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6.1 Digestion and Absorption (Major group of organs (:no_entry:Alimentary…
6.1 Digestion and Absorption
Major group of organs
:no_entry:Alimentary canal - organs which food pass through
Salivary Gland - moisten food and start starch breakdown
Pancreas - release a broad range of enzyme into the small intestine and hormone that regulates blood
Liver - take the nutrients to make chemicals for body and detoxifies, storage organ, produce bile and breakdown haemoglobin
Gall Bladder - store bile which is used to emulsify fat and and released via the bile duct
:no_entry:Accessory organs - only aids in digestion
Oesophagus- connect the oral cavity to the stomach and move the bolus down by peristalsis
Stomach - churn and mix food with gastric pits that release enzymes that begin protein digestion and make the stomach pH2
Small intestine - long highly folded tube to absorb nutrients
Large Intestine - water and mineral are absorbed
Method of Indigestion
:explode:Mechanical Digestion
:1234:Chewing by Mouth
Tongue - pushes food around mouth and into oesophagus
Teeth- grind against food, make it smaller
Epiglottis - stop food from going down the trachea
:1234: How do food move :question:
Peristalsis
Longitudinal muscle contract and move food
Segmentation
contraction of circular muscle and allow greater mixing of chyme
:1234:Churning by Stomach
Muscle in stomach lining - mix food with digestive enzyme
Several hours process, food turn into a paste called chyme
Chyme enters the duodenum
:explode:Chemical Digestion
Pancreatic Juice
Digestive enzyme made in ribosome of pancreatic gland cells Processed in the Golgi Apparatus. Secreted by Exocytosis
Amylase to digest starch
Lipase to digest triglycerides and phospholipids
Protease to digest protein
Small Intestine and Enzyme
The pancreatic enzyme
Starch -> maltose and amylase
Triglycerides -> fatty acid and glycerol
phospholipids -> fatty acid + glycerol + phosphate
protein and polypeptide -> shorter peptides
Gland in Small Intestine Lining
Nuclease digest DNA and RNA into nucleotides
Maltase = maltose->glucose
Lactase = lactose-> glucose + galactose
Sucrase= sucrose-> glucose +fructose
Dipeptidases= dipeptides-> amino acid
Exopeptidases digest peptides until dipeptide is left
Absorption
Method of Absorption
Nutrients must past from lumen to capillaries or lacteal
Fatty acid and glycerol absorbed by simple diffusion
Fatty acid also facilitated diffuse using a fatty acid transporter
Steps of glucose transport
Sodium potassium pump pump sodium ions by active transport from the cytoplasm to the interstitial spaces inside villus and potassium the other way, making a concentration gradient of sodium in the cytoplasm low.
Sodium glucose co-transporter transfer glucose and sodium together from the intestine into the cytoplasm of the villus through passive facilitated diffusion.
Glucose channels allow glucose to move by facilitated diffusion from the cytoplasm to the interstitial spaces inside the villus and into the blood cappilaries.
Villi
Increase the surface area for better rate of absorption
Its epithelium must form a barrier from harmful substance but allow nutrients to diffuse
What do they absorb :question:
Glucose, fructose, galactose and other monosaccharides.
any of the twenty acids to make protein
fatty acid, glycerol, monoglycerides
bases from nucleotides that have been digested
mineral ions such as calcium, potassium, sodium
vitamins such as ascorbic acid which is vitamin c
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