Chapter 5 - Nutrition in Humans (Updated) PDF

CHAPTER 05 Nutrition in Humans 1 Chapter 5 Nutrition in Humans 5.1 What Is Nutrition? 5.2 What Is Digestion? 5.3 What Is Absorption? 5.4 What Happens To The Absorbed Nutrients? 5.5 What Are The Effects Of Alcohol Consumption?...

CHAPTER 05 Nutrition in Humans 1 Chapter 5 Nutrition in Humans 5.1 What Is Nutrition? 5.2 What Is Digestion? 5.3 What Is Absorption? 5.4 What Happens To The Absorbed Nutrients? 5.5 What Are The Effects Of Alcohol Consumption? 2 5.1 What Is Nutrition? Learning Outcomes After this section, you should be able to: describe the functions of main regions of the alimentary canal and the associated organs: mouth, salivary glands, oesophagus, stomach, duodenum, pancreas, gall bladder, liver, ileum, colon, rectum, anus, in relation to ingestion, digestion, absorption, assimilation and egestion of food, as appropriate. 3  5.1 What Is Nutrition? Learning Outcomes After this section, you should be able to: describe peristalsis in terms of rhythmic wave-like contractions of the muscles to mix and propel the contents of the alimentary canal. 4 5.1 What Is Nutrition? Video – How Does Food Turns Into Poop? 5 5.1 What Is Nutrition? Nutrition is the process by which organisms obtain food and energy for growth, repair and maintenance of the body. 6  5.1 What Is Nutrition? What Are The Processes Involved In Nutrition? Absorption & Assimilation Ingestion The digested food molecules are absorbed Food is taken into into the cells. the body. These food molecules are converted into new Digestion protoplasm or used to provide energy through Large food assimilation. molecules are broken down Egestion into smaller Undigested food is soluble removed from the body. molecules. 7  5.1 What Is Nutrition? The human digestive system consists of the alimentary canal and the accessory organs associated with it. salivary gland mouth pharynx oesophagus stomach gall bladder liver pancreas small intestine large intestine rectum 8 anus  5.1 What Is Nutrition? What Are The Organs Associated With The Gut? The liver, gall bladder , pancreas and salivary glands aid in the digestion of food in the gut. The liver is made up of five lobes. The gall bladder Liver cells secrete stores bile bile. temporarily. The pancreas secretes pancreatic juice, which helps digest food. 9 5.1 What Is Nutrition? The Mouth & The Buccal Cavity Food enters the body through the mouth, which leads into the buccal cavity. The buccal cavity is the inside of the mouth and the beginning of the alimentary canal. 10 5.1 What Is Nutrition? The Mouth & The Buccal Cavity Teeth physically breaks large pieces of food into smaller pieces, increasing the surface area of the food to increase rate of enzymatic action on the food. Salivary glands that secrete saliva into the mouth. A tongue that mixes food with saliva and moves the food to the back of the 11 mouth during swallowing. 5.1 What Is Nutrition? The Pharynx The pharynx is the part of the alimentary canal that connects the buccal cavity to the oesophagus and the larynx (voice-box). The pharynx also leads to the trachea (wind-pipe). 12 5.1 What Is Nutrition? If both food and air must pass through the pharynx to enter the oesophagus and trachea, how will food be prevented from entering the trachea when swallowing? 13 5.1 What Is Nutrition? Breathing The larynx has a slit-like opening called the glottis, which is covered by a flap-like tissue known as the epiglottis. During breathing, air passes into the trachea, the larynx moves downwards, and the glottis is open. pharynx epiglottis glottis larynx trachea 14 5.1 What Is Nutrition? What Is Different About This Picture? pharynx epiglottis food particle larynx trachea During swallowing, the larynx moves upwards, and the epiglottis covers the glottis, preventing food particle from entering the trachea. 15 5.1 What Is Nutrition? The Oesophagus The oesophagus or gullet is a narrow, muscular tube. It passes through the thorax (chest) and joins the mouth to the stomach. The wall of the oesophagus contains two layers of antagonistic muscles – longitudinal (outer wall) & circular (inner wall) muscles. These muscles are present along the whole gut from the oesophagus to the rectum, to push food along the gut via peristalsis. 