B4

Explain the significance of villi in increasing the interal surface area of the small intestine

The villi of the small intestine project into the intestinal cavity, greatly increasing the surface area for food absorption and adding digestive secretions. The villi. The villi (one is called a villus) are tiny, finger-shaped structures that increase the surface area. They have several important features: wall just one cell thick - ensures that there is only a short distance for absorption to happen by diffusion and active transport. Villi are specialized for absorption in the small intestine as they have a thin wall, one cell thick, which enables a shorter diffusion path. They have a large surface area so there will be more efficient absorption of fatty acids and glycerol into the blood stream. The small intestine has millions of tiny finger-like projections called villi. These villi increase the surface area for more efficient food absorption. Within these villi, are present numerous blood vessels that absorb the digested food and carry it to the bloodstream. Villi are filled with blood capillaries, and the blood constantly moving in them means that a steep concentration gradient is maintained. This increases the amount of dissolved, digested food that can be absorbed into the bloodstream from the small intestine. Villi is the plural of villus. The epithelial cells that cover each villus themselves have projections called microvilli . These all increase the surface area over which digested food - now simple molecules - is absorbed.

List the chemical elements that make up carbohydrates, fats and proteins

Carbohydrates and fats are made up of carbon, hydrogen and oxygen. Proteins contain carbon, hydrogen, oxygen and nitrogen. Carbohydrates and lipids are made of only carbon, hydrogen, and oxygen (CHO). Proteins are made of carbon, hydrogen, oxygen, and nitrogen (CHON).

List the principle sources of, and describe the dietary importance of:

Carbohydrates: Carbohydrates are made of carbon,hydrogen, and oxygen. They are used as a source of energy for the body. Energy is stored in the chemical bonds of the glucose molecules. Once glucose is digested and transported to your cells, a process called cellular respiration releases the stored energy and converts it to energy that your cells can use. Carbohydrates are digested and converted into glucose, which can be absorbed into the bloodstream. Once absorbed, glucose molecules travel in the blood to the body's cells where they are used for respiration. Carbohydrates provide the body with glucose, which is converted to energy used to support bodily functions and physical activity. Carbohydrates are polymers which are formed by monomers joining together by covalent means to form those macromolecules. Glucose is oxidised to release its energy, which is then stored in ATP molecules. Energy is stored in the chemical bonds of the glucose molecules. Once glucose is digested and transported to your cells, a process called cellular respiration releases the stored energy and converts it to energy that your cells can use. Fats: Fat helps the body absorb vitamin A, vitamin D and vitamin E. fat is a source of the fat-soluble vitamins A, D, E and K. Fats are stored under the skin and are essential for health. These vitamins are fat-soluble, which means they can only be absorbed with the help of fats. Fats store energy, insulate us and protect our vital organs. Fats insulate the body, helping reduce fluctuations in our body temperature. Fat helps give your body energy, protects your organs, supports cell growth, keeps cholesterol and blood pressure under control, and helps your body absorb vital nutrients. It protects the vital organs. to provide an insulating layer which helps the body to maintain a constant temperature. It also forming cell membranes. Lipids can also supply cells with energy. Fats are nutrients in food that the body uses to build nerve tissue (including the brain and nerves) and hormones. If fats eaten aren't burned as energy or used as building blocks, they're stored by the body in fat cells. Often, excess carbohydrates are converted into fats for storage. When we don't have enough carbohydrates for respiration, we can break down and respire fats, too. Proteins: Your body uses proteins to make new cells for growth, and repair damaged tissues. They help repair and maintain vital tissues and, are crucial for the growth of all organs systems including bones and muscles. In digestion, protein molecules break down long chains of amino acids (peptides), to single amino acids. Protein is extremely important in building muscle because the amino acids (the building blocks of protein) help repair and maintain muscle tissue. Protease enzymes and the duodenum and ileum digest proteins to form peptides. These chains or monomers of amino acids are used by the body to rebuild muscle fibres. your body repairs or replaces damaged muscle fibers through a cellular process where it fuses muscle fibers together to form new muscle protein strands. Enzymes are proteins comprised of amino acids linked together in one or more polypeptide chains. This sequence of amino acids in a polypeptide chain is called the primary structure. This, in turn, determines the three-dimensional structure of the enzyme, including the shape of the active site. Enzymes are made from amino acids, and they are proteins. When an enzyme is formed, it is made by stringing together between amino acids in a very specific and unique order. The chain of amino acids then folds into a unique shape. When proteins are broken down into amino acids, they are used in the synthesis to produce hormones. Vitamins, limited to C and D C: Vitamin C (ascorbic acid) is needed to help heal wounds and maintain healthy connective tissue (which gives support to other tissues and organs). Vitamin C (ascorbic acid) is a nutrient your body needs to form blood vessels, cartilage, muscle and collagen in bones. Vitamin C is also vital to your body's healing process. The endothelial cells lining blood vessels form a tight barrier, which is weakened (permeabilized) by inflammation. Vitamin C tightens the endothelial barrier and maintains its integrity during inflammation. Vitamin C is equally important to the maintenance of bone health as calcium because it regulates the flow of calcium into the bloodstream. This is done by promoting the absorption of calcium from food. Vitamin C, also known as ascorbic acid, is required for the synthesis of collagen. It is also a highly effective antioxidant protecting cells from damage by free radicals. Studies have shown that the vitamin can help speed the healing process of wounds. It also helps the body absorb iron from food. Studies on vitamin C have found that it can stimulate the production of collagen and proteoglycan (both of which are important parts of joint cartilage) and can protect against the breakdown of cartilage in animal studies. D: These nutrients are needed to keep bones, teeth and muscles healthy. Vitamin D helps your body absorb calcium and maintain strong bones throughout your entire life. Your body produces vitamin D when the sun's UV rays contact your skin. The sun's energy turns a chemical in your skin into vitamin D3, which is carried to your liver and then your kidneys to transform it to active vitamin D. Vitamin D is needed to maintain healthy bones and teeth. Vitamin D can help with faster muscle recovery after intense exercise and may even prevent muscle damage caused by the exercise. The main function of vitamin D is to help the body absorb calcium for strong teeth and bones. The human body can make vitamin D when our skin is exposed to sunlight. Vitamin D is needed to maintain healthy bones and teeth. Vitamin D deficiency leads to rickets and bone pain. Mineral salts, limited to calcium and iron Ca: Calcium is needed to maintain healthy bones and teeth, for normal blood clotting and to control muscle contractions. The symptoms of calcium deficiency include weak bones and teeth, poor clotting of the blood and muscle spasms. Your body needs calcium for muscles to move and for nerves to carry messages between your brain and every part of your body. Calcium also helps blood vessels move blood throughout your body and helps release hormones that affect many functions in your body. Calcium is needed to maintain healthy bones and teeth, for normal blood clotting and to control muscle contractions. Importance of Calcium Ions. Ca2+ ions play an important role in muscle contraction by creating interactions between the proteins, myosin and actin. The nerve endings in your muscle cells release calcium ions, which then bind to activator proteins which signal your muscles to contract and relax. The high calcium concentrations let the neuron know that it's time to release its neuro-transmitters, the chemical messages neurons use to communicate with each other. Calcium is important for healthy blood pressure because it helps blood vessels tighten and relax when they need to. Calcium strengthens the hard outer shell of your tooth called enamel, Calcium and collagen work together to make bones strong and flexible. Fe: Red blood cells use a molecule called hemoglobin to transport oxygen around the body. To make hemoglobin, cells require iron to build a component called heme. Iron is needed to produce haemoglobin, found in red blood cells. Iron is needed to prevent anaemia. iron helps blood formation and is also a form of enzyme and iron is the center of haemoglobin with binds with oxygen for transport in the body. Your body uses iron to make hemoglobin. This is the protein in your red blood cells that carries oxygen around your body. This is present in red blood cells and helps them transport oxygen around the body. Iron is a major component of hemoglobin, a type of protein in red blood cells that carries oxygen from your lungs to all parts of the body. Without enough iron, you will experience anaemia. Fe transports oxygen in your body, regulate cell growth, maintain brain function, metabolism and endocrine (hormone production) function and it also plays a role in energy production and immune function. Fibre, roughage: Fiber, also known as roughage that the body can't break down. Fiber is a type of carbohydrate that the body can't digest. Though most carbohydrates are broken down into sugar molecules, fiber cannot be broken down into sugar molecules, and instead it passes through the body undigested. Dietary fiber increases the weight and size of your stool and softens it. A bulky stool is easier to pass, decreasing your chance of constipation. The undigested fiber creates "bulk" so the muscles in the intestine can push waste out of the body. If you have loose, watery stools, fiber may help to solidify the stool because it absorbs water and adds bulk to stool. Helps maintain bowel health. Dietary fibre is important because it provides bulk, which helps the walls of the intestine move food and faeces along the gut. Lack of dietary fibre can lead to constipation. Another name for stool is feces. It is made of what is left after your digestive system (stomach, small intestine, and colon) absorbs nutrients and fluids from what you eat and drink. Sometimes a bowel movement isn't normal. Water: Carries nutrients and oxygen to cells. Lessens burden the on kidneys and liver by flushing out waste products. Get rid of wastes through urination, perspiration, and bowel movements. Helps dissolve minerals and nutrients to make them accessible to your body. It keeps your body at a normal temperature. The water we drink is absorbed by the intestines, and circulated throughout the body in the form of body fluids such as blood. The nutrients and oxygen dissolve into water as it moves around the body, and diffuse out of the substance. Drinking water helps dilute your urine and ensures that you'll urinate more frequently— allowing bacteria to be flushed from your urinary tract before an infection can begin. Water helps the kidneys remove wastes from your blood in the form of urine. Water also helps keep your blood vessels open so that blood can travel freely to your kidneys, and deliver essential nutrients to them. The body water has an important role as a thermoregulator, regulating the overall body temperature by helping dissipate heat. If the body becomes too hot, water is lost through sweat and the evaporation of this sweat from the skin surface removes heat from the body.

