In addition the concentration of blood and tissue fluid must be controlled as they will have affect osmotic effects on solutions.
The exchange of gases carbon dioxide and oxygen are also important for efficient cell processes.
Carbon dioxide if it is allowed to accumulate creates acidic conditions unsuitable for enzyme function. Oxygen depletion reduces the rate of respiration and undermines important processes such as active transport.
Homeostasis is the name given to the combination of process that controls the internal environment. Failing to control such conditions leads to inefficiencies, system failures and in some instances can be fatal.
Homeostasis involves monitoring levels of variables and correcting changes in levels by negative feedback mechanisms.
Notice that this response will modify the internal environment and that these new conditions will in turn become the new stimuli.
The cycle will continue until conditions are reduced back to within narrow acceptable limits (fixed regulation point).
Notice that system works responding to conditions lower that and higher than the fixed regulation point.
Examine the model above notice that the connections between receptors, coordinators and effectors could be either by hormone or by neurons. Central Nervous System (CNS) which co-ordinates responses and includes the brain and spine.
Receptors are the specialised cells that can detect internal changes and convert this information into nerve impulses.
Coordinators are regions of the central nervous system (brain, spine) that determine the appropriate response.
Control of body temperature including the transfer of heat in blood, the role of sweat glands and skin arterioles, and shivering.
This systems is slower than that of the nervous system but the response tends to be longer lasting.
It should be noted that one hormone can have a number of target tissues and the responses can be quite different from each of the targets. Respiration: Some tissues are entirely dependent on blood sugar as a respiratory substrate being unable to either store glucose of metabolise fat. The blood content of water, urea and salts is determined by the filtering mechanism of the kidney. If the blood is hypotonic then more water is removed from the blood and the urine produced will be dilute. If the blood is hypertonic then water is retained in blood and increased levels of salts released. Jerusalem, November 12, 2009 - How a specific gene within the pancreas affects secretion of insulin has been discovered by researchers from the Hebrew University of Jerusalem's Institute for Medical Research Israel-Canada led by Dr.
Blood glucose levels are tightly regulated by secretion of insulin from beta cells in the pancreas.
The work of the multi-national research team explored the role of LKB1, a gene involved in many cellular functions, whose role in the pancreas was not examined before. The findings have potentially great implications for those suffering from diabetes (excessive blood sugar) due to insufficient production of insulin in the pancreas.
Since it was shown that LKB1 negatively regulates both insulin content and secretion, the way has now been opened to possible development of a novel therapy that would limit the presence of this gene in pancreas beta cells, thus enhancing insulin secretion.
The researchers involved in the project, whose findings were published recently in the journal Cell Metabolism, were led by Dr.
The body contains a large variety of ions, or electrolytes, which perform a variety of functions. Electrolytes in living systems include sodium, potassium, chloride, bicarbonate, calcium, phosphate, magnesium, copper, zinc, iron, manganese, molybdenum, copper, and chromium. These six ions aid in nerve excitability, endocrine secretion, membrane permeability, buffering body fluids, and controlling the movement of fluids between compartments. Excretion of ions occurs mainly through the kidneys, with lesser amounts lost in sweat and in feces. Hyponatremia is a lower-than-normal concentration of sodium, usually associated with excess water accumulation in the body, which dilutes the sodium. A relative decrease in blood sodium can occur because of an imbalance of sodium in one of the body’s other fluid compartments, like IF, or from a dilution of sodium due to water retention related to edema or congestive heart failure. Some insulin-dependent diabetic patients experience a relative reduction of potassium in the blood from the redistribution of potassium. Hyperkalemia, an elevated potassium blood level, also can impair the function of skeletal muscles, the nervous system, and the heart.
Hypochloremia, or lower-than-normal blood chloride levels, can occur because of defective renal tubular absorption. Bicarbonate ions result from a chemical reaction that starts with carbon dioxide (CO2) and water, two molecules that are produced at the end of aerobic metabolism. The bidirectional arrows indicate that the reactions can go in either direction, depending on the concentrations of the reactants and products. About two pounds of calcium in your body are bound up in bone, which provides hardness to the bone and serves as a mineral reserve for calcium and its salts for the rest of the tissues.
