Gland: Stomach Acid

THE STOMACH

Phosphorus works in the stomach to stabilize sugars and activate starches by the twofold process of phosphorylation. Phosphorus in conjunction with HCl, pepsin, zinc, and vitamin C via the thymus helps in the:
1. Stabilization of sugar-simple sugars are easily oxidized (combusted) before they reach the liver, resulting in low sugar levels. Pepsin stabilizes these simple sugars, so they can be transferred to the liver for storage.
2. Activation of starches-HCl is necessary to breakdown oily carbohydrates (grains), which are difficult to oxidize (combust), thus making them readily available for oxidation.
The above two mechanisms establish an HCl-pepsin balance in the stomach for proper pH digestion.
The presence of both HCl and pepsin in the stomach are critical for preparing carbohydrates and proteins for further digestion in the small intestines. Phosphorus indicates the amount of acid balance in the body. It does this by regulating secretions of HCl and pepsin in the stomach by the foods you eat. For example, when you eat foods that are high in phosphoric acid, there will be a release of pepsin to neutralize the acid. On the other hand, foods low in phosphoric acid content will cause large amounts of HCl to be released. Phosphorus then carries carbohydrates across the intestinal wall for absorption by the liver. Phosphorus also affects the intrinsic factor function by releasing alkaline B vitamins into inorganic foods, converting them into organic foods for storage in the liver sinusoids.
Patients that have an acid pH in their stomach should avoid excessive amounts of acid forming foods such as meats, dairy, grains and junk foods.
Patients that have an alkaline pH should avoid excessive amounts of alkaline forming foods such as fruits and vegetables.
Diet has a dramatic affect on the acidity or alkalinity of the stomach and is usually the culprit in stomach conditions.
The 3 Phases Of Gastric Secretion
1. The Cephalic Phase- which is the result of hunger, sight, smell and thought about food neurologically controlled by the cerebral cortex that project to appetite centers in the amygdala or hypothalamus. This phase accounts for 1/5th of the digestive juices produced.
2. The Gastric Phase- when the food enters the stomach it excites long vasovagal and local enteric nerves that stimulate the release of gastric juices accounting for 2/3rds of the 1500 ml’s released daily.
3. The Intestinal Phase – once the food enters the duodenum, it triggers the release of gastrin from the intestinal mucosa thus inhibiting the release of gastric juices. The presence of food in the small intestines initiates an enterogastric reflex, which also inhibits gastric secretions. The presence of secretin and cholecystokinin are responsible for pancreatic enzyme release. Cholecystokinin releases bile via the gallbladder and also inhibits gastric function. Acids, protein by-products, gastric inhibitory peptide, vasoactive intestinal polypeptide, and somatostatin all inhibit gastric secretions. Since the stomach is poor at absorption, very little takes place. It is only when you reach the small intestines that you find folds known as valvulae conniventes, which increase the surface area of the small intestines 3 fold. Extending from these conniventes are small projections called villi, which increase the absorption another 10 fold. These villi are close together and their outer epithelial cells form a brush border protruding into the chyme. This increases the absorptive power another 600 fold. This makes the surface of the small intestines 250 sq. meters (About the size of a tennis court). The absorptive capacity of the small intestines is astounding. It can absorb several kilograms of carbohydrates, 500-1000 grams of fat (20-40 ounces), 500-700 grams (20-28 ounces) of protein, and 20 or more liters of water daily.