Define catalysts and enzymes

Catalysts are substances that increase or decrease the rate of a chemical reaction but remain unchanged. Enzymes are proteins that increase rate of chemical reactions converting substrate into product. Catalysts: Increase the speed of a reaction, it is organic in nature. Catalysts take part in a reaction, catalysts bring two substances that don't react directly inorder to produce a product. The catalysts regenerate, which means they return back to their original form. They bind with one reactant, which is different from it's original form, and then bind with another reactant to react both together and form a new product. Thus they regerneate. Catalysts: A catalyst is a substance which increases the rate of the reaction without itself undergoing any change. Catalysts participate in a chemical reaction and increase its rate. They do not appear in the reaction's net equation and are not consumed during the reaction. Catalysts allow a reaction to proceed via a pathway that has a lower activation energy than the uncatalyzed reaction. Catalyst. a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change. Enzyme. a substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction. A catalyst lowers the activation energy by changing the transition state of the reaction. The reaction then goes through a different pathway/mechanism than the uncatalyzed reaction. The catalyst does not change the net energy difference between reactant and product. A catalyst is a substance that speeds up a chemical reaction, or lowers the temperature or pressure needed to start one, without itself being consumed during the reaction. Catalysis is the process of adding a catalyst to facilitate a reaction. Catalyst: A substance that speeds up a chemical reaction but is not consumed or altered in the process. Catalysts are of immense importance in chemistry and biology. All enzymes are catalysts that expedite the biochemical reactions necessary for life. Enzymes: Are catalysts that speed up the rate of a chemical reaction without being changed or used up in the reaction. Are proteins. Enzymes are biological catalysts and are produced by living organisms to speed up the biochemical reactions they need in order to survive. Without the use of catalysts, these biochemical processes (such as respiration and digestion ) would happen too slowly and the organism would not survive. Digestive enzymes are substances that help you digest your food. They're secreted by the salivary glands and cells lining the stomach, pancreas, and small intestine. Sometimes people have a digestive enzyme deficiency. An enzyme is a substance that acts as a catalyst in living organisms, regulating the rate at which chemical reactions proceed without itself being altered in the process. The biological processes that occur within all living organisms are chemical reactions, and most are regulated by enzymes. Enzymes are proteins that function as biological catalysts . So, they are molecules that speed up a chemical reaction without being changed by the reaction. Enzymes are biological catalysts - they speed up chemical reactions. Enzymes are required for most of the chemical reactions that occur in organisms . These reactions occur in the breakdown of chemical molecules, which we see in the digestive system. Enzymes are proteins that act as biological catalysts - this means they speed up reactions without being used up. An enzyme works on the substrate , forming products. An enzyme's active site and its substrate are complementary in shape. An enzyme will only work on one substrate - it is substrate specific. Enzymes are protein molecules which act as catalysts to speed up reactions. They are not used-up in these reactions. Enzymes can be grouped into two types: Those that break larger molecules apart (like digestive enzymes). Enzymes are proteins that catalyze (i.E. Pace up) biochemical reactions and will not be modified throughout the reaction. The molecules at which enzymes act are known as substrates, and enzyme converts them into different molecules, known as merchandise. Enzymes scale down the activation vigor in a number of ways. Enzymes in our bodies are catalysts that speed up reactions by helping to lower the activation energy needed to start a reaction. Each enzyme molecule has a special place called the active site where another molecule, called the substrate, fits. Enzymes are biological catalysts. Catalysts lower the activation energy for reactions. The lower the activation energy for a reaction, the faster the rate. Thus enzymes speed up reactions by lowering activation energy. Enzymes speed up chemical reactions by lowering the amount of activation energy needed for the reaction to happen.

Describe the functions of the regions of the alimentary canal

Describe the functions of the regions of the alimentary canal Mouth: Where food enters the alimentary canal and digestion begins by amylase enzyme in the saliva starting the digestion of starch. The mouth is the beginning of the digestive tract. In fact, digestion starts before you even take a bite. Your salivary glands get active as you see and smell that pasta dish or warm bread. After you start eating, you chew your food into pieces that are more easily digested. Digestion of food starts in the mouth. Teeth break down the food and mix it with the enzymes in saliva. This is a thin tube that connects the mouth to the stomach. When you put food in your mouth, your teeth break the food into smaller pieces, and the salivary glands under your tongue and on the sides and roof of your mouth release saliva. This saliva mixes with your food to make it easier to swallow. Salivary glands play an important role in digestion because they make saliva. Saliva helps moisten food so we can swallow it more easily. It also has an enzyme called amylase that makes it easier for the stomach to break down starches in food. Oesophogus: Muscular tube which moves ingested food to the stomach. The primary function of your esophagus is to carry food and liquid from your mouth to your stomach. When you swallow, food and liquid first move from your mouth to your throat (pharynx) The oesophagus or food pipe is an organ in the human digestive system that transfers food particles to the stomach for its ingestion. Oesophagus. Also known as the gullet, this 25cm-long tube contracts to shift chewed food down to your stomach. The squeezing motion of the muscles is called peristalsis and it occurs throughout the digestive system. A slimy mucus is also oozed from the oesophagus to help the food on its way. The esophagus serves to pass food and liquids from the mouth down to the stomach. This is accomplished by periodic contractions (peristalsis) instead of gravity. With vomiting, these contractions are reversed, allowing stomach contents to be returned to the mouth to spit out. The function of the esophagus is to transport material from the mouth to the stomach, and to prevent GER by providing an important barrier, that is, the lower esophageal sphincter (LES), to the retrograde flow of gastric contents into the esophagus. Peristalsis is a series of wave-like muscle contractions that move food through the digestive tract. It starts in the esophagus where strong wave-like motions of the smooth muscle move balls of swallowed food to the stomach. Esophageal peristalsis consists of sequential contraction of the circular muscles of the muscularis propria, which is largely mediated by acetylcholine. This sequential contraction serves to occlude the esophageal lumen and push the bolus aborally. Stomach: pepsin?????? Your stomach is a muscular organ that digests food. It is part of your gastrointestinal (GI) tract. When your stomach receives food, it contracts and produces acids and enzymes that break down food. When your stomach has broken down food, it passes it to your small intestine. The four key components of gastric digestive function are its function as a reservoir, acid secretion, enzyme secre- tion and its role in gastrointestinal motility. The stomach's main job is to store and digest the food and drink we take during our meals. It produces hydrochloric acid and enzymes that aid in the digestion of food and other foreign particles such as germs. The stomach is an important organ in the digestive system. After food has been chewed in the mouth and swallowed, it enters the stomach via the oesophagus. The stomach produces strong acid. This kills many harmful microorganisms that might have been swallowed along with the food. The primary functions of the stomach are to break down food after feeding and releases nutrients (nutrients are actually absorbed in small intestine), store food, "sanitize" food with HCL, gastric juices are released to continue chemical digestion , breaking down protein Liver: The liver is a large organ in the abdomen that performs many important bodily functions, including blood filtering. It is also considered a gland because it makes chemicals the body needs. The liver regulates most chemical levels in the blood and produces a product called bile. Bile is a fluid that is made and released by the liver and stored in the gallbladder. Bile helps with digestion. It breaks down fats into fatty acids, which can be taken into the body by the digestive tract. Bile contains: Mostly cholesterol. Bile juice is a digestive fluid produced by the liver. It is stored and concentrated in the gallbladder. Its main function is to convert fats in food into fatty acids, which are absorbed in the gut. Below are the important functions of bile. The liver is responsible for synthesizing bile salts; these salts are transferred into the gallbladder as bile. The gallbladder stores bile, which it then secretes into the small intestine. Bile contributes to digestion by breaking up large fat globules, a process known as emulsification. Bile salts helps in emulsification of fats, i.e., breaking down of the large fat droplets into very small micelles. Bile also activates lipase enzymes, which digests fats. Bile is a substance produced by the liver and stored in the gall bladder. Bile is secreted into the small intestine where it has two effects: it neutralises the acid - providing the alkaline conditions needed in the small intestine. Your gallbladder is part of your digestive system. Its main function is to store bile. The bile ducts are a series of thin tubes that go from the liver to the small intestine. Their main job is to allow a fluid called bile to go from the liver and gallbladder into the small intestine, where it helps digest the fats in food. Bile is secreted into the small intestine where it has two effects: it neutralises the acid - providing the alkaline conditions needed in the small intestine. it emulsifies fats - providing a larger surface area over which the lipase enzymes can work. Bile salts and acids are transported in a fluid that contains water, sodium, chloride, and bicarbonates. This fluid is produced in the liver, and it serves to neutralize hydrochloric acid passed from the stomach into the small intestine. Pancreas: The pancreas is a long, flat gland that lies in the abdomen behind the stomach. During digestion, your pancreas produces pancreatic juices called enzymes. These enzymes break down sugars, fats, and starches. They are carbohydrases, lipase and protease. It is part of the digestive system and produces insulin and other important enzymes and hormones that help. Your main pancreatic duct connects with your bile duct. This duct transports bile from your liver to your gallbladder. From the gallbladder, the bile travels to part of your small intestine called the duodenum. Both the bile and the pancreatic enzymes enter your duodenum to break down food. Function: The pancreatic duct carries the exocrine secretions of the pancreas (enzymes and bicarbonate) to the small intestine (dueodenum). Function: The bile duct and pancreatic ducts enter the wall of the duodenum where they form a bulb called the hepatopancreatic ampulla. Small intestine: The small intestine has three parts: the duodenum, jejunum, and ileum. It helps to further digest food coming from the stomach. It absorbs nutrients (vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body. The small intestine is part of the digestive system. The small intestine is especially adapted to allow absorption to take place very efficiently. It has a very rich blood supply. Digested food molecules are small enough to pass through the wall of the intestine into the bloodstream. Water, minerals salts and vitamins are also absorbed in the small intestine. Firstly it is very long, meaning there is a lot of time for nutrients to be absorbed. Secondly it has villi which are finger-like projections that increase the surface area for absorption. These villi are also covered in micro-villi further increasing surface area. The main function of the small intestine is absorption of nutrients and minerals from food. It is the site of complete digestion in humans. It absorbs digested food completely. It receives bile juice from the liver and pancreatic juice from the pancreas. The main function of the small intestine is absorption of nutrients and minerals from food Duodenum: The bile is alkaline, it can neutralise the HCL from stomach The first part of the small intestine, called the duodenum is principally involved in digestion. Large insoluble food molecules such as proteins, lipids and starch are chemically broken down into smaller molecules in reactions catalysed by digestive enzymes. The first part of the small intestine. It connects to the stomach. The duodenum helps to further digest food coming from the stomach. It absorbs nutrients (vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body. duodenum, the first part of the small intestine, which receives partially digested food from the stomach and begins the absorption of nutrients. Ileum: The ileum helps to further digest food coming from the stomach and other parts of the small intestine. It absorbs nutrients (vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body. The small intestine connects the stomach and the colon. The ileum is the final portion of the small intestine, measuring around 3 meters, and ends at the cecum. It absorbs any final nutrients, with major absorptive products being vitamin B12 and bile acids. Ileum. This is the longest part of the small intestine. Secretes endopeptidases and exopeptidases. Endopeptidases break proteins into small polypeptides by breaking the bonds in the middle. The ileum follows the duodenum and jejunum and is separated from the cecum by the ileocecal valve (ICV). In humans, the ileum is about 2-4 m long, and the pH is usually between 7 and 8 (neutral or slightly basic). Large intestine: The 4 major functions of the large intestine are recovery of water and electrolytes, formation and storage of faeces and fermentation of some of the indigestible food matter by bacteria. The ileocaecal valve controls the entry of material from the last part of the small intestine called the ileum The large intestine has 3 primary functions: absorbing water and electrolytes, producing and absorbing vitamins, and forming and propelling feces toward the rectum for elimination. The major function of the large intestine is to absorb water from the remaining indigestible food matter and transmit the useless waste material from the body. The major functions of the large intestine are: reabsorption of water and mineral ions such as sodium and chloride. formation and temporary storage of feces. Food which cannot be broken down - mainly fibre - passes into the large intestine. Water is absorbed into the blood. Large intestine: The large intestine includes the colon, rectum and anus. It's all one, long tube that continues from the small intestine as food nears the end of its journey through your digestive system. The large intestine turns food waste into stool and passes it from the body when you poop. The large intestine has 3 primary functions: absorbing water and electrolytes, producing and absorbing vitamins, and forming and propelling feces toward the rectum for elimination. The large intestine absorbs water from the chyme and stores feces until it can be defecated. Food products that cannot go through the villi, such as cellulose (dietary fiber), are mixed with other waste products from the body and become hard and concentrated feces. In the large intestine peristalsis helps water from undigested food be absorbed into the blood stream. Then, the remaining waste products are excreted through the rectum and anus. Colon: The colon's job is to dehydrate what's left of the food and form it into stool. It does this by slowly absorbing water and electrolytes as its muscle system moves the waste along. Meanwhile, bacteria living in your colon feed on the waste and break it down further, completing the chemical part of the digestive process. The colon removes water and some nutrients and electrolytes from partially digested food. The remaining material, solid waste called stool, moves through the colon, is stored in the rectum, and leaves the body through the anus. The colon is part of the digestive system. The large intestine has 3 primary functions: absorbing water and electrolytes, producing and absorbing vitamins, and forming and propelling feces toward the rectum for elimination. The 4 major functions of the large intestine are recovery of water and electrolytes, formation and storage of faeces and fermentation of some of the indigestible food matter by bacteria Ascending colon: The role of the ascending colon is to absorb the remaining water and other key nutrients from the indigestible material, solidifying it to form stool. Transverse colon: absorbs water and salts from the indigestible material. The transverse colon is a segment of the large intestine that passes horizontally across the abdomen and sits beneath other organs in the abdominal cavity. As the longest and most mobile part of the colon, the transverse colon plays an essential role in digestion and the excretion of waste products. As the longest and most mobile part of the colon, the transverse colon plays an essential role in digestion and the excretion of waste products. It also helps absorb water and salts from digested food, making it easier for waste products to move through the body. Descending colon: The descending colon is a section of the large intestine. It is the left part of the colon that passes downward. It is responsible for storing the remains of digested food before they pass through the rest of the colon and rectum for elimination. The large intestine plays a role in the absorption of nutrients. The descending colon stores feces that will eventually be emptied into the rectum. The sigmoid colon contracts to increase the pressure inside the colon, causing the stool to move into the rectum. Rectum:which is a storage area for feces. The rectum is a straight, 8-inch chamber that connects the colon to the anus. The rectum's job is to receive stool from the colon, let you know that there is stool to be evacuated (pooped out) and to hold the stool until evacuation happens Any undigested food passes into the rectum where it is stored as faeces. Anus: The anus is the last part of the digestive tract. It is a 2-inch long canal consisting of the pelvic floor muscles and the two anal sphincters (internal and external) . The lining of the upper anus is able to detect rectal contents. It lets you know whether the contents are liquid, gas, or solid. This is the opening at the very end of the digestive system through which faeces leaves the body. The last part of the digestive tract, the anus, consists of pelvic floor muscles and two anal sphincters (internal and external). Together their jobs are to detect rectal contents, whether they are liquid, gas or solid, and then control when stool should and shouldn't be excreted from your body.