Hypocalcemia, or abnormally low calcium blood levels, is seen in hypoparathyroidism, which may follow the removal of the thyroid gland, because the four nodules of the parathyroid gland are embedded in it.
Hypophosphatemia, or abnormally low phosphate blood levels, occurs with heavy use of antacids, during alcohol withdrawal, and during malnourishment. Sodium is reabsorbed from the renal filtrate, and potassium is excreted into the filtrate in the renal collecting tubule.
Recall that aldosterone increases the excretion of potassium and the reabsorption of sodium in the distal tubule. In the distal convoluted tubules and collecting ducts of the kidneys, aldosterone stimulates the synthesis and activation of the sodium-potassium pump ([link]).
Calcium and phosphate are both regulated through the actions of three hormones: parathyroid hormone (PTH), dihydroxyvitamin D (calcitriol), and calcitonin. PTH is released from the parathyroid gland in response to a decrease in the concentration of blood calcium. Calcitonin is released from the thyroid gland in response to elevated blood levels of calcium. Electrolytes serve various purposes, such as helping to conduct electrical impulses along cell membranes in neurons and muscles, stabilizing enzyme structures, and releasing hormones from endocrine glands. Drinking seawater dehydrates the body as the body must pass sodium through the kidneys, and water follows. Explain how the CO2 generated by cells and exhaled in the lungs is carried as bicarbonate in the blood.
How can one have an imbalance in a substance, but not actually have elevated or deficient levels of that substance in the body? Without having an absolute excess or deficiency of a substance, one can have too much or too little of that substance in a given compartment.
Endocrine glands are ductless glands that produce and release hormones to the blood through diffusion. Endocrine glands may be strictly endocrine, such as the pituitary, thyroid, parathyroid, adrenal, pineal and thymus; or they may be organs that have hormone production as one of many functions, such as the pancreas, gonads, hypothalamus, and others.

Hormones are long-distance chemical signals that are secreted by the cells to the extracellular fluid and regulate the metabolic functions of other cells.
Most hormones are amino acid based, but gonadal and adrenocortical hormones are steroids, derived from cholesterol. Water-soluble hormones (all amino acid-based hormones except thyroid hormone) exert their effects through an intracellular second messenger that is activated when a hormone binds to a membrane receptor. Lipid-soluble hormones (steroids and thyroid hormone) diffuse into the cell, where they bind to intracellular receptors, migrate to the nucleus, and activate specific target sequences of DNA. Target cell response depends on three factors: blood levels of the hormone, relative numbers of target cell receptors, and affinity of the receptor for the hormone.
The concentration of a hormone reflects its rate of release, and the rate of inactivation and removal from the body. The half-life of a hormone is the duration of time a hormone remains in the blood, and is shortest for water-soluble hormones. Permissiveness occurs when one hormone cannot exert its full effect without another hormone being present (reproductive hormones need thyroxine to properly stimulate development of reproductive organs). Synergism occurs when more than one hormone produces the same effects in a target cell, and their combined effects are amplified (glucagon + epinephrine together stimulate more glucose release from the liver than when each acts alone). Antagonism occurs when one hormone opposes the action of another hormone (glucagon antagonizes insulin). Nervous system modulation allows hormone secretion to be modified by the nervous stimulation in response to changing body needs. The pituitary gland is connected to the hypothalamus via a stalk, the infundibulum, and consists of two lobes: the anterior pituitary, or adenohypophysis, and the posterior pituitary, or neurohypophysis. Two neurohormones are synthesized by the hypothalamus and secreted by the posterior pituitary.
Growth hormone (GH) indirectly (through insulin-like growth factors, IGFs) stimulates body cells to increase in size and divide.
