Transcript Digestion
Digestion Begins Hi there. I’m Mr Stomach and I’m here to tell you about your digestive system. The THREE MAIN stages of food processing are: INGESTION DIGESTION ABSORPTION ELIMINATION Eating food Break food into small molecules Enzyme hydrolysis breaks bonds Take up small molecules from digestive compartment Undigested material passes out of body. Different organisms ingest food in different ways. FLUID FEEDERS I’m eating my way through leaves SUBSTRATE FEEDERS live in or on their food eating their way through it SUSPENSION FEEDER Ingests small marine invertebrates and fish filtered by baleen from enormous volumes of water. Maggots substrate feed on the dead carcass Ingest fluid as food. Ex mosquito o I feed off nectar in flowers. I’m a fluid feeder too. Big bad wolf will eat you! BULK FEEDERS eat large pieces of food. INTRACELLULAR DIGESTION cell engulfs the food particle PHAGOCYTOSIS OR PINOCYTOSIS food particle is digested in a vacuole when fused with lysosomes Usually reserved for one celled creatures like the protist amoeba but also used by the sponge --animal porifera Only good if the food particles are very small.(smaller than the cell) Spongebob at your service. Got holes? Phylum POREifera EXTRACELLULAR DIGESTION breakdown food outside the cell. Food prey can be much larger than the cell digesting it. Digestive pouch – gastrovascular cavity – digestion and distribution of nutrients ex Oxygen nutrient etc. polyp Gsatrovascular cavity medusa cnidarian Jellyfishing, Jellyfishing! DID YOU KNOW? Radial symmetry of hydra and flower Jellyfish are not “fish” and have radial symmetry Portuguese Man of War Bilateral symmetry has bilateral symmetry. It means there are is a member of the same two sides. phylum cnidaria Watch out for jellyfish on the beach. The wind is blowing them in. I heard you should urinate on the skin if you are stung Don’t do that. The venom may release more. Remove stingers (nematocyts) with very hot salt water. Add baking soda paste and reapply every 15 min. This will denature the protein venom. GASTROVASCULAR CAVITY DIGESTION –DIGESTIVE POUCH GASTRODERMIS secretes digestive enzymes Think of it like a marble bag. Same way in or out! This is a hydra. A freshwater polyp. It is stationary and catches prey that swim by. It has only one opening to the digestive cavity. It acts as both anus an mouth. Food in Waste out MOST ANIMALS USE THE DIGESTIVE TUBE FOOD IN DIGESTIVE TRACT OR ALIMENTARY CANAL WASTE OUT ADVANTAGES ; More efficient with 1.Specialized structures along pathway 2.Food processed in stages 3.Ingest more food while food still in the tube I’ve got a little earthworm in this jar students. Do you know what you call a segmented worm? An ANNELID. I’m gotta jar “ANNA LID” that I keep earthworm in! HaHaHa Ha Annelids are segmented worms esophagus Crop food Pharynx storage suck food in Typholosole projection increases intestine surface area Gizzard grind with sand Intestine digest and absorb Mouth foregut and crop Mesenteron midgut Digestion stomach with gastric caeca Intestine absorbs nutrients Malpighian tubules are used in excretion of uric acid, not digestion Proctodaeum hindgut rectum anus HERBIVORES usually have longer digestive systems than carnivores to allow for the greater digestion time required to break up plant matter. You can see from the grasshopper short digestive tube it is very inefficient for a herbivore. BIRD DIGESTION PROVENTRICULUS AND VENTRICULUS ACT AS STOMACH In latin ventriculus means stomach! So I guess you could call me Mr. Ventriculus. Now let’s concentrate on the human digestive system. We should start with a general description of the food pathway. salivary mouth Esophagus Glands and ducts Food pathway stomach duodenum Gall bladder Small intestine liver Remember DJ ileum D=duodenum J=jejunum Ileum jejunum ileum pancreas Caecum Large intestine The best DJ is DJ ileum! Rectum Anus Ascending colon Transverse colon Descending colon Sigmoid colon Now let’s take a look at the sphincter valves between the structures A sphincter says what mouth Esophagus Cardiac sphincter stomach Pyloric sphincter duodenum Small intestine jejunum ileum Ileocaecal sphincter Large intestine Rectum Anal sphincter Anus Caecum Ascending colon Transverse colon Descending colon Sigmoid colon The pathway of the food begins in the mouth. Food is both mechanically and chemically digested here. Palatine tonsil : lymph immune system. Removal if overactive TONSILLECTOMY MECHANICAL DIGESTION: Food is crushed and physically broken down by the mouth. CHEMICAL DIGESTION: Salivary amylase hydrolyzes starch and glycogen to smaller polysaccharides and maltose. Note: Uvula is the proper name for this structure. It moves back to block the nasal passageway so food does not pass up into the nasal chamber. Three salivary glands: Parotid gland Sublingual gland Submandibular gland Here is Mr. Tooth to tell us about dentition. Dentition is a description of the teeth. This can help identify carnivores, herbivores and omnivores. Fang adaptation -Hollow inside to inject venom. Prey swallowed whole. Prominent canine incisor teeth indicate a carnivore. Jaw restricted to up and down motion. No chewing- tear and swallow food Teeth are broad and ridged to grind plant material. Omnivores have unspecialized dentition. Humans have incisors for cutting, pointed but short canines for piercing and tearing and premolars and molars for grinding. Did you know your teeth are alive? They get oxygen and nutrients just the same as other tissues. If a tooth blood supply is lost due to damage, the tooth will die and turn black as shown in the picture enamel dentine Pulp with bloodflow Please get this plaque off me. Saliva contains bicarbonate base that neutralizes acid, but not if the plaque is thick Enamel outer layer is the hardest substance in the body. Dentine is hard but not resistant to the acids of the mouth. If plaque builds up bacteria produce acids which will eventually erode the enamel . Once gone the dentine dissolves rapidly. Take a look at this diagram of the healthy tooth. You can see that the root is actually longer than the crown. Don’t wiggle your teeth. It will crack the cementum of the periodontal membrane that holds the tooth in place. Once destroyed, it is not replaced! Cementum The tooth will continually get looser until it falls out. SPOTLIGHT ON DENTISTRY Everybody wants great teeth and a great smile. But is brushing your teeth really good enough? Periodontal disease is actually the main reason for adult tooth loss. Periodontal membrane is the inflammation of the gums. Bacteria get between the tooth and the gum. Inflammation of the gum traps the bacteria beneath the gum-line in anaerobic conditions leading eventually to white blood cells engulfing them and Gums recede and bone loss occurs! dying (that is pus) –Called an ABCESS. To stop periodontal disease floss or use a rubber tip gum stimulator regularly. Plus you should get your teeth cleaned regularly at the dentist Few people know this but gum disease is actually connected to heart attacks and strokes. Bacteria can enter the blood stream through the bleeding gums and cause or worsen inflammation in other parts of the body like heart tissue. Digestion Part 1 Ends