The Digestive System For we are all, really, just doughnuts J. Schwieger

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Transcript of The Digestive System For we are all, really, just doughnuts J. Schwieger

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The Digestive System For we are all, really, just doughnuts J. Schwieger Slide 2 Alimentary Canal The alimentary canal is the mucous membrane-lined tube of the digestive system. This is the tube where digestion takes place, and from which wastes are eliminated. It extends from the mouth to the anus and includes the pharynx (throat), esophagus (gullet), stomach, and intestines. It is also called digestive tract. Slide 3 . Slide 4 Mouth Teeth and saliva begin digestion process Tongue pushes and helps to manipulate food so it can be masticated properly Uvula is an extension of the soft palate: it helps to cover the nasal passages Slide 5 Slide 6 Cougar Skull Cougars are also diphyodonts and heterodonts. Their molars (carnasial teeth) overlap each other to allow for a scissors like cutting action. The incisors are for catching and holding. Slide 7 Wolf Skull - note the same carnasial molars. Wolves are diphodonts as well. Slide 8 Brown Bear Skull - note the crest on the skull for the mandible muscle. Slide 9 Sperm Whale This is the lower jaw of a Sperm Whale on display in a museum in Maine. One of the jaws on display is 18 feet long! The teeth can be 6 inches long! Whales teeth are all the same. They get only one set. It is estimated that this individual was 75 feet long and weighed 60 tons (120,000 lbs.) Slide 10 Sperm Whale Juvenile Male This 33 foot individual was photographed near the Bonin islands in the Pacific. Their teeth are adapted for holding the squid and fish they catch during their deep, hour long dives. This male could grow as long as 80-85 feet and weigh as much as 70 tons (140,000 lbs.) They are the largest carnivore on the planet and they have the largest brain of any creature ever known. Slide 11 Scrimshaw Scrimshaw is drawings done on Sperm Whale teeth. They have become rare and valuable collectors items. These two examples are from the JFK museum. The teeth are approximately 5 inches long. Slide 12 Ivory Ivory is a hard, white, opaque substance that is the bulk of the teeth and tusks of animals such as the elephant, hippopotamus, walrus, mammoth and toothed whales. Prior to the introduction of plastics, it was used for billiard balls, piano keys, buttons and ornamental items. The word "ivory" was traditionally applied to the tusks of elephants. The chemical structure of the teeth and tusks of mammals is the same regardless of the species. Slide 13 Elephants In contrast to humans, elephants get 6 sets of molars. Teeth are not, however, exchanged from the bottom to the top (vertically), as in humans and most mammals, but rather from the back to the front (horizontally). Elephant calves are born with approximately 2 small molar teeth, about the size of a thumbnail, in both the upper and the lower jaw. In the course of time the molar tooth next in size slowly moves from the back to the front and thus replaces the old tooth. Slide 14 Elephant Graveyard When the last tooth is worn down, it becomes difficult for elephants to chew their food properly. Then they usually start to look around for softer vegetation, which grows in the swamps. In the end old elephants succumb to their weakness and die at the water's edge. Old elephants' inclination to die in one and the same area has enabled the rise of the fairy tale and myth of the elephant's graveyard. Slide 15 What are tusks? Elephants' tusks correspond to other mammals' incisor teeth. One of the tusk's unique characteristics is that it does not have a coat of dental enamel. Two thirds of a tusk is visible. The first third is lodged in the skull's tooth socket. Two thirds of the tusk are 'alive'. This means that they have pulp cavities which are filled with a tissue which has an abundance of blood vessels and branches of nerves. This is why tusks are sensitive to pressure and blows. A tusk breaking off can have disastrous consequences for the elephant concerned. In the worst case if the odontic nerve and the pulp are exposed the animal dies of the enormous pain. Slide 16 Crocodile teeth Teeth grow in a socket. If the tooth is lost a new one will grow from an adjacent socket. Once that tooth is lost it cannot be replaced. Crocodiles grow continuously throughout the lives. The largest ever recorded is a specimen of the Salt Water Crocodile. It was captured in a river in Northern Australia It was 26 feet long and weighed 4,000 lbs. The jaws measured 6 feet long. Slide 17 Teeth Enamel is composed of CaPO 4 and CaCO 3 Dentin is hard and calcified, though not as hard as the enamel. Connective tissue called pulp fills the pulp cavity within the crown of the tooth. The joint between the teeth and the gums is a fibrous joint. Problems with teeth include, not having a 2 nd set, not having a baby tooth, wisdom teeth problems, decay, cracking and breaking and gum disease. Slide 18 