Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Digestion in oral cavity and stomach Extension . Digestion Digestion: Breaking down large, nutrient macromolecules into simpler molecules for use by an organism. Food enters the mouth and goes through mechanical and chemical changes as it passes through the alimentary canal. Types of Nutrients • Micronutrients- vitamins, minerals, & water • Macronutrients- proteins, lipids, carbohydrates, etc… Organs involved in digestion Mouth The gastrointestinal (GI) tract involves the stomach, small intestine and colon. Oesophagus Stomach Small intestine Colon Anus Rectum Mouth Mastication is the action of the teeth and the jaws working together to break food down. Food needs to be chewed to be broken down into pieces small enough to swallow. Breaking the food down also gives it a larger surface area for the digestive enzymes to work on. There are two different types of teeth in the mouth - Incisors to tear food e.g. meat - Molars to grind the food. Common characteristic of the mouth cavity digestion • 1. Primary analyses of substances, which are coming to organism – taste analyzes; • 2. Reflector signals from receptor, which are present in these area to the another organs of digestive system, to the central nerve system – medulla oblongata, stomach, small intestine, pancreas; • 3. Chemical processing of food; • 4. Mechanical processing of food; • 5. Absorption of some substances. Anatomy of the Mouth and Throat • Chewing of food is important, because fruits and vegetables have cellulose which must be broken before the food can be utilized. In the mouth cavity begin digestion of carbohydrates, which help to the functional activity of pancreas. Functions of salivary glands • In the mouth cavity open three pair of big salivary glands and a lot of small buccal glands. Submandibular and sublingual glands consist of the cells of serum and mucous types and secrete serous and mucus types of saliva. Parotid glands consist of the serum types cells and secrete serous type of saliva. Small buccal glands consist of mucous types of cells; produce mucous saliva with a big quantity of water. Saliva necessary for our digestion. In a mouth chewing a food by teeth and lingual. In the mouth cavity begin digestion of carbohydrates by alfa-amilase – ptyalin. To secrete different types of saliva for digestion processes – with a big quantity of water or organic and inorganic substances. • In the mouth cavity open three pair of big salivary glands and a lot of small buccal glands. • Submandibular and sublingual glands consist of the cells of serum and mucous types and secrete serous and mucus types of saliva. • Parotid glands consist of the serum types cells and secrete serous type of saliva. The Major Salivary Glands Quantity, composition and properties of saliva • By day produce 0,8-1,5 L of saliva. Composition of saliva: • water, • organic – alpha-amylase, lipase, phosphatase, RNAase, DNAase, mucin, substances for protective – lisocim, thiocianates, antibodies • inorganic substances – sodium, potassium, calcium, chlorites, etc. Role of saliva in vitality of human • • • • • • • • 1. Moisten of solid food; 2. Dissolving of substances; 3. Moisten of mouth; 4. Cover food; 5. To help of swallowing; 6. Primary hydrolyzing of carbohydrates; 7. Antibacterial properties; 8. Neutralized the stomach juice. Influence of autonomic nerves on secretor activity of salivary glands • Stimulation of the parasympathetic nerve supply causes profuse secretion of watery saliva with a relatively low content of organic material. • Stimulation of the sympathetic nerve supply causes profuse secretion of saliva with small quantity of water with a relatively big content of organic material. Oesophagus • Approximately 25cm long • Moves food from the throat to the stomach – Muscle movement called peristalsis • If acid from the stomach gets in here that’s heartburn. Peristalsis • series of involuntary wave-like muscle contractions which move food along the digestive tract Stomach • Stores the food you eat • Chemically breaks it down into tiny pieces • Mixes food with digestive juices • Acid in the stomach kills bacteria Functions of stomach • 1. Digestive (mechanical treatment, absorption, evacuation, secretion, storage); • 2. Excretory; • 3. Incretory. mouth break up food digest starch kill germs moisten food stomach kills germs break up food digest proteins store food sphincter sphincter Secretion activity of stomach • Production of stomach juice per day – near 2,5 L of juice. • Their main components – enzymes, HCl and mucin. • pH of morning saliva is neutral, after eating – sour – 0,8-1,5. Composition of stomach juice and their properties • There are 2 types of glands • The oxyntic (or gastric) glands secrete hydrochloric acid, pepsinogen, intrinsic factor, and mucus. • The pyloric glands secrete mainly mucus. The main cells (peptic or chief cells) produce non active enzymes (pepsinogens). There are 7 pepsinogens. They hydrolyzed proteins. • Optimum pH of its activity is 1,5-2,0. Pepsinogens whose activity the most in the condition of pH 3,2-3,5 is gastrecsin. In the stomach juice produces lipase and gelatinize. HCl produce in parietal or oxyntic cells. pH of it secrete is near 0,8. These processes need energy of lipids. Mechanism of it production: Cl- actively transported in the canaliculi, Na+ – from the canal into cytoplasm. H2O dissociated to H+ and OH-. H+ actively go into canaliculi in change of K+. In these processes take place Na+,K+-ATPase. CO2, which produce in cells act with H+ and syntheses HCO-. This anion go into the cell in change by Cl-. Phases of stomach secretion • Cephalic phase is caused by nervous system. It has conditional and unconditional reflexes. Conditional reactions caused by appearance of food, it smell and other stimulus, which are connect with food. Unconditional influences is parasympathetic and beginning from receptors of tongue and other receptors of the oral cavity. From these receptors impulses pass through the fibers of n. trigeminus, n. facialis, n. glossopharyngeus, n. vagus to the medulla oblongata. Impulses return to stomach by n. vagus. Except neuron influences this phase has humoral influences – brunch of n. vagus produce hormone gastrin. These phase is very short. Phases of stomach secretion • Stomach phase • is depends on the quantity of food, which are present in stomach. It has vago-vagal reflexes (by mean of central nerves system) and local – peripheral reflexes, which are closed in stomach walls. Duration of these phase is longer and quantity of juice is much. It has humoral mechanisms too (production of gastrin and histamin. Phases of stomach secretion • Intestine phase: • presence of food in the upper portion of small intestine can cause the stomach to secrete small amount of gastric juice. This probably results of gastrin are also released by the duodenal mucosa in response to distension or chemical stimuli of the same type as those that stimulate the stomach gastrin mechanism. . In norm gastric juice secretion must be NN Indexes Empty stomach Basal secretion Stimulated secretion 1. pH to 3,5 1,5-2 1,3-1,4 2. Production of common 10-35 HCl, mmol/L 40-60 80-100 3. Production of free HCl, 0-20 mmol/L 20-40 65-85 4. Debit of common HCl, to 1,5 mmol/hour 1,5-5,5 8-14 5. Debit of mmol/hour 1-4 6,5-12 free HCl, to 1