16 5.1 What Is Nutrition? What Are Antagonistic Muscles? Antagonistic muscles are a pair of muscles whose movements oppose each other i.e. when one muscle contracts, the other relaxes and vice versa. 17 5.1 What Is Nutrition? What Is Peristalsis? Peristalsis refers to the rhythmic, wave-like muscular contractions in the wall of the alimentary canal. It facilitates the movement of digested food along the gut. It also enables food to be mixed with digestive juices. 18  5.1 What Is Nutrition? How Do The Antagonistic Muscles In The Gut Wall Help In The Movement Of Food? Wall contracts here. The circular Wall dilates here. The longitudinal muscles contract and the muscles contract and the circular longitudinal muscles relax. The muscles relax. This widens the lumen food is pushed forward. to allow food to enter. Longitudinal muscles Circular muscles food mass Longitudinal muscles Circular muscles 19 5.1 What Is Nutrition? The Stomach The stomach is a distensible muscular bag, with thick and well-developed muscular walls. It lies to the left side of the abdominal cavity and is partly covered by the liver. 20 5.1 What Is Nutrition? The Stomach The inner surface of the stomach wall has numerous pits, the walls of which are lined with gastric glands. These glands secrete gastric juices which plays an important part in digestion. 21 5.1 What Is Nutrition? The Small Intestine The small intestine consists of a U-shaped duodenum (the first part of the small intestine) and the much-coiled ileum. In humans, the small intestine is about 6 m long and is where most of the digestive processes occur. Water and nutrients from the food we eat are absorbed in the small intestine. 22 5.1 What Is Nutrition? The Small Intestine The lining of the walls of the small intestines contains glands that secrete digestive enzymes. With these enzymes and the enzymes from the pancreas, food is digested. The surface area is Microvilli in the increased by the epithelium of villi numerous folds in its increase surface inner wall. area. Villi in the inner walls increase surface area. 23 5.1 What Is Nutrition? The Large Intestine The large intestine is shorter than the small intestine Opens into the large intestine in the right side of the abdominal cavity. The large intestine is about 1.5 m long and consists of the 24 colon, rectum (a short muscular tube) and anus. 5.1 What Is Nutrition? The Large Intestine Comprises colon, rectum and anus. No chemical & physical digestion does not occur. Colon absorbs 90% of remaining water and mineral salts the undigested food material. Rectum temporarily stores faeces (undigested matter). When the rectum contracts, the faeces are egested out of the body through the anus. 25 5.1 What Is Nutrition? Organs & Glands Associated With The Gut The Liver & The Gall Bladder The liver is the largest gland in the body. It is dark red in colour and its upper surface touches the diaphragm and the lower surface is in contact with the stomach and the small intestine. 26 5.1 What Is Nutrition? Organs & Glands Associated With The Gut The Liver & The Gall Bladder Attached to the lower surface of the liver are three blood vessels: Hepatic artery (IN) Hepatic portal vein (ACROSS) Hepatic vein (OUT) 27 5.1 What Is Nutrition? Organs & Glands Associated With The Gut The Liver & The Gall Bladder Liver cells produce and secrete bile, an alkaline greenish-yellow liquid containing bile salts. Bile is not an enzyme – Does not chemically digest food but it aids in the physical digestion of fats. – Temporarily stored in the gall bladder, a structure embedded in the liver. – Contraction of the gall bladder leads to bile secreted into the duodenum via the bile duct. The liver has 4 other important functions to perform apart from its role in digestion. 28 5.1 What Is Nutrition? Organs & Glands Associated With The Gut The Pancreas The pancreas is a gland lying in the loop of the duodenum, connected by the pancreatic duct. The bile duct joins the pancreatic duct, just before the pancreatic duct opens into the duodenum. 29 5.1 What Is Nutrition? Organs & Glands Associated With The Gut The Pancreas The pancreas produces pancreatic juice which contains digestive enzymes, amylase, lipase and protease. The pancreas also secrete the hormone insulin and glucagon, which plays an important role in the control of the blood sugar level in the body. 30 Learning Outcomes (Success Criteria) I am able to:  or  describe the functions of the following structures in relation to ingestion, digestion, absorption, assimilation and egestion of food 1) mouth (1) 2) oesophagus (2) 3) stomach (3) 4) duodenum (4) 5) ileum (5) 6) pancreas (6) 7) gall bladder (7) 8) liver (8) 9) colon (9) 10) rectum (10) 11) anus (11) describe peristalsis. explain the function of peristalsis. 