Testosterone and estrogen
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Pancreas
• Glucagon- extremely potent hyperglycemic agent
o Breakdown glycogen to glucose
o Synthesis of glucose from lactic acid
o Release of glucose to the blood by liver cells
• Insulin- lowers blood glucose levels
o Inhibits the breakdown of glycogen to glucose
o After glucose enters a target cell, insulin binding triggers
enzymatic activities that
1. Catalyze the oxidation of glucose for ATP production
2. Join glucose molecules together to form glycogen
3. Convert glucose to fat
Gonads
• Male and female gonads produce steroid sex hormones
• Testosterone and estrogen are responsible for the maturation of
reproductive organs
o Produced in the testes and ovaries
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Pineal Gland
• Hangs from the roof of the third
ventricle in the diencephalon
o Melatonin-sleep hormone
Affects the timing of puberty
Thymus
• Part of the immune system- diminishes
in size with age
The effects of illicit drugs, alcohol, and
tobacco on the endocrine
SHS exposure contributes to disruptions
in thyroid function
 Smoking has multiple effects on pituitary,
thyroid, and adrenal glands; testicular
and ovarian function
 Alcohol’s affects hormone synthesis,
storage and release; hormone transport in
plasma /proteins; and effects on hormone
receptors and second messenger systems
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Alcohol affects production of hormones
such as progesterone and estrogen, and
alters the amounts of hormones produced
during the menstrual cycle
 Cocaine inhibits Prolactin secretion
 THC appears to depress prolactin, thyroid
gland function, and growth hormone while
elevating adrenal cortical steroids
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Effects of endocrine malfunction
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Adrenal Gland:
Function
1. The adrenal medulla is responsible for releasing hormones such as
adrenaline into the blood stream. The adrenal cortex produces and releases
other types of hormones that control how the body makes use of fats,
carbohydrates and proteins. The adrenal cortex is also responsible for the
production of the male hormone testosterone in both men and women, as well
as the production of the hormone mineralocorticoids. Mineralocorticoids control
blood pressure and levels of potassium and salt.
Removal
2. Although the adrenal glands produce important hormones, it is possible to
remove one or both and maintain some degree of a normality. The removal of
one or both of the adrenal glands is called an adrenalectomy. Living with one
adrenal gland is possible without the use of hormonal supplements. But
hormonal supplements are usually required when both adrenal glands are
removed.
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Effects of Complete Removal
3. Partial or complete adrenal gland removal is only done
in cases of adrenal cancer. Therefore, the patient must be
prepared to deal not only with the drop in essential
hormone production, but also with the side effects of
chemotherapy and/or radiation treatment.
To replace the hormonal production of the adrenal glands,
a patient is often placed on hormone replacement
therapies. Without this type of hormone replacement, the
patient can develop other major health problems, such as
diabetes, obesity, high-blood pressure and other symptoms
of a nonfunctioning metabolism. Despite hormone
replacement, radiation and chemotherapy, the prognosis
for five-year survival is not positive. Statistics show that 65
to 90 percent of those who have received treatment will
still die within five years.
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Pancreas:
If your pancreas malfunctions (cancer) or your
pancreas is removed, then you die.
Thyroid:
Removal of the thyroid gland results in death because
it regulates calcium which messes up your body.
Pineal:
Removal of the pineal gland and reduction in
melatonin output have been implicated in the
increased incidence of breast cancer (laboratory
animals). Patients with breast cancer often exhibit
lower levels of melatonin – also shown to be
protective against genetic damage and stimulates the
immune system.
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Pituitary:
With removal of pineal gland, these things do not happen,
probably resulting in death.
Growth
Blood Pressure
Some aspects of pregnancy and childbirth including stimulation of
uterine contractions during childbirth
Breast Milk production
Sex Organ functions in both men and women
Thyroid Gland function
The conversion of food into energy (metabolism)
Water and osmolarity regulation in the body
Secretes ADH (antidiuretic hormone) to control the absorption of
water into the kidneys
Temperature regulation