Identify the types of human teeth.

Incisors are sharp, and are used for cutting food into small chewable pieces. Canines are at corners, and are even sharper - they're also used to bite into and tear food. grip and rip Premolars: These have a flat surface, and are used to chew and grind food. Molars serve the same purpose as premolars, and also have flat surfaces.

Types of tests: I B B E

Iodine solution to test for starch: Iodine is yellow, red or brown, according to the solvent and the concentration. The basic principle involved in the iodine test is that Amylose interacts with starch to form a blue-black colored complex with the iodine. Amylose in starch is responsible for the formation of a deep blue color in the presence of iodine. The iodine molecule slips inside of the amylose coil to give a special color. In the presence of starch, iodine turns a blue/black colour. Starch is detected using iodine solution . This turns blue-black in the presence of starch. Benedict's solution to test for reducing sugars: Benedict's Test is used to test for simple carbohydrates/reducing sugars. The Benedict's test identifies reducing sugars (monosaccharide's and some disaccharides), which have free ketone or aldehyde functional groups. We can use a special reagent called Benedict's solution to test for simple carbohydrates like glucose. Benedict's solution is blue but, if simple carbohydrates are present, it will change colour - green/yellow if the amount is low and red if it is high. A precipitate will also form if the sugars are present and the quantity of this gives an indication as to the quantity of sugars in the test sample. Biuret test for proteins: We used Biuret's reagent to detect the presence of proteins in solution. The reagent is pale blue when pure, but when mixed with proteins, the resulting reaction produces a pale purple color. The principle of biuret test is conveniently used to detect the presence of proteins in biological fluids. A Biuret test is a chemical test used to determine the presence of a peptide bond in a substance. It is based on the biuret reaction in which a peptide structure containing at least two peptide links produces a violet colour. Since all proteins and peptides possessing at least two peptide linkage. In this test, the presence of peptides results in the formation of pale purple coloured (or mauve coloured)coordination compounds of the copper(II) ion (when the solution is sufficiently alkaline). That is because proteins are made up of polypeptides, which in turn, are made of amino acids joined by peptide bonds. The longer the polypeptide chain is, the more peptide bonds there are, and therefore, the more intense the violet colour will be when biuret test is applied. Polypeptide: A peptide consisting of 2 or more amino acids. Amino acids make up polypeptides which, in turn, make up proteins. A protein molecule is made from a long chain of these amino acids, each linked to its neighbor through a covalent peptide bond (Figure 3-1). Proteins are therefore also known as polypeptides. Each type of protein has a unique sequence of amino acids, exactly the same from one molecule to the next. Ethanol emulsion test for fats and oils: Ethanol is colourless. The emulsion test is a method to determine the presence of lipids using wet chemistry. The procedure is for the sample to be suspended in ethanol, allowing lipids present to dissolve (lipids are soluble in alcohols). A MILKY-WHITE EMULSION is a positive result: lipid is present. Ethanol turns colourless when fat is not present. Since lipids are insoluble in water, if there are any lipids in the food sample, the lipids dissolved in ethanol will be repelled by the water. And cloudy white droplets will disperse through the water. This is called an emulsion. Ethanol extracts the lipid from the crushed solid sample. As ethanol is miscible with lipids no change is seen upon its addition to the solid and liquid samples.

Explain the causes and effects of protein-energy malnutrition e.g. kwashiorkor and marasmus.

Kwashiorkor a form of malnutrition caused by protein deficiency in the diet/is a severe form of protein-energy malnutrition (protein deficiency), mainly found in poor parts of the world. People who have this condition are getting enough energy from their food, but their diet does not contain enough protein-rich food. Eventually, the body begins to swell, because too much liquid stays in the body. This swelling usually begins in the legs, but can involve the whole body, including the face. The proteins help to hold salt and water inside the blood vessels so fluid does not leak out into the tissues. As protein deprivation continues, one sees growth failure, loss of muscle mass, generalized swelling (edema), and decreased immunity. A large, protuberant belly is common. Marasmus is similar to kwashiorkor but, while kwashiorkor is caused by an inadequate intake of energy from protein, marasmus is caused by an inadequate intake of energy from all nutrients. Symptoms of marasmus include stunted growth, and loss of fat and muscle mass leading to a wasted appearance. Protein-energy malnutrition: According to World Health Organization, protein energy malnutrition (PEM) refers to "an imbalance between the supply of protein and energy and the body's demand for them to ensure optimal growth and function".[1] It is a major public health problem in India. Protein-energy malnutrition (PEM) is a common childhood disorder and is primarily caused by deficiency of energy, protein, and micronutrients. PEM manifests as underweight (low body weight compared with healthy peers), stunting (poor linear growth), wasting (acute weight loss), or edematous malnutrition (kwashiorkor). PEM is caused by starvation. It is the disease that develops when protein intake or energy intake, or both, chronically fail to meet the body's requirements for these nutrients. PEM has always been a common disease, and humans have adaptive mechanisms for slowing and, in most cases, arresting its progress. Protein malnutrition: Insufficient intake of nitrogen-containing food (protein) to maintain a nitrogen balance or nitrogen equilibrium. Children are particularly prone to develop protein malnutrition. Protein-energy malnutrition or PEM is the condition of lack of energy due to the deficiency of all the macronutrients and many micronutrients. It can occur suddenly or gradually. It can be graded as mild, moderate or severe. In developing countries, it affects children who are not provided with calories and proteins. Children suffering from kwashiorkor are always underweight for their age but they often have a swollen abdomen as their diet may contain a lot of carbohydrate. Marasmus - the most severe form of PEM, where there is a lack of both protein and energy in the diet. Kwashiorkor: Kwashiorkor - caused by a lack of protein in the diet, most common in children under 2. Often caused by poverty as high protein foods tend to be more expensive and scarcer. Like marasmus, kwashiorkor is a type of malnutrition caused by protein deficiency. It mainly occurs in children who are weaning off breast milk, while marasmus can develop in infants. If your diet has a lot of carbohydrates and very little proteins, you may develop kwashiorkor. The main cause of kwashiorkor is not eating enough protein or other essential vitamins and minerals. It's most common in developing countries with a limited food supply, poor hygiene, and a lack of education about the importance of giving babies and children an adequate diet. Kwashiorkor, a severe protein deficiency, causes fluid retention and a protruding abdomen. On the other hand, the condition marasmus, which results from severe calorie deficiency, leads to wasting and significant fat and muscle loss (5). Kwashiorkor is a disease marked by severe protein malnutrition and bilateral extremity swelling. It usually affects infants and children, most often around the age of weaning through age 5. The disease is seen in very severe cases of starvation and poverty-stricken regions worldwide. loss of muscle mass. an enlarged tummy ("pot belly") regular infections, or more serious or long-lasting infections. red, inflamed patches of skin that darken and peel or split open. dry, bri ttle hair that falls out easily and may lose its colour. failure to grow in height. tiredness or irritability. Marasmus: On the other hand, the condition marasmus, which results from severe calorie deficiency, leads to wasting and significant fat and muscle loss (5) Marasmus - the most severe form of PEM, where there is a lack of both protein and energy in the diet. People suffering from this have a much lower body weight than normal and look emaciated. Marasmus is a type of protein-energy malnutrition that can affect anyone but is mainly seen in children. You can get marasmus if you have a severe deficiency of nutrients like calories, proteins, carbohydrates, vitamins, and minerals. Marasmus disease is caused due to vitamin deficiency. It usually occurs when a person's diet does not contain all the vitamins and nutrients that the body needs to function. It involves wasting of body tissues, mainly muscles, and subcutaneous fat and it resulted in severe restrictions in energy intake. Nutrient deficiency is the main cause of marasmus. It occurs in children that don't ingest enough protein, calories, carbohydrates, and other important nutrients. This is usually due to poverty and a scarcity of food. There are several types of malnutrition. Marasmus is a type of protein-energy malnutrition that can affect anyone but is mainly seen in children. You can get marasmus if you have a severe deficiency of nutrients like calories, proteins, carbohydrates, vitamins, and minerals. ‌ It is more common in developing countries, like in some areas of Asia and Africa Marasmus is a condition primarily caused by a deficiency in calories and energy, whereas kwashiorkor indicates an associated protein deficiency, resulting in an edematous appearance.

