The Digestive System

2. Tongue – strongest muscle in body Saliva : Amylase =starch into maltose. Lysozyme = damages bacterial cell wall. An average person produces 25,000l in a lifetime (enough to fill 2 swimming pools) An average person swallows 295 times while eating dinner Incidentally, chewing is hard work and expends a lot of energy. Scientists have calculated that chewing gum increases energy consumption by 20%, by chewing calorie-free gum during waking hours and not changing any other aspect of energy balance, a person should lose about 5 kg of fat per year. Alexander Fleming discovered lysozyme during a deliberate search for medical antibiotics. Over a period of years, he added everything that he could think of to bacterial cultures, looking for anything that would slow their growth. He discovered lysozyme by chance. One day, when he had a cold, he added a drop of mucus to the culture and, much to his surprise, it killed the bacteria. He had discovered one of our own natural defenses against infection. Unfortunately, lysozyme is a large molecule that is not particularly useful as a drug. It can be applied topically, but cannot rid the entire body of disease, because it is too large to travel between cells. Fortunately, Fleming continued his search, finding a true antibiotic drug five years later: penicillin. Tongue – strongest muscle in body Saliva : Amylase =starch into maltose. Lysozyme = damages bacterial cell wall. An average person produces 25,000l in a lifetime (enough to fill 2 swimming pools) An average person swallows 295 times while eating dinner Incidentally, chewing is hard work and expends a lot of energy. Scientists have calculated that chewing gum increases energy consumption by 20%, by chewing calorie-free gum during waking hours and not changing any other aspect of energy balance, a person should lose about 5 kg of fat per year. Alexander Fleming discovered lysozyme during a deliberate search for medical antibiotics. Over a period of years, he added everything that he could think of to bacterial cultures, looking for anything that would slow their growth. He discovered lysozyme by chance. One day, when he had a cold, he added a drop of mucus to the culture and, much to his surprise, it killed the bacteria. He had discovered one of our own natural defenses against infection. Unfortunately, lysozyme is a large molecule that is not particularly useful as a drug. It can be applied topically, but cannot rid the entire body of disease, because it is too large to travel between cells. Fortunately, Fleming continued his search, finding a true antibiotic drug five years later: penicillin.

3. Peristalsis - A series of normal coordinated, rhythmic muscle contractions that occurs automatically to move food through the digestive Tract (oesophagus, small intestine, large intestine) , urine from the kidneys through the ureters into the bladder, and bile from the gall bladder into the duodenum.Peristalsis - A series of normal coordinated, rhythmic muscle contractions that occurs automatically to move food through the digestive Tract (oesophagus, small intestine, large intestine) , urine from the kidneys through the ureters into the bladder, and bile from the gall bladder into the duodenum.

4. What causes our stomach to growl? Stomach growling occurs when the stomach receives signals from your brain to begin digestion but the stomach is empty. Your brain might sense you're running low on energy (glucose) or even seeing or smelling something you want to eat can get things going. The motion of the stomach muscles begins, but the organ is hollow. The movement of the muscles mixing the acids of the stomach in the hollow space of the stomach produces vibrations we hear as growling, or rumbling, or gurgling. What causes our stomach to growl? Stomach growling occurs when the stomach receives signals from your brain to begin digestion but the stomach is empty. Your brain might sense you're running low on energy (glucose) or even seeing or smelling something you want to eat can get things going. The motion of the stomach muscles begins, but the organ is hollow. The movement of the muscles mixing the acids of the stomach in the hollow space of the stomach produces vibrations we hear as growling, or rumbling, or gurgling.

