The Endocrine System

Most people believe that the human body is mostly controlled by the nervous system and the electrical impulses it sends out.  However, a significant portion of bodily control is handled by the endocrine system.  Instead of sending out electrical signals, the endocrine system sends out chemical signals in the form of hormones.

The endocrine system is composed of a series of endocrine glands that release their various hormones directly into the bloodstream.  These hormones are directly involved in the body’s development, growth, metabolism, mood, organ function and reproduction.  Glands of the endocrine system include the pituitary, adrenals, hypothalamus, pancreas, thyroid, parathyroid, pineal and reproductive.

I.          Pituitary Gland – The pituitary gland is also known as the ‘master gland’ as it produces a variety of hormones that controls the rest of the endocrine system.  For being so important and having so much control over the rest of the endocrine glands and bodily functions, the pituitary is relatively small as it is only about the size of pea.  It is located on the lower front side of the brain in its own small boney compartment.  It consists of three sections: anterior lobe, intermediate lobe and the posterior lobe.

A.        Anterior Lobe – Hormones and their functions in the anterior lobe of the pituitary include:

1.         Growth Hormone (GH) – Stimulates growth and cell reproduction, especially in the younger stages of life.  It also helps in some regenerative responses throughout the body, such as recovering from an injury.

2.         Thyroid-Stimulating Hormone (TSH) – Stimulates the thyroid gland to function properly.

3.         Adrenocorticotropic Hormone (ACTH) – Stimulates the cortex section of the adrenal glands.

4.         Follicle-Stimulating Hormone (FSH) – Stimulates and controls the development and growth during the maturation phases of puberty and reproductive processes.

5.         Prolactin (PRL) – Stimulates the lactating changes to the breasts and the production of breast milk.

6.         Luteinizing Hormone (LH) –

i.          Females – Stimulates ovulation and the development of the corpus luteum which is the site in the ovary where an ovum or egg has just been released.

ii.         Males – Stimulates the production of the leydig cells in the testes which produce the male hormone testosterone.

B.        Intermediate Lobe – Produces melanocyte-stimulating hormone (MSH) which helps control the melanocytes in the skin which contain the pigment melanin.

C.        Posterior Lobe – Hormones and their functions in the posterior lobe of the pituitary include:

1.         Antidiuretic Hormone (ADH) – Also known as vasopressin, controls the water balance by stimulating the kidneys to absorb more or less water from the blood.

2.         Oxytocin – Controls the uterus, cervix and vagina during labor and childbirth.  Also helps to stimulate breast feeding.

II.         Adrenal Glands – The adrenal glands are a set of triangular shaped glands that sit atop the kidneys.  They have an outer cortex and an inner medulla, each producing different hormones.

A.        Adrenal Cortex – The outer cortex of the adrenal glands produce a hormone called corticosteroids.  This hormone controls the levels of salt and water in the body, our metabolic rate, sexual development, sexual function, immune system and the body’s response to stress.

B.        Adrenal Medulla – The inner medulla produces a hormone called epinephrine, also known as adrenaline.  In times of stress or fright, epinephrine is released into the blood stream causing the heart rate to increase, blood vessels and air passages to dilate.  All of these functions help the body to get more oxygen to the muscles during the time of stress.

III.        Hypothalamus Gland – The hypothalamus gland is located just below the thalamus gland and just above the pituitary gland.  The main function of the hypothalamus is to connect the nervous system with the endocrine system by controlling the functions of the pituitary gland.  As the brain processes changes in temperature, daylight and mood, its signals are transmitted to the hypothalamus which in turn relays those changes in the form of chemical secretions to the pituitary gland.

IV.       Pancreas – Among the various functions of the pancreas it serves as part of the endocrine system by producing the hormones insulin and glucagon.

A.        Insulin – Insulin is a hormone that reduces the sugar level in the bloodstream.  Too much sugar in the blood can cause diabetes which can affect the brain, vision, heart, kidneys, circulation and feet.

B.        Glucagon – Glucagon is a hormone that increases the sugar level in the bloodstream.  In times of stress or hard work, the muscles use more blood sugar as an energy source.  During these times, glucagon can increase the blood sugar level to provide more energy to the muscles.  Under normal conditions, glucagon and insulin work together to maintain a normal and healthy blood sugar level.

V.        Thyroid – Thyroid gland is shaped somewhat like a butterfly and is located in lower part of the neck.  It produces two hormones: thyroxin and triiodothyronine.

A.        Thyroxin – Also spelled thyroxine, it helps in controlling growth and development, oxygen consumption, metabolism of fats, carbohydrates, proteins, electrolytes and water.  It also is involved with regulating vitamin requirements, resistance to some infections and reproduction.  As a general rule, people that have a low thyroxin level feel tired and have a tendency to gain weight and are placed on a regimen of a supplemental thyroxin medication.

B.        Triiodothyronine – Helps control body temperature, metabolism, growth and development.  In some way or other, this hormone is directly or indirectly involved with most of the body’s functions including gene expression.

