Access to HE - Unit 7 Human Nutrition and Digestive System Presentation Script PDF

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Summary

You are required to deliver a presentation that explains the following areas:
• The structures and functions of the digestive system.
• The processes of mechanical and chemical digestion including the optimum conditions for the enzymes involved. You must discuss at least two specific nam...

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Presentation Script Slide One – (Title) Within this presentation I will be discussing the structures and functions of the organs which make up the digestive system; explaining the meaning of mechanical and chemical digestion and the enzymes involved. Finally, I will be discussing food groups and their sources, and how eating these foods can achieve a balanced diet. Slide Two – (The function of the digestive system) The function of the digestive system is to digest and absorb nutrients. It is mainly formed of the digestive tract, which is a series of structures and organs in which food and liquid pass through to be absorbed, distributed and digested. The digestive tract, also known as the G.I tract, also features a structure which eliminates waste through excretion. Slide Three - (The digestive tract) The G.I tract starts in the mouth and ends at the anus. Within adults it can measure up to 30 metres in length and is split into 8 compartments; the mouth, esophagus, stomach, liver, gallbladder, pancreas, small intestine and large intestine. These 8 organs all work together to co-ordinate the movement of food as it travels through the digestive system and through the digestive stages, starting with ingestion and ending with defecation (Grove, 2014). Slide Four – (The mouth) Digestion begins in the mouth whereby the mechanical breakdown of food begins through mastication. Within the oral cavity, the teeth begin to bite and tear the food, breaking large food molecules into smaller molecules. The tongue mixes food with saliva and creates a bolus, a small, rounded ball of food created just before swallowing and it enables the food to pass through the esophagus easily due to the lubrication from the saliva (Bowen, 2018). Saliva is produced within the salivary glands. It has many benefits and is an important factor when it comes to digestion. The sympathetic and parasympathetic nervous systems offer a constant supply of saliva to the mouth, even when food is not present. An enzyme called amylase is found within the secretions of the membranes which line the oral cavity and the salivary glands. Amylase helps to soften and break down food so that the digestive process can begin after swallowing. Once the bolus has been swallowed; it begins its journey into the pharynx (Bailey, 2019). Slide Five - (The pharynx and esophagus) Once the bolus has entered the pharynx, the constrictor muscles within the pharynx contract, pushing food over the epiglottis and into the esophagus, initiating peristalsis which is the contractions of muscles. The epiglottis is a small, leaf-shaped flap which prevents food from entering the trachea and the lungs, thus avoiding choking. When “food goes down the wrong way”, we have a natural reaction to cough. This is the feeling of food or liquid entering the trachea and the coughing motion forces it back up into the pharynx. The esophagus is roughly 8 inches long and connects the pharynx to the stomach. It carries masticated food through the diaphragm and passes it through the lower esophageal sphincter into the stomach. The lower esophageal sphincter closes once food passes it to ensure food does not travel back up into the esophagus (Hoffman, 2020). Slide Six - (The stomach) Once the bolus has reached the stomach, it is churned with the help of hydrochloric acid and it forms into a thick, semi-fluid mass called a chyme. The chyme is mixed with enzyme rich gastric juices in order to be further digested so it can pass through the pyloric sphincter and into the small intestine. It takes a few hours for food to be digested within the stomach and it is during

this time whereby pepsin, a stomach enzyme, breaks down most of the protein within the food (Hershey, 2016). Slide Seven - (Small intestine/gallbladder & liver) The small intestine is roughly 6 metres in length and is a long, muscular tube which is responsible for breaking down food using enzymes from the pancreas and bile from the gallbladder. It is divided into three parts; the duodenum, the jejunum and the ileum. The duodenum is the site where most of the digestion and absorption takes place and it’s this location where bile from the gallbladder and enzymes from the pancreas combine together with the chyme and the final stage of digestion begins. The liver has many functions but its main role within the digestive system is to produce bile, which helps to break down fats into fatty acids. Bile contains; cholesterol, bile salts, water, body salts and bilirubin, which is a breakdown product of red blood cells. Once produced by the liver, it is carried to the gallbladder via bile ducts where it is stored (Adams, 2018). Slide Eight - (Small intestine) The duodenum is the first section of the small intestine and is responsible for the breaking-down process. Once the chyme has passed through the duodenum, it passes through the jejunum and ileum, which are responsible for the absorption of nutrients within the bloodstream. It’s within these two sections whereby tiny villi cover the lining of the small intestinal walls. The tiny villi are covered in small projections which increase the surface area of the surrounding walls and it is this increased contact which causes efficient food absorption. The contents within the small intestine begin semi-fluid and once the nutrients have been absorbed, they leave in liquid form and travel to the large intestine or colon (Paul, 2018). Slide Nine - (Large intestine) The large intestine is the final stage of the G.I tract and its function is to absorb water and salts from the chyme and to store feces. It measures 1.5 metres in length and is made up of; the cecum, colon, rectum and anus. The colon is the longest part of the large intestine and is split into four sections; ascending colon, transverse colon, descending colon and the sigmoid colon, which connects to the rectum. Once all of the remaining nutrients have been removed, the waste is transferred to the sigmoid colon and rectum where it is stored prior to being excreted through the process of defecation which occurs within the anal canal. The anus is the final organ within the digestive tract and it is here where stools leave the body. A muscular ring called the anal sphincter keeps the anus closed until bowel movements are required (Bradford, 2016). Slide Ten - (Mechanical digestion) As the human body is unable to absorb large molecules, any food consumed must be first broken down. This occurs through both mechanical and chemical digestion. Mechanical digestion involves physical movements to break down food and it begins in the mouth with mastication and then moves to the stomach where churning of food begins. The involuntary contractions of muscles within the esophagus, stomach and intestines known as peristalsis is also a part of chemical digestion. Slide Eleven - (Chemical digestion) Without chemical digestion our bodies wouldn’t be able to absorb the nutrients we consume. It occurs within the mouth, stomach and small intestines and is a process whereby chemical agents such as enzymes, acids and bile break down different nutrients such as

