The Neuroendocrine System as a Constitutional System for Botanical Therapy
The Neural Endocrine System: A Brief Introduction
The endocrine system helps regulate and maintain various body functions by synthesizing (making) and releasing hormones, chemical messengers. The major areas of control and integration include responses to stress and injury, growth and development, absorption of nutrients, energy metabolism, water and electrolyte balance, reproduction, birth, and lactation. The endocrine system is composed of glands that release their hormones directly into the bloodstream for chemical signaling of target cells. These glands include the pituitary gland, the pineal gland, the hypothalamus, the thyroid gland, the parathyroid glands, the thymus, the adrenal glands, the ovaries (in females) or testes (in males), and the pancreas
Typically, the body synthesizes hormones in one part and transports it to another through the bloodstream or lymph. Endocrine glands have a rich blood supply through which hormones travel to reach their target organs. Hormones alter the metabolism of target organs by increasing or decreasing their activity. These changes in activity are strictly balanced to maintain homeostasis (a stable internal environment).
Hypothalamus and Pituitary Gland
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Glands are of two types. Endocrine glands do not have a duct system and are called ductless glands. These glands release hormones directly into the blood or lymph. Exocrine glands such as the sudoriferous (sweat) glands contain ducts. Ducts are tubes leading from a gland to its target organ.
The endocrine system and the nervous system are so closely associated that they are collectively called the neuroendocrine system. Neural control centers in the brain control endocrine glands. The main neural control center is the hypothalamus, also known as the "master switchboard." Suspended from the hypothalamus by a thin stalk is the pituitary gland. The hypothalamus sends messages to the pituitary gland; the pituitary gland, in turn, releases hormones that regulate body functions
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Negative Feedback Regulation
An example of negative feedback is the regulation of the blood calcium level. The parathyroid glands secrete parathyroid hormone, which regulates the blood calcium amount. If calcium decreases, the parathyroid glands sense the decrease and secrete more parathyroid hormone. The parathyroid hormone stimulates calcium release from the bones and increases the calcium uptake into the bloodstream from the collecting tubules in the kidneys. Conversely, if blood calcium increases too much, the parathyroid glands reduce parathyroid hormone production. Both responses are examples of negative feedback because in both cases the effects are negative (opposite) to the stimulus.
Positive Feedback Regulation
Positive feedback mechanisms control self-perpetuating events that can be out of control and do not require continuous adjustment. In positive feedback mechanisms, the original stimulus is promoted rather than negated. Positive feedback increases the deviation from an ideal normal value. Unlike negative feedback that maintains hormone levels within narrow ranges, positive feedback is rarely used to maintain homeostatic functions.
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The pea-size pituitary gland is called the "master gland" because it regulates many key functions. The pituitary gland has an adenohypophysis (anterior lobe) and a neurohypophysis (posterior lobe). The adenohypophysis produces and secretes seven hormones in response to commands from the hypothalamus:
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The Autonomic Nervous System (ANS) Sympathetic and Parasympathetic
• In mammals, the part of the nervous system that controls those functions not controlled voluntarily, including the heart rate, activity of the intestines, and the production of sweat. There are two divisions of the autonomic nervous system. The sympathetic system responds to stress, when it speeds the heart rate, increases blood pressure, and generally prepares the body for action. The parasympathetic system is more important when the body is at rest, since it slows the heart rate, decreases blood pressure, and stimulates the digestive system.
• At all times, both types of autonomic nerves carry signals that bring about adjustments in visceral organs. The actual rate of heartbeat is the net outcome of opposing signals. Today, it is known that the word ‘autonomic’ is misleading – the reflexes managed by this system are actually integrated by commands from the brain and spinal cord (the central nervous system).
• The sympathetic nervous system corresponds generally to yang Qi
• The parasympathetic nervous system corresponds to yin qi.
The Adrenal Glands
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The adrenal glands are on top of each kidney. Each gland has a cortex (outer region) and a medulla (inner region). The cortex secretes glucocorticoids such as cortisol, mineralocorticoids, and small amounts of androgens and estrogens responsible for some secondary sex characteristics. Glucocorticoids raise blood sugar levels by increasing gluconeogenesis (synthesis of glucose from amino acid). This action ensures glucose supplies for the body when it is under stress. Mineralocorticoids such as aldosterone promote sodium (salt) reabsorption by stimulating the kidneys to absorb more sodium from the blood.
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The medulla "emergency gland" develops from nervous tissue; the autonomic nervous system controls its secretions. The medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline), chemicals that raise the blood levels of sugar and fatty acids. These hormones also increase the heart rate and force of contraction. These effects prepare the body for the "Fight or Flight" response (instant physical activity), enabling the individual to think quicker, fight harder, and run faster. These hormones also constrict the blood vessels supplying the skin, kidneys, gastrointestinal tract, and other areas of the body not needed for the response.
Adrenal Glands
The Adrenals and TCM Kidneys
In Traditional Chinese Medicine the Kidneys are the source qi for the entire body. In fact, the Chinese are not simply referring to their urinary function but constitutionally to their ability to regulate the hormones for the entire body. Like the adrenals that are divided between hormones secreted by the cortex and the medulla. Kidney yin hormones would be the cortical hormones of the adrenal cortex while kidney yang hormones are those stimulating hormones secreted by the adrenal medula. This have a homeostatic yin-yang relationship with each other.
Ovaries and testes
• The ovary is the site of estrogen and progesterone synthesis. Estrogen is required to form the ovum (egg) during oogenesis and prepares the uterus for implanting a fertilized egg. Progesterone prepares the breasts for lactation during pregnancy and works with estrogen to regulate the menstrual cycle.
• The testes produce the hormone testosterone. Testosterone is required for sperm formation during spermatogenesis, the development of male external genitalia, and secondary sexual traits such as beard growth, chest hair, and enlarged thyroid cartilage.
Sympathetic Dominance
Typical yang type A personality: rapid heart rate, emotionally driven, tendency towards constipation, insomnia, hypertension and hyperactivity. They have a tendency towards high blood pressure, irregular bowel movements, arrhythmias, angina, nervous strain, arteriosclerosis, bursitis, dental caries, cystitis, diabetes, low endurance, cold extremities (?), dryness, slow fat metabolism, tension headaches, slow tissue healing, irritability, indigestion, hyper sensitivity to pain, little sweating, underweight, cravings sweets, thick eyebrows, strong libido, large pupils, highly reactive to stimulus.
In Traditional Chinese Medicine these would be more excess yang, deficient yin types.
In Ayurvedic Medicine they would be more Pitta (fire) humour types.
Parasympathetic Dominance
They have good digestion, tends towards loose stool and diarrhea, poor muscle tone, lethargy, fall asleep easily, good stamina. They may have an excessive appetite, allergies, osteoarthritis, asthma, low blood pressure, poor bladder control, dermatoses, diverticulosis, eczema, edema, loss of energy after eating sweets, bleeding gums, oily hair, shingles, histamine reactions, obesity, osteoporosis, sexual difficulties, impotence, excessive HCL, timid, slower, tendency to feel cold, crave warm, spicy foods.
In Traditional Chinese Medicine they might be excess, yin, deficient yang types.
In Ayurvedic medicine they would be more kapha dosha (water humour.
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