Describe the effects of malnutrition in relation to starvation, coronary heart disease, obseity and scurvy

Malnutrition: Malnutrition is a serious health problem. It happens when people do not eat the right amounts of nutrients . Too little food, or a lack of nutrients, can cause deficiency diseases or death. Too much food results in obesity . This may cause heart disease or type 2 diabetes. Malnutrition is the result of not eating a balanced diet. There may be: wrong amount of food: too little or too much. incorrect proportion of main nutrients. Starvation: Starvation is caused by consuming too little food (maybe due to lack of food supply or a mental disorder causing an intense fear of gaining weight). This leads to intense weight loss, organ damage and in serious cases, death. Coronary heart disease (CHD) is when cholesterol sticks to the walls of your arteries. starvation, widespread or generalized atrophy (wasting away) of body tissues either because food is unavailable or because it cannot be taken in or properly absorbed. During starvation, most tissues utilise fatty acids and/or ketone bodies to spare glucose for the brain. Glucose utilisation by the brain is decreased during prolonged starvation as the brain utilises ketone bodies as the major fuel. High concentrations of ketone bodies result in significant excretion of ketones Coronary heart disease: The coronary arteries supply blood to the heart muscle. These may become blocked by a build-up of fatty plaques containing cholesterol , resulting in coronary heart disease. If a coronary artery is blocked, the blood supply to part of the heart muscle is cut off. It is A disease in which there is a narrowing or blockage of the coronary arteries (blood vessels that carry blood and oxygen to the heart). Coronary heart disease is usually caused by atherosclerosis (a buildup of fatty material and plaque inside the coronary arteries). Coronary artery disease is caused by plaque buildup in the wall of the arteries that supply blood to the heart (called coronary arteries). Plaque is made up of cholesterol deposits. Plaque buildup causes the inside of the arteries to narrow over time. This process is called atherosclerosis. In coronary heart disease, the blood vessels to the heart are narrowed, putting the heart under stress. In the long term this can cause angina, a form of chest pain. When the blood supply to part of the wall of the heart becomes completely blocked, the result is a sudden and potentially fatal heart attack. Caused by the buildup of cholesterol and other fatty substances within the body's arteries. Cholesterol causes an artery to become narrow, restricting blood flow to the organ it is supplying. If this happens in the coronary arteries it is known as coronary heart disease. CAD happens when coronary arteries struggle to supply the heart with enough blood, oxygen and nutrients. Cholesterol deposits, or plaques, are almost always to blame. These buildups narrow your arteries, decreasing blood flow to your heart. This can cause chest pain, shortness of breath or even a heart attack. Obesity: 'Obese' is a medical term used to describe a person with a high excess of body fat. Obesity: A term used to describe people with a large fat content, caused by an imbalance of calories consumed to energy expenditure. Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health. 'Obese' is a medical term used to describe a person with a high excess of body fat. A person is described as obese if their body mass index (BMI) is greater than 30 kg/m². BMI is just one way to measure obesity. An obese person is at greater risk of type 2 diabetes , heart disease and some types of cancer. Scurvy: Vitamin C deficiency causes scurvy. Symptoms of scurvy include bleeding gums, bulging eyes and scaly skin. a disease caused by a deficiency of vitamin C, characterized by swollen bleeding gums and the opening of previously healed wounds. Vitamin C deficiency leads to scurvy. The symptoms of scurvy include bleeding and swelling of the gums, loss of teeth, tiredness and muscle and joint pain. Scurvy is a severe vitamin C deficiency. The human body needs vitamin C to produce collagen (the tissue that connects your muscles and bones and makes up your skin), heal wounds, support your immune system, and help in many other internal processes. a disease caused by a deficiency of vitamin C, characterized by swollen bleeding gums and the opening of previously healed wounds, which particularly affected poorly nourished sailors until the end of the 18th century. Scurvy is caused by not having enough vitamin C in your diet for at least 3 months. Vitamin C is mainly found in fruit and vegetables. swelling, or edema. petechiae, or small red spots resulting from bleeding under the skin. corkscrew hairs. gum disease and loss of teeth. The symptoms of scurvy include bleeding and swelling of the gums, loss of teeth, tiredness and muscle and joint pain.

Explain what a monomer and polymer is

Monomer: A monomer is a single atom, small molecule, or molecular fragment that, when bonded together with identical and similar types of monomers, form a larger, macromolecule known as a polymer. A monomer is a molecule that forms the basic unit for polymers, which are the building blocks of polymers (Monomers are small molecules that can be joined to form more complex molecules called polymers in a repeated fashion). Monomers bind to other monomers to form repeating chain molecules through a process known as polymerization. (Monomers form polymers by the formation of chemical bonds or the supramolecular binding through a process called polymerization). Monomers may be either natural or synthetic in origin. Monomers are the smaller units from which larger molecules are made. Polymers are molecules made from a large number of monomers joined together. Monosaccharides, amino acids and nucleotides are examples of monomers. Many small individual molecules, called monomers, are joined up to form a polymer. The process of monomers (small molecules) joining up to form a polymer (long molecule) is called polymerisation. Polymer: A polymer is any of a class of natural or synthetic substances composed of very large molecules, called macromolecules, which are multiples of simpler chemical units called monomers. Polymers make up many of the materials in living organisms and are the basis of many minerals and man-made materials. The clinical use of polymeric materials in the body to repair and restore damaged or diseased tissues and organs is substantially increasing on an annual basis Polymers are not restricted to monomers of the same chemical composition or molecular weight and structure. Some natural polymers are composed of one kind of monomer. Most natural and synthetic polymers, however, are made up of two or more different types of monomers; such polymers are known as copolymers. Polymers are chains with an unspecified number of monomeric units. Homopolymers are polymers made by joining together monomers of the same chemical composition or structure. How are polymers formed? Monomers are the building blocks of polymers. They are joined together with chemical bonds to form polymers. Polymers consist of monomers. The monomers combine with each other using covalent bonds to form larger molecules known as polymers. In doing so, monomers release water molecules as byproducts. This type of reaction is known as dehydration synthesis, which means "to put together while losing water. Polymers are formed by two main ways called addition and condensation polymerization. In addition, polymerization, an initiator (or catalyst) reacts with a starting monomer. The result of this initiation reaction is a monomer attached to the initiator with an unsatisfied bond.

Identify the main regions of the alimentary canal and associated organs.

Mouth, salivary glands Oesophagus Stomach Pancreas, liver, gall bladder Small intestine (duodenum + ileum) Large intestine (colon +rectum) Anus. The organs listed above make up your alimentary canal. Note: the alimentary canal is called a 'canal' because it is essentially one long canal that starts at your mouth and ends at your anus. Note: your small intestine is made up of three parts. The 'C' shaped curve immediately after the stomach is the first part of your small intestine. It's called the duodenum. After the duodenum is the jejunum, followed by the ileum. The jejunum and ileum don't look significantly different. You don't strictly need to know this, it's just useful to know. Food enters your body via the mouth, and leaves the body via the anus. Associated organs: Your salivary glands empty into your mouth using ducts.The liver produces bile, a substance that is important for digestion. The bile is emptied into the gall bladder, where it is stored.The pancreas and gall bladder both empty into the duodenum.

State that the large molecules are made from smaller molecules, limited to:

Starch and glycogen from glucose - Glucose: Glucose is the main type of sugar in the blood and is the major source of energy for the body's cells. Glucose comes from the foods we eat or the body can make it from other substances. Glucose is carried to the cells through the bloodstream. Simple carbohydrates: These carbohydrates are composed of sugars (such as fructose and glucose) which have simple chemical structures composed of only one sugar (monosaccharides) or two sugars (disaccharides). Glucose, or blood sugar, is the main source of energy for your body's cells, tissues, and organs. In starch, the glucose monomers are in the α form (with the hydroxyl group of carbon 1 sticking down below the ring), and they are connected primarily by 1 4 glycosidic linkages(i.e., linkages in which carbon atoms 1 and 4 of the two monomers form a glycosidic bond). Linear glycogen chains consist of glucose molecules linked together by α-1,4 glycosidic bonds. At each of the branch points, two glucose molecules are linked together by α-1,6 glycosidic bonds. The non-reducing ends of the glycogen molecule are the sites where both synthesis and degradation occur. - Starch: Starch is a chain of glucose molecules which are bound together, to form a bigger molecule, which is called a polysaccharide. There are two types of polysaccharide in starch: Amylose - a linear chain of glucose. Amylopectin - a highly branched chain of glucose. Starch is a polymer. A polymer is a long and repeating chain of the same molecule stuck together. Starch is a long-chain polymer of glucose molecules joined together. Starch is the most important energy source for humans. The body digests starch by metabolizing it into glucose, which passes into the bloodstream and circulates the body. Glucose fuels virtually every cell, tissue, and organ in the body. If there is excess glucose, the liver stores it as glycogen. Polymers are not restricted to monomers of the same chemical composition or molecular weight and structure. Some natural polymers are composed of one kind of monomer. Most natural and synthetic polymers, however, are made up of two or more different types of monomers; such polymers are known as copolymers. - Glycogen: When the body has extra glucose, it stores it in the liver and muscles. This stored form of glucose is called glycogen. Glycogen is like your backup fuel. It releases glucose into the bloodstream when the body needs a quick energy boost or when a person's blood glucose level drops. Glycogen is a glucose polysaccharide occurring in most mammalian and nonmammalian cells, in microorganisms, and even in some plants. It is an important and quickly mobilized source of stored glucose. In vertebrates it is stored mainly in the liver as a reserve of glucose for other tissues. Like starch, glycogen is a polymer of glucose monomers. Glycogen is usually stored in liver and muscle cells. Glycogen is a branched biopolymer consisting of linear chains of glucose residues. Like amylopectin, glucose units are linked together linearly by α(1→4) glycosidic bonds from one glucose to the next. Glycogen is the reserve polysaccharide in the body and is mainly comprised of hepatic glycogen. Glycogen is synthesized in the liver and muscles. When the body doesn't need to use the glucose for energy, it stores it in the liver and muscles. This stored form of glucose is made up of many connected glucose molecules and is called glycogen. α-D-Glucose combines to form glycogen continuously. glycogenesis, the formation of glycogen, the primary carbohydrate stored in the liver and muscle cells of animals, from glucose. Glycogenesis takes place when blood glucose levels are sufficiently high to allow excess glucose to be stored in liver and muscle cells. glycogenolysis, process by which glycogen, the primary carbohydrate stored in the liver and muscle cells of animals, is broken down into glucose to provide immediate energy and to maintain blood glucose levels during fasting. In animal cells, glucose is generally stored in the form of glycogen. This is done to not upset the osmotic balances in the cell. Glucose molecules are soluble in water and thus can cause the cell to become hypertonic. This will result in the entry of water molecules within the cells and cause it to lyse. Proteins from amino acids - Amino aicds: a simple organic compound. Amino acids are molecules that combine to form proteins. Amino acids and proteins are the building blocks of life. Amino acids are the monomers that make up proteins. Specifically, a protein is made up of one or more linear chains of amino acids, each of which is called a polypeptide. When connected together by a series of peptide bonds, amino acids form a polypeptide, another word for protein. The polypeptide will then fold into a specific conformation depending on the interactions (dashed lines) between its amino acid side chains.Amino acids are the building blocks that form polypeptides and ultimately proteins. Consequently, they are fundamental components of our bodies and vital for physiological functions such as protein synthesis, tissue repair and nutrient absorption. Amino acids are small molecules that are the building blocks of proteins. Proteins serve as structural support inside the cell and they perform many vital chemical reactions. An amino acid is an organic compound characterized by having a carboxyl group, amino group, and side-chain attached to a central carbon atom. Amino acids are used as precursors for other molecules in the body. Linking amino acids together forms polypeptides, which may become proteins Within a protein, multiple amino acids are linked together by peptide bonds, thereby forming a long chain. Peptide bonds are formed by a biochemical reaction that extracts a water molecule as it joins the amino group of one amino acid to the carboxyl group of a neighboring amino acid. - Proteins: Proteins are made up of smaller units called amino acids, which are attached to one another in long chains. Proteins are organic molecules composed of Carbon, Hydrogen, Oxygen and Nitrogen. Proteins - polymers are known as polypeptides; monomers are amino acids Proteins are built as chains of amino acids, which then fold into unique three-dimensional shapes. Bonding within protein molecules helps stabilize their structure, and the final folded forms of proteins are well-adapted for their functions. The chemistry of amino acid side chains is critical to protein structure because these side chains can bond with one another to hold a length of protein in a certain shape or conformation. Charged amino acid side chains can form ionic bonds, and polar amino acids are capable of forming hydrogen bonds. Fats and oils from fatty acids and glycerol - Fatty acids: Fatty acids are the building blocks of the fat in our bodies and in the food we eat. During digestion, the body breaks down fats into fatty acids, which can then be absorbed into the blood. Fatty acid molecules are usually joined together in groups of three, forming a molecule called a triglyceride. Triglycerides are tri-esters consisting of a glycerol bound to three fatty acid molecules. Triglycerides are the main constituents of vegetable fat and body fat in humans and other animals. Molecules that are long chains of lipid-carboxylic acid found in fats and oils and in cell membranes as a component of phospholipids and glycolipids. (Carboxylic acid is an organic acid containing the functional group -COOH.) Fatty acids come from animal and vegetable fats and oils. Generally, a fatty acid consists of a straight chain of an even number of carbon atoms, with hydrogen atoms along the length of the chain and at one end of the chain and a carboxyl group (―COOH) at the other end. It is that carboxyl group that makes it an acid (carboxylic acid).fatty acid. a compound consisting of a chain of carbon atoms with an acid group at one end. Fatty acids are lipid monomers that consist of a hydrocarbon chain with a carboxyl group attached at the end. Fatty acids form complex polymers such as triglycerides, phospholipids, and waxes. Steroids are not considered true lipid polymers because their molecules do not form a fatty acid chain. Lipids - polymers called diglycerides, triglycerides; monomers are glycerol and fatty acids. In a fat molecule, the fatty acids are attached to each of the three carbons of the glycerol molecule with an ester bond through the oxygen atom. During the ester bond formation, three molecules are released. Since fats consist of three fatty acids and a glycerol, they are also called triacylglycerols or triglycerides. - Glycerol: glycerol. Three-carbon compound with three hydroxyl groups; component of fats and oils., Combines with fatty acids to make lipids. Glycerol is a small organic molecule with three hydroxyl (OH) groups, while a fatty acid consists of a long hydrocarbon chain attached to a carboxyl group. In a fat molecule, the fatty acids are attached to each of the three carbons of the glycerol molecule with an ester bond through the oxygen atom. During the ester bond formation, three molecules are released. Since fats consist of three fatty acids and a glycerol, they are also called triacylglycerols or triglycerides. - Fats: A fat molecule consists of two kinds of parts: a glycerol backbone and three fatty acid tails. Glycerol is a small organic molecule with three hydroxyl (OH) groups, while a fatty acid consists of a long hydrocarbon chain attached to a carboxyl group. Fats and oils are organic compounds that, like carbohydrates, are composed of the elements carbon (C), hydrogen (H), and oxygen (O), arranged to form molecules. Triglycerides, cholesterol and other essential fatty acids—the scientific term for fats the body can't make on its own—store energy, insulate us and protect our vital organs. They act as messengers, helping proteins do their jobs. Since fats consist of three fatty acids and a glycerol, they are also called triacylglycerols or triglycerides. Triacylglycerols: Triacylglycerol is formed by the joining of three fatty acids to a glycerol backbone in a dehydration reaction. Three molecules of water are released in the process. A fat molecule consists of two main components: glycerol and fatty acids. Glycerol is an alcohol with three carbons, five hydrogens, and three hydroxyl (OH) groups. Fatty acids have a long chain of hydrocarbons with a carboxyl group attached and may have 4-36 carbons; however, most of them have 12-18. A fat (or oil) is formed when three fatty acid molecules react with a glycerol molecule to yield a triglyceride (and three water molecules). (See Figure 1.) Fats in the body are transported and stored as triglycerides. Fat is a source of essential fatty acids, which the body cannot make itself. Fat helps the body absorb vitamin A, vitamin D and vitamin E. These vitamins are fat-soluble, which means they can only be absorbed with the help of fats. - Oils: Fats and oils are composed of molecules known as triglycerides, which are esters composed of three fatty acid units linked to glycerol. An increase in the percentage of shorter-chain fatty acids and/or unsaturated fatty acids lowers the melting point of a fat or oil. At room temperature oils are liquid and fats are solid but they have the same basic chemical structures. They are long chain molecules (esters) made up of two sections, a glycerol part joined to a fatty acid part. Fat and oil molecules may be saturated or unsaturated. A triglyceride that is liquid at room temperature. Compare: fat. A slippery or viscous liquid or liquefiable substance not miscible with water. Any of a group of liquid edible fats that are obtained from plants. Fats and oils are esters of glycerol and three fatty acids. They are important in the diet as energy sources and as sources of essential fatty acids and fat-soluble vitamins, which tend to associate with fats. Oils and fats supply calories and essential fats and help your body absorb fat-soluble vitamins such as A, D, E and K. The type of fat is just as important for health as the total amount of fat consumed. That's why it's important to choose healthier unsaturated fats.