31 Chapter 5 Nutrition in Humans 5.1 What Is Nutrition? 5.2 What Is Digestion? 5.3 What Is Absorption? 5.4 What Happens To The Absorbed Nutrients? 5.5 What Are The Effects Of Alcohol Consumption? 32 5.2 What Is Digestion? Learning Outcomes After this section, you should be able to: describe the functions of enzymes (e.g. amylase, maltase, protease, lipase) in digestion, listing the substrates and end- products. 33 5.2 What Is Digestion? What Is Digestion? Digestion is the breakdown of large, complex and insoluble nutrient molecules into smaller, simple and soluble nutrient molecules. 34 5.2 What Is Digestion? What Is Digestion? Physical Digestion Chemical Digestion Involves mechanical Involves break-down of break-up of large complex and food into smaller insoluble nutrient particles to increase molecules into simple surface area to and soluble nutrient volume ratio molecules that can be By chewing absorbed. By churning of the Involves hydrolytic stomach. reactions catalysed by By peristalsis digestive enzymes 35  5.2 What Is Digestion? In The Mouth 2 1 The salivary Food in the mouth glands in the stimulates the mouth secrete salivary gland. saliva, which is mixed with the food by the tongue. 3 The saliva contains mucin which softens the food. Salivary amylase digests starch to maltose. Optimum pH for salivary amylase is at pH 7. 36  5.2 What Is Digestion? In The Mouth 4 The chewing action of teeth / mastication breaks up larger pieces of food into smaller pieces to increase the surface area-to-volume ratio. 6 The boli are swallowed 5 and passed down into the oesophagus via the Tongue rolls the food into small, pharynx. slippery, round masses or boli. 37 5.2 What Is Digestion? In The Oesophagus bolus oesophagus Peristalsis in the walls of the oesophagus push the bolus into the stomach. 38 5.2 What Is Digestion? In The Stomach Entry of bolus stimulates the release of gastric juice by the gastric glands. gastric gland gastric juice bolus Peristalsis mixes the food with the gastric juice. Churning of the stomach also breakdown large substances into smaller substances. 39 5.2 What Is Digestion? In The Stomach Gastric juice is a dilute solution of hydrochloric acid, mucus and protease. The hydrochloric acid: – denatures salivary amylase – provides an acidic medium for the action of protease – kills harmful microorganisms in food 40  5.2 What Is Digestion? In The Stomach The protease digests proteins into polypeptides. protease proteins polypeptides What is the difference between a protein and a polypeptide? 41 5.2 What Is Digestion? In The Stomach The mucus layer protects the stomach wall against being digested by the enzymes it produces. The mucus also moistens the food to allow easy movement within the stomach. Peristalsis in the stomach helps to churn the food, which is broken down both physically and chemically. 42 5.2 What Is Digestion? In The Stomach gastric gland gastric juice bolus Food remains in the stomach for 3 to 4 hours. The partially digested food, now known as chyme, passes into the duodenum when the pyloric sphincter relaxes. 43 5.2 What Is Digestion? In The Stomach Chyme enters the duodenum and stimulates the release of: - pancreatic juice by the pancreas - bile by the gall bladder - intestinal juice by the small intestine These alkaline fluids neutralise the acidic chyme. The alkaline medium is needed for the action of intestinal and pancreatic enzymes. 44  5.2 What Is Digestion? In The Small Intestine 1 2 The gall The pancreas bladder secretes releases its pancreatic juice, stored bile. which contains the The bile passes enzymes through the bile pancreatic duct into the amylase, duodenum. pancreatic lipase 3 and protease. The intestinal juice secreted by the intestinal glands contains the enzymes maltase, proteases and intestinal lipase. These enzymes digest food molecules. 