Biochemistry: Digestive System Notes Assignment

Biochemistry: Digestive System Notes Assignment Words: 1965

The Stomach is located on the left side of the body above the waist and behind the ribs. It performs four major functions: (1) the bulk storage of ingested food. 2) the mechanical breakdown of ingested food, (3) the disruption of chemical bonds in food material through the action of acids and enzymes, and (4) the production of intrinsic factor, a globetrotting whose presence in the digestive tract is required for the absorption of vitamin 8-12 in the small intestine.

About 2-4 L of food can be stored in the stomach. Bolus (chewed food) enters the stomach and leaves as chem. (liquid food) to the small intestine. Like the walls of esophagi, the walls of stomach are strong and muscular. They contract with enough force to break food into smaller pieces as glands in the stomach walls release tomato Juices. There are two distinct processes in the stomach: (a) Mechanical, the churning of food, contraction of walls by the stomach, and breaking down the food into smaller pieces. B) Chemical, the secretion of hydrochloric acid (HCI) and possession from glands along the walls of the stomach, conversion of possession to pepsin to break down proteins. The layers of muscle on the stomach contain the glands and gastric pits which consist of mucous cells, parietal cells, and chief cells. Mucous cells give off mucus. Parietal cells give off HCI and intrinsic factor. Chief cells vive off enzymes that break down proteins. Gastric Secretion Gastric mucous/ Stomach mucous secretes 1. 2 to 1. 5 L of gastric Juice per day.

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Gastric juice renders food particles soluble, initiate digestion (particularly of proteins), and converts the gastric contents to a similitude mass called chem., thus preparing it for further digestion in small intestine. It is a variable mixture of water, HCI, electrolytes, and organic substances. This Juice is highly acidic because of its HCI contents and rich in enzymes. Stomach walls are protected from digestive Juices by the membrane n the surface of the epithelial cells bordering the lumen of the stomach; this membrane is rich in lepidopterist, which are resistant to attack by acid.

The process of gastric digestion can be divided into three (3) phases: Cephalic, controlled by the central nervous system, Gastric, regulated by short reflexes of the enteric nervous system, coordinated in the wall of stomach, and Intestinal, regulated by hormones of the digestive tract. The Cephalic phase -begins when you see, smell, taste, or think of food. This stage, which is directed by the CANS, prepares your stomach to receive food. The Gastric phase -begins with the arrival of food in the stomach and builds on the stimulation provided during the cephalic phase .

The stimuli that initiate the gastric phase are ( distension of the stomach, (2) an increase in the pH of the gastric contents, and (3) the presence of undigested materials in the stomach, especially proteins and peptides. The Intestinal phase -begins when chime starts to enter the small intestine. When the chem. contains lipids from the digestion of fats or contains enough HCI to bring its pH below 2, gastric secretion is inhibited. INTESTINAL DIGESTION he part of digestion carried on in the intestine, affecting all foodstuffs, including star chess, fats, and proteins.

Small Intestine -is the portion of the digestive system most responsible for absorption of nutrients from food into the bloodstream. -has an expanded surface area with inner folds, called plicate, villa and microvolt(brush border of the small intestine). Large intestine -is the portion of the digestive system most responsible for absorption of water from the indigestible residue of food. Intestinal Digestion Process. 1 . When the work of digestion is completed in the stomach the food is poured wrought the pyloric orifice into the small intestine where it undergoes further changes. 2.

In the small intestine majority of digestion and absorption occurs where the milky chem. enters the duodenum. Duodenum part of the small intestine that is closest to the stomach. A naturalization chamber in which the chem. from the stomach is mixed with bicarbonate. Iron and calcium, are taken up most efficiently in the duodenum 3. It then enters the Jejunum, is the place where most nutrients are actively absorbed. Jejunum the middle section of the small intestine. Place where most nutrients are actively absorbed. Mini acids as well as most vitamins and minerals are absorbed in the Jejunum. Active fat absorption also occurs in the duodenum and the Jejunum *The majority of starch is also digested in the duodenum and Jejunum 4. Then goes to the ileum, which is responsible for completing the digestion of nutrients and for reabsorbing the bile salts that have helped to solubility (keep in solution), the fats. Ileum the final part of the small intestine. Responsible for completing the digestion of nutrients and for reabsorbing the bile salts. The place where vitamin 812 is selectively absorbed into your body.

Eater passing through the small intestine, t Large Intestine food, which at this point is primarily fiber food stays longer in the large intestine passes into the large intestine. – spends six to 72 hours in your large intestine before final removal contains an ecosystem of bacteria that can ferment much of this fiber, producing many nutrients necessary for the health of the colon cells. – proportion bacteria – first part of the large intestine is called the scum. – Food then travels upward in the ascending colon. -the food travels across the abdomen in the transverse colon. – goes back down the there side of the body in the descending colon. And then through the sigmoid colon. PANCREATIC JUICE Definition: -It is a clear, colorless, alkaline secretion of the exocrine part of the pancreas necessary for digestion. Composition: – It is composed of two secretors products critical to proper digestion: 1 Bicarbonates – It is secreted by the epithelial cells lining the small pancreatic ducts. – This made the pancreatic acid to be alkaline. – It neutralizes the acid in chem. to protect the intestinal wall and to create the proper environment for the functioning of pancreatic enzymes. 2. Digestive Enzymes – These enzymes are synthesized and secreted by the exocrine china cells.

