Metabolic Fate of Nutrients Flashcards
Why is nutrition important?
To develop and maintain a state of health
How many diseases are due to diet?
4 out of top 10
What diseases are caused by diet?
Heart disease
Some cancers
Stroke
Type 2 diabetes
What is food?
Substance when eaten, digested and absorbed provides at least 1 nurtrient
What are nutrients?
Substance which is digested and absorbed to promote bodily function
What are the three categories of nutrient?
Macromolecules
Micromolecules
Water
What are macromolecules?
Proteins
Fats
Carbohydrates
What are micromolecules?
Minerals
Vitamins
What is energy released from food used for?
Muscle activity Secretion by glands Maintenance of membrane potentials Synthesis of molecules Absorption of foods from GIT Cell division Thermoregulation
What are the three main processes that require energy?
Basal metabolic rate
Thermic effect of food
Physical activity
(other)
What is the basal metabolic rate?
Number of calories needed at rest for normal bodily function
50-70% daily calories needed
What is the thermic effect of food?
Energy required for the digestion and absorption of food
5-10% of energy expenditure
What is physical activity
Variable %
Movement of skeletal muscles
What are other factors that might require energy?
Temperature changes Pregnancy Lactation Growth Age Health
What is sarcopenia?
Loss of muscle mass with aging
What is a typical western diet?
10% protein
40% carbohydrate
40% fat
What are the acceptable ranges for macronutrients?
10-15% protein
55-75% carbohydrate
15-30% fat
What is the calorie content of glucose?
4kcal/g
Why is glucose the preferential source of energy?
Readily available primary source of energy for CNS and red blood cells but also used by other tissues
How is glucose stored?
As glycogen
How is glycogen produced?
Glycogenesis
Where is glycogen stored?
Liver
Muscle
How is glycogen utilised?
Glycogenolysis
Where is glucose released from muscle stores of glycogen used?
In that muscle
Where is glucose released from liver stores of glycogen used?
All around the body
How much ATP can be derived from one mole of glucose?
36
What is the calorie content of fat?
9kcal/g
What does not use fat?
The central nervous system
Red blood cells
What do fats require to be metabolised?
Large amounts of oxygen
Are fats soluble in water?
No
What are fats used for?
Incorporation in body structures Protection of organs Insulation Satiety Fat soluble vitamins Energy tissue
How much ATP can be extracted from 1 mole of palmitic acid?
130
What is the calorie content of protein?
4kcal/g
What are proteins used for?
Broken down into amino acids
Manufacture new proteins
Build new tissue
Oxidised to produce energy, urea formed is excreted by kidney
What is nitrogen balance?
Balance = N intake - N excreted
What is the nitrogen balance in adults?
Equilibrium
What does a positive nitrogen balance suggest?
Pregnancy
Growth
Recovery
What does a negative nitrogen balance suggest?
Starvation Trauma Infection Sepsis Tissue destruction
What is dietary fibre?
Non-starch polysaccharides
What are the two types of dietary fibre?
Soluble
Insoluble
What is insoluble dietary fibre?
Cellulose
Wheat
Leafy vegetables
Pulses
What is the role of insoluble dietary fibre?
Provides bulk to the gut to prevent constipation
Reduces dumping syndrome by slowing gastric emptying and retarding glucose absorption
What is soluble dietary fibre?
Pectins
Plant gums
Mucilage
What is the role of soluble dietary fibre?
Absorbs water in intestine to soften stool
Lowers cholesterol
Reduces bowel cancer risk as binds to carcinogens and toxins and fermentation decreases cell proliferation
Which vitamins are water soluble?
B complexes
C
Which vitamins are fat soluble?
A
D
E
K
What is the role of water soluble vitamins?
Enzyme cofactors
Protein synthesis
Antioxidant
What is the role of fat soluble vitamins?
Development Immune system Vision Antioxidant Immune function Calcium metabolism Blood clotting
Which vitamins can be stored?
Water soluble vitamins cannot be stored and need regular intake
Fat soluble vitamins are stored in liver and adipose tissue
Which minerals are needed for body health?
Fe Ca Mg Mn Na K Zn
What is rickets?
Vitamin D deficiency
Poor mineralisation of bone
Deformation of load-bearing bones
What is scurvy?
Chronic deficiency of vitamin C
Destruction of collagen
Damage to myelin
Leads to paralysis/death
What is pernicious anaemia?
Vitamin 12 deficiency Decreased red blood cell count Megaloblasts (large immature red blood cells) Leads to death if not treated Caused by gastrectomy or PPI inhibitors
What is iron deficiency anaemia?
Low haemoglobin Reduced amount of red blood cells Paler red blood cells Leads to fatigue, paler, shortness of breath Treated with iron supplements
Why is water essential?
Prevent dehydration Solvent for most materials Important for metabolism and excretion Thermoregulation Osmoregulation
What is the equation for regulation of body mass?
Energy intake = energy expended + energy stored
Energy balance = intake - expenditure
What is the definition of appetite?
Desire to eat food
Felt as hunger
Regulates adequate energy intake to maintain metabolic needs
What is the definition of satiety?
Absence of hunger
What regulates hunger and satiety?
Brain
What part of the brain is responsible for hunger and satiety?
Hypothalamus
What is the hunger centre?
Lateral hypothalamus
What is the satiety centre?
Ventromedial hypothalamus
Explain the glucostatic control of hunger
Decrease in glucose = hungry
Increase in glucose = satiety
Explain the adipostatic control of hunger
Increase in fat stored = satiety
Which neurotransmitters affect the hypothalamus?
Serotonine
Dopamine
What is loss of appetite?
Anorexia
What are the physiological causes of anorexia?
Anaemia Cancer Intestinal disorders/parasites Liver disorders Malabsorption syndrome Mouth disorders Loss of taste
What are the psychological causes of anorexia?
Depression
Stress
Anxiety
What are environmental causes of anorexia?
Altitude
Acute cold
How is 97% of energy stored?
Adipose tissue
What is an advantage of carbohydrates as a fuel source?
More ATP can be generated per unit time
Metabolism is a balance of what?
Catabolism
Anabolism
What decreases fat metabolism?
Insulin
What increases fat metabolism?
Glucagon
Adrenaline
Glucocorticoids
What are innate causes of obesity?
Monogenic mutation (leptin) Prader-Willi syndrome
What are acquired causes of obesity?
Overeating Inactivity Aging Stress Drugs
What are physiological consequences of obesity?
Stroke Hypertension Joint damage Cardiovascular disease Diabetes Cancer Fertility problems
Compare glucose to fructose
Fructose is sweeter than glucose
Fructose is more readily converted to triglycerides
Fructose does not stimulate insulin secretion
Food intake remains high
How does insulin affect appetite?
Insulin triggers leptin release which lowers hunger
How is obesity treated with drugs?
Sibutramine suppresses appetite
Block endocannabinoid system
Orlistat inhibits pancreatic lipase
How is obesity treated with lifestyle changes?
Exercise
Calorie restricted diet
How is obesity treated surgically?
Gastric band
Gastric balloon
What is starvation marked by?
Liver synthesis of glucose and ketone bodies
Gluconeogenesis
Ketogenesis
What is the purpose of starvation mechanisms?
To preserve plasma glucose to maintain brain and spinal cord
How quickly is blood glucose and stored glycogen exhausted?
24 hours