There are four types of glands that are found in the gastrointestinal tract:
1. Salivary cells are found in the mouth, pancreas, and the liver
2. Mucous glands- Mucous contains, water, electrolytes, glycoproteins, and HCO3
ions. The function of mucous is to adhere tightly to the food while it coats the
intestinal wall. Mucous prevents food from contacting the mucosa. Mucous also
causes fecal particles to adhere together to form a mass. Mucous is also very
resistant to digestive juices, and can buffer acids or alkaline enzymes. The
esophagus also secretes mucous. The mucous glands secrete mucous in response
to vagal stimulation, gastrointestinal enzymes, and irritating factors. Mucous glands
that are in the upper duodenal area between the pylorus and papilla of vata are
called “Brunner’s glands”. Crypts of Lieberkuhn are found in the small intestines.
3. Tubular cells- are found in the stomach and are of 2 types: the oxyntic or gastric and the pyloric. The first, oxyntic, are your parietal and chief cells. The parietal cells secrete HCl, intrinsic factor for B12 absorption, and histamine. The chief cells secrete pepsinogen, intrinsic factor and mucous. The second type of tubular gland is called the pyloric gland. The pyloric glands mainly secrete mucous
but also pepsinogen and gastrin. The oxyntic glands are located in the body and fundus of the stomach comprising 80% of the stomach; the pyloric glands are found in the antral portion of the stomach. These tubular cells are also found in the upper part of the small intestines. Pepsinogen, which is not reactive, is activated and transformed into pepsin by coming in contact with HCl. Pepsin is a proteolytic
enzyme that is highly reactive in an acid media between (1.8-3.5). Therefore, both HCl and pepsin are responsible for protein digestion. Other enzymes of the stomach include gastric lipase and amylase; both are extremely weak and play a minor role in the digestion of fats and starches. Gelatinase, another enzyme, is responsible for liquification of proteoglycans found in meat. The stomach also secretes intrinsic factor, which is responsible for B12 absorption in the ileum.
B12 is responsible for red blood cell maturation. Gastric secretions have a pH of 1.0-3.5.
4. The stomach also secretes gastric amylase and lipase.
The Neurotransmitters Affecting Gastric Secretions Are:
1. Acetylcholine-which is responsible for pepsinogen via peptic cells, gastrin via gastric cells, HCl via parietal cells and mucous secretions.
2. Gastrin (2 types G17 and G34) named for the number of amino acids that make them up, and histamine (an amino acid derivative) both stimulate HCl production.
When gastric or acetylcholine are present histamine has a much stronger effect on acid production. All of these neurotransmitters activate receptor sites on secretory cells, which stimulate the secretory process. Amino acids, caffeine and alcohol can also stimulate gastric secretory activity.

Neural Control Of The Gastrointestinal System
The GI tract is controlled by:
A. Reflex activity between the brain stem (vagus nerve dorsal motor nuclei), such as the stomach motor and secretory activity, pain and strong powerful colonic contractions.
B. The spinal cord via the autonomic nervous system. The sympathetic division extends from T5-L3 forming the celiac and mesenteric plexuses and the sympathetic chain ganglion, which inhibits peristalsis and digestive secretions by the inhibition of the myenteric and submucosal plexus with norepinephrine. Usually, they control long range communication between the stomach, small intestine, ileocecal valve and the colon, by controlled slowing or speeding up of movement of food and fecal material.
C. The parasympathetic outflow division originates from S1-S3 and stimulates the movement of fecal material and reabsorption of H2O and electrolytes. Remember that almost all sympathetic or parasympathetic activity is afferent in nature. This means that distention, mucosal irritation from foods, drugs, preservatives, pH etc. send afferent messages to the brain stem initiating the proper course of action to occur.
D. The GI tract has its own nervous system called the enteric nervous system and is found in the gut wall extending from the esophagus to the anus (100 million neurons are the number of neurons in the spinal cord). The enteric nervous system releases the following neurotransmitters: acetylcholine, norepinephrine, ATP, serotonin, dopamine, cholecystokinin, substance P, vasoactive intestinal polypeptide, somatostatin, and leu-enkephalin. Acetylcholine stimulates intestinal activity norepinephrine inhibits intestinal activity.