VI.       Parathyroid Glands – The parathyroid glands are tiny glands attached to the thyroid gland in the neck.  They produce two hormones: parathyroid hormone and parathormone.

A.        Parathyroid Hormone – Controls the amount of calcium in the bloodstream and bones.

B.        Parathormone – Controls amount of calcium and phosphorus in the bloodstream and functions in blood clotting and in neuromuscular excitation.

VII.      Pineal Gland – The pineal gland is a tiny gland located deep in the center of the brain.  It produces melatonin which helps to regulate sleep cycles.  It is also involved in some of the hormonal changes that take place during adolescence.

VIII.     Reproductive Glands – Also referred to as the gonad glands, they are responsible for the production of sex hormones.

A.        Females – The ovaries produce estrogen and progesterone which stimulates the sexual development that takes place during puberty.  They also control the formation and release of ovum (eggs) and the menstruation cycle.  The place from where an egg is released in the ovary is known as the corpus luteum.  The corpus luteum is yellowish tissue that produces progesterone which causes the uterus to become more suited for the implantation of the fertilized egg and provide nourishment to the embryo.  If the egg is not fertilized, the corpus luteum will cease producing progesterone in about 10-14 days, which in turn triggers the menstruation cycle.

B.        Males – The male testes produce the male hormone testosterone in the leydig cells.  Testosterone stimulates the sexual development that takes place during puberty including the growth of facial hair and changes to the vocal chords.  Testosterone also stimulates the production of male sperm cells.

The proper function of the endocrine system is vital to the health and well being of the human body.  As mentioned above in several places, improper functioning can lead to numerous and often serious condition including diabetes, hypothyroidism, hyperthyroidism and goiters to name a few.

Another condition that is more common than many people may be aware of is pituitary tumors.  I was totally unaware of their frequency of occurrence until this past year when my oldest daughter Crystal was diagnosed with a tumor and/or cyst on her pituitary gland.  When she was diagnosed, I started doing some research on them and found several sources that said nearly 20%-25% of adults may have a pituitary tumor by the time they reach old age (my daughter is only 34).  Many of these tumors are benign and remain small and may have little to no effect on the function of the pituitary gland.

However, in a number of cases involving pituitary tumors, the tumor can take over the production of some or all of the pituitary hormones resulting in such things as weight gain, sluggishness, retention of fluids and swelling in the lower extremities and reproductive problems.  If the tumors become too large for the small boney capsule where the pituitary gland is located, it can put pressure on the optic nerve and affect the person’s vision including blindness.  In Crystal’s case, her vision was getting blurred, especially in one eye.  The tumor was also producing nearly 7 times the amount of steroidal hormones causing her to gain a significant amount of weight.

The most frequent treatment for a pituitary tumor is for a surgeon to go through the nasal passage and cut into the boney pituitary cavity.  In Crystal’s case, it turned out that she had a tumor (benign – praise God) that was encapsulated in a cyst.  According to the surgeons, this is very rare.  Her surgery was six months ago and she is still having problems with the pituitary not functioning properly.  An endocrinologist has been trying to find the right dosages of artificial hormones to help her body function normally but she is still having complications from the whole process.

Crystal’s neurosurgeon and endocrinologist told her that the life expectancy for someone that loses total function of the pituitary gland is usually about 1-3 months, even with artificial hormones.  They said it is because the pituitary controls so many bodily functions that they cannot replace all of the hormones needed to sustain life.

Once again we see how intricately involved and complex the human body is.  Each organ, gland, nerve, blood vessel and each system relies on each other to function properly.  Evolutionists still want you to believe that all of this complexity and interconnectiveness is merely the product of millions of years of random mutations.  Each system must have evolved at the same time and the same rate in order for the organism to survive.  Just one evolutionary delay, say perhaps a delay in the evolution of the pituitary gland and the rest of the mutational changes would have collapsed and the organism die.

When I look at the human body and all of its intricate design and function, I can’t help but see the wondrous hand of our omniscient God who made man in His own image.

For you formed my inward parts;
you knitted me together in my mother’s womb.
I praise you, for I am fearfully and wonderfully made.
Wonderful are your works;
my soul knows it very well.
My frame was not hidden from you,
when I was being made in secret,
intricately woven in the depths of the earth.

Psalm 139:13-15

Fearfully & Wonderfully Made (DVD)

When does life begin?

Take a journey from conception to birth with Dr. David Menton, former professor of anatomy at the prestigious Washington University School of Medicine in St. Louis. Dr. Menton provides both a biblical and scientific answer to the question of when life begins.

Taken from one of Dr. Menton’s lectures, this video will reveal the wondrous design of the womb along with the numerous miracles involved along every step of the development of the unborn child.

Following the tragic starvation induced death of Terry Schiavo, Dr. Menton clearly shows the value and sanctity of human life.

With grace and sensitivity Dr. Menton concludes with a salvation message and explanation of the second birth process as described in John 3.

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