110 - Digestion

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What is the importance of digestion?
To digest food to simple nutrients so they can be absorbed
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What are the two componants of digestion and what are some examples
1. GI Tract (Mouth, pharynx, oesophagus, stomach, small intestive, large intestine, colon, rectum and **** 2. Accessary digestive organs (Teeth, tounge, salivary glands, liver, gall bladder and pancreas)
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What is the transit time of digestion?
20-140 hours ( 1 - 6 days)
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What is the weight of faeces produced a day?
150 - 250 g
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How many litres of fluid does the GI secrete a day?
7-8 litres
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What are the 6 basic processes of digestion and decribe what is involved?
1. Ingestion (Consuming) 2. Secretion (Salive gastric and intestinal juice and bile) 3. Mixing and propultion (Stomach and mouth thrashing) 4. Digestion (Chemical change of nutrients) 5. Aborbtion 6. Defaecation
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What are the layers of the GI wall and what do they contain?
1, Mucosa (Inner lining with mucous membrane) 2. Submucosa (Connective tissue with blood and lymph) 3. Muscularis (Skeletal muscle - voluntary swallowing) 4. Serosa (Connective tissue and epithelial cells)
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What are the two brached nervous systems that control the GI tract?
1. Myenteric plexus (Motor neurons for motility) 2. Submucosal plexus (Controls secretion)
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What are the two branched nervous systems from the ANS and how do they affect digestion?
1. Sympathetic branch ( Decrease in GI secretion and motility) 2. Parasympathetic ( Increases GI secretion and motility)
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Decribe the process of initial ingestion and how componants are adapted
1. Mouth (Ulva to prevent food entering nasopharynx) 2. Teeth (Mastication with tounge to form bolus) 3. Parasympathetic branch stimulates silvary glands 4. enzymes (Ligual lipase and amylase) 5. Taste
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What muscle is the stomach sealed with?
Oesaphageal sphincter on top and Pylaric sphincter on bottom
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What are the 3 muscle layers of the stomach?
Longitudinal, cirular and diagnal - Motility
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What is the stomach covered by?
Thick layer of mucus to reduce friction
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Functions of the Stomach
1. Secretes gastric juice to form chime which activates lingual ligase and deactivates amylase 2. Peristalsis 3. Secretes Gastrin 4. Juices: acid, pepsinogen, lipase, intrinsic factor and mucus
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Which cells of the stomach does Acetylcholine stimulate?
Parietal cells
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What do Parietal cells produce?
HCl
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What does histamine enhance in the stomach?
Acetylcholine affects (More HCl) and Gastrin
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Decribe the control of gastric secretion
1. Cephalic phase: Senses (Smell taste) - Cereral cortex - hypothalamus( - facial nerves - salivary nerves -) And gasric glands produce gastric juice 2. Chemo/ stretch receptors - nerve impulses - peristalysys 3. Secretion
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What does gastrin do?
Released into the blood by G cells when food enter stomach, when blood levels rise more gastic acid (HCL) produced and stimulates liver and pancreas
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Why is peptin only activated in the stomach?
Digests protein so would digest self, stomach has thick mucus lining
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What affects does gastrin have on motility and the pylaris syphincter?
It increases motility and relaxes the pylaris sphyincter which stimulates emptying into the duodenum
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What enzymes are present in the mouth?
Inactive lingual lipase, Amylase which hyrolyses starch
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What enzymes are present in the stomach?
Ligual lipase, gastric lipase and pepsin
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What substances are present in the small intestine?
Pancreatic juice, bile and intestinal juice
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Decribe the 3 sections of the small intestine
1. duodenum (Folded, Plicae, short, gall bladder and pancreas secretion) 2. Jejunum (Taller plicae and digestion) 3. Illeum (Fewer plicae and digestion)
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What are plicae?
circular folds in intestine to increase surface area
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What is the intestinal juice made up of?
Crypts of lieberkuhn (Gland secretion) : Water, muscus, enzymes (Pepidases and disacharidases), Hormones (CCK - stimulares fat and protein digestion) and lysozyme (Antibacteria)
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What fluid does the pancreas secrete, what enzymes?
Alkaline fluid with amylose and proteases
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What does the liver secrete for digestion and where is it stored?
Bile salts stored in gall bladder
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What do bile salts do to the chyme?
Neutralise it and emulsify fat
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What are the proteolytic enzymes and what do they do?
1. Pepsinogen (Lowers stomach PH - pepsin) 2. Trypinogen (Enterokinase in Small intestine - trypsin - chymotrypsinogen - procarboxypeptidase
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What happens to fat in the stomach?
Is binds together making it easier to break down
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What does bile salt + fat make?
Micelle
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What are the 3 broken down nutrients at the end of digestion?
Amino acids, monosaccharides and (glycerol, Free FAs, monoglycerides and mixed micelle)
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Card 2

Front

What are the two componants of digestion and what are some examples

Back

1. GI Tract (Mouth, pharynx, oesophagus, stomach, small intestive, large intestine, colon, rectum and **** 2. Accessary digestive organs (Teeth, tounge, salivary glands, liver, gall bladder and pancreas)

Card 3

Front

What is the transit time of digestion?

Back

Preview of the front of card 3

Card 4

Front

What is the weight of faeces produced a day?

Back

Preview of the front of card 4

Card 5

Front

How many litres of fluid does the GI secrete a day?

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