The enteric nervous system is composed of 2 plexuses
1. myenteric plexus (Auerbach’s) found between the circular and longitudinal fibers and controls peristaltic movement. The myenteric plexus is composed of linear chains of interconnecting neurons. When stimulated it increases:
• Tonic contractions
• Rhythmic contractions
• Velocity of conduction
• Rate of rhythm
· · ·
Please note that the myenteric plexus does play a role in inhibition of the pyloric sphincter and the ileocecal valve.
2. Submucosal plexus (Meissner’s plexus) is found in the submucosa and is responsible for digestive secretions and blood flow. The purpose of the enteric nervous system is to control peristalsis and digestive secretions short range over small distances. This is most beneficial since the body uses a finer control over the local digestive process.
Digestion And Absorption In The Gastrointestinal Tract
Carbohydrate Digestion- There are 3 major sources of carbohydrates in the diet
Sucrose, a disaccharide known as cane sugar
Lactose, a disaccharide known as milk sugar
Starches (grains), which are long polysaccharides
When monosaccharides form disaccharides, hydrogen is removed from one monosaccharide and a hydroxyl group is removed from the other monosaccharide, forming water in a process (condensation). When disaccharides split into monosaccharides the process is called hydrolysis (the addition of water to form the 2 monosaccharides). Humans cannot digest cellulose.
Carbohydrate digestion starts in the mouth via an alpha amylase known as ptyalin, secreted by the parotid glands. This enzyme hydrolyzes starches into maltose and other small polymers of glucose (3-9 glucose molecules long.). 3-5% of all starches are digested in the mouth. As the food enters the stomach ptyalin continues to digest the carbohydrates so that within 1 hour, upon entering the stomach, most of the carbohydrates are converted into maltose. When the pH falls below 4.0 ptyalin starts to become inactive. By the time the chyme reaches the duodenum and jejunum, pancreatic amylase, which is much more potent then ptyalin (more concentrated), converts the remaining polymers into maltose.
In the lining membranes of the intestinal lumen (microvilli brush border) there are four enzymes produced:
Lactase, which splits lactose into galactose and glucose
Sucrase, which splits sucrose into fructose and glucose
Maltase, which splits maltose into glucose.
Alpha Dextrinase, which splits all of the above as well as dextrins

2. Protein Digestion-Protein digestion starts in the stomach via pepsin. Pepsin is also important for digesting collagen, an albuminoid found in meats. Pepsin is most active at a pH of 2-3. The HCl produced by the body has a pH of .8. When proteins leave the stomach they are mostly in the form of proteases, peptones, and large polypeptides. When the chyme reaches the small intestines the pancreatic enzymes trypsin and chymotrypsin split proteins into small peptides and carboxypolypeptidase then split a small percentage of these into amino acids. The bulk of the peptides are broken down by the multiple peptidases located in the brush border of the intestinal membrane.
The most important peptidases are aminopolypeptidase and several dipeptidases. These split the proteins down to di and tri-peptides, which enter the microvilli membrane into the interior of the epithelial cell where other peptidases break up the remaining di and tripeptides into amino acids to be absorbed into the blood stream. Please note that di, tri, and polypeptides can still enter the blood stream and can cause allergic reactions. 99 % of all protein is absorbed as amino acids.
3. Fat Digestion The most abundant fat in the diet is in the form of triglycerides, which contains a glycerol nucleus and 3 fatty acids (stearic, and palmitic acid, which are saturated and oleic acid which is unsaturated). All 3 come from animal and not plant origin. The usual diet contains phospholipids, cholesterol and cholesterol esters.
Cholesterol is formed in the liver from degraded products of fatty acid molecules, which give cholesterol its fatty characteristics. Fat (butterfat) is digested in the stomach via gastric lipase (tributyrase) in very small amounts. 99% of fat digestion takes place in the intestines via bile. Bile contains bile salts and a phospholipid known as lecithin in the form of ionized sodium salts. Bile salts have the ability to form micelles, small globules of fat attached to the bile salt. This occurs because the sterol portion of the bile salt is highly soluble in fat and a polar portion of the bile salts and lecithin are highly soluble in water. This reducing and changing of the polarity reduces the interfacial tension between the fat cells so digestive enzymes can continue to break down the fat. This increases the total surface area of the fat a 1000 fold. Pancreatic lipase is responsible for splitting 99% of the triglycerides into 3 fatty acids and 2 monossachrides.
Cholesterol, its ester (cholesterol +1 molecule of a fatty acid) and phosopholipids (via cholesterol ester hydrolase and phospholipidase respectively) are broken down via hydrolysis of the fatty acids from their molecular structures. The bile salts, when attached to lipids create micelles, which are highly charged and increase the absorption of these fatty acids, glycerol, free cholesterol and the remaining portion of the phospholipids. Please note that without bile salts much of the fat will be blocked from entering the blood stream.

