The Digestive System

Topics: Digestion, Stomach, Liver Pages: 5 (1729 words) Published: April 13, 2013
Digestion is the mechanical and chemical breaking down of food into smaller components, to a form that can be absorbed, for instance, into a blood stream. Digestion is a form of catabolism; a break down of macro food molecules to smaller ones. The digestive process also involves creating waste to be eliminated. The digestive track (gut) is a long twisting tube that starts in the mouth and ends at anus. It’s made up of a series of muscles that coordinate the movement of food and other cells that produce enzymes and hormones, to aid in the breakdown of food so then it can be absorbed to bloodstream. Along the way are three other organs that are needed for digestion: liver, gallbladder and pancreas. Mechanical digestion it is chewing (mastication) of food to break it up into smaller pieces and turning food within stomach, so then futher chemical digestion can take place. Chemical digestion occurs when food particles enter the mouth, stomach or small intestine where they come into contact with digestive enzymes, acid, fluids, allcaine fluids ect., which digest the food particles to the end stage of digestion. Ad2

Pharynx/oral cavity/tongue/stomach/pancreas/pancreatic duct/common bile duct/small intestine/descending colon/rectrum/anal canal/anus/appendix/cecum/ascending colon/transerve colon/duodenum/gallbladder/liver/diaphragm/esophagus/submandibular/sublingual/parotid/-salivary glans Ad3

The mouth (teeth, tongue, hard palate, soft palate, tonsils) which is called oral cavity, is the first part of digestive system. The tongue, teeth, hard palate and soft palate helps to mix and to reduce size of food put into the mouth. The parotid glands, the sublingual and the submaxillary grans secret saliva to help the process of chewing food. Saliva contain salivary amylase enzyme responsible for breaking down sugars and starches. The epiglottis prevents food from entering the larynx-at the upper-part of the respiratory system. The tongue helps also to swallow the food. Ad4

Esophagus is a tube that connect pharynx to stomach. The food bolus formed in the buccal activity has to reach stomach for futher digestion and this is facilitated by esophagus. The structure of esophagus also contribiutes to its function. It’s a muscular tube consisting of 3 layers. The outer most layer has smooth muscle. Food (bolus) act as stimuli and smooth muscle starts contracting causing peristaltic movement that helps in movement of food bolus to stomach. The movement of esophagus is wavey (like squeezing a toothpaste). In nutshell, esophagus runs from oral cavity to stomach through diaphragm. It conduct food by peristalisys. It’s a passageway for food only (respiratory system branches off at the top of esophagus). Ad5

1 cardiac sphincter 1 gastric pits
2 fundus 2 mucous neck cells 3 body 3 parietal cell 4 logitudinal muscle layer 4 chief cell
5 circular muscle layer 5 entero-endocrine cell 6 oblique muscle layer
7 rugae 8 pylorus 9 pyloric sphincter
Main function of stomach is to store food, turn it into a liquid and release small amounts of it over time to the rest of the alimentary canal. Stomach is highly elastic (can hold 2l of food and drink). It realases a gastric juice made up of mucus, enzymes and acids. Mucus protect the cells of stomach and help to lubricate food. HCI kills bacteria from food and creates perfect environment for pepsin to work. Pepsinogen (active-pepsin) works to break down protein into peptides. The extra muscular layer of stomach helps for more segmentation, movement and griding of food. Ad6

1 microvili, 2 lacteal, 3 blood capillaries, 4 goblet cell, 5 lymphatic vessel 1 duodeum, 2 jejulum, 3 ileum
Small intestine it’s a huge area-600m2 that helps to absorb nutrients. The walls are like large circular walls with finger like projections called villi-o.5mm long. On each villi...
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