5 — nutrition in human Flashcards

Question

Explain how the villus is adapted in absorption of digested nutrients in mammals. [4]

Answer 1

A. Villi r finger-like projections in SI that increase SAtV ratio for faster absorption Purpose of microvilli in SI [2]: Microvilli increases surface area to volume ratio of villi of the small intestine; [1] To increase rate of absorption of digested food molecules into the blood stream/ lacteal of the villi; [1] 1. Each villus has a one-cell-thick epithelial wall → to provide a shorter distance for faster absorption of digested nutrients. [1] 2. Presence of numerous microvilli on the epithelial cells of the villus → to increase its surface area to volume ratio for faster absorption of digested nutrients. [1] 3. Each villus has a lacteal → for the absorption and transport of fat molecules. [1] 4. Each villus is rich in blood capillaries → for faster absorption of glucose and amino acids. [1] 5. There is a continuous blood flow to maintain a steep concentration gradient → for faster absorption of digested nutrients into the blood capillaries by diffusion. [1]

Answer 2

Fatty acids & glycerol enter by diffusion across epithelium where they combine to form tiny fat globules b4 entering lacteal.

Answer 3

- Total surface area of villi - Thickness of epithelium - Steepness of concentration gradient

Answer 4

- Reduced villi decrease SAtV ratio in absorption of digested nutrients like glucose, amino acids, fat globules formed from fatty acids and glycerol. - Absorption of digested nutrients is slower compared to normal. - Patient suffer from malnutrition

Answer 5

- Excess acid in chyme gg to SI will change SI pH to non-optimum pH in SI - Pancreatic and intestinal digestive enzymes will denature - Reduced digestion n absorption of nutrients leading to weight loss

Answer 6

- Eat smaller but frequent meals to reduce stomach workload for digestion - Avoid alcohol consumption to reduce inflammation of stomach lining (depends on qs) - Ingestion of digestive enzymes supplement with each meal to aid in digestion of nutrients in stomach and SI (depends on qs)

Answer 7

- Transports absorbed glucose to liver -> most of glucose r excess -> [insulin produced by pancreas stimulates] liver to convert excess glucose to glycogen n stored; glucose transported by hepatic vein to diff parts of body - Transports absorbed amino acids to liver -> excess amino acids converted to urea (found in urine produced by kidney) by deamination in liver -> transported by hepatic vein to diff parts of body

Answer 8

- IF ENOUGH GLUCOSE: fats not broken down n used to build protoplasm like cell membranes - IF GLUCOSE IN SHORT SUPPLY: fats broken down to prov energy needed for vital activities in body - Excess fat stored in adipose tissues beneath skin n around heart & kidneys - Adipose tissues protect organs by acting as shock absorbers

Answer 9

CARBS METABOLISM: A. The liver helps to regulate the blood glucose concentration in the blood plasma with the aid of insulin and glucagon. [1] - If the blood glucose concentration is higher than the norm, the islets of Langerhans in the pancreas will be stimulated to release more insulin. [1] This stimulates the liver to convert excess glucose into glycogen for storage in liver and muscles. [1] Hence, blood glucose level decreases and returns back to the norm. [1] - If the blood glucose concentration is lower than the norm, the islets of Langerhans in the pancreas will be stimulated to release more glucagon. [1] This stimulates the liver to convert stored glycogen into glucose, which is released into the bloodstream. [1] Hence, blood glucose level increases and returns back to the norm. [1] Excess glucose can be converted to fats in the liver. [1] B. Deamination of amino acids into urea by the removal of amino group. [1] - amino acids used to synthesise plasma proteins such as prothrombin and fibrinogen in liver that is essential for blood clotting [1] - excess amino acids undergo deamination in liver [1] - Amino group of amino acids are removed n converted to urea in liver and excreted in kidneys. [1] - Carbon residues of amino acids from deamination r converted to glucose in the liver. Excess glucose will be converted and stored as glycogen in the liver. [1] C. Produces bile, which emulsifies large fat globules into smaller fat droplets for subsequent faster chemical digestion of fat molecules into fatty acids and glycerol by lipase. [1] D. Detoxification of harmful substances such as alcohol, to less harmful or harmless substances. [1] - Harmful substances like alcohol broken down by liver to make harmless, as it can cus dmg to digestive system + slow down brain functions - Liver cells contains an enzyme which breaks down alcohol to compounds that can be used in respiration, prov energy for cell activities E. Breakdown of hormones [1] F. Iron storage from breakdown of haemoglobin; [1] G. Synthesis of plasma proteins such as fibrinogen [1]

