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Assignment 1 Nutrition and Digestion
Transcript of Assignment 1 Nutrition and Digestion
1. Know the concepts of nutrition
Describe nutrition, including nutritional requirements using common terminology associated with nutrition
Describe the structure and function of the digestive system
What you need to include:
Macronutrients, micronutrients, fibre, nutritional requirements and common terminology
Structure and function of the digestive system
the means by which your body take in energy and nutrients in food to sustain growth and development.
any substance derived from plants or animals containing a combination of carbohydrates, fats, proteins, vitamins, minerals fibre, water and alcohol.
nutrient required by your body in daily amounts greater than a few grams e.g. carbohydrate, fat and protein.
a person's usual eating habits and food consumption.
commonly referred to as fat tissue, is a type of connective tissue that serves as the body's most abundant energy reserve.
the building blocks of protein
Macronutrients are needed by the body in large amounts in order to function properly. These include
All three macronutrients perform a vital role within the body:
there are two types of carbohydrates simple and complex. This nutrient provides the body with readily available energy.
main role to build and repair tissue.
primary function is to provide a concentrated source of energy.
Carbohydrates form your body's most readily available source of energy and can be accessed rapidly.
Carbohydrate foods are divided up into two basic types:
Are easily digested and absorbed
Provide a quick release of energy
Three classifications, monosaccharide, disaccharides and polysaccharides
The simplest carbohydrate unit is the monosaccharide, which is commonly known as Glucose. Monosaccharides include fructose, which is commonly known as fruit sugar and found in fruits and vegetables
Two monosaccharide’s together form a disaccharide or double sugar e.g Sucrose (table sugar), Lactose (found in milk), Maltose (found in cereals)
Longer chains of simple sugars units are called polysaccharides or complex sugars. These allow large quantities of glucose to be stored as starch in the cells of plants of as glycogen in the muscles and liver of animals. Complex carbohydrates are an important source of energy since they are broken down slowly and release energy over longer periods.
After eating foods containing carbohydrate blood sugar levels rise, stimulating the release of insulin to normalise blood sugar levels and to aid the transport of glucose form the blood to the cells.
Glucose is used to produce adenosine triphosphate (ATP), the compound required for muscle contraction.
Excess carbohydrate not required to replenish glycogen stores is converted to fat and stored as adipose tissue.
Carbohydrates can only be stored as glycogen in the muscles. Day to day stores of glycogen are influenced by dietary carbohydrate intake and levels of exercise. Regular exercise can encourage your muscles to adapt to store more glycogen. This is important for endurance athletes.
Proteins are essential for maintaining optimal health and physical performance.
The smallest units of proteins are called amino acids. The body needs all 20 amino acid to repair and build tissue and to sustain optimal growth and functioning.
Different proteins contain different numbers and combinations of amino acids.
Your body is unable to make 8 and these which are called essential amino acids (EAAs). Therefore these are a necessary part of your diet.
The remaining 12 are called non-essential amino acids. Your body is able to synthesise these if all the EAAs are present.
Protein is used as a secondary source of energy if carbohydrate and fat are limited e.g. towards the end of an endurance event
One gram of protein= 4Kcals
Excess protein can not be stored so it provides immediate energy. All proteins carry out functional roles, so daily protein ingestion is required. If your protein intake exceeds requirements to support growth and repair, the excess is used converted to fat or carbohydrate and stored.
Proteins are split into two groups:
Complete= food that contains EAAs
Examples are meat, poultry, fish, eggs, milk, cheese and yoghurt. (animal sources)
Incomplete= Non-essential AAs
Examples are cereals, bread, rice, pasta, nuts and seeds. (plant sources)
Vegetarians and vegans must ensure that they eat a variety of these in careful combinations to ensure adequate intake of all EAA's; e.g. beans and wheat complement each other well
Fat is an essential nutrient, with a primary function of providing a concentrated source of energy, forming your body's largest potential energy store. In addition, fats are used to protect and cushion vital organs and act as an insulator.
Triglycerides form the basic component of fat which consists of 3 molecules with 3 fatty acids attached. When digested and absorbed fats are broken down into 2 main types saturated and unsaturated.
Fatty acids contain chains of carbon atoms to which hydrogen atoms attach. The number of carbon atoms determines whether a fatty acid is saturated or unsaturated.
Unsaturated fatty are generally liquid at room temperature. There are two types of unsaturated fat-
which is olive oil, corn oil, peanuts and peanut butter.
which is soft margarine, low-fat spread, sunflower oil, oily fish and nuts.
Saturated fats generally solid at room temperature e.g butter and ordinary margarine found in meat, eggs, cream, cakes, chocolate and dairy products.
Fat is your largest energy source and is more than twice as energy dense
than other macronutrients having 9 calories per one gram.
Vitamins and minerals are referred to as micronutrients as they are required in much smaller amounts. Despite the relatively small requirements for these nutrients, many play a vital role in regulating chemical reactions in your body.
Vitamins are vital, non-caloric nutrients required in very small amounts. They perform specific metabolic functions and prevent deficiency diseases.