Chloride

ELECTROLYTES

The blood electrolytes include sodium, potassium, chloride, and the bicarbonate (HCO3) ion.
Sodium, potassium, and chloride enter the body via ingestion of food.
Carbon dioxide, on the other hand, originates within the body via the metabolic process of carbohydrates, fats, and proteins.
Normally the excretion of sodium, potassium, and water is equal to their intake. The kidneys secrete 80-90 percent of all electrolytes.
Excessive carbon dioxide stimulates the respiratory centers in the brainstem to increase respiration. Therefore, the kidneys and the lungs control sodium, chloride, potassium, water, and carbon dioxide thus exerting control over the acid/alkaline balance in the body.
There are also many other organs, and glands involved in this process, such as the posterior pituitary, adrenals, bowel, and uterus/prostate.
The purpose of electrolytes is to set up a shifting mechanism in the cell membrane via oxidation, allowing increased or decreased permeability to that membrane site.
Sodium, which is found in high concentration outside the cell, has the ability to gather up substances (foods) and bring them to active membrane sites.
Chloride is found in the cell membrane and acts as a “doorman” allowing or disallowing exchanges between the intracellular and extracellular fluids.
Potassium, which is found in high concentrations within cells, oxidizes chloride, and allows sodium, with the food to cross the cell membrane and enter the cell.
Sodium, potassium, chloride, calcium, and hydrogen are all transported via active transport.
CHLORIDE

Chloride a blood electrolyte, and is the major anion and exists in the extracellular spaces as part of the sodium chloride or HCl molecules.
Chloride is used for assessing pH, and electrolyte balance.
From a physiologic perspective, the primary purpose of chloride is to regulate the quantity of carbohydrates and proteins entering into the cells, by inhibiting the exchange of mineral controlled substances across the cell membrane and responds to the oxidative power of potassium.
Chloride the major anion is predominantly found in the extracellular spaces as part of sodium chloride or in the stomach as hydrochloric acid.
Chloride maintains cellular integrity by its influence on acid-base and water balance as well as osmotic pressure. Chloride has a reciprocal power with other anions by decreasing or increasing when there are too many or not enough anions. Aldosterone has a direct effect of reabsorption of sodium and an indirect effect on the increased absorption of chloride.
Chlorides are lost via the GI tract through vomiting or diarrhea and thru the kidneys during times of diuresis.

Chloride also responds to the antioxidant media (cell membrane) by mobilizing, and collecting sodium/food aggregates on a selectively permeable basis. This reaction is under the influence of the adrenal medulla/epinephrine/norepinephrine thereby maintaining energy stores.
Chloride also assists in the production of HCl via the chief cells in the stomach.
In the bowel, chloride is important in preventing the passage of water out of the body. Therefore, chloride literally blocks the flow of water/gas exchange across a cell membrane. This is extremely important in the intestines and bladder.

Chloride plays a vital role during the conduction of a neurological impulse where sodium lines up on the outside of a cell membrane, and potassium on the inside of the cell membrane, during the resting stage or polarized state. In a normal nerve fiber, the permeability of the membrane to potassium is about 100 times that of sodium. The sodium-potassium pump moves three sodium ions to the exterior of the cell, for every two potassium ions that are moved to the interior of the cell, creating a net positive charge to the outside of the cell membrane for each revolution of the sodium-potassium pump. This creates a positively charged external membrane and a negatively charged internal membrane, which sets up a membrane electrical potential. As a neurological impulse is transmitted down the nerve, (which is the excitation phase of an impulse), sodium crosses the cell membrane, and enters into the cell, while potassium moves to the external portion of the membrane.

This then creates the depolarization of the cell membrane, thereby creating a negative charge on the outside, and a positive charge on the inside. The transmission of each impulse along the nerve fiber reduces infinitesimally as the concentration differences of sodium and potassium between the inside and outside of the cell membrane change slightly. In so doing allows the nerve fiber to transmit between 100, 000 to 50, 000, 000 impulses before the concentration differences are rundown.

