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level: 6.1 Digestion

Questions and Answers List

level questions: 6.1 Digestion

QuestionAnswer
What is food? (2)substance that is consumed for nutrition to grow and reproduce solid and are large complex molecules
Steps of food processing? (idaae)ingestion digestion absorption assimilation elimination
Why is digestion of food molecules necessary? (2)small molecules are more soluble (easier to absorb) small molecules can form new products (reassembled)
What is the alimentary canal? (5)all the organs which food passes through oesophagus, stomach, small + large intestine
What are accessory organs? (5)help with digestion but food doesn't pass through these organs salivary glands, pancreas, liver and gall bladder
What is the oesophagus? (2)tube connecting the mouth to stomach food is mixed w saliva to form bolus + moved down by peristalsis
what is the stomach? (3)temporary storage releases digestive juices + highly acidic environment secretes proteases
What is the small intestine? (2)absorbs nutrients has 3 sections: duodenum, jejunum + ileum
What is the large intestine? (2)absorbs water and dissolved minerals changes undigested material into semi solid feces for excretion
what is the salivary glands for? (3)releases saliva to moisten food = bolus includes parotid, submandibular and sublingual gland secretes amylase
What is the pancreas for? (2)produces digestive enzymes and hormones enzyes are released into the small intestine via the duodenum
What is the liver for? (3)converts absorbed materials into chemicals used for detoxification, metabolism, storage and bile production stores and metabolizes nutrients to regulate chemical composition
What is the gall bladder for? (2)stores and releases bile bile salts are released via the bile duct to emulsify fats
How is digested food moved through the body? (2)peristalsis: longitudinal muscles = squeezes the food through happens in the stomach and intestines (contract and relax to move the food in one direction) segmentation: circular muscles = food moves back and forth (mixes with enzymes) bidirectional
What is mechanical digestion? (2)food is physically broken down into smaller pieces chewing (mouth), churning (stomach), segmentation (intestines)
What is chemical digestion? (2)food is broken down with chemicals saliva, stomach acids, bile and pancreatic juices
What is a digestive enzyme? (4)a protein that acts as a biological catalyst by speeding up the rate of a chemical reaction by lowering the activation energy they aren't changed or used up in the reaction allows digestion to happen at body temp at sufficient speeds specific molecules which bind to specific substrates
What are the different types of digestive enzymes? (4)amylase: carbohydrates = monosaccharides lipase + bile: lipid = fatty acids + monoglycerides peptidases: protein = amino acids nucleases: nucleic acid = nucleotides
Where are enzymes secreted from?mainly produced by the pancreas = secreted into small intestine salivary glands secrete amylase stomach secretes proteases
How are carbohydrates digested? (7)starch is the main polysaccharide and has 2 types: amylose: glucose monomers in linear chains amylopectin: monomers in branched chains STARCH is digested by AMYLASE = MALTOSE (Disaccharide) MALTOSE is digested by MALTASE = GLUCOSE (Monosaccharide) Glucose monomers is used for cell respiration / processed and stored in the liver as GLYCOGEN (polysaccharide) occurs in small intestine and products are transported to the liver
What are inactive precursors? (zymogen)needs a biochemical change (eg: hydrolysis reaction revealing the active site) = active enzyme.
How are proteins digested? (5)proteases are secreted as inactive precursors (zymogens) so that they don't digest the cells that made them Proteases can be activated with specific enzymes or chemical agents(low pH = acidic conditions) Starts in stomach and continues in small intestine pepsin: made and used in stomach (pepsinogen), activated by hydrochloric acid trypsin: made in pancreas (trypsinogen), activated by enterokinase in the intestine
How are lipids digested? (4)lipids are insoluble in water so they are combined with proteins to be transported in blood lipids are emulsifies with bile salts before being chemically digested by lipase components are combined w protein = chylomicrons = transported to liver liver converts chylomicrons = soluble lipoproteins
What is absorption? (3)movement of a fluid across a membrane nutrients absorbed into bloodstream within the small intestine = transported to cells by the liver Water and dissolved mineral ions are absorbed in the large intestine
