Nutrition 1: Normal Physiology Flashcards
Define nutrition.
The process by which a living organism receives nutrients from its environment and uses them to promote its vital activities.
Define nutrient.
A substance which is digested and absorbed to promote bodily function.
List 6 nutrients.
Macromolecules:
1 - Proteins.
2 - Fats.
3 - Carbohydrates.
Micromolecules:
4 - Minerals.
5 - Vitamins.
Other:
6 - Water.
What is the basal metabolic rate?
The number of calories needed at rest for normal body function (50-70% calories needed / day).
What is the thermic effect of food?
The amount of energy expenditure above the basal metabolic rate due to the cost of processing food for use and storage.
What are the 3 main processes that require energy?
1 - Basal metabolic rate.
2 - Thermic effect of food.
3 - Ohysical activity.
What are the current UK daily calorie intake guidelines?
- Males: 2500kcal.
- Females: 2000kcal.
List 7 factors that may affect individual nutritional requirements.
1 - Quality and quantity of food.
2 - Efficiency of digestive system.
3 - Age.
4 - Health.
5 - Sex.
6 - Level of activity.
7 - Bad habits.
Describe the composition of a typical current western diet in terms of protein, carbohydrate and fat.
- 12% protein.
- 46% carbohydrate.
- 42% fat.
How does the composition of diet differ in developing countries as opposed to developed countries?
Developing countries have a much higher energy contribution from carbohyrates relative to fat and proteins.
What are the aceptable macronutrient distribution ranges for protein carbohydrate and fat?
- Protein: 10-15%.
- Carbohydrate: 55-75%.
- Fat: 15-30%.
How do simple carbohydrates differ from complex carbohydrates?
1 - Simple carbohydrates are made up of mono- and disaccharides, as opposed to polysaccharides (starches).
2 - Simple carbohydrates usually require refining / partial hydrolysis, whereas complex carbohydrates are used in the undigested form.
3 - Simple carbohydrates are more easily absorbed than complex carbohydrates.
4 - Simple carbohydrates release energy more quickly than complex carbohydrates.
What is the calorie density of carbohydrates?
~4kcal/g for all (both simple and complex) carbohydrates,
What are the final breakdown products of carbohydrates?
Which of these is the most abundant?
1 - Glucose (most abundant).
2 - Fructose.
3 - Galactose.
What proportion of saccharides does glucose account for in the blood?
Why?
- 95%, because:
- 80% of final product of carbohydrates are glucose.
- Most fructose and galactose are converted into glucose in the liver.
Where do glycogenesis and glycogenolysis occur?
In the liver and muscles.
What is the glycaemic index (GI)?
What are the effects of high GI and low GI foods?
- A ranking of carbohydrates on a scale of 0-100 according to the extent to which they raise blood sugar.
- High GI - Rapid digestion and absorption + marked increase in blood glucose.
- Low GI - Slow digestion and absorption + gradual raise in blood glucose.
List 5 factors that affect a food’s GI.
1 - Physical form.
2 - Fat and acid content (slows down carbohydrate digestion and absorption).
3 - Ripeness (more ripe fruits have more glucose).
4 - Fibre content (fibre makes carbohydrate difficult to break down).
5 - Type of starch.
List the types of fat found in the diet.
1 - Triglycerides.
2 - Phospholipids.
3 - Sterols (mainly cholesterol).
List 2 functions of sterols.
1 - Hormones (sexual).
2 - Involved in the formation of bile salt.
List 2 essential fatty acids.
1 - α-linolenic acid (omega-3).
2 - Linoleic acid (omega-6)
List 2 non-essential fatty acids.
1 - Palmitic acids (C16:0).
2 - Oleic acids (C18:1).
List 2 functions specific to essential fatty acids.
1 - Metabolic processes.
2 - Cell membrane components.
List 2 functions specific to non-essential fatty acids.
1 - Insulation.
2 - Source of energy.
What is the calorie density of fats?
~9kcal/g for all fats.
List 7 general functions of fats.
1 - Source of energy.
2 - Incorporation in body structures ( e.g.cell membranes).
3 - Protection around vital organs.
4 - Insulation.
5 - Satiety (leptin).