45 5.2 What Is Digestion? Digestion Of Different Foods The carbohydrates, proteins and fats in food are broken down into smaller molecules by specific enzymes. Carbohydrases such as amylases and maltase act on carbohydrates. Proteases act on proteins Lipases act on fats. 46 5.2 What Is Digestion? Digestion Of Different Foods – Carbohydrates Carbohydrate digestion begins in the mouth. Salivary amylase in the mouth catalyses chemical digestion of starch into maltose. Partial digestion occurs as food remains for a short period of time in the mouth. No digestion of carbohydrates occurs in the stomach. Carbohydrates are fully digested in the small intestine into simple sugars which can be absorbed 47 into the blood stream 5.2 What Is Digestion? Digestion Of Different Foods – Carbohydrates In the mouth salivary amylase starch maltose In the small intestine pancreatic amylase maltase Starch maltose glucose Cellulose is not digested at all in humans. 48 5.2 What Is Digestion? Digestion Of Different Foods – Proteins Protein digestion begins in the stomach. Protease digests some proteins to polypeptides. Undigested proteins are digested by protease in the small intestines to polypeptides. The polypeptides produced are further digested by protease in the small intestines into amino acids, which can then be absorbed into the bloodstream. protein polypeptide amino acids 49 5.2 What Is Digestion? Digestion Of Different Foods – Proteins In the stomach stomach protease protein polypeptide In the small intestine intestinal intestinal protease protease protein polypeptide amino acids 50 5.2 What Is Digestion? Digestion Of Different Foods – Fats Fat digestion begins in the small intestine (duodenum). Bile, produced by the liver and stored in the gall bladder, helps to emulsify fats. Bile reduces the attractive force between the fat molecules. Bile physically breaks down large fat globules into small fat droplets. 51 5.2 What Is Digestion? Digestion Of Different Foods – Fats No chemical digestion has taken place. Emulsification increases surface area-to-volume ratio of the fats, catalysing rate of chemical digestion by pancreatic and intestinal lipases. Fats will be digested to release fatty acids and glycerol. pancreatic lipase fats fatty acids + glycerol 52  5.2 What Is Digestion? Digestion Of Different Foods Region Secretion Source Enzyme (s) Action salivary salivary Mouth saliva starch → maltose glands amylase gastric proteins → polypeptide Stomach gastric juice protease glands Large fat globules bile liver – → small fat droplets protease proteins → polypeptides pancreatic pancreatic starch → maltose pancreas Small juice amylase intestine fats → fatty acids + glycerol lipase protease polypeptide → amino acids intestinal epithelial lipase fats → fatty acids + glycerol juice cells maltase maltose → glucose 53 Learning Outcomes (Success Criteria) I am able to:  or  describe the functions of the following enzymes in digestion and list the substrates and end- products. Amylase – salivary & pancreatic amylase Maltase Protease – stomach and intestinal protease Pancreatic lipase 54 Chapter 5 Nutrition in Humans 5.1 What Is Nutrition? 5.2 What Is Digestion? 5.3 What Is Absorption? 5.4 What Happens To The Absorbed Nutrients? 5.5 What Are The Effects Of Alcohol Consumption? 55 5.3 What Is Absorption? Learning Outcomes After this section, you should be able to: describe the structure of a villus and its role, including the role of capillaries and lacteals in absorption. 56 5.3 What is Absorption? Absorption is the process whereby digested food substances are absorbed into the body cells via the bloodstream. The small intestine is the site of absorption of the products of digestion. 57 5.3 What Is Absorption? How Is The Rate Of Absorption Influenced? The rate of absorption depends on: – surface area – thickness of separating membrane – concentration gradient Absorption at the small intestine is made more efficient with the following adaptations: – large surface area – thin separating membrane – steep concentration gradient 58 5.3 What Is Absorption? How Is The Small Intestine Adapted For Absorption? Increased surface area to volume ratio increases rate of absorption of digested food molecules. The surface area is increased by the Microvilli in the numerous folds in its epithelium of villi inner wall. increase surface area. Villi in the inner walls increase surface area. 59 5.3 What Is Absorption? How Is The Small Intestine Adapted For Absorption? The surface area to volume ratio is increased for increased rate of absorption. The surface area to volume ratio is increased by the numerous folds in its inner wall; inner walls with finger-like projections called villi; which possess microvilli on the epithelium. 