Human Nutrition

• Humans need different nutrients to survive, which can be obtained through a balanced diet.
• A balanced diet consists of all the food groups in the correct proportions.
• Carbohydrates provide energy for respiration in cells and examples of carbohydrates include rice, pasta, and potatoes.
• Fats are used as long-term stores of energy and a layer of fat under the skin acts as insulation.
• Cheese, fatty meats, and butter are examples of fats.
• All cells contain protein, which is a vital substance for growth and repair of tissues.
• Proteins are found in fish, meat, and eggs.
• Vitamin C maintains healthy skin and gums and a vitamin C deficiency causes a disease called scurvy where wounds don't heal and there is excessive bleeding.
• Vitamin C is found in citrus fruits like oranges and lemons.
• Vitamin D helps the body absorb calcium which is needed for strong bones and teeth and a vitamin D deficiency leads to a condition called rickets that causes weak and soft bones as well as deformities.
• Dairy products, fish oil, and eggs contain vitamin D.
• Mineral ions like calcium are also essential for human nutrition and calcium is needed for strong and healthy bones and teeth.
• Calcium also has a role in blood clotting and milk, cheese, and eggs are examples of foods rich in calcium.
• Iron which is another important mineral is needed to make hemoglobin which is present in red blood cells and helps carry oxygen around the body.
• Iron is found in red meat and some green vegetables like spinach.
• Fiber or roughage helps food to move through the stomach and intestines and is found in vegetables, fruits, and whole grains.
• Water is needed for chemical reactions to take place in cells and can be obtained from both drinks and food.
• The role of the digestive system is to break down large insoluble molecules into smaller soluble food molecules to provide the body with nutrients.
• The parts of the digestive system include the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus.
• The associated organs of the digestive system are the salivary glands, pancreas, liver, and gall bladder.
• The duodenum is the first part of the small intestine, the ilium is the second part of the small intestine, and the colon makes up the larger part of the large intestine.
• Digestion can be subdivided into physical digestion and chemical digestion.
• Bile is a greenish Brown fluid which helps in digestion, it is made by the liver and stored in the gall bladder, and it is secreted into the duodenum through the bile duct.
• Digestion is the breakdown of food into smaller pieces without changing the food molecules.
• Physical digestion occurs as the stomach walls squeeze the food to liquefy it.
• Bile is alkaline so it neutralizes the hydrochloric acid which comes from the stomach, and it breaks down large drops of fat into smaller ones, a process known as emulsification.
• The structure of a tooth includes the enamel, dentine, pulp cavity, nerves, blood vessels, cement, and it is embedded in bone and gums.
• Assimilation is the uptake and use of nutrients by cells, when the nutrients move from the circulatory system to the cells.
• Ingestion is the taking of substances, such as food and drink, into the body, also known as eating or drinking.
• Absorption is the movement of nutrients from the intestines into the blood, when the nutrients move from the digestive system into the circulatory system.
• Physical digestion takes place in the stomach as well as in the mouth.
• The lining of the stomach contains muscles which contract to physically squeeze and mix the food with the strong digestive juices that are present in the stomach.
• Physical digestion is mainly carried out by the teeth in the mouth, the stomach and the bile in the duodenum.
• The liver is where bile is produced, bile is stored in the gall bladder, and it is released through the bile duct into the duodenum, the first part of the small intestine.
• Humans have different types of teeth: incisors, canines, premolars, and molars.
• Physical digestion increases the surface area of food for the action of enzymes.
• Physical digestion is the breakdown of food into smaller pieces without changing the food molecules.
• Bile also plays an important role in physical digestion.
• Ejection is the removal of undigested food from the body as feces.