Endocrine System
https://reasonandscience.catsboard.com/t1800-endocrine-system
http://www.innerbody.com/image/endoov.html#full-description
Anatomy of the Endocrine System
Hypothalamus
The hypothalamus is a part of the brain located superior and anterior to the brain stem and inferior to the thalamus. It serves many different functions in the nervous system, and is also responsible for the direct control of the endocrine system through the pituitary gland. The hypothalamus contains special cells called neurosecretory cells—neurons that secrete hormones:
Thyrotropin-releasing hormone (TRH)
Growth hormone-releasing hormone (GHRH)
Growth hormone-inhibiting hormone (GHIH)
Gonadotropin-releasing hormone (GnRH)
Corticotropin-releasing hormone (CRH)
Oxytocin
Antidiuretic hormone (ADH)
http://www.creationofman.net/chapter3/chapter3_1.html
Suppose that everyone in the world, about 6 billion people, works for the same organization. Everyone has his own special job. Hundreds of thousands, sometimes millions of people gather under the same roof to perform a common task. There is such a tight web of administration and information that every one of these 6 billion people is informed individually by means of a cellular phone as to what he or she has to do. For example, if one of these people is employed in a factory, he may sometimes be told to increase the speed of production, sometimes to slow it down, and sometimes to alter the product. Finally, imagine that an organized plan and communications system exist so that millions of people throughout the hundreds of thousands of different locations all over the world work according to this common plan.
Now, let's enlarge our example a little. Imagine that the population of the world is much greater than it is at present, but that our organization functions even more efficiently.
The communication and coordination of the many branches of an international company is very complicated. Directors, managers, engineers and advertisers have to be in touch with one another at all times. The communication network in the human body is millions of times more complex than that of the largest international company.
Suppose that the population is fifteen thousand times greater than it is today, that there are fifteen thousand other planets like this Earth and that the 6 billion people crowded onto each planet make up a total of 100 trillion people. Further suppose that this collection of human beings works together in perfect harmony, each individual being informed by cellular phone as to what he has to do.
This example is beyond our power to conceive, but is actually a simplified description of an existing organization, which operates every second throughout the whole world among the approximately 100 trillion cells that make up the human body.
As you are reading this, millions of operations are happening in your body. In these operations there is a calculation of the needs of every cell in every part of the body, and a determination of what function each cell must perform; measures are taken to respond to the requirements of the cells and each cell is informed individually as to what it must do.
For example, what allows you to read this book are your eye cells, and to nourish them, glucose is required. To respond to those needs, a system was established in your body that calculates how much sugar there is in your blood and that keeps the amount stable. There is a great plan, organized by the web of communication among the cells, that calculates how many times a minute your heart must beat, the level of calcium stored in your body, the amount of blood your kidneys filter and thousands of other such details. This system of chemical communication that ensures that the 100 trillion cells work in harmony with one another is called the hormone system.
The hormone system, together with the nervous system, ensures the coordination of the cells of the body. If we compare the nervous system to messages sent over the Internet, the hormone system can be compared to a letter sent by post: it is slower, but its effect lasts longer.
When we examine these systems that control the body, a fact becomes clear that most people are not aware of. Most people are convinced that they themselves control the direction of their lives. If you asked someone, "How much of your body do you control?" he would surely say, "All of it." But this answer contradicts the scientific facts.
A person is in control of a very limited part of his body, and even of that part his control is only partial. For example, he can use his body to walk, or to speak or he can use his hands to work, but deep within his body there are thousands of chemical and physical operations going on without his knowing about or willing them. Anyone who thinks that he is completely in charge of his own body (or his own life) is greatly mistaken.
The two Governors of our body: The Hypothalamus and the Pituitary Gland
The fact that you are able to sit comfortably in your chair and read these sentences is due to systems that organize the internal balance of your body for your benefit. For example, no matter what the temperature outside, your body must always be kept at a constant temperature, usually between 36.5 and 37.5 degrees. A sudden fall or rise in body temperature may result in death. The body temperature of a healthy individual, thanks to these systems, will vary at most 0.5 of a degree. In the same way, the pressure of the blood in the veins, the amount of fluid in the blood, and the speed at which the cells function must be delicately measured, and the existing balance safeguarded at every moment.
Let us imagine the efforts needed to artificially ensure these balances. First, imagine that there exist delicate thermometers in a few places in the body, special devices to measure the density of the blood in the veins, and mini laboratories to control the rate of speed at which the cells function. Then, imagine that all these thousands of tiny devices located in every point in the body must make the right assessments every second and transmit the information they receive to a highly advanced computer.