Most vitamins are required to maintain health but cannot be produced by your body so they need to come from your diet or supplements. The exceptions are vitamin D which your body is able to synthesise by the action of sunlight and vitamin K which is produced by the bacteria in the large intestine are supplied by the body.
Vitamins play essential roles in regulating metabolic processes, particularly those that release energy. They also support growth, the immune and nervous system functions and some are involved in producing hormones.
Vitamins are split into two forms:
Fat-soluble vitamins are found in the fatty or oily parts of foods. Once digested they are absorbed and transported in the lymph and ultimately reach the blood. As a result of their insolubility in water, they are not excreted in the urine and can accumulate in the liver and adipose tissue.
Water-soluble vitamins (B&C) facilitate the use of energy within your body. To much of these vitamins are excreted in urine as your body has limited stores. It should be noted that vitamins are destroyed by foood processing and preparation.
Minerals are non-caloric nutrients that are essential to life, and like vitamins they are required in small or trace amounts. Minerals play an important role in nerve function and muscle contraction; other regulate fluid balance in your body. Levels of minerals are closely controlled by absorption and excretion to prevent excessive build up.
Minerals are split into two categories:
such as calcium as they are required in large amounts, sometimes as much as several hundred milligrams per day.
such as copper and selenium are required in much smaller amounts (micrograms per day)
'Athletes eat and train they don't diet and exercise'
Fibre is a complex carbohydrate which resists digestion by the stomach and small intestine and provides bulk which aids the transit of food through the digestive system.
A high fibre diet helps keep your bowel functioning efficiently and prevents and treats certain diseases e.g cancer of the colon, diabetes, heart disease and irritable bowel syndrome.
Two types of fibre:
- found in oats, rye, barley, beans, fruit and vegetables. They control blood glucose and cholesterol.
- found in whole-wheat bread, rice, pasta, wholegrain cereals, fruit and vegetables. They prevent bowel disorders.
Both are needed for a healthy diet- 18 grams per day
To support health and performance, it is recommend that around 50-60% of your total calorie intake is derived from carbohydrates.
Greater intake is required for endurance athletes e.g a marathon runner may need to get 65-70% of their total energy from carbohydrates.
On average females should eat 250g of carbohydrate and males 300g per day.
Carbohydrate requirements based on daily activity levels:
<1hr = 4-5g per kg of body weight (g)
1hr = 5-6g per kg of body weight (g)
1-2hrs = 6-7g per kg of body weight (g)
2-3hrs = 7-8g per kg of body weight (g)
Active individuals have higher protein requirements in order to promote tissue growth and repair following training.
Protein intake should represent 12-15% of your total daily energy intake.
Daily protein requirements based on type of activity:
Mainly sedentary - 0.75-1.0g of protein per kg of body weight (g)
Mainly edurance - 1.2-1.4g of protein per kg of body weight (g)
Mainly strength - 1.2-1.7g of protein per kg of body weight (g)
The recommended fat intake is 30-35% of total calorie intake
70g per day for females
90g per day for males
Only 6-10% should be from saturated fats
Athletes involved in regular intense activity should reduce their overall fat intake to around 25-30% to achieve adequate carbohydrate intake, but in absolute terms this equates to the same quantity of intake as athletes will be eating more calories to meet their increased energy requirements.
P2 Structure & function of the digestive system
Digestion can be considered a multi-stage process following the ingestion of raw materials (food you eat), It involves mechanical and chemical elements in the process that ultimately leads to enzymes in your food into smaller compounds that can be absorbed by your body.
The movement of digested food from the stomach and small intestines into the body tissues and blood. Absorption happens in the villi that line the small intestine. These finger-like projections provide a large area for absorption to take place. Each villi has a network of capillaries to quickly absorb nutrients.
This is the removal of potentially poisonous end-products from metabolism, normally in your urine and faeces. Kidneys play a huge part in excretion of urine and the large intestines eliminate solid or semi solid waste.
The kidneys are in charge of keeping the blood constant by filtering it to remove any excess water and waste products which are then secreted. Every 24hrs the kidneys filter around 150 litres of blood and produce around 1.5 litres of urine.
1. Digestion starts in the month. Your teeth and jaws crush and grind food to mix it with saliva, which contains the enzyme amylase that begins the breakdown of start.
2. You then swallow food, which enters the oesophagus, the tube that connects your mouth to your stomach. Food is squeezed along the oesophagus; it takes around 3-6seconds for food to travel from your mouth to your stomach.
3. Your stomach churns food up into a liquid called chyme. Lining your stomach are cells that produce and release gastric juices containing enzymes and hydrochloric acid, which assist in the breakdown of food.
4. From your stomach the chyme passes to your duodenum and then to your small intestine, a tube 6m long.
5. As chyme enters your small intestine, it is mixed with more digestive juices, the time from your pancreas. Pancreatic juice contains bile made by the liver as well as enzymes to further assist the breakdown of carbohydrate, protein and fat.
6. Your gall bladder, store and concentrates bile until it is required for digestion. Then it is released into your digestive tract to emulsify fats and neutralise the acids in partly digested food.
7. The small intestine continues to squeeze chyme through your digestive system to your large intestine and eventually the rectum and anal canal