Direct effects are insulin-sparing: mobilization of fatty acids for fuel, inhibition of insulin activity, release of glucose from liver to blood, and stimulation of amino acid uptake by cells. The thyroid gland consists of hollow follicles with follicle cells that produce thyroglobulin, and parafollicular cells that produce calcitonin. Thyroid hormone consists of two amine hormones: thyroxine (T4) and triiodothyronine (T3), that act on all body cells to increase basal metabolic rate and body heat production.
The parathyroid glands contain chief cells that secrete parathyroid hormone, or parathormone.
The adrenal glands, or suprarenal glands, consist of two regions: an inner adrenal medulla and an outer adrenal cortex. The adrenal cortex produces corticosteroids from three distinct regions: the zona glomerulosa, the zona fasciculata, and the zona reticularis. The adrenal medulla contains chromaffin cells that synthesize epinephrine and norepinephrine (stimulus is acetylcholine released by preganglionic sympathetic fibers).
Insulin is an anabolic hormone and will stimulate not only glucose uptake but also storage in the form of glycogen (glycogenesis), fat (lipogenesis) and amino acid incorporation into proteins (inhibits amino acid breakdown by liver to form new glucose molecules - gluconeogenesis).
Stimuli for insulin release are primarily high blood glucose levels but insulin release is also potentiated by rising blood levels of amino acids and fatty acids and release of acetylcholine by parasympathetic neurons (all of these things happen after a meal). Glucagon is released by the pancreas in response to low blood glucose levels (primarily) and raises blood glucose levels back to within normal range by stimulating glycogenolysis, gluconeogenesis, and release of glucose to the blood by the liver. Indirectly receives input from the visual pathways in order to determine the timing of day and night.
Adipose tissue produces leptin, which acts on the CNS to produce a feeling of satiety; secretion is proportional to fat stores. Adipocytes also produce adiponectin, which enhances insulin activity, and resistin, an insulin antagonist.
Osteoblasts in bone produce osteocalcin, which stimulates pancreatic beta cells to divide and secrete more insulin. Adiponectin levels are low in type II diabetes, suggesting higher levels may help reverse the insulin resistance characteristic of type II diabetes. Endocrine glands derived from mesoderm produce steroid hormones; those derived from ectoderm or endoderm produce amines, peptides, or protein hormones.
Environmental pollutants have been demonstrated to have effects on sex hormones, thyroid hormone, and glucocorticoids. This traps a 'boundary layer' of warm air that reduces the temperature gradient and in turn reduces heat loss. Specifically, they studied the implications of beta cell-specific loss of the LKB1 gene, using a mouse model system.  They were able to show that eliminating this gene from beta cells causes the production and secretion of more insulin than normal beta cells, resulting in an enhanced response to increases in blood glucose levels. Yuval Dor of the Institute for Medical Research Israel-Canada of the Hebrew University-Hadassah Medical School and included students Zvi Granot, Avital Swisa, Judith Magenheim and Miri Stolovitch-Rain,  as well as scientists from Kobe University in Japan, and American researchers from the University of Pennsylvania, Washington University in St. Dor has been conducting research in collaboration with renowned Canadian Diabetes expert Dr.
Some ions assist in the transmission of electrical impulses along cell membranes in neurons and muscles. In terms of body functioning, six electrolytes are most important: sodium, potassium, chloride, bicarbonate, calcium, and phosphate. In a clinical setting, sodium, potassium, and chloride are typically analyzed in a routine urine sample.
It is responsible for one-half of the osmotic pressure gradient that exists between the interior of cells and their surrounding environment. An absolute loss of sodium may be due to a decreased intake of the ion coupled with its continual excretion in the urine. At the cellular level, hyponatremia results in increased entry of water into cells by osmosis, because the concentration of solutes within the cell exceeds the concentration of solutes in the now-diluted ECF. It can result from water loss from the blood, resulting in the hemoconcentration of all blood constituents. It helps establish the resting membrane potential in neurons and muscle fibers after membrane depolarization and action potentials. Similar to the situation with hyponatremia, hypokalemia can occur because of either an absolute reduction of potassium in the body or a relative reduction of potassium in the blood due to the redistribution of potassium. When insulin is administered and glucose is taken up by cells, potassium passes through the cell membrane along with glucose, decreasing the amount of potassium in the blood and IF, which can cause hyperpolarization of the cell membranes of neurons, reducing their responses to stimuli.