However, it is not enough that these assessments are made alone; at the same time, it is also necessary to know, according to the available data, which actions must be taken and what kind of command must be given to which cells.
Of course, even with the state of today's technology, it is still impossible to place thousands of thermometers, a mini laboratory, and pressure measuring devices in the depths of the human body. Yet a special system with the finest possible design has been placed from birth deep in the human body.
Thousands of different receivers measure such things as the body's temperature and the pressure in the blood vessels. Then they send this information to a very special computer. This computer is the area of the brain called the hypothalamus.
YOUR BODY'S HIDDEN MANAGER: THE HYPOTHALAMUS
The hypothalamus is the general director of the hormone system; it has the vital task of ensuring the internal stability of the human body. At every moment, the hypothalamus assesses messages coming to it from the brain and the depths of the body. Afterwards, it performs a number of functions, such as maintaining a stable body temperature, controlling blood pressure, ensuring a fluid balance, and even proper sleep patterns.
The hypothalamus is located directly under the brain and is the size of a hazel nut.
A considerable amount of information relative to the body state is sent to the hypothalamus. Information is transmitted to it from every point in the body, including the sense centers in the brain. It then analyses the information it has received, decides what measures are to be taken, what changes must be made in the body, and causes the appropriate cells of the body to carry out its decisions.
The basic point that must be noticed here is this: the hypothalamus is an organ composed of unconscious cells. A cell does not know how long a human being needs to sleep; it cannot calculate what the body's temperature should be. It cannot make the best decision based on the information at hand, and it cannot make another cell in a far removed area of the body carry out this decision. Yet the cells in the hypothalamus act in an extraordinarily conscious manner to ensure that the necessary balances in the body are maintained.
Most of the information about the human body comes to the hypothalamus. The hypothalamus interprets this information, makes the necessary decisions and causes the cells put these decisions into practice. On the left, we see the position of the hypothalamus in the brain.
One of the most important functions of the hypothalamus is to form a bridge between the hormonal system and the other system that controls and oversees the body-the nervous system. The hypothalamus not only directs the hormonal system, but also the nervous system with a high degree of expertise.
The hypothalamus has a very important assistant in its role of governing the body; this assistant informs the appropriate body areas of the decisions that have been taken. For example, when there is a drop in blood pressure, bits of information are set into motion, and these inform the hypothalamus of the change in pressure; then the hypothalamus decides what measures must be taken to raise it and informs its assistant of its decision.
In order to effect the decision, the helper knows which cells must receive the command. It writes messages in a language that these cells can understand and transmits them immediately. The cells obey the command they have received and take the appropriate action to raise the blood pressure.
This assistant to the hypothalamus is the pituitary gland, which also has a very important influence on the hormonal system.
Pituitary gland
http://en.wikipedia.org/wiki/Pituitary_gland
In vertebrate anatomy, the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 grams (0.018 oz) in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) covered by a dural fold (diaphragma sellae). The posterior pituitary (or neurohypophysis) is a lobe of the gland that is functionally connected to the hypothalamus by the median eminence via a small tube called the pituitary stalk (also called the infundibular stalk or the infundibulum). The anterior pituitary (or adenohypophysis) is a lobe of the gland that regulates several physiological processes (including stress, growth, reproduction, and lactation). The pituitary gland sits in the hypophysial fossa, situated in the sphenoid bone in the middle cranial fossa at the base of the brain. The pituitary gland secretes nine hormones that regulate homeostasis.
Between the hypothalamus and the pituitary gland there is a marvelous system of communication. These two pieces of flesh actually communicate like two conscious human beings. The hypothalamus has complete control over the pituitary gland and its vital secretion of several hormones.
For example, the hypothalamus of a growing child sends a message to the pituitary gland with the command, "secrete the growth hormone" and the pituitary gland then secretes the growth hormone exactly as needed.
Something similar happens when the cells of the body need to work faster; this time there is a two-stage chain of command. The hypothalamus sends an order to the pituitary gland which, in turn, sends the order to the thyroid gland. The thyroid gland secretes the proper amount of thyroid hormone and the cells of the body begin to work faster.
The location of the hormonal glands under the control of the hypothalamus in the body.
