Transcript Slide 1
The Digestive System Throat Anatomy Mouth Chemical and Mechanical Digestion occur here Salivary Glands • 3 types of Salivary Glands • Lubrication and binding • Liquifies dry food • Oral hygiene • Initiates starch digestion – amylase • evaporative cooling in some species Epiglottitis Base of tongue Back of Throat eh-pih-glah-tis The epiglottis is super for swallowing. It's the part of your body that flops down over the windpipe when you swallow to keep food from going into your lungs. Without your epiglottis, you would cough or choke every time you eat. Esophagus This organ moves the swallowed food to the stomach by peristalsis. Peristalsis: Involuntary waves of muscle contraction that keep food moving along in one direction How it works Esophagus The Top 1/3 of the esophagus is skeletal muscle, the lower 2/3 is smooth muscle in two layers Stomach • stores the food that was eaten • churn its contents into a chyme • partially digests protein • absorbs water, aspirin and alcohol • mucosa - composed entirely of mucus producing cells • gastric pits - these depressions interrupt the stomach lining and contain gastric glands that produce HCl and pepsinogen •muscle layers - smooth muscle in three layers • • • • Small Intestine Digestion of all groups of food continue here Digested food is absorbed Indigestible foods are moved to the large intestine villi - fingerlike folds of the mucosa - increase surface area thereby increasing absorption Villi These cells live only for a few days, die and are shed into the lumen to become part of the ingesta to be digested and absorbed. Virtually all nutrients, including all amino acids and sugars, are absorbed through the villi Pancreas Enzymes from this organ digest all of the food groups; hormones help control blood sugar • Enzymes secreted by the pancreas help break down carbohydrates, fats, proteins, and acids in the small intestine • Made of protein and is located behind the stomach • Long, irregularly shaped gland • Yellowish in color • About 7 inches (17.8 cm) long and 1.5 inches (3.8 cm) wide. • Two of the main pancreatic hormones are insulin and glucagon • These hormones work together to maintain the proper level of sugar in the blood • Insulin works to lower blood sugar • Glucagon works to increase blood sugar Liver •The liver is the largest glandular organ of the body •It weighs about 3 lb (1.36 kg) •It is reddish brown in color • Divided into four lobes of unequal size and shape. • Many functions • Convert glucose to glycogen • Produce urea (the main substance of urine) • Make certain amino acids (the building blocks of proteins) • Filter harmful substances from the blood • Storage of vitamins and minerals (vitamins A, D, K and B12) • Maintain a proper level of glucose in the blood • The liver is also responsible for producing cholesterol • Produces about 80% of the cholesterol in your body. • Break down fats Gall Bladder Removed gallbladder with gall stones Large Intestine The large intestine takes 12 to 25 hours to finish up the remaining processes of the digestive system. Food is not broken down any further in this stage of digestion. The large intestine simply absorbs vitamins that are created by the bacteria inhabiting the colon. It is also very important in absorbing water and compacting the feces. It is also responsible for passing along solid waste. The large intestine houses over 700 species of bacteria that perform a variety of functions. Appendix The organ that was once thought to be vestigial — lacking a specific function in the body — is now believed to produce and protect good bacteria in the digestive tract. The gut is full of good bacteria that aid in digestion, but diseases such as cholera and amoebic dysentery can clear out these microbes. It is now believed that the function of the appendix is to regenerate and store the helpful bacteria. How it All Works! Human Digestive System