6 - Carriers of fat-soluble vitamins to assist absorption from intestine.
7 - Effective prolonged energy storage.
List 2 properties of fats that make weight loss difficult.
1 - They are insoluble in water so are difficult to access.
2 - They require a large amount of oxygen to metabolise (4x more than carbohydrates).
How many molecules of ATP are produced by one mole of palmitic acid?
130.
How many molecules of ATP are produced by one mole of glucose?
36/38.
What is the percentage composition by mass of proteins for animals and plants?
- Animal: 15-20%.
- Plant: 1-2%,
Why does the body need a more regular supply of proteins that carbohydrates / fats?
Because excess amino acids cannot be stored.
What are phytochemicals?
Metal binding substances produced by plants.
Give an example of a health benefit of phytochemials.
Protection against diseases.
Give an example of a disadvantage of phytochemicals.
Interfere with absorption of minerals, e.g. iron, reducing their bioavailability.
Define bioavailability.
The proportion of a drug or other substance which enters the circulation when introduced into the body and so is able to have an active effect.
What is nitrogen balance?
Nitrogen intake - nitrogen excreted.
List 3 factors that may lead to a positive nitrogen balance.
1 - Pregnancy,
2 - Growth.
3 - Recovery.
List 3 factors that may lead to a negative nitrogen balance.
1 - Starvation.
2 - Trauma / tissue destruction.
3 - Infection / sepsis.
How does nitrogen enter and leave the body?
- Nitrogen enters the body as amino acids.
- Nitrogen leaves the body as ammonium salts.
List 4 functions of proteins.
1 - To form the amino acid pool.
2 - To manufacture new proteins.
3 - To build new tissue.
4 - To produce energy through oxidation (not a main function).
Give an example of a hormone that promotes anabolism of fats, glucose and amino acids.
Insulin.
List 4 hormones that promote catabolism of fats, glucose and amino acids.
1 - Glucagon.
2 - Adrenaline.
3 - Cortisol.
4 - Growth hormone.
List 3 catabolic products of fats.
1 - Fatty acids.
2 - Glycerol.
3 - Ketone bodies.
What happens to excess glucose from the diet?
It is used in lipogenesis.
What is the body’s order of preference of fuel?
- Depends on intensity and duration of activity, but generally:
1 - Carbohydrate.
2 - Fat.
3 - Protein.
List 3 disadvantages of using fatty acids rather than glucose for metabolism.
1 - More oxygen is required to metabolise fatty acids than glucose.
2 - Beta oxidation of fatty acids generates superoxide (a free radical).
3 - The rate of ATP generation is slower with amino acids than glucose.
Which forms of ATP storage are used during short-duration exercise, and in which order?
1 - ATP stored in muscles is used first.
2 - ATP is formed from creatine phosphate and ADP.
3 - Glycogen in the muscles is broken down into glucose, which is oxidised to generate ATP.
4 - Bloodborne fatty acids and glucose take over at ~30minute mark, where bloodborne fatty acids are used more than bloodborne glucose.
What are the two types of dietary fibre?
Soluble and insoluble.
List 5 functions of dietary fibre.
Souble:
1 - Reduces cell proliferation.
2 - Binds to and increases the speed of excretion of dietary carcinogens and toxins.
Insoluble:
3 - Slows gastric emptying.
4 - Retards glucose absorption.
General:
5 - Important for the maintenance of a healthy gut flora.
What is dumping syndrome?
A group of symptoms, including weakness, abdominal discomfort, and sometimes abnormally rapid bowel evacuation, occurring after meals in some patients who have undergone gastric surgery.
Which vitamins are water soluble?
B complexes and C.
Which vitamins are fat soluble?
A, D, E, K.
What is the primary function of vitamin B complexes?
B complexes are enzyme cofactors.
List 2 functions of vitamin C.
1 - Protein synthesis.
2 - Antioxidant.
What is the primary function of vitamin A?
Development of various tissues.
List 2 functions of vitamin E.
1 - Immune function.
2 - Antioxidant.
What is the primary function of vitamin D?
Calcium metabolism.
What is the primary function of vitamin K?
Blood clotting.
Where are fat soluble vitamins stored?
In the liver and in adipose tissue.