When the adrenal glands
In mammals, the adrenal glands (also known as suprarenal glands) are endocrine glands that sit at the top of the kidneys. They are chiefly responsible for releasing hormones in response to stress through the synthesis of corticosteroids such as cortisol and catecholamines such as adrenaline (epinephrine) and noradrenaline. They also produce androgens in their innermost cortical layer. The adrenal glands affect kidney function through the secretion of aldosterone, and recent data (1998) suggest that adrenocortical cells under pathological as well as under physiological conditions show neuroendocrine properties; within normal adrenal glands, this neuroendocrine differentiation seems to be restricted to cells of the zona glomerulosa and might be important for an autocrine regulation of adrenocortical function.[1]
(which produce several very important hormones) must be activated or the reproductive organs must produce their hormones, the hypothalamus again sends a message to the pituitary gland, which directs it to the relevant areas and ensures the required hormones in those areas are secreted.
The hormones produced by the hypothalamus to direct the pituitary gland include:
Growth hormone-releasing hormone
Thyrotropin-releasing hormone
Corticotropin-releasing hormone
Gonadotropin-releasing hormone.
In some cases the hypothalamus, in order to intervene in the activity of the cells, uses two hormones that it has secreted itself. To store these hormones, it first sends them to the pituitary gland, then, when required, it ensures that they are secreted by the pituitary gland. These hormones are:
Vasopressin (an antidiuretic, i.e., water retaining, hormone)
Oxytocin
These two hormone molecules produced by the hypothalamus are very small. One of them is only three amino acids large. The hypothalamus hormones are distinguished from other hormones not only by being small; they also differ from other hormones by the distance they cover in the body. Hormones generally travel a long distance from the hormonal gland where they were produced to the designated organ. However, the hypothalamus hormones reach the pituitary gland after passing through only a capillary vessel a few millimeters thick. They never enter the general circulatory system.
The hypothalamus produces the hormones that activate the pituitary gland, and when necessary, it also produces hormones that stop the pituitary gland at the appropriate time from secreting a certain hormone. In this way, it has complete control over the activity of the pituitary gland.
https://reasonandscience.catsboard.com/t1800-endocrine-system
http://www.innerbody.com/image/endoov.html#full-description
Anatomy of the Endocrine System
Hypothalamus
The hypothalamus is a part of the brain located superior and anterior to the brain stem and inferior to the thalamus. It serves many different functions in the nervous system, and is also responsible for the direct control of the endocrine system through the pituitary gland. The hypothalamus contains special cells called neurosecretory cells—neurons that secrete hormones:
Thyrotropin-releasing hormone (TRH)
Growth hormone-releasing hormone (GHRH)
Growth hormone-inhibiting hormone (GHIH)
Gonadotropin-releasing hormone (GnRH)
Corticotropin-releasing hormone (CRH)
Oxytocin
Antidiuretic hormone (ADH)
http://www.creationofman.net/chapter3/chapter3_1.html
Suppose that everyone in the world, about 6 billion people, works for the same organization. Everyone has his own special job. Hundreds of thousands, sometimes millions of people gather under the same roof to perform a common task. There is such a tight web of administration and information that every one of these 6 billion people is informed individually by means of a cellular phone as to what he or she has to do. For example, if one of these people is employed in a factory, he may sometimes be told to increase the speed of production, sometimes to slow it down, and sometimes to alter the product. Finally, imagine that an organized plan and communications system exist so that millions of people throughout the hundreds of thousands of different locations all over the world work according to this common plan.
Now, let's enlarge our example a little. Imagine that the population of the world is much greater than it is at present, but that our organization functions even more efficiently.
The communication and coordination of the many branches of an international company is very complicated. Directors, managers, engineers and advertisers have to be in touch with one another at all times. The communication network in the human body is millions of times more complex than that of the largest international company.
Suppose that the population is fifteen thousand times greater than it is today, that there are fifteen thousand other planets like this Earth and that the 6 billion people crowded onto each planet make up a total of 100 trillion people. Further suppose that this collection of human beings works together in perfect harmony, each individual being informed by cellular phone as to what he has to do.
This example is beyond our power to conceive, but is actually a simplified description of an existing organization, which operates every second throughout the whole world among the approximately 100 trillion cells that make up the human body.
As you are reading this, millions of operations are happening in your body. In these operations there is a calculation of the needs of every cell in every part of the body, and a determination of what function each cell must perform; measures are taken to respond to the requirements of the cells and each cell is informed individually as to what it must do.
For example, what allows you to read this book are your eye cells, and to nourish them, glucose is required. To respond to those needs, a system was established in your body that calculates how much sugar there is in your blood and that keeps the amount stable. There is a great plan, organized by the web of communication among the cells, that calculates how many times a minute your heart must beat, the level of calcium stored in your body, the amount of blood your kidneys filter and thousands of other such details. This system of chemical communication that ensures that the 100 trillion cells work in harmony with one another is called the hormone system.