These enzymes help in the digestion of essential macromolecules into their observable forms. -The enzymes are classified according to their substrates: Proteases -proteins Amylase -carbohydrates Lipase and phosphates -lipids Nuclease -nucleic acids The secretion of Pancreatic Juice is controlled by two hormones: secretion (for bicarbonates) and collection’s (digestive enzymes) *Pancreatic Enzymes: Proteases These enzymes are responsible for protein catabolic that is by the hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein.

Two major pancreatic proteases: 1 Trying -secreted as an inactive precursor trapshooting. *Trapshooting is a single polypeptide chain with molecular weight of 25,000 and activated by a duodenal mucosa enzyme entertainers or introspected which cleaves hydroelectrically a terminal hexameter. – Formation of sufficient trying activates the rest of the precursor autocratically. – Trying acts on peptide bonds where carboy groups are contributed by argentine or lysine present deep inside the lopsided chain (antipodeans) at an optimum pH of 8. 0. Certain inorganic ions, chiefly calcium, help activation and also accelerate the action of trying. 2. ) Chemisorptions -secreted as an inactive precursor comprehension. *Comprehension is a single polypeptide chain of molecular weight approximately 25,700 and is activated by trying. -It prefers large hydrophobic residues such as the amino acids. – It acts preferentially on peptide bonds where carbonyl groups belong to aromatic amino acids like tyrosine and phenylalanine, at an optimum pH of 8. 0. -It also acts readily upon amides and esters of susceptible amino acids. – Unlike trying, chemisorptions coagulates milk. Carbohydrates -is the other proteolysis enzyme of the pancreatic Juice, secreted as prestidigitation’s and activated by trying. – Being an expeditions, it cleaves off terminal amino acids with free carbonyl groups. LIPASE – is a powerful lipstick enzyme which hydrolysis triglycerides to lower triglycerides and free fatty acids. NUCLEASE – The nuclease- ribs-nuclease and deoxyribonucleic, which break up nucleic acid to nucleotides, are also present in the pancreatic Juice. ELASTICS cuts peptide bonds next to small, uncharged side chains such as those of Elaine and serine.

AMYLASE – is an a-amylase (similar to fatality) of molecular weight 45,000 and requires chloride ions for activation. – This enzyme continues the starch digestion process. It hydrolysis starch to maltose by splitting the 1-4 glycoside linkages at an optimum pH of 6. 5 to 7. 2. -It completes digestion of carbohydrate, producing glucose, a small molecule that is absorbed into your blood and carried throughout your body. – It also digests glycogen. * Mammalian – It is a starch-digesting amylase that converts starch into sugar. It is used therapeutically as a digestive aid and as an anti-inflammatory agent.

Terms: Genome – an inactive precursor that prevents cell’s self-digestion Antipodeans – cleaves off amino acids inside the polypeptide chain Expeditions – cleaves off terminal amino acids with free carbonyl groups Intestinal Juice Intestinal Juices The complex enzymes which break down food in all the main food groups. They are clear to pale yellow, watery secretion composed of hormones, digestive enzymes, mucus, and neutralizing substances released from the glands and mucous- membrane lining of the small and large intestines. Neutralize hydrochloric acid coming from the stomach; release gastrointestinal hormones into the bloodstream.

The main function of intestinal Juice is to dissolve fibrin and to emulsify fats. Intestinal Juice is capable of being extracted with glycerin and is closely related to the properties of the secretion of the pancreas. Intestinal Enzymes All digestive enzymes are hydrolysis in which they control the hydrolysis. They speed up the breakdown (hydrolysis) of food molecules into their ‘building block components. How the enzyme does works? There are four kinds of Intestinal Enzymes Sucrose Lactate Maltase Peptidases Sucrose – is the name given too number of enzymes that catalyst the hydrolysis of sucrose to fructose and glucose.

It is also called as Inverters. Present in yeast and in the intestine mucosa of animals. Localize in the brush border (a chemical barrier through which food is absorbed) that coats the intestinal villa. Lactate – any of a group of enzymes found in the small intestine, liver, and kidney of mammals that catalyst the breakdown of lactose (milk sugar) into the simple sugars glucose and calaboose. Particularly abundant during infancy. Produced by the mucous membrane cells that line the intestinal walls; granules localize in the brush border (a chemical barrier through which food must pass to be absorbed) that coats the intestinal villa.

Peptidases – also called protease or proteins, is a type of enzyme that helps to break down proteins in the body. This type of enzyme occurs naturally in the living things and forms part of many metabolic processes Break down proteins by destroying the chains between their amino acids, and many can usually be found in the digestive tract. When protein enters the body, it needs to be digested and broken own into smaller molecules so that it can be used. This type of enzyme is responsible for this catabolic process. They were the first enzymes to be studied because of their abundance in the digestive system.

They are the most important group of proteolysis enzymes in cuscus enteritis. Because they bring about the final breakdown polypeptides to amino acids. Maltase – enzyme that catalysts the hydrolysis of the disaccharide maltose to the simple sugar glucose. Is found in plants, bacteria, and yeast; in humans and other vertebrates. It is thought to be synthesized y cells of the mucous membrane lining the intestinal wall. The glucose so produced is either utilized by the body or stored in the liver as glycogen (animal starch).

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