Investigate and describe the effects of changes in temperature and pH on enzyme activity

The activation energy is the energy required to start a reaction. Enzymes are proteins that bind to a molecule, or substrate, to modify it and lower the energy required to make it react. As the temperature increases, the molecules move faster and therefore collide more frequently. The molecules also carry more kinetic energy. Thus, the proportion of collisions that can overcome the activation energy for the reaction increases with temperature. pH: Each enzyme has an optimum pH range. Changing the pH outside of this range will slow enzyme activity. Extreme pH values can cause enzymes to denature. Enzyme concentration: Increasing enzyme concentration will speed up the reaction, as long as there is substrate available to bind to. The pH an enzyme works best at is its 'optimum pH'. Most enzymes in our body have an optimum pH of 7, and an optimum temperature of 37oC, because those are the conditions in most parts of our body, and our enzymes are well adapted to function inside us. One exception is pepsin. This enzyme is present in our stomach, and functions best in our stomach's acidic (HCl) conditions - pH2. The general rule goes: the lower the temperature (when lower than optimum temperature), the slower the enzyme works; the higher the temperature (when higher than optimum temperature), the less the enzyme works. The lower the pH (when lower than optimum), the less the enzyme functions; the higher the pH (when higher than optimum), the less the enzyme works. Each enzyme works within quite a small pH range. There is a pH at which its activity is greatest (the optimal pH). This is because changes in pH can make and break intra- and intermolecular bonds, changing the shape of the enzyme and, therefore, its effectiveness. Temperature: As the temperature increases so does the rate of enzyme activity. An optimum activity is reached at the enzyme's optimum temperature. A continued increase in temperature results in a sharp decrease in activity as the enzyme's active site changes shape. It is now denatured. An increase in temperature beyond the optimum causes the enzyme's active site to become denatured . This means the active site loses its important shape and can no longer form enzyme-substrate complexes, leading to a decrease in enzyme activity. pH: Changing the pH will affect the charges on the amino acid molecules. Amino acids that attracted each other may no longer be. Again, the shape of the enzyme, along with its active site, will change. Extremes of pH also denature enzymes. Enzymes are also sensitive to pH . Changing the pH of its surroundings will also change the shape of the active site of an enzyme. Many amino acids in an enzyme molecule carry a charge DENATURING: PH Enzymes are also sensitive to pH. Changing the pH of its surroundings will also change the shape of the active site of an enzyme. Many amino acids in an enzyme molecule carry a charge. Within the enzyme molecule, positively and negatively charged amino acids will attract. This contributes to the folding of the enzyme molecule, its shape, and the shape of the active site. Changing the pH will affect the charges on the amino acid molecules. Amino acids that attracted each other may no longer be. Again, the shape of the enzyme, along with its active site, will change. Extremes of pH also denature enzymes. The changes are usually, though not always, permanent. Enzymes work inside and outside cells, for instance in the digestive system where cell pH is kept at 7.0pH to 7.4pH. Cellular enzymes will work best within this pH range. Different parts of the digestive system produce different enzymes. These have different optimum pHs. The optimum pH in the stomach is produced by the secretion of hydrochloric acid. The optimum pH in the duodenum is produced by the secretion of sodium hydrogencarbonate. TEMPERATURE: At low temperatures, the number of successful collisions between the enzyme and substrate is reduced because their molecular movement decreases. The reaction is slow. The human body is maintained at 37°C as this is the temperature at which the enzymes in our body work best. This not true of the enzymes in all organisms. How temperature affects enzyme action Higher temperatures disrupt the shape of the active site, which will reduce its activity, or prevent it from working. The enzyme will have been denatured. Enzymes therefore work best at a particular temperature. Proteins are chains of amino acids joined end to end. This chain is not straight - it twists and folds as different amino acids in the chain are attracted to, or repel each other. Each enzyme is comprised of proteins made of these twisting and folding amino acids, and therefore the enzyme has a unique shape. This structure is held together by weak forces between the amino acid molecules in the chain. High temperatures will break these forces. The enzyme, including its active site, will change shape and the substrate no longer fit. The rate of reaction will be affected, or the reaction will stop.

Explain the functions of hydrochloric acid in gastric juicee, imited to low pH Denaturing enzymes in harmal microorganisms in food Giving the optimum pH for protease activity

The hydrochloric acid in the gastric juice breaks down the food and the digestive enzymes split up the proteins. The acidic gastric juice also kills bacteria. The mucus covers the stomach wall with a protective coating. The low pH of the stomach acid denatures (changes the structure of) the proteins in the bacteria, causing them to die.

State the causes of dental decay in terms of coating of bacteria and food on teeth, the bacteria respiring sugars in the food, producing acid which dissolves the nemal and detine.

Tooth decay happens when the hard outer enamel of the tooth is damaged. This can happen when bacteria in the mouth convert sugars into acids that react with the enamel. Bacteria can then enter the softer dentine inside. Tooth decay can be prevented by: avoiding foods with a high sugar content using toothpaste and drinking water containing fluoride regular, effective brushing to prevent the build-up of plaque (a sticky layer on the teeth) Fluoride compounds may be added to toothpaste and public water supplies. Fluoride reduces tooth decay by: reducing the ability of bacteria on plaque to produce acid helping to replace calcium ions and phosphate ions lost by tooth enamel because of acid attack However, there are arguments against fluoridation of drinking water. For example: some people say that they should not be forced to consume fluoride excessive fluoride can cause grey or brown spots on teeth Tooth decay happens when the hard outer enamel of the tooth is damaged. This can happen when bacteria in the mouth convert sugars into acids that react with the enamel. Bacteria can then enter the softer dentine inside. Cavities, also called tooth decay or caries, are caused by a combination of factors, including bacteria in your mouth, frequent snacking, sipping sugary drinks and not cleaning your teeth well. When large amounts of bacteria reside in the same area, this results in multiple acid attacks on the teeth. This acid will eventually erode the tooth enamel and cause a dental cavity. Sugars are bacteria's most preferred food choice and the bacteria in your mouth feed predominantly on sugars from food and beverages. The cause of cavities is acid from bacteria dissolving the hard tissues of the teeth(enamel, dentin and cementum). The acid is produced by the bacteria when they break down food debris or sugar on the tooth surface. The acid is produced by bacteria that are found within the plaque - a sticky and thin film that repeatedly forms over the teeth. When sugar is consumed it interacts with the bacteria within the plaque to produce acid The main cause of tooth decay is sugar. If we do not keep our teeth clean, plaque (a sticky film of bacteria) will start to build up on them. Then, whenever we consume sugary food or drink, the bacteria in the plaque use the sugar as food for cellular respiration. The bacteria release acid as a waste product, and this acid begins to dissolve the calcium salts in tooth enamel. Once the hard enamel has been dissolved, the much softer dentine and pulp will be exposed to the acid and a painful cavity can form. Enamel is the outer white layer of the tooth - the part we can see. It is the hardest part of the tooth and the hardest substance in the body. It is a calcium phosphate mineral. The calcium we absorb from our diet is assimilated into our teeth as well as our bones. Dentine is a hard bone-like substance, but it is softer than enamel. Most of the tooth is made from dentine, which surrounds and connects to the pulp. The pulp forms the centre of the tooth and contains blood vessels and nerves. There are nerves attached to the teeth, through holes in the bottom of each tooth. These nerves let us know how hard we are biting and allow us to tell if things are hot or cold. Cementum attaches the teeth to the jawbone and the gums form a layer around the teeth helping to keep the teeth in place. plaque and tar tar are formed

Explain ezymes action with reference to the complementary shape of the active site of an enzyme and its substrate and the formation of a product.