Chloride is a major contributor to the osmotic pressure gradient between the ICF and ECF, and plays an important role in maintaining proper hydration.
Its principal function is to maintain your body’s acid-base balance by being part of buffer systems. A deficiency of vitamin D leads to a decrease in absorbed calcium and, eventually, a depletion of calcium stores from the skeletal system, potentially leading to rickets in children and osteomalacia in adults, contributing to osteoporosis. Hypercalcemia, or abnormally high calcium blood levels, is seen in primary hyperparathyroidism.
Bone and teeth bind up 85 percent of the body’s phosphate as part of calcium-phosphate salts.
In the face of phosphate depletion, the kidneys usually conserve phosphate, but during starvation, this conservation is impaired greatly. The control of this exchange is governed principally by two hormones—aldosterone and angiotensin II. Aldosterone is released if blood levels of potassium increase, if blood levels of sodium severely decrease, or if blood pressure decreases. This action increases the glomerular filtration rate, resulting in more material filtered out of the glomerular capillaries and into Bowman’s capsule.

Sodium passes from the filtrate, into and through the cells of the tubules and ducts, into the ECF and then into capillaries.
The hormone activates osteoclasts to break down bone matrix and release inorganic calcium-phosphate salts. The hormone increases the activity of osteoblasts, which remove calcium from the blood and incorporate calcium into the bony matrix. The ions in plasma also contribute to the osmotic balance that controls the movement of water between cells and their environment.
It is transformed into carbonic acid and then into bicarbonate in order to mix in plasma for transportation to the lungs, where it reverts back to its gaseous form. Such a relative increase or decrease is due to a redistribution of water or the ion in the body’s compartments.
The stimulus for GHRH release is low blood levels of GH as well as hypoglycemia, low blood levels of fatty acids, and high blood levels of amino acids. Hypersecretion of GH in childhood results in gigantism; in adulthood hypersecretion of GH causes acromegaly (increase in size of flat bones after epiphyseal plates of long bones have sealed). Thryroid releasing hormone (TRH) from the hypothalamus stimulates TSH release; Thyroid hormone (Thyroxine) exerts negative feedback control of both TRH and TSH. Excretion of ketoacids (with their negative charge) by the kidney is accompanied by loss of cations, particularly K+ and Na+. Secretion of resistin is proportional to fat stores; secretion of adiponectin is inversely proportional to fat stores. Their work opens the way for a new understanding of possible paths to battle diabetes and diabetes-related health problems, which are on the rise all over the world. More than 90 percent of the calcium and phosphate that enters the body is incorporated into bones and teeth, with bone serving as a mineral reserve for these ions. In contrast, calcium and phosphate analysis requires a collection of urine across a 24-hour period, because the output of these ions can vary considerably over the course of a day. The excess water causes swelling of the cells; the swelling of red blood cells—decreasing their oxygen-carrying efficiency and making them potentially too large to fit through capillaries—along with the swelling of neurons in the brain can result in brain damage or even death. Hormonal imbalances involving ADH and aldosterone may also result in higher-than-normal sodium values. An absolute loss of potassium can arise from decreased intake, frequently related to starvation. In such a situation, potassium from the blood ends up in the ECF in abnormally high concentrations. Chloride functions to balance cations in the ECF, maintaining the electrical neutrality of this fluid. Hyperchloremia, or higher-than-normal blood chloride levels, can occur due to dehydration, excessive intake of dietary salt (NaCl) or swallowing of sea water, aspirin intoxication, congestive heart failure, and the hereditary, chronic lung disease, cystic fibrosis. Carbon dioxide is converted into bicarbonate in the cytoplasm of red blood cells through the action of an enzyme called carbonic anhydrase. A little more than one-half of blood calcium is bound to proteins, leaving the rest in its ionized form. Phosphate is found in phospholipids, such as those that make up the cell membrane, and in ATP, nucleotides, and buffers. Hyperphosphatemia, or abnormally increased levels of phosphates in the blood, occurs if there is decreased renal function or in cases of acute lymphocytic leukemia.