What is assimilation?conversion of nutrients into a fluid or solid part of an organism
What are the layers of the small intestine? (5)Serosa: protective outer layering Muscle layer: for digestive movement Outer = lOngitudinal (peristalsis) Inner = cIrcular (segmentation) Submucosa: connective tissue layer Mucosa: Inner layer for absorption
What are villi? (4)finger-like projections on the epithelial lining of the intestine absorb monomers formed by digestion + mineral ions & vitamins increase the surface area = optimize absorption rate Epithelial cells are connected by tight junctions = impermeable barrier bw body tissues and digestive juices
What are the key features of villi? MR SLIMMicrovilli = increases SA :Vol ratio Rich capillary network = transports digested products Single later epithelium = minimise diffusion distance Lacteals = absorb lipids into lymphatic system Intestinal glands = exocrine pits release enzymes Membrane proteins = help transport products
What are the different transport mechanisms for different nutrients? (4) SFSOSimple diffusion = hydrophobic (fats) cross the hydrophobic part of the membrane. Then passes through the lacteals Facilitated diffusion = monosaccharides, vitamins and minerals are transported by channel proteins helps hydrophilic food pass through the hydrophobic part of the membrane Secondary Active Transport = glucose + amino acids are co-transported with sodium ions (Active translocation) with a transport protein Osmosis: water diffuses across membrane passively as ions and solutes move across in the small and large intestine
How does bulk transport work? (pinocytosis)endocytosis vesicles form around fluid containing dissolved materials takes less time than using membrane proteins
How can we model absorption?size specific permeability of the intestinal membrane can be modeled with dialysis tubing the tubing is impermeable to polysaccharides (starch) but is permeable to maltose = semi permeable rate of digestion can be measures by osmosis
Draw the digestive systemStomach: J-shaped bag + connected to oesophagus and small intestine Liver: right-angled triangle left of stomach Bile duct (connected to gall bladder) and pancreatic duct Small intestine should be thinner than the large intestine
How does chewing break down food? (2)grinding action of teeth and the tongue pushes the food to the back of the throat travels down the throat as a bolus
How does churning break down food in the stomach?stomach lining muscles squeezes and mixes the food with digestive juices
How does stomach acids break down food?gastric glands release digestive acids = low pH (2) acidity denatures proteins and other macromolecules = digestion mucous membrane on epithelium prevents the acids damaging the gastric lining pancreas releases bicarbonate ions (alkaline) to neutralise the acids before entering the intestine
How does bile break down food? (3)made in the liver and stored in the gall bladder before released into small intestine bile salts mix with fat globules = smaller droplets (emulsification) = increases total SA for lipase activity
What are key features of the villi epithelium? (4) (Just Mix Monkey Poop)Tight Junctions: impermeable barrier = keeps digestive juices separate from tissues + maintains conc gradient + 1 way movement Microvilli: increase SA = more absorption + immobilized enzymes and channel proteins on the microvilli to increase uptake Mitochondria: ATP for active transport and pinocytosis Pinocytotic vesicles: bulk transport of fluid and dissolved solutes
label intestine diagramlabelled
What do the hormones produced in the pancreas do? (4)produces insulin and glucagon which is released from the endocrine glands regulates the conc of glucose in blood insulin lowers blood glucose levels = increases glycogen synthesis and storage in liver glucagon increases blood glucose levels = limits synthesis and storage
Describe the method for measuring meniscus levels (5)dialysis tubing attached to gunnel and filled with starch solution (control) another tubing is attached to a thistle funnel with starch and amylase solution (Experiment) placed in beakers of water over time water moves into tubing by osmosis (towards solute) = water line rises (meniscus) amylase tube will have less solute bec starch is being digested = lower meniscus
Describe the method for measuring maltose diffusiondialysis tubing filled with starch and kept in a beaker of water (control) second tubing filled with starch and amylase and kept in a beaker of water (Experiment) amylase in 2nd tube will digest the starch into maltose = small enough to diffuse out into beaker presence of amltose can be tested with Benedicts test