When an enzyme binds its substrate, it forms an enzyme-substrate complex. This complex lowers the activation energy of the reaction and promotes its rapid progression by providing certain ions or chemical groups that actually form covalent bonds with molecules as a necessary step of the reaction process. A substrate enters the active site of the enzyme. This forms the enzyme-substrate complex. The reaction then occurs, converting the substrate into products and forming an enzyme products complex. The products then leave the active site of the enzyme. The active site of an enzyme is the region where a substrate binds with the enzyme before it undergoes a chemical reaction. This region converts substrates into products at a lower reaction rate. More importantly, it is a region that is consists of three to four amino acids where a chemical reaction can take place. A substrate binds to an enzyme at the active site, which has a complementary shape, and the substrate is converted to product. Each different type of enzyme will usually act on only one substrate to catalyse one biological reaction. Enzymes are specific because different enzymes have differently shaped active sites. The shape of the active site of an enzyme is complementary to the shape of its specific substrate . A substrate enters the active site of the enzyme. This forms the enzyme-substrate complex. The reaction then occurs, converting the substrate into products and forming an enzyme products complex. The products then leave the active site of the enzyme. An enzyme attracts substrates to its active site, catalyzes the chemical reaction by which products are formed, and then allows the products to dissociate (separate from the enzyme surface). The combination formed by an enzyme and its substrates is called the enzyme-substrate complex. The forces that attract the substrate to the surface of an enzyme may be of a physical or a chemical nature. Electrostatic bonds may occur between oppositely charged groups—the circles containing plus and minus signs on the enzyme are attracted to their opposites in the substrate molecule. When the substrate fits into the active site of the enzyme, the enzyme catalyses a reaction that breaks the substrate down into the product. The product is then released from the active site and the enzyme remains unchanged, so can catalyse another reaction. The positions, sequences, structures, and properties of these residues create a very specific chemical environment within the active site. A specific chemical substrate matches this site like a jigsaw puzzle piece and makes the enzyme specific to its substrate. An enzyme attracts substrates to its active site, catalyzes the chemical reaction by which products are formed, and then allows the products to dissociate (separate from the enzyme surface). Usually, an enzyme molecule has only two active sites, and the active sites fit with one specific type of substrate. An active site contains a binding site that binds the substrate and orients it for catalysis. A substrate enters the active site of the enzyme. This forms the enzyme-substrate complex. The reaction then occurs, converting the substrate into products and forming an enzyme products complex. The products then leave the active site of the enzyme. An enzyme works on the substrate , forming products. An enzyme's active site and its substrate are complementary in shape. An enzyme will only work on one substrate - it is substrate specific. Enzymes and substrates collide to form enzyme-substrate complexes. The shape of an enzyme's active site is complementary to the shape of its specific substrate or substrates. This means they can fit together. The shape of an enzyme is very important because it has a direct effect on how it catalyzes a reaction. An enzyme's shape is determined by the sequence of amino acids in its structure, and the bonds which form between the atoms of those molecules. The shape of the enzyme determines which chemical reaction it will speed up. ... -May strain the bonds of the substrate or put chemical groups of the active site in the correct position to speed up the reaction. An enzyme attracts substrates to its active site, catalyzes the chemical reaction by which products are formed, and then allows the products to dissociate (separate from the enzyme surface). The combination formed by an enzyme and its substrates is called the enzyme-substrate complex. The part of the enzyme into which the substrate binds and undergoes reaction is the active site. These sites are small pockets on the tertiary structure where ligands bind to it using weak forces. The substrate simply fits into the active site to form a reaction intermediate. In this model the enzyme molecule changes shape as the substrate molecules gets close. The change in shape is 'induced' by the approaching substrate molecule. In a reaction, you generally have two types of chemicals: the reactants and the products. The reactants react together to form the products. In an enzymatic reaction (i.e. a reaction catalysed by an enzyme), the reactants are known as 'substrates'. Enzymes work on substrates to form products. Enzymes have an 'active site' - this is the part of the enzyme that binds to the substrate. Every enzyme's active site is 'specific'. This means that one particular active site can only bind to one type of substrate. There are a lot of theories that explain how enzymes work. One of the most important ones is the lock and key mechanism. This is the mechanism you need to learn for your syllabus: The shape of the active site is 'complementary' to its substrates - this means that the substrate(s) fits into the enzyme in the same way a key fits into a lock. This complementary nature is what makes the enzyme specific to a substrate. So, in a reaction, the substrate will be randomly moving around. As a result of this random motion, the substrate will collide with and bind to an enzyme that it is specific to. This results in the formation of an enzyme-substrate complex. The enzyme then catalyses the reaction - either breaking up a substrate (a catabolic reaction) or joining two substrates together (an anabolic reaction). It then releases the products, to make space for more substrates, so that the enzyme can catalyse more reactions. What are the substates?: reactant in a chemical reaction is called a substrate when acted upon by an enzyme. induced fit: Proposes that the initial interaction between enzyme and substrate is relatively weak, but that these weak interactions rapidly induce conformational changes in the enzyme that strengthen binding.

State what is meant by the term balanced diet for humans

A balanced diet contains the correct amount of all food groups. The food groups are: carbohydrates, lipids, proteins, vitamins, minerals, dietary fibre and water. Each food group has its own role to play within a healthy diet. Your diet needs depend on age, height, gender, muscle mass and activity level. A balanced diet is a diet that contains all the main nutrients in the correct amounts and proportions to maintain good health. A balanced diet is a diet in which all the components needed to maintain health are present in appropriate proportions. Diet is the variety of foods that are eaten over a period of time. As no single food provides all of the body's required nutrients, an individual's diet should be balanced across a variety of foods. Individual foods are not necessarily healthy or unhealthy. A balanced diet is one that fulfills all of a person's nutritional needs. Humans need a certain amount of calories and nutrients to stay healthy. A balanced diet provides all the nutrients a person requires, without going over the recommended daily calorie intake. A balanced diet is the one which contains a variety of foods in such quantities and proportions that the need for energy, amino acids, vitamins, minerals, water and roughage is adequately met for maintaining health, vitality and general well being.

Define absorption

Absorption is the movement of digested food molecules through the wall of the intestine into the blood vessel and lacteal by diffusing through the wall from a higher to a lower concentration. The small intestine is the region where digested food is absorbed. The small intestine has a large internal surface area for absorption to happen quickly and efficiently. This large surface area is due to the presence of many finger-like projections called villi. The good blood supply around the villi quickly takes away absorbed nutrients, this maintains a steep concentration gradient so that more diffusion of digested nutrients from the small intestine into the blood can occur. Absorption is the movement of digested food molecules from the digestive system into the blood (glucose and amino acids) and lymph (fatty acids and glycerol) Water is absorbed in both the small intestine and the colon, but most absorption of water also happens in the small intestine. Absorption is the movement of digested food molecules through the wall of the intestine into the blood or lymph . The small intestine is the region where digested food is absorbed. Most absorption happens in the ileum. The process of taking nutrients from the digestive system into the blood so they can be used in the body. Absorption. The simple molecules that result from chemical digestion pass through cell membranes of the lining in the small intestine into the blood or lymph capillaries. This process is called absorption. Absorption is a chemical or physical phenomenon in which the molecules, atoms and ions of the substance getting absorbed enters into the bulk phase (gas, liquid or solid) of the material in which it is taken up. Absorption is the condition in which something gets mixed or absorbed completely in another substance. Absorption is the movement of digested food molecules through the wall of the intestine into the blood or lymph. Digestion is completed in the small intestine. By now, most carbohydrates have been broken down to simple sugar, proteins to amino acids, and fats to fatty acids and glycerol. Absorption occurs when the small intestine breaks down nutrients that are then absorbed into your bloodstream and carried to cells through your body. Digestion is important for breaking down food into nutrients, which the body uses for energy, growth, and cell repair.

State the function of amylase & carbohydrase, protease, lipase

Amylase: Secreted: From salivary glands into the mouth and from the pancreas into the duodenum. Enzymes can break down nutrients into small, soluble molecules that can be absorbed. For example, amylase causes the breakdown of starch into simple sugars. Amylases' main function is to hydrolyze the glycosidic bonds in starch molecules, converting complex carbohydrates to simple sugars. There are three main classes of amylase enzymes; Alpha-, beta- and gamma-amylase, and each act on different parts of the carbohydrate molecule. The amylase enzyme helps to break down starch into sugars. This enzyme is made in the salivary glands, pancreas and small intestine, and works in the mouth and small intestine In addition to the pancreas, amylase is also released in saliva in the mouth and is known as salivary amylase. Amylase is responsible for the breaking of the bonds in starches, polysaccharides, and complex carbohydrates into easier to absorb simple sugars. Acts on the starch in food, breaking it down into smaller carbohydrates. Pancreatic amylase completes this digestion, by breaking down these smaller carbohydrates to their simplest form: glucose. Substrate - starch and carbohydrates (polysaccharides). End product - glucose Carbohydrase: any of a group of enzymes (such as amylase) that promote hydrolysis or synthesis of a carbohydrate (such as a disaccharide) Carbohydrases. Carbohydrases break down carbohydrates in several regions of the digestive system. Most of the carbohydrate we eat is starch, so this will be the main substrate in the early part of digestion for enzyme action. Protease: Secreted: The stomach and the pancreas proteolytic enzyme, also called protease, proteinase, or peptidase, any of a group of enzymes that break the long chainlike molecules of proteins into shorter fragments (peptides) and eventually into their components, amino acids. Protease enzymes are responsible for breaking down proteins in our food into amino acids. Then different enzymes join amino acids together to form new proteins needed by the body for growth and repair. Protease enzymes are produced in your stomach, pancreas and small intestine. Function: Protease breaks down proteins. The break down the peptide bonds in protein foods to liberate the amino acids needed by the body. Example of a protease is pepsin, which is found in the stomach. Proteases are a powerful tool for modifying the properties of food proteins and producing bioactive peptides from proteins. They are widely used in the production of value-added food ingredients and food processing for improving the functional, nutritional and flavor properties of proteins. Protease: A general term for any enzyme that breaks down protein molecules into their monomers - amino acids. Substrate - proteins (or polypeptides). End product - Lipase: Secreted: The pancreas. In the digestive system there are enzymes called lipases that can catalyse the digestion of lipids into fatty acids and glycerol. Most digestion of lipids happens in the duodenum. The pancreas produces a lipase enzyme that mixes with the food in the duodenum. Lipase is an enzyme the body uses to break down fats in food so they can be absorbed in the intestines. Lipase is produced in the pancreas, mouth, and stomach. Lipase enzyme breaks down dietary fats into smaller molecules known as glycerol and fatty acids. A little quantity of lipase, known as gastric lipase is produced by the cells of the stomach. This enzyme mainly digests fat present in the food. lipase, any of a group of fat-splitting enzymes found in the blood, gastric juices, pancreatic secretions, intestinal juices, and adipose tissues. Lipases hydrolyze triglycerides (fats) into their component fatty acid and glycerol molecules. Lipase: A general term for any enzyme that breaks down fat molecules (usually triglycerides) into glycerol and fatty acids. Substrate - fats (triglycerides). End product - glycerol and fatty acids.