proteins and carbohydrates. Whilst mastication breaks food down to a certain extent, the digestive system relies on chemical digestion to break down food particles small enough to be absorbed by cells. Chemical digestion begins in the mouth. As we begin to chew, our brains stimulate the production of saliva, which contains lipase and amylase. It’s these enzymes which begin the chemical digestive process; lipase breaks down fat whereas amylase breaks down starch into sugar. Within the stomach, digestive enzymes such as pepsin and gastric lipase are secreted to break down proteins and triglycerides further. It’s the small intestine where most of the chemical digestion takes place and it is where many of the digestive enzymes are secreted, such as lactase which digests lactose and sucrase which digests sugars (Nall, 2018). Slide Twelve - (Enzymes) Enzymes play a massive part in the digestive process. They are specialised protein molecules which create chemical reactions in the body and they work to speed up the reactions taking place within the cells to support life. There are three main types of enzymes; lipase, amylase and protease, each of which break down different nutrients. Enzymes work better under optimum conditions and; heat, disease or chemicals can seriously affect how enzymes function. The optimum temperature is that of the human body, which is 37 degrees Celsius. If the body temperature increases, the enzymes will break down and if the body temperature is too cold, the enzymes will function too slowly. The pH balance within the human body also determines how well enzymes will function. A low pH determines something is acidic and a high pH determines something is basic, also known as alkaline. Enzymes function best within a very narrow pH range which is dependent upon where the enzyme is within the body. If the pH environment surrounding an enzyme is too acidic or basic, the structure and function of the enzyme itself will change (Roland, 2019). Enzymes have an area called the active site which is where chemical reactions take place. The active sites are unique in shape and only a certain type of molecule will fit inside them. Once the reaction has occurred, the products leave the site, leaving it empty so the process can begin again. Slide Thirteen - (Pepsin) Pepsin is one of the main digestive enzymes within the body and its purpose is to break down proteins within the stomach. Once they have been broken down, they turn into smaller proteins known as polypeptides and once this has happened, they are ready for absorption by the small intestine. Glands within the stomach lining produce a protein known as pepsinogen which reacts with the hydrochloric acid within the stomach which then converts it into pepsin. Pepsin also kills bacteria and separates the vitamin B12 from the protein so it can further be used (Blue, 2018). Slide Fourteen - (Lactase) Lactase is another digestive enzyme and is commonly secreted from the lining of the small intestine and its role is to break down lactose which is a sugar found within dairy products. During the break down process, lactase breaks down lactose into smaller molecules known as glucose and galactose so they can be further digested. People with lactose intolerance suffer due to being unable to produce sufficient lactase to break down sugars. Lactase has an optimum pH balance range between 2.0 and 7.0 with 6.0 being the optimum level (Wong, 2021). Slide Fifteen - (Balanced Diet) In order for the human body to grow and work effectively, a balanced diet is essential. A balanced diet consists of a variety of nutrients and foods from 5 different food groups. It is recommended that adult women consume 2,000 calories per day and adult men consume 2,500. It is recommended to; eat 5 portions of fruit and veg per day, drink around 6 to 8 glasses of water and try to

lead an active lifestyle. Without a balanced diet, we are more prone to disease, infection and fatigue, so it is vital to encourage a balanced diet from a young age (Krans, 2020). Slide Sixteen – (5 Food groups) There are five different food groups which make up a balanced diet. The first group is fruit and vegetables and we should try to eat 5 pieces of fresh fruit or veg a day. They are a fantastic source of vitamins and minerals which support our immune system. The second food group is carbohydrates such as pasta, bread and potatoes. They supply our body with energy and make us feel fuller for longer as well as keeping our bowels moving. The third food group is protein, often found in meat, fish, and eggs. Protein keeps our muscles strong and is important for our immune system. The fourth food group is dairy, found in milk and cheese. Dairy products are a great source of protein, vitamins and minerals including calcium which is essential for healthy bones. The last food group is fats which are found within oils and spreads. Fats contain a range of vitamins such as vitamin E which is important for fighting infections. Having a balanced diet featuring foods and nutrients from each of the five food groups enable us to live healthy lives....