As the neurological impulse passes, the sodium-potassium ATPase pump re-establishes the sodium-potassium ratio back to normal (repolarization). The pumping activity is dramatically increased approximately eightfold to restore the membrane back to the polarized state.
The chloride shift to the inside of the cell membrane during the final stages makes the inside of the cell, even more, negative, which further helps repolarize the cell.
Chloride generally increases and decreases with plasma or serum sodium levels.

CHLORIDE IS HIGH WHEN

General considerations:

¬ Drink plenty of water
¬ Decrease sodium levels
¬ Increase fat-soluble vitamins D, E, K, and A

Phosphorus

PHOSPHORUS
85% of the total phosphorus exists as phosphates or esters in the body and is found chiefly in the skeleton and is combined with calcium. 14% of the phosphorus is found in intracellular tissues and 1 % is found in the extracellular fluid. Therefore phosphorus levels are a poor indicator of levels of phosphates in the body.

Phosphorus runs inversely to calcium levels in the body at a calcium to phosphorus ratio of 10 to 4. Therefore, calcium can be a great indicator for phosphorus as well.
As calcium levels increase in the serum, phosphorus levels decrease, and when calcium levels decrease phosphorus levels increase. In fact, causes of high calcium also cause low phosphorus. The controlling factor of phosphorus is parathormone (PTH), which is also the calcium-controlling factor. Phosphorus helps calcium through the cell membrane by increasing the permeability of the cell membrane via oxygen displacement.

1. Phosphorus is responsible for growth and development by way of:
✓ bonding
✓ polymer function
✓ hydration
✓ chemical transport, and
✓ buffering

2. Phosphorus is also responsible for bone formation

3. Phosphorus and metabolism of glucose
Phosphorus is also required for the metabolism of glucose via phosphorylation. Phosphorylation is when a phosphate radical promoted by glucokinase in the liver, or hexokinase in other cells captures the glucose and once inside the cells keeps it there. The exception to this occurs in the liver, the kidneys, and the intestinal epithelial cells.
Ingestion of carbohydrates causes phosphorus to enter RBC’s with glucose causing a reduction of serum phosphorus levels and lipids.
Phosphorus also works in the stomach to stabilize sugars and activate starches by the twofold process of phosphorylation.
Phosphorylation and its counterpart, dephosphorylation, turn many protein enzymes on and off, thereby altering their function and activity.
By altering pepsin/HCL levels phosphorus can:

a. Stabilize simple sugars-simple sugars are easily oxidized (combusted) before they reach the liver, resulting in low sugar levels. Pepsin stabilizes these simple sugars, so they can be transferred to the liver for storage.

b. Activation of starches- HCl is necessary to breakdown oily carbohydrates (grains), which are difficult to oxidize (combust). Thus making them readily available for oxidation.

The above two mechanisms establish an HCl-pepsin balance in the stomach for proper pH digestion.
The presence of both HCl and pepsin in the stomach are critical for preparing carbohydrates, as well as proteins for further digestion in the small intestines.

4. The regulation and maintenance of the acid-base balance in the body by maintaining glandular acidity.

5. The storage and transfer of energy from one part of the body to the other.

6. Used in the Production of phospholipids (90 % produced by the liver): lecithin, A cephalin, and sphingomyelin
Phospholipids are necessary for:
Proper brain function (sphingomyelins)
Phospholipids are a major constituent of lipoproteins which can affect function, formation and transport of these lipoproteins causing serious cholesterol abnormalities
Production of cell membranes
Thromboplastin production produced from A cephalin

7. Intracellular phosphorus is used for:
Energy transport formation of ATP from ADP and creatine phosphate via oxidative phosphorylation.
Major constituent of plasma membranes (phospholipids)
Major constituent of DNA and RNA (nucleic acids)
Calcium transport and osmotic fluid pressure
General nutritional considerations when phosphorus is high:

1. Patient should increase water intake
2. Reduce fat intake
3. Reduce Vitamin D intake if overdosing
4. An isotonic saline solution (sea salt) will decrease phosphorus levels
5. Also, decrease phosphorus in the diet and add calcium carbonate to your diet

General considerations when phosphorous is low:

1. Vitamin D deficiency
2. Calcium deficiency
3. Magnesium deficiency
4. Patient needs a high protein diet