The hormone system, together with the nervous system, ensures the coordination of the cells of the body. If we compare the nervous system to messages sent over the Internet, the hormone system can be compared to a letter sent by post: it is slower, but its effect lasts longer.
When we examine these systems that control the body, a fact becomes clear that most people are not aware of. Most people are convinced that they themselves control the direction of their lives. If you asked someone, "How much of your body do you control?" he would surely say, "All of it." But this answer contradicts the scientific facts.
A person is in control of a very limited part of his body, and even of that part his control is only partial. For example, he can use his body to walk, or to speak or he can use his hands to work, but deep within his body there are thousands of chemical and physical operations going on without his knowing about or willing them. Anyone who thinks that he is completely in charge of his own body (or his own life) is greatly mistaken.
The two Governors of our body: The Hypothalamus and the Pituitary Gland
The fact that you are able to sit comfortably in your chair and read these sentences is due to systems that organize the internal balance of your body for your benefit. For example, no matter what the temperature outside, your body must always be kept at a constant temperature, usually between 36.5 and 37.5 degrees. A sudden fall or rise in body temperature may result in death. The body temperature of a healthy individual, thanks to these systems, will vary at most 0.5 of a degree. In the same way, the pressure of the blood in the veins, the amount of fluid in the blood, and the speed at which the cells function must be delicately measured, and the existing balance safeguarded at every moment.
Let us imagine the efforts needed to artificially ensure these balances. First, imagine that there exist delicate thermometers in a few places in the body, special devices to measure the density of the blood in the veins, and mini laboratories to control the rate of speed at which the cells function. Then, imagine that all these thousands of tiny devices located in every point in the body must make the right assessments every second and transmit the information they receive to a highly advanced computer.
However, it is not enough that these assessments are made alone; at the same time, it is also necessary to know, according to the available data, which actions must be taken and what kind of command must be given to which cells.
Of course, even with the state of today's technology, it is still impossible to place thousands of thermometers, a mini laboratory, and pressure measuring devices in the depths of the human body. Yet a special system with the finest possible design has been placed from birth deep in the human body.
Thousands of different receivers measure such things as the body's temperature and the pressure in the blood vessels. Then they send this information to a very special computer. This computer is the area of the brain called the hypothalamus.
YOUR BODY'S HIDDEN MANAGER: THE HYPOTHALAMUS
The hypothalamus (from Greek ὑπό = under and θάλαμος = room, chamber) is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland (hypophysis).
The hypothalamus is located below the thalamus, just above the brainstem. In the terminology of neuroanatomy, it forms the ventral part of the diencephalon. All vertebrate brains contain a hypothalamus. In humans, it is roughly the size of an almond.
The hypothalamus is responsible for certain metabolic processes and other activities of the autonomic nervous system. It synthesizes and secretes certain neurohormones, often called releasing hormones or hypothalamic hormones, and these in turn stimulate or inhibit the secretion of pituitary hormones. The hypothalamus controls body temperature, hunger, important aspects of parenting and attachment behaviors, thirst,[1] fatigue, sleep, and circadian rhythms.
The hypothalamus is the general director of the hormone system; it has the vital task of ensuring the internal stability of the human body. At every moment, the hypothalamus assesses messages coming to it from the brain and the depths of the body. Afterwards, it performs a number of functions, such as maintaining a stable body temperature, controlling blood pressure, ensuring a fluid balance, and even proper sleep patterns.
The hypothalamus is located directly under the brain and is the size of a hazel nut.
A considerable amount of information relative to the body state is sent to the hypothalamus. Information is transmitted to it from every point in the body, including the sense centers in the brain. It then analyses the information it has received, decides what measures are to be taken, what changes must be made in the body, and causes the appropriate cells of the body to carry out its decisions.
The basic point that must be noticed here is this: the hypothalamus is an organ composed of unconscious cells. A cell does not know how long a human being needs to sleep; it cannot calculate what the body's temperature should be. It cannot make the best decision based on the information at hand, and it cannot make another cell in a far removed area of the body carry out this decision. Yet the cells in the hypothalamus act in an extraordinarily conscious manner to ensure that the necessary balances in the body are maintained.
Most of the information about the human body comes to the hypothalamus. The hypothalamus interprets this information, makes the necessary decisions and causes the cells put these decisions into practice. On the left, we see the position of the hypothalamus in the brain.