Define assimilation

Assimilation - the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells. Assimilation is the process through which an organism absorbs nutrients from outside its body before assimilation the complex form of food is converted into the simpler one, so that it can easily be absorbed by the cells. Assimilation is the process of absorption of vitamins, minerals, and other chemicals from food as part of the nutrition of an organism. The process of utilization of digested food; for energy and for growth and repair is called assimilation. Assimilation. It is the process of synthesizing simple macromolecules absorbed from the digested food molecules. The conversion of nutriment into the fluid or solid substance of the body, by the processes of digestion and absorption is called assimilation

Outline the role of bile in emulsifying fats to increase the surface area for chemical digestion of fat to fatty acids and glycerol by lipase.

Bile is a fluid that is made and released by the liver and stored in the gallbladder. Bile helps with digestion. It breaks down fats into fatty acids, which can be taken into the body by the digestive tract. Bile contains: Mostly cholesterol. The bile released into the duodenum contains bile pigments (bilirubin and biliverdin), bile salts, cholesterol and phospholipids but no enzymes. Bile salts helps in emulsification of fats, i.e., breaking down of the large fat droplets into very small micelles. Bile also activates lipase enzymes, which digests fats. Bile salts act as an emulsifier because they have a hydrophilic (water loving) head that is attracted to water molecules and a hydrophobic (water hating) tail that is attracted to lipid molecules. When bile enters the small intestine, it will mix with the fat globules and will cause them to break down into smaller units called emulsion droplets. This process is called emulsification. Emulsification greatly increases the surface area of the fat on which the lipase can actually act on. Fats are digested by lipases that hydrolyze the glycerol fatty acid bonds. Bile salts emulsify the fats to allow for their solution as micelles in the chyme and to increase the surface area for the pancreatic lipases to operate. When digesting fats, bile acts as an emulsifier to break the large fat globules into smaller emulsion droplets. Emulsified fats provide a larger area for the fat-digesting enzymes (lipase) to act, making the process quicker. The role of bile in fat digestion is to: Emulsify fat in the small intestine When digesting fats, bile acts as an emulsifier to break the large fat globules into smaller emulsion droplets. The use of this is that it gives the fat a much larger surface area on which the lipase enzymes (fat digesting) can act on, which in turn makes it a much quicker and efficient process.

Outline the role of bile in neutralising the acidic mixture of food and gastric juices entering the duodenum from the stomach, to provide a suitable pH for enzyme action.

Bile is secreted into the small intestine where it has two effects: it neutralises the acid - providing the alkaline conditions needed in the small intestine. it emulsifies fats - providing a larger surface area over which the lipase enzymes can work. Bile is the greenish-yellow fluid (consisting of waste products, cholesterol, and bile salts) that is secreted by the liver cells to perform 2 primary functions: To carry away waste. To break down fats during digestion. Bile is an alkaline substance produced by cells in the liver. Before being released into the small intestine bile is stored in the gallbladder. Bile contains bile acids, which are critical for digestion and absorption of fats and fat-soluble vitamins in the small intestine. Bile is made in the liver and stored in the gall bladder. Bile emulsifies fatty acids and lipids, breaking large chains into smaller droplets. This increases the surface area for enzymes (lipase) to act on, therefore increasing the rate of digestion/the breakdown of fats.

Define digestion

Digestion is the process by which food is broken down to be absorbed into the blood stream and distributed around the body. The process is started by saliva in the mouth breaking down carbohydrates. In the stomach, enzymes and acid in digestive juices break down proteins, sugars and fats. Digestion is the breakdown of carbohydrates, proteins and fats into small soluble substances to be absorbed into the blood. Digestion begins in the mouth, when we chew and swallow, and is completed in the small intestine. Digestion is defined as the process of breaking down large, insoluble molecules of food into smaller, water-soluble molecules which can then be readily absorbed by the body. The human body uses the process of digestion to break down food into a form that can be absorbed and used for fuel. The organs of the digestive system are the mouth, esophagus, stomach, pancreas, liver, Bile duct, gallbladder, small intestine (illeum and duodenum), large intestine and anus. There are two types of digestion: Mechanical digestion — food is physically broken into smaller parts. Chemical digestion — food is broken down by acids and enzymes into its basic units. It occurs from mouth to the intestine. Mechanical digestion facilitates the chemical digestion while chemical digestion facilitates the absorption of nutrients. Mechanical digestion must start before chemical digestionbecause the food must be in much smaller particles for the chemicals to break them down. Amylase, proteases and lipases are enzymes that are important in digestion. Biology (Single Science) Nutrition, digestion and excretion. digestion, sequence by which food is broken down and chemically converted so that it can be absorbed by the cells of an organism and used to maintain vital bodily functions. Chemical digestion is a vital part of the digestive process. Without it, your body wouldn't be able to absorb nutrients from the foods you eat. While mechanical digestion involves physical movements, such as chewing and muscle contractions, chemical digestion uses enzymes to break down food. Digestion is the process by which food is broken down to be absorbed into the blood stream and distributed around the body. The process is started by saliva in the mouth breaking down carbohydrates. In the stomach, enzymes and acid in digestive juices break down proteins, sugars and fats. The human digestive system has two functions: breaks down complex food substances. provides the very large surface area for maximum absorption of food.

Define chemical digestion

Digestion mainly takes place chemically, where bonds holding the large molecules together are broken to make smaller and smaller molecules. Chemical digestion is controlled by enzymes which are produced in different areas of the digestive system. In chemical digestion, food is broken down by the action of chemical agents (such as enzymes, acids and bile) Involves breaking down large, insoluble molecules into small, soluble ones. Digestion mainly takes place chemically, where bonds holding the large molecules together are broken to make smaller and smaller molecules. Chemical digestion is controlled by enzymes which are produced in different areas of the digestive system. Chemical digestion involves the secretions of enzymes throughout your digestive tract. These enzymes break the chemical bonds that hold food particles together. This allows food to be broken down into small, digestible parts. In chemical digestion, food is broken down by the action of chemical agents (such as enzymes, acids and bile). Chemical digestion is the chemical breakdown of food into small chemical substances. It occurs from mouth to the intestine. It needs to be changed into small, soluble molecules. Mechanical digestion is the physical process of preparing the food for chemical digestion. It involves chewing (in the mouth), mixing, churning (in the stomach and intestine) and segmentation (in the intestine). The small intestine is the site of most chemical digestion and almost all absorption. Chemical digestion breaks large food molecules down into their chemical building blocks, which can then be absorbed through the intestinal wall and into the general circulation. Chemical digestion involves the secretions of enzymes throughout your digestive tract.These enzymes break the chemical bonds that hold food particles together. This allows food to be broken down into small, digestible parts.

Define egestion

Egestion - the removal of undigested food materials. On reaching the end of the small intestine, all the digested food products, along with the minerals and vitamins that are useful to the body, should have been removed from the watery contents. the process of removing undigested waste material from the body by excretion. Egestion happens when these faeces pass out of the body through the anus. Egestion is the act of excreting unusable or undigested material from a cell, as in the case of single-celled organisms, or from the digestive tract of multicellular animals. Egestion is the discharge or expulsion of undigested material (food) from a cell in case of unicellular organisms, and from the digestive tract via the anus in case of multicellular organisms. the act or process of discharging undigested or waste material from a cell or organism specifically : defecation. Excretion. The process involves removing undigested waste products food from the body of the organism. The process by which undigested is eliminated from the body is called egestion. Egestion: Removal of throwing out of the undigested food from the body is called egestion.

Define ingestion

Food enters the digestive system through the mouth. This process is called ingestion. Once in the mouth, the food is chewed to form a ball of food called a bolus. This passes down the oesophagus and into the stomach. The large pieces of food that are ingested have to be broken into smaller particles that can be acted upon by various enzymes. This is mechanical digestion, which begins in the mouth with chewing or mastication and continues with churning and mixing actions in the stomach. substances that enters the digestive system through the mouth. This process is called ingestion. Once in the mouth, the substances undergoes mechanical digestion which is the physical break down of substances. This passes down the oesophagus and into the stomach . Ingestion - the taking of substances nto the body through the mouth. The large pieces of food that are ingested have to be broken into smaller particles that can be acted upon by various enzymes. This is mechanical digestion, which begins in the mouth with chewing or mastication and continues with churning and mixing actions in the stomach. Mechanical digestion - the breakdown of food into smaller pieces without chemical change to the food molecules. Chemical digestion - the breakdown of large, insoluble molecules into small, soluble molecules. Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms ingestion takes place by absorbing a substance through the cell membrane. Ingestion: The process of taking in the food is called ingestion. Digestion: The process of breaking complex food substances into simple molecules is called digestion. Ingestion is the process of taking in food through the mouth. In vertebrates, the teeth, saliva, and tongue play important roles in mastication (preparing the food into bolus). While the food is being mechanically broken down, the enzymes in saliva begin to chemically process the food as well. Food is taken into the mouth where it is physically broken down by the teeth into smaller pieces.

State the functions of the HCl acid in gastric juice, limited to killing bacteria in food and giving and acid pH of enzymes.

Hydrochloric acid is a strong acid secreted by the parietal cells, and it lowers your stomach's pH to around 2. Hydrochloric acid converts pepsinogen into pepsin and breaks various nutrients apart from the food you eat. It also kills bacteria. It acts on pepsinogen and activates it to pepsin so that it can act on food bolus entering the stomach and convert proteins to smaller peptides. 2) It is an acid so it kills germs and bacteria entering our body system through food. Gastric acid activates pepsinogen into the enzyme pepsin, which then helps digestion by breaking the bonds linking amino acids, a process known as proteolysis. In addition, many microorganisms have their growth inhibited by such an acidic environment, which is helpful to prevent infection. The hydrochloric acid in the gastric juice breaks down the food and the digestive enzymes split up the proteins. The acidic gastric juice also kills bacteria. Hydrochloric acid (HCl) is a powerful acid made in the stomach. It has several important functions, including killing microorganisms, activating enzymes (including the protein-digesting enzyme pepsin), enhancing the absorption of minerals, and breaking down the connective tissue in meat. The hydrochloric acid in the gastric juice breaks down the food and the digestive enzymes split up the proteins. The acidic gastric juice also kills bacteria. The mucus covers the stomach wall with a protective coating. Many bacterial pathogens, such as Escherichia coli, Salmonella Typhimurium, and H. pylori, can circumvent the acid conditions of the stomach by developing adaptive mechanisms that allow these bacteria to survive in acid environments. Glands in the lining of the stomach release gastric juice. You have already learnt that gastric juice contains a strong acid, which kills the bacteria on or in our food. The low pH of the stomach acid denatures (changes the structure of) the proteins in the bacteria, causing them to die. Gastric juice also contains a particular protease enzyme called pepsin. Pepsin catalyses the breakdown of proteins into smaller molecules called peptides. Later, these peptides are broken down into amino acids. Pepsin works fastest in a low pH environment. This is why stomach acid is released. As well as killing bacteria, the acid lowers the pH in the stomach to suit the enzymes in gastric juice. Note, however, that some other proteases work best in the alkaline environment of the small intestine. This is covered in the text that follows.

