8Movements of the Alimentary Canal PeristalsisPropels contents forwardAlternates between circular and longitudinal muscles.Mixing MovementsUses circular and longitudinal muscles simultaneously to cause a “mixing” or “churning” type of movement.Mixing can be done all along the canal, but is most noticeable in the stomach.
10Mouth Functions Small amount of digestion (starch/CHO) Receive food TasteReceive foodMoisten food and prepare for further processing
11Salivary Glands Exocrine glands composed of mucous and serous cells ParotidLargest of the main glands, secretes mostly serous fluidSubmandibularsecretes equal amounts of serous and mucous fluidsSublingualsecretes mostly mucous fluidSaliva components:98% water2% - antibacterial components,mucus,electrolytes (Na, Ca, K, Mg),amylase (salivary)Salivary Amylase breaks down CHO, therefore……..CHO DIGESTION BEGINS IN THE MOUTH11
13Swallowing known as deglutination allows food to pass from the mouth to the pharynx to the esophaguscan start as a “voluntary” action, but quickly becomes involuntary“Bolus” passes along hard palate then to soft palate with tongue pushing towards oropharynx.bolus is prevented from gaining entry into the larynx by the epiglottis
14The EsophagusPierces the diaphragm through the esophageal hiatusCircular muscles that close off before entering the stomach: cardiac sphincter ( aka gastroesophageal sphincter, lower esophageal sphincter)Function – propel food into stomachTHERE IS NO DIGESTIVE FUNCTION14
16PROTEIN DIGESTION BEGINS IN THE STOMACH Gastric glandsFunctionMucous cellssecretes mucousParietal cellssecretes HCl (acid), intrinsic factor (protein released to allow intestine to absorb vit B12)Chief cellssecretes pepsinogen (an inactive form of pepsin). Once this mixes with HCl, it becomes pepsin and is able to breakdown protein into amino acids.temporary storage tank for foodsite for mechanical and chemical breakdown of proteins….PROTEIN DIGESTION BEGINS IN THE STOMACH**cells in the lining of the mucosa continuously secrete bicarbonate to protect the stomach lining from self digestion. So this, along with mucous, protects the lining.
19Functions of the Pancreas: Releases enzymes that digest fats, proteins, carbohydrates, and nucleic acidsProduces alkaline (basic) fluid to neutralize acidic chyme in small intestineProduces insulin and glucagon to regulate sugar metabolismPancreatic juicepancreatic amylase breaks down CHOpancreatic lipase breaks down fatsproteinase (Trypsin) breaks down proteinsnuclease breaks down nucleic acid into nucleotides (from DNA and RNA)* Pancreatic juice is very alkaline, which helps neutralizes the fluid and allows the intestine to absorb properly.
22Liver Lobes: 2 lobes, left and right Hepatic Lobules: cylindrical structures which are the functional units of the liver.Contain:hepatocytes,bile canals and ducts,artery (hepatic),vein (hepatic portal on perimeter and central vein draining sinusoids into hepatic veins),sinusoids (blood filled spaces between hepatocytes),Kupffer cells (specialized macrophages).
24Liver Functions Makes and secretes bile Stores some vitamins and iron DetoxificationStores glucoseModifies fats so the body can use them more efficientlyForms plasma proteinsHelps excrete by-products of RBC (bilirubin) into bileSynthesizes urea (by-product of protein metabolism), released into blood and sent out in urine
25BileEmulsify fatsStored in the gall bladder & becomes 5x more concentratedProduced by HepatocytesPasty yellow/green substanceContents: bilirubin, cholesterol, salts, water, sodium and potassium and sometimes small amounts of copper and other metalsAbout 1 liter per day is made by the liverAbout 95% of all salts found in bile are reabsorbed in the body in the lower small intestine