One of the most important functions of the hypothalamus is to form a bridge between the hormonal system and the other system that controls and oversees the body-the nervous system. The hypothalamus not only directs the hormonal system, but also the nervous system with a high degree of expertise.
The hypothalamus has a very important assistant in its role of governing the body; this assistant informs the appropriate body areas of the decisions that have been taken. For example, when there is a drop in blood pressure, bits of information are set into motion, and these inform the hypothalamus of the change in pressure; then the hypothalamus decides what measures must be taken to raise it and informs its assistant of its decision.
In order to effect the decision, the helper knows which cells must receive the command. It writes messages in a language that these cells can understand and transmits them immediately. The cells obey the command they have received and take the appropriate action to raise the blood pressure.
This assistant to the hypothalamus is the pituitary gland, which also has a very important influence on the hormonal system.
Pituitary gland
http://en.wikipedia.org/wiki/Pituitary_gland
In vertebrate anatomy, the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 grams (0.018 oz) in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) covered by a dural fold (diaphragma sellae). The posterior pituitary (or neurohypophysis) is a lobe of the gland that is functionally connected to the hypothalamus by the median eminence via a small tube called the pituitary stalk (also called the infundibular stalk or the infundibulum). The anterior pituitary (or adenohypophysis) is a lobe of the gland that regulates several physiological processes (including stress, growth, reproduction, and lactation). The pituitary gland sits in the hypophysial fossa, situated in the sphenoid bone in the middle cranial fossa at the base of the brain. The pituitary gland secretes nine hormones that regulate homeostasis.
Between the hypothalamus and the pituitary gland there is a marvelous system of communication. These two pieces of flesh actually communicate like two conscious human beings. The hypothalamus has complete control over the pituitary gland and its vital secretion of several hormones.
For example, the hypothalamus of a growing child sends a message to the pituitary gland with the command, "secrete the growth hormone" and the pituitary gland then secretes the growth hormone exactly as needed.
Something similar happens when the cells of the body need to work faster; this time there is a two-stage chain of command. The hypothalamus sends an order to the pituitary gland which, in turn, sends the order to the thyroid gland. The thyroid gland secretes the proper amount of thyroid hormone and the cells of the body begin to work faster.
The location of the hormonal glands under the control of the hypothalamus in the body.
When the adrenal glands
In mammals, the adrenal glands (also known as suprarenal glands) are endocrine glands that sit at the top of the kidneys. They are chiefly responsible for releasing hormones in response to stress through the synthesis of corticosteroids such as cortisol and catecholamines such as adrenaline (epinephrine) and noradrenaline. They also produce androgens in their innermost cortical layer. The adrenal glands affect kidney function through the secretion of aldosterone, and recent data (1998) suggest that adrenocortical cells under pathological as well as under physiological conditions show neuroendocrine properties; within normal adrenal glands, this neuroendocrine differentiation seems to be restricted to cells of the zona glomerulosa and might be important for an autocrine regulation of adrenocortical function.[1]
(which produce several very important hormones) must be activated or the reproductive organs must produce their hormones, the hypothalamus again sends a message to the pituitary gland, which directs it to the relevant areas and ensures the required hormones in those areas are secreted.
The hormones produced by the hypothalamus to direct the pituitary gland include:
Growth hormone-releasing hormone
Thyrotropin-releasing hormone
Corticotropin-releasing hormone
Gonadotropin-releasing hormone.
In some cases the hypothalamus, in order to intervene in the activity of the cells, uses two hormones that it has secreted itself. To store these hormones, it first sends them to the pituitary gland, then, when required, it ensures that they are secreted by the pituitary gland. These hormones are:
Vasopressin (an antidiuretic, i.e., water retaining, hormone)
Oxytocin
These two hormone molecules produced by the hypothalamus are very small. One of them is only three amino acids large. The hypothalamus hormones are distinguished from other hormones not only by being small; they also differ from other hormones by the distance they cover in the body. Hormones generally travel a long distance from the hormonal gland where they were produced to the designated organ. However, the hypothalamus hormones reach the pituitary gland after passing through only a capillary vessel a few millimeters thick. They never enter the general circulatory system.
The hypothalamus produces the hormones that activate the pituitary gland, and when necessary, it also produces hormones that stop the pituitary gland at the appropriate time from secreting a certain hormone. In this way, it has complete control over the activity of the pituitary gland.
Last edited by Admin on Thu Sep 13, 2018 4:25 am; edited 6 times in total