Its net effect is to conserve and increase water levels in the plasma by reducing the excretion of sodium, and thus water, from the kidneys.
Angiotensin II also signals an increase in the release of aldosterone from the adrenal cortex.
PTH also increases the gastrointestinal absorption of dietary calcium by converting vitamin D into dihydroxyvitamin D (calcitriol), an active form of vitamin D that intestinal epithelial cells require to absorb calcium. Imbalances of these ions can result in various problems in the body, and their concentrations are tightly regulated.
This may be due to the loss of water in the blood, leading to a hemoconcentration or dilution of the ion in tissues due to edema. In the event that calcium and phosphate are needed for other functions, bone tissue can be broken down to supply the blood and other tissues with these minerals.
Adjustments in respiratory and renal functions allow the body to regulate the levels of these ions in the ECF. This excess sodium appears to be a major factor in hypertension (high blood pressure) in some people.
The low levels of potassium in blood and CSF are due to the sodium-potassium pumps in cell membranes, which maintain the normal potassium concentration gradients between the ICF and ECF.
This can result in a partial depolarization (excitation) of the plasma membrane of skeletal muscle fibers, neurons, and cardiac cells of the heart, and can also lead to an inability of cells to repolarize. The paths of secretion and reabsorption of chloride ions in the renal system follow the paths of sodium ions. In people who have cystic fibrosis, chloride levels in sweat are two to five times those of normal levels, and analysis of sweat is often used in the diagnosis of the disease. Calcium ions, Ca2+, are necessary for muscle contraction, enzyme activity, and blood coagulation. Additionally, because phosphate is a major constituent of the ICF, any significant destruction of cells can result in dumping of phosphate into the ECF. In a negative feedback loop, increased osmolality of the ECF (which follows aldosterone-stimulated sodium absorption) inhibits the release of the hormone ([link]). Aldosterone and angiotensin II control the exchange of sodium and potassium between the renal filtrate and the renal collecting tubule.
All of the ions in plasma contribute to the osmotic balance that controls the movement of water between cells and their environment. Phosphate is a normal constituent of nucleic acids; hence, blood levels of phosphate will increase whenever nucleic acids are broken down. Bicarbonate is the one ion that is not normally excreted in urine; instead, it is conserved by the kidneys for use in the body’s buffering systems. For the heart, this means that it won’t relax after a contraction, and will effectively “seize” and stop pumping blood, which is fatal within minutes.
Once in the lungs, the reactions reverse direction, and CO2 is regenerated from bicarbonate to be exhaled as metabolic waste. In addition, calcium helps to stabilize cell membranes and is essential for the release of neurotransmitters from neurons and of hormones from endocrine glands. Aldosterone’s effect on potassium is the reverse of that of sodium; under its influence, excess potassium is pumped into the renal filtrate for excretion from the body. Sodium is freely filtered through the glomerular capillaries of the kidneys, and although much of the filtered sodium is reabsorbed in the proximal convoluted tubule, some remains in the filtrate and urine, and is normally excreted. Potassium is excreted, both actively and passively, through the renal tubules, especially the distal convoluted tubule and collecting ducts. Because of such effects on the nervous system, a person with hyperkalemia may also exhibit mental confusion, numbness, and weakened respiratory muscles. Potassium participates in the exchange with sodium in the renal tubules under the influence of aldosterone, which also relies on basolateral sodium-potassium pumps.

Blood test glucose fasting results female
High sugar readings diabetes
Diabetes reading of 10 years


  1. 27.12.2013 at 17:18:31

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    The terms of the Creative Commons Attribution License ( ), which permits unrestricted and methylation pathways.

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  3. 27.12.2013 at 19:22:25

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  4. 27.12.2013 at 23:19:55

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