60 5.3 What Is Absorption? How Is The Small Intestine Adapted For Absorption? The one-cell thick(thin) walls of the villi make it easy for nutrients to pass through to the bloodstream. The length of the small intestine (~ 6 m) increases the time for absorption. The epithelial cells contain many mitochondria to provide energy for active transport of nutrients into the villi.` 61  5.3 What Is Absorption? How Is The Small Intestine Adapted For Absorption? Lacteal/ lymphatic capillary helps Blood capillaries to transport fats network help to to the body. transport amino acids and glucose to the body. 62 5.3 What Is Absorption? How Is The Small Intestine Adapted For Absorption? Many capillaries are present to help carry away absorbed nutrients quickly, maintaining a constant concentration gradient. Blood capillaries network help to transport amino acids and glucose to the body. Lacteal/lymphatic capillary helps to transport fats to the body. 63 5.3 What Is Absorption? How Does Absorption Take Place In The Intestines? By Diffusion: – Glucose and amino acids diffuse into the blood capillaries of the villi. – Glycerol and fatty acids diffuse into the epithelium and combine to form minute fat. globules which enter the lymphatic capillary. By Active transport: – Glucose and amino acids are absorbed by active transport. 64 5.3 What Is Absorption? What Happens To Undigested And Unabsorbed Matter? They are stored temporarily in the rectum and discharged as faeces through the anus. This Photo by Unknown Author is licensed under CC BY-SA- NC The discharging of faeces from the body is known as egestion or defecation. 65 Learning Outcomes (Success Criteria) I am able to:  or  describe the structure of a villus. describe the role of villi, including the role of capillaries and lacteals in absorption. 66 Chapter 5 Nutrition in Humans 5.1 What Is Nutrition? 5.2 What Is Digestion? 5.3 What Is Absorption? 5.4 What Happens To The Absorbed Nutrients? 5.5 What Are The Effects Of Alcohol Consumption? 67 5.4 What Happens to Absorbed Nutrients Learning Outcomes After this section, you should be able to: state the function of the hepatic portal vein as the transport of blood rich in absorbed nutrients from the small intestine to the liver. state the role of the liver in: – conversion of glucose to glycogen and vice versa – fat digestion – metabolism of amino acids and the formation of urea – breakdown of alcohol – breakdown of hormones 68 5.4 What Happens to Absorbed Nutrients How Are Glucose And Amino Acids Transported And Utilised? The blood capillaries that supply the small intestine unite to form the hepatic portal vein. The hepatic portal vein transports glucose and amino acids to the liver. liver hepatic portal capillaries vein 69  5.4 What Happens to Absorbed Nutrients How Are Glucose And Amino Acids Transported And Utilised? The hepatic portal vein carries the absorbed sugars to the liver. hepatic vein hepatic artery In the liver: – Most of the sugars are converted to glycogen Hepatic portal and stored. vein carries – Glucose is transported absorbed by the hepatic vein to sugars to the the different parts of liver. the body. 70 5.4 What Happens to Absorbed Nutrients How Are Glucose And Amino Acids Transported And Utilised? Glucose is the energy source for all cells in the body. Glucose is oxidized during cellular respiration to release energy which the cells use for their activities. Insulin regulates the amount of glucose that enters the blood stream, thus affecting the osmotic potential of the blood too. 71 5.4 What Happens to Absorbed Nutrients Glucose & Glycogen Insulin stimulates the liver to convert excess glucose to glycogen, which are stored in muscle and liver cells. Glucose is transported by the hepatic vein to the different parts of the body for the body cells to use. 72  5.4 What Happens to Absorbed Nutrients How Are Glucose And Amino Acids Transported And Utilised? hepatic vein hepatic artery In the liver: ▪ Excess amino acids are converted to urea by Hepatic portal vein deamination. carries ▪ Amino acids are absorbed transported by the amino acids hepatic vein to the to the liver. different parts of the body to be utilised. 