Salivary Glands Found in your mouth and throat. The main ones secrete saliva into your mouth through ducts. About 1 to 1.5 L/day. 99% is water. Main enzyme is amylase to assist in the digestion of starch. Also mucins, lysosomes, urea and bicarbonates to control pH Parotid through ducts near upper teeth. Submandibular through ducts under your tongue Sublingual through many ducts in the floor of your mouth. Slide 19 Diseases of Salivary Glands Stones can collect and block the ducts. Most common salivary gland infection is mumps. (parotid glands)(virus) Infections can pass from lymph glands Cancer is rare, painful and treatable. Slide 20 Pharynx Common tube for food and air (nasopharynx, oropharynx and laryngopharynx.) Epiglottis reflexively closes over the opening of the trachea so food and liquids do not go to lungs (aspiration) Spasm of diaphragm is hiccups. Uvula extension of soft palate. Slide 21 =Ww0YTjA1f0E Slide 22 Esophagus Function; transport food to stomach. Soft palate (uvula) closes over nasal cavity. Laryngopharynx - epiglottis - prevents food from getting into lungs. Cardiac sphincter - prevents stomach material from backflowing into esophagus. Deglutition - swallowing Voluntary - tongue pushing food, Involuntary - esophagus contracting to push food to stomach. Not well protected from harsh chemicals. Slide 23 Slide 24 Esophagus Muscular tube leading to stomach. Two layers of muscles longitudinal and circular Peristalsis- wavelike motion of esophagus to push food to stomach Slide 25 Harmon Killebrew and Esophageal cancer He died of this disease last summer. According to the National Cancer Institute, there were 16,640 cases of esophageal cancer, and 14,500 deaths from the affliction in 2010. His symptoms included loss of weight and difficulty in swallowing. All the causes aren't known, but some of the leading risk factors for the disease include smoking, obesity and heavy alcohol consumption. This is a disease that commonly occurs after age 55. It is more common in men than women. Slide 26 Slide 27 High acidity (pH = 2) allows enzyme pepsinogen to start protein digestion. Three layers of muscles to churn and mix the bolus. Does not absorb a lot of material (alcohol, aspirin) Destroys most harmful materials. Specialized cells produce alkaline mucus to protect itself. Food remains in the stomach 3-4 hours. The chewed food (bolus) becomes chyme. Slide 28 Hiatal Hernia A situation where part of the stomach extrudes above the diaghragm. This can cause the cardiac sphincter to leak stomach fluid into the sensitive esophagus. This leakage can cause burning, heartburn and even lesions or ulcers. Symptoms include belching, nausea, chest pains and difficulty taking a deep breath. Slide 29 Ulcers At any one time, about one in 25 adults will have an active stomach ulcer. During their lifetime one in 7 men and one in 12 women will have this potentially serious condition. Ulcers are areas of damage to the lining of the stomach, as in a gastric ulcer, or the upper part of the intestine (duodenal ulcer). A number of factors cause ulcers. These include prolonged use of anti- inflammatory drugs (often used to treat arthritis), smoking, alcohol, diet and stress. Slide 30 Ulcers The symptom of an ulcer is pain in the upper part of the abdomen just below the breast bone. The pain generally occurs when the stomach is empty. The pain is often relieved by food or antacid medication. More serious symptoms occur if the ulcer bleeds. On rare occasions an ulcer will perforate through the stomach or duodenal wall. This is a major emergency requiring surgery. Most ulcers respond well to treatment with drugs which heal them. Slide 31 Heliobacter pylori This is a bacterial organism that is responsible for many stomach diseases. It enters the body through infected food and the bacterium hides in the mucus layer of the stomach protecting itself against the low pH of the stomach. With stomach ulcers, H. pylori infection is found in 60 to 80 percent of the cases. It is still uncertain how the infection acts to cause the ulcer. It probably weakens the protective mucous layer of the stomach. This allows acid to seep in and injure the underlying stomach cells. There is still a great deal of research to be done to unravel this relationship. Slide 32 Greater Omentum A large fold of connective tissue that hangs down over the intestines and interconnects the stomach, duodenum and the large intestine. It can have lots of adipose tissue (fatty apron) Contains lymph nodes which help fight infection and prevent its spread to the peritoneum. Falciform ligament, attaches the liver to the diaphragm. Lesser omentum suspends to stomach and the first part of the duodenum Slide 33 Diaphragm The diaphragm is a thin dome- shaped muscle which separates the thoracic cavity (lungs and heart) from the abdominal cavity (intestines, stomach, liver, etc.). It is involved in respiration, drawing downward in the chest on inhalation, and pushing upward in exhalation. Slide 34 Pancreas Elongated organ containing exocrine (ducted) and endocrine g