Define mechanical digestion

Mechanical digestion is the physical process of preparing the food for chemical digestion. It involves chewing (in the mouth), mixing, churning (in the stomach and intestine) and segmentation (in the intestine). Mechanical digestion is the breakdown of food into smaller pieces without chemical change to the food molecules. Mechanical digestion is the physical act of breaking down the food by non-chemical means. Mechanical digestion begins in the mouth by the physical act of mastication (chewing). The specialized teeth break down the food as it is cut by the incisors, torn by the cuspids and ground by the molars. It is mainly carried out by the chewing action of the teeth, the churning action of the stomach and the emulsification of fats by bile in the duodenum. Mechanical digestion involves physically breaking down food substances into smaller particles to more efficiently undergo chemical digestion. The role of chemical digestion is to further degrade the molecular structure of the ingested compounds by digestive enzymes into a form that is absorbable into the bloodstream. Teeth break down food in the mouth mechanically, this means they grind it up. Chemical digestion occurs when enzymes digest food into nutrients. Bile is produced by your liver and stored in the gall bladder. Mechanical digestion begins in your mouth with chewing, then moves to churning in the stomach and segmentation in the small intestine. Peristalsis is also part of mechanical digestion. Transpiration is defined as the loss of water vapour from plant leaves by evaporation of water at the surfaces of the mesophyll cells followed by diffusion of water vapour through the stomata. Mechanochemistry is the interplay between mechanical and chemical energies. It applies mechanical energy - in the form of rubbing, grinding or milling, for example - to bring about chemical reactions. Mechanical Digestion. the breaking down of food physically through chewing and churning, making digestion easier. Mechanical digestion is a purely physical process that does not change the chemical nature of the food. Instead, it makes the food smaller to increase both surface area and mobility. It includes mastication, or chewing, as well as tongue movements that help break food into smaller bits and mix food with saliva. Mechanical digestion of food in which the food gets broken down into smaller chunks, increases the surface area for the action of enzymes and thus facilitate the chemical digestion which involves breaking down the food into simpler nutrients(so that they can be absorbed) by help of enzymes. The rate of digestion increases as the surface area increases. The explanation for this is that the mechanism that accelerates and supports the number of enzymes in digestion. And this is one of the enzyme individuals that function more effectively on larger surfaces. Mechanical digestion is a purely physical process that does not change the chemical nature of the food. Instead, it makes the food smaller to increase both surface area and mobility. It includes mastication, or chewing, as well as tongue movements that help break food into smaller bits and mix food with saliva. Mechanical digestion of food in which the food gets broken down into smaller chunks, increases the surface area for the action of enzymes and thus facilitate the chemical digestion which involves breaking down the food into simpler nutrients(so that they can be absorbed) by help of enzymes.

State the significance of chemical digestion in the alimentary canal in producing small soluble molecules that can be absorbed.

State the significance of chemical digestion in the alimentary canal in producing small soluble molecules that can be absorbed. Chemical digestion is the breakdown of larger nutrient molecules into small soluble molecules, usually with the aid of enzymes. It's only possible to absorb the small water soluble molecules, as only these molecules are able to diffuse into the blood and lymph, across the gut wall. Chemical digestion is a vital part of the digestive process. Without it, your body wouldn't be able to absorb nutrients from the foods you eat. While mechanical digestion involves physical movements, such as chewing and muscle contractions, chemical digestion uses enzymes to break down food. Chemical digestion breaks large food molecules down into their chemical building blocks, which can then be absorbed through the intestinal wall and into the general circulation.

Descibe the structure of a villus

Villi are specialized for absorption in the small intestine as they have a thin wall, one cell thick, which enables a shorter diffusion path. They have a large surface area so there will be more efficient absorption of fatty acids and glycerol into the blood stream. The villi are small, finger-like projections about a millimeter in length that protrude from the circular folds. They cover the entire surface of the folds. The villi are separated by small crypts, which are small pockets where the cells grow and divide rapidly. The villi in the small intestine provide a large surface area with an extensive network of blood capillaries. This makes the villi well adapted to absorb the products of digestion by diffusion and active transport. Each villus is covered in many microscopic microvilli. The villi. The villi (one is called a villus) are tiny, finger-shaped structures that increase the surface area. They have several important features: wall just one cell thick - ensures that there is only a short distance for absorption to happen by diffusion and active transport. Thin cell wall (micro-villis)/epitheial cells: Microvilli on the surface of epithelial cells such as those lining the intestine increase the cell's surface area and thus facilitate the absorption of ingested food and water molecules. cilia hair Blood capillaries The blood capillaries absorb most nutrients, but the fats and fat-soluble vitamins are absorbed by the lacteals. Lacteal Lacteals absorb some of the fatty acids and glycerol produced during the digestion of fats and vitamins and transport them to the lymphatic system.

Describe the roles of capillaries and lacteals in villi.

Villi that line the walls of the small intestine absorb nutrients into capillaries of the circulatory system and lacteals of the lymphatic system. Villi contain capillary beds, as well as lymphatic vessels called lacteals. Fatty acids absorbed from broken-down chyme pass into the lacteals. Each villus has a network of capillaries and fine lymphatic vessels called lacteals close to its surface. The epithelial cells of the villi transport nutrients from the lumen of the intestine into these capillaries ( amino acids and carbohydrates) and lacteals (lipids). A lacteal is a lymphatic capillary that absorbs dietary fats in the villi of the small intestine. Triglycerides are emulsified by bile and hydrolyzed by the enzyme lipase, resulting in a mixture of fatty acids, di- and monoglycerides. network of blood capillaries - transports glucose and amino acids away from the small intestine in the blood. internal structure called a lacteal - transports fatty acids and glycerol away from the small intestine in the lymph.

Explain the causes and effects of vitamin D and iron deficiencies

Vitamin D: There are two conditions that can occur as a result of a lack of vitamin D in the diet. In children a deficiency of vitamin D is called rickets - a condition affecting bone development that can lead to deformity of the skeleton. In adults, this is called osteomalacia - a very painful condition caused by the bones being weak, or 'soft'. Symptoms of vitamin D deficiency can include muscle weakness, pain, fatigue and depression. To get enough D, look to certain foods, supplements, and carefully planned sunlight. Vitamin D deficiency can lead to a loss of bone density, which can contribute to osteoporosis and fractures (broken bones). Severe vitamin D deficiency can also lead to other diseases. In children, it can cause rickets. Rickets is a rare disease that causes the bones to become soft and bend. Rickets is the softening and weakening of bones in children, usually because of an extreme and prolonged vitamin D deficiency. Rare inherited problems also can cause rickets. Vitamin D helps your child's body absorb calcium and phosphorus from food. Vitamin D deficiency symptoms include bone pain and muscle weakness and rickets (a disease where the bone tissue doesn't properly mineralize, leading to soft bones and skeletal deformities). Vitamin D deficiency is most commonly caused by a lack of exposure to sunlight. Some disorders can also cause the deficiency. The most common cause is lack of exposure to sunlight, usually when the diet is deficient in vitamin D, but certain disorders can also cause the deficiency. Vitamin D is needed to maintain healthy bones and teeth. Vitamin D deficiency leads to rickets and bone pain. Vitamin D deficiency can lead to a loss of bone density, which can contribute to osteoporosis and fractures (broken bones). Severe vitamin D deficiency can also lead to other diseases. In children, it can cause rickets. Rickets is a rare disease that causes the bones to become soft and bend. Fe: Iron deficiency anaemia is a condition where the body lacks iron in its red blood cells. This results in less oxygen being transported to cells and can cause symptoms such as tiredness and lack of energy, shortness of breath and pale skin. Without enough iron, your body can't produce enough of a substance in red blood cells that enables them to carry oxygen (hemoglobin). As a result, iron deficiency anemia may leave you tired and short of breath Iron deficiency causes anaemia. People with anaemia become tired and weak because their blood does not transport enough oxygen. This most common type of anemia is caused by a shortage of iron in your body. Your bone marrow needs iron to make hemoglobin. Without adequate iron, your body can't produce enough hemoglobin for red blood cells.

State that water is important as a solvent

Water is called the universal solvent because more substances dissolve in water than in any other chemical. This has to do with the polarity of each water molecule. water dissolves many substances because it contains extremely polar hydrogen bonds. The hydrogen side of each water (H2O) molecule carries a slight positive electric charge, while the oxygen side carries a slight negative electric charge. Because of its polarity and ability to form hydrogen bonds, water makes an excellent solvent, meaning that it can dissolve many different kinds of molecules. Water's extensive capability to dissolve a variety of molecules has earned it the designation of "universal solvent," and it is this ability that makes water such an invaluable life-sustaining force. On a biological level, water's role as a solvent helps cells transport and use substances like oxygen or nutrients. Water is commonly known as the universal solvent - although it isn't truly universal - because it is able to dissolve more substances than any other liquid. Additionally, its property as a solvent is extremely important to life as it is able to transport chemicals, minerals, and nutrients essential to life.

Explain how age, gender and activity affect the dietary needs of humans including during pregnancy and whist breastfeeding.

Your calorie needs depend on age, height, gender, muscle mass and activity level. Muscle burns more calories than fat, so people with more muscle require more calories. Because women tend to be smaller and carry less muscle mass than men, their calorie needs are generally lower. Older adults tend to consume less energy-dense sweets and fast foods, and consume more energy-dilute grains, vegetables and fruits. Daily volume of foods and beverages also declines as a function of age. Your dietary requirements depend on your age, sex and activity. - Age: The energy demand increases until we stop growing. While children are growing they need more protein per kilogram of body weight than adults do. Children have greater needs for energy, water and oxygen as they go through growth processes. Young bodies also absorb nutrients from the foods they eat more quickly than do older bodies. In addition to fueling active young bodies, good nutrition can stabilize energy, sharpen minds and smooth out moods. - Sex: Generally, males use up more energy than females. Consistently, women are reported to have higher intakes of fruit and vegetables, higher intakes of dietary fiber and lower intakes of fat. In accordance with such more healthy food choice, women usually attach greater importance to healthy eating. Your dietary requirements depend on your age, sex and activity. Generally, males use up more energy than females. Your calorie needs depend on age, height, gender, muscle mass and activity level. Muscle burns more calories than fat, so people with more muscle require more calories. Because women tend to be smaller and carry less muscle mass than men, their calorie needs are generally lower. - Age: The energy demand increases until we stop growing. While children are growing they need more protein per kilogram of body weight than adults do. - Sex: Generally, males use up more energy than females. In general, the greater a person's mass , the more energy they need. Men tend to need more energy than women, and Your calorie needs depend on age, height, gender, muscle mass and activity level. Muscle burns more calories than fat, so people with more muscle require more calories. Because women tend to be smaller and carry less muscle mass than men, their calorie needs are generally lower. Pregnancy: A woman's energy needs increase when she is pregnant. This is mainly because she is carrying extra mass. During pregnancy, your body supplies blood and oxygen to your baby, so the demand for iron goes up to keep up with the increase in blood supply. The mother still requires calcium to help maintain her bone mass and reduce her risk of osteoporosis. However requirements increase during the last three months of pregnancy as the baby's skeleton begins to develop.