73 5.4 What Happens to Absorbed Nutrients How Are Glucose And Amino Acids Transported And Utilised? The hepatic vein distributes amino acids to be used for growth and repair in worn-out cells; and to form enzymes and hormones and antibodies. Amino acids are transported by the hepatic vein to the different parts of the body to be utilised. 74 5.4 What Happens to Absorbed Nutrients How Are Fats Transported And Utilised? Fatty acids and glycerol absorbed by small intestines into the lacteal (lymphatic capillaries) rejoins to form fats. The lymphatic capillaries join to form larger lymphatic vessels, which discharge fats into the bloodstream. Blood carries the fats to all parts of the body, as well as to the liver. In the liver, fats are converted into forms that can 75 either be broken down or stored. 5.4 What Happens to Absorbed Nutrients How Are Fats Transported And Utilised? 76 5.4 What Happens to Absorbed Nutrients How Are Fats Transported And Utilised? Under normal conditions when there is a sufficient supply of glucose, fats are not broken down. Instead, fats are used to build protoplasm, c.f., cell membrane. When glucose is in short supply, e.g., fasting, fats are broken down to provide the energy needed for vital activities of the body. 77 5.4 What Happens to Absorbed Nutrients How Are Fats Transported And Utilised? Excess fats are stored in special tissues called adipose tissues, which can be found beneath the skin and around the heart and the kidneys. Adipose tissues protect these organs by acting as shock absorbers. 78 Video – How The Digestive System Works 79  5.4 What Happens to Absorbed Nutrients What Are The Functions Of The Liver? Detoxification Regulation of blood glucose concentration Production of bile Breakdown of hormones Deamination 80 5.4 What Happens to Absorbed Nutrients What Are The Functions Of The Liver? Production of bile – stored temporarily in the gall bladder. Deamination of amino acids ▪ Excess amino acids are deaminated, where the amino groups are removed and converted to urea. ▪ The urea formed is removed from the body in the urine. The remains of the deaminated amino acids are converted into glucose in the liver. Any excess glucose formed this way is converted into glycogen. 81 5.4 What Happens to Absorbed Nutrients What Are The Functions Of The Liver? R ammonia H2N – C – COOH glucose converted into stored as H urea glycogen excreted in urine 82 5.4 What Happens to Absorbed Nutrients What Are The Functions Of The Liver? ▪ Regulation of Blood Glucose Concentration – The pancreas contains special group of cells known as the islets of Langerhans which secrete the hormone insulin and glucagon into the bloodstream. Both insulin and glucagon together help to regulate the blood glucose levels. 83 5.4 What Happens to Absorbed Nutrients What Are The Functions Of The Liver? This Photo by Unknown Author is licensed under Pancreas CC BY-NC islets of Langerhans secrete insulin Liver converts Increase in glucose into Blood glucose blood glucose glycogen level levels above decreases normal & returns to normal levels islets of Langerhans secrete glucagon Decrease in Liver converts glycogen into Blood glucose blood level increases glucose glucose & returns to levels below normal levels normal 84 5.4 What Happens to Absorbed Nutrients What Are The Functions Of The Liver? Increase in blood glucose Decrease in blood glucose levels above normal levels below normal When blood glucose levels When blood glucose levels increase and exceeds decreases and falls below normal levels, islets of normal levels, islets of Langerhans secrete Langerhans secrete insulin. glucagon. Insulin stimulates liver to Glucagon stimulates liver to convert excess glucose to convert/breakdown glycogen, causing blood glycogen to glucose, glucose level decrease. causing blood glucose level increase. 85 5.4 What Happens to Absorbed Nutrients What Are The Functions Of The Liver? Regulation of glucose and amino acids concentration maintains blood osmotic potential. Breakdown of hormones. 86 5.4 What Happens to Absorbed Nutrients What Are The Functions Of The Liver? Detoxification of alcohol and harmful toxins to convert them into harmless substances in the body. The liver cells contain an enzyme, alcohol dehydrogenase which breaks down alcohol to compounds that can be used in respiration, providing energy for cell activities. 