5. Mucous – lubricates food. Prevents stomach self-digesting. Prevents attachment of bacteria HCl – stomach pH = 1-2. Kills bacteria, helps breakdown food, activales pepsinogen, deactivates amylase Pepsinogen (pro-enzyme) – activated by HCl – pepsin (this prevents the enzyme from digesting cells that produce it). Breaks proteins down into peptidesMucous – lubricates food. Prevents stomach self-digesting. Prevents attachment of bacteria HCl – stomach pH = 1-2. Kills bacteria, helps breakdown food, activales pepsinogen, deactivates amylase Pepsinogen (pro-enzyme) – activated by HCl – pepsin (this prevents the enzyme from digesting cells that produce it). Breaks proteins down into peptides

6. NaHCO3 = neutralises acid Once trypsinogen and chymotrypsinogen are released into the lumen of the small intestine, they must be converted into their active forms in order to digest proteins. Trypsinogen is activated by the enzyme enterokinase, which is embedded in the intestinal mucosa. Once trypsin is formed it activates chymotrypsinogen, as well as additional molecules of trypsinogen. The net result is a rather explosive appearance of active protease once the pancreatic secretions reach the small intestine. Trypsin and chymotrypsin digest proteins into peptides and peptides into smaller peptides, but they cannot digest proteins and peptides to single amino acids. Insulin Glucagon Emulsification = breaks fats and oils into tiny droplets, increasing surface area to aid digestion Salad dressingNaHCO3 = neutralises acid Once trypsinogen and chymotrypsinogen are released into the lumen of the small intestine, they must be converted into their active forms in order to digest proteins. Trypsinogen is activated by the enzyme enterokinase, which is embedded in the intestinal mucosa. Once trypsin is formed it activates chymotrypsinogen, as well as additional molecules of trypsinogen. The net result is a rather explosive appearance of active protease once the pancreatic secretions reach the small intestine. Trypsin and chymotrypsin digest proteins into peptides and peptides into smaller peptides, but they cannot digest proteins and peptides to single amino acids. Insulin Glucagon Emulsification = breaks fats and oils into tiny droplets, increasing surface area to aid digestion Salad dressing

15. Aas can’t be stored – become toxic and hence aas not needed are broken down by liver in a process known as deaminationAas can’t be stored – become toxic and hence aas not needed are broken down by liver in a process known as deamination

16. The ileum is 4m long. It produces enzymes that are responsible for the final stages of digestion. The main job of the ileum is absorption and the inside surface of the ileum is also covered in villi, which increase the surface area which can absorb nutrients, such as vitamins, amino acids and simple sugars. These nutrients are absorbed into the bloodstream and distributed around the body. By the time the food leaves the ileum, most of the useful nutrients have been absorbed. The ileum is 4m long. It produces enzymes that are responsible for the final stages of digestion. The main job of the ileum is absorption and the inside surface of the ileum is also covered in villi, which increase the surface area which can absorb nutrients, such as vitamins, amino acids and simple sugars. These nutrients are absorbed into the bloodstream and distributed around the body. By the time the food leaves the ileum, most of the useful nutrients have been absorbed.

18. Probiotics are live micro-organisms that, when consumed in adequate amounts, confer a health benefit to the host.   They are the 'good', 'friendly' or 'beneficial' bacteria which when ingested act to maintain a healthy gastrointestinal (GI) tract and help to fight illness and disease. These good health-promoting bacteria can provide a protective effect against potentially harmful bacteria, known as pathogens , which also reside in the GI tract.   The human GI tract is inhabited by two kilograms of bacteria, known as commensals, representing over 400 different species.   These bacteria are critical for normal development of the intestine and for defence against infections and are vital for our health.   Bacteria in the gut are known to: Aid digestion and break down toxins Produce vitamins B12 and K Stimulate the immune system Probiotics are live micro-organisms that, when consumed in adequate amounts, confer a health benefit to the host.   They are the 'good', 'friendly' or 'beneficial' bacteria which when ingested act to maintain a healthy gastrointestinal (GI) tract and help to fight illness and disease. These good health-promoting bacteria can provide a protective effect against potentially harmful bacteria, known as pathogens , which also reside in the GI tract.   The human GI tract is inhabited by two kilograms of bacteria, known as commensals, representing over 400 different species.   These bacteria are critical for normal development of the intestine and for defence against infections and are vital for our health.   Bacteria in the gut are known to: Aid digestion and break down toxins Produce vitamins B12 and K Stimulate the immune system