Answer 10

Short term - Slows down brain functions such as blurred vision, poor muscular coordination, poor judgement and longer reaction time [1] - Reduced self-control [1] Long term - any 3 of the following 4 points: - Liver cirrhosis [1] - Alcohol addiction which leads to withdrawal symptoms [1] - Increases the risk of gastric ulcers as alcohol stimulates acid secretion in the stomach, affecting the digestive system [1] - Wet brain - Shrinkage of brain volume - Heavy consumption of alcohol during pregnancy may interfere with the development of the foetus’ brain -> may lead to lifelong physical, mental and behavioural problems. Impact of alcohol to human digestive system: - LT(long term): Alcohol stimulates acid secretion in stomach -> excess stomach acid increase risk of gastric ulcers - LT: Alcoholic cirrhosis caused by too much alcohol may lead to haemorrhage in liver, liver failure n death Impacts of alcohol on nervous system: - ST(short term): Alcohol is a depressant and slows down some brain functions. Its effects vary from 1 person to another. - ST: Reduced self control. Ppl r carefree n may do things they regret aft effects of alcohol worn off. - Reduces reaction spd, Longer reaction time; Slurred speech, blurred vision + poor muscular coordination. Judgement deteriorates, tend to underestimate speed -> May drive faster with less caution, reactions r slower. Higher tendency for drunk drivers to involve in traffic accidents. Social implications: Alcoholics may, - end up neglecting their work and families. - exhibit violent behaviour, especially towards family members. - be at a higher risk of committing crimes.

Answer 11

Gallstones may block the bile duct, preventing bile from entering the duodenum. Lack of bile released from the gall bladder into the duodenum [1]; no emulsification of fats to small fat globules/droplets, lesser surface area for digestion of fats by lipase [1], hence there will be slower rate of fat digestion. [1].

Answer 12

Surface area to volume ratio of the villi will decrease and this reduces the rate of absorption of digested food molecules. [1] Due to a decrease in the number of villi, lesser glucose and amino acid molecules will be absorbed into the blood stream. [1] Lesser fats will be absorbed into the lacteals.[1]

Answer 13

Many people had greater awareness and were educated on the harmfulness of excessive consumption of alcohol on the liver, resulting in reduction in alcohol consumption. [1]/ Higher cost of alcohol due to alcohol tax which results in reduction in alcohol consumption [1]/ Better medical treatment hence people do not get serious condition [1]

Answer 14

Enzymes are involved in chemical digestion in the body where large molecules are digested to smaller molecules; [1] In the mouth, starch is digested by salivary amylase in saliva, produced by salivary glands, to maltose and the optimum pH of salivary amylase is pH 7; [1] In the stomach, protein is digested by pepsin, produced by gastric glands, in the gastric juice, to polypeptides and the optimum pH of pepsin is pH 2; [1] In the duodenum, pancreatic juice produced by pancreas contains pancreatic lipase, pancreatic amylase and trypsin. Pancreatic lipase digests emulsified fats to fatty acids and glycerol/ Pancreatic amylase digests starch to maltose/ Trypsin digests proteins to polypeptides; [1] In the small intestine, intestinal juice produced by intestinal glands contains intestinal lipase, maltase and peptidase. Maltase digests maltose to glucose/ Peptidase (erepsin) digests polypeptides to amino acids/ Intestinal lipase digests emulsified fats to fatty acids and glycerol; [1]