87 Learning Outcomes (Success Criteria) I am able to:  or  state the function of the hepatic portal vein. state the role of the liver in conversion of glucose to glycogen and vice versa. state the role of the liver in fat digestion. state the role of the liver in metabolism of amino acids and the formation of urea. state the role of the liver in breakdown of alcohol. state the role of the liver in breakdown of hormones. 88 Chapter Nutrition in Humans 5 5.1 What Is Nutrition? 5.2 What Is Digestion? 5.3 What Is Absorption? 5.4 What Happens To The Absorbed Nutrients? 5.5 What Are The Effects Of Alcohol Consumption? 89 Learning Outcomes After this section, you should be able to: outline the effects of alcohol consumption on the brain (e.g. increased reaction time, reduced self-control), the long-term effects of excessive consumption (e.g. liver disease and brain damage) and the social implications. 90 5.5 What Are The Effects Of Alcohol Consumption? Harmful Effects On The Digestive System Alcohol stimulates acid secretion in the stomach. Excessive stomach acid increases the risk of gastric uclers. Prolonged alcohol abuse may lead to liver cirrhosis – a disease in which the liver cells are destroyed and replaced by fibrous tissues, making the liver less able to function. 91 5.5 What Are The Effects Of Alcohol Consumption? Harmful Effects On The Digestive System Patients with alcoholic cirrhosis may haemorrhage in the liver. This can lead to liver failure and subsequently death. Healthy Cirrhosis 92 5.5 What Are The Effects Of Alcohol Consumption? Harmful Effects On The Digestive System Alcohol is a depressant. It slows down some brain functions. Its effect vary from one person to another. Alcohol reduces self-control and increases reaction time. He may end up doing things that he may regret after the effects of alcohol have worn off. 93 5.5 What Are The Effects Of Alcohol Consumption? Short-Term Effects of Alcohol Consumption Other effects of intoxication includes slurred speech, blurred vision and poor muscular coordination – clumsy and unable to walk properly. Judgement deteriorates and tends to underestimate speed. Drunk drivers have a higher tendency to be involved in traffic accidents as he may drive faster and yet reactions is slower. 94 5.5 What Are The Effects Of Alcohol Consumption? Long-Term Effects Of Alcohol Consumption On The Brain ‘Wet brain’ – a type of dementia caused by brain damage. Alcohol interferes with the absorption of vitamin B1 (thiamine) in the small intestine. Vitamin B1 is part of an enzyme needed to break down sugar to release energy for brain activities, e.g., construction of nerve impulses 95 5.5 What Are The Effects Of Alcohol Consumption? Long-Term Effects Of Alcohol Consumption On The Brain Shrinkage of brain volume – brain becomes smaller, especially the region associated with memory and reasoning. Heavy consumption of alcohol during pregnancy may interfere with the development of the fetus’ brain, which may lead to lifelong physical, mental and behavioural problems. 96 5.5 What Are The Effects Of Alcohol Consumption? (1) Causes liver (2) Slows down cirrhosis some brain functions What are some of the (6) Increases harmful effects of (3) Reduced the risks of excessive alcohol self-control gastric ulcers consumption? (5) Frequent (4) Causes intake may lead symptoms of to addiction ‘drunkenness’ 97 5.5 What Are The Effects Of Alcohol Consumption? Social Implications Addiction to alcohol – unable to stop drinking until a person is drunk – the body becomes dependent on alcohol and becomes an alcoholic. ▪ Neglect work and families. ▪ Exhibit violent behaviour, especially towards family members. ▪ Commit crime under influence. 98 Learning Outcomes (Success Criteria) I am able to:  or  describe the effects of alcohol consumption on the brain. describe the long-term effects of excessive consumption of alcohol. describe the social implication on consumption of alcohol. 99 BIG IDEAS Disciplinary Idea – Systems The digestive system consists of the alimentary canal and the associated organs that work collaboratively to break down large, insoluble molecules of food into smaller soluble molecules that can be absorbed and assimilated by the body. Disciplinary Idea – Structure & Function The various organs in the alimentary canal are adapted for the digestion, absorption, and assimilation of food. 100