23. Nutrition and Metabolism Flashcards
Name the types of carbohydrates?
Monosaccharides, disaccharides and polysaccharides
Why is cellulose useful?
It’s not digested in humans but it’s an important source of fibre
Why are lipids useful for energy storage?
Twice as much energy per gram than sugars and proteins, especially useful if using lots of energy
What is special about fatty acids?
Most of them can be synthesized
Name the water soluble vitamins?
Vitamins B and C
How long does the absorptive state last?
Up to 4 hours after a meal
How is gestational diabetes controlled?
Usually by diet and exercise but in some cases may need oral hypoglycaemics or insulin?
What is the daily requirement of fat?
Should be less than 30% of daily calorie intake, GDA 70g/days of which 20g saturated
What are the two metabolic states?
Absorptive and postabsorptive
What does adrenaline do?
Stimulates gycogenolysis and lipolysis (especially in injury, fear, anger and stress)
How much of the body mass is protein?
12-15%
What are the sources of saturated fats?
Animal origin e.g. butter and meat
How would you test for diabetes mellitus?
Urinalysis for glucosuria (glucose in urine) followed by glucose tolerance test
What happens to proteins on ingestion?
Broken down into amino acids in digestive tract then synthesis of new proteins Also transamination (making amino acids) in liver
What are amino acids made up of?
An amino group (NH2+) and a carboxyl (acid) group (COO-)
What are the uses of lipids?
Energy storage Absorption of fat-soluble vitamins Plasma membranes and myelin Precursor of steroids, bile salts, vit D and prostaglandins
During pregnancy, how much fibre should you eat and why?
Increase fibre as peristalsis slows resulting in constipation
What are the two types of metabolism?
Anabolism (building up)
Catabolism (breaking down)
How does insulin effect blood glucose?
LOWERS it
Where is glucagon secreted from?
Pancreatic alpha cells
Diabetics will have what fasting glucose levels?
> 7mmol/L or after 2 hrs a level of >12mmol/L
What is normal blood (plasma) glucose?
3.5-8.0 mmol/L
What is the GDA of carbohydrates?
230g/day which is greater than other nutrients
How are carbohydrates anabolysed?
Glucose converted to glycogen or triglycedrides for storage
What happens during the post aborptive state?
No absorption occurs. Mainly catabolic processes
What are the problems with excess fibre consumption?
Interferes with mineral absorption - iron, calcium etc
Name the fat soluble vitamins?
Vitamin A, D, E, K
What are essential nutrients?
Nutrients that can’t be synthesized by the body so must be included in the diet
What is a macro-nutrient?
Nutrients required in large amounts
How are lipids transported in the blood?
Combined with proteins to make lipoprotein droplets which are transported in the blood
What can energy be measured in?
Kilojoules (kJ) or kilocalories (kcal)
When are lipoproteins formed?
Constantly being formed and degraded
How many amino acids are there?
20 - 8 of them must be ingested as they can’t be synthesize by the body (essential amino acids)
Describe what happens during glycolysis?
Glucose is quickly metabolised to 2 molecules of ATP and 2 moles of pyruvic acid (aka pyruvate). No oxygen is required.
What is glycogenesis?
Synthesis of glycogen from glucose
What is HBA1C?
Glycated hemoglobin
What happens to blood glucose during absorptive state?
Blood glucose is high
What hormones are involved with blood glucose?
Insulin - decreases blood glucose
Glucagon - increases blood glucose
How long does the post absorptive state last?
From 4 hours to next meal
What happens to cause gestational diabetes?
Renal threshold for glucose falls secondary to an increase in glomerular filtration rate
What is metabolic rate?
Rate of energy released from cells
Name the macro-nutrients?
Water, carbohydrates, proteins and fats
What is a complete protein?
A complete protein contains ALL the essential amino acids
What do HDLs do?
They remove the cholesterol and return it to the liver for elimination
Give some examples of parts of the body made up of proteins?
Skeletal muscles Enzymes Hormones Cell membrane receptors Collagen Haemoglobin Hair and Nails
Name the monosaccharides?
Glucose, galactose and fructose
Name the micro-nutrients?
Minerals and vitamins
What is sodium required for?
Water balance and nerve conduction
What are the types of lipoproteins that transport lipids?
Chylomicrons (protein coated lipid droplets) Very low density lipoproteins (VDLs) Low density lipoproteins (LDLs) High density lipoproteins (HDLs)
What happens in lipid anabolism?
Fatty acids and glycerol –> triglycerides
Lipogenesis - triglycerides formed from amino acids and glucose
What is the RDA of sodium?
6g/day but only need approx. 2g/day but typical diet contains about 4.5g/day
What are HDLs?
They are empty shells that are made in the liver and are transported to the tissues e.g. blood vessels
What is metabolism?
The chemical and phsyical reactions that occur in the body to ensure continued growth and functioning
What is metabolism?
What we do with the nutrients once they are delivered to the cell
What nutrient is important in pregnancy?
Protein - for growth of mother and baby
What does the density of lipoproteins refer to?
the protein/fat ratio
What do VDLs do?
Transport triglycerides and cholesterol from liver to adipocytes where triglycerides are stored
Where would you complete proteins?
In animal products e.g. eggs, meat and milk
What are the two metabolic states?
Absorptive and postabsorptive
What is normal fasting glucose?
3.5-5.5 mmol/L
What nutrients need to be restricted in children?
Children over 6 months, low salt and no added sugar
Name the polysaccharides?
Starch, glycogen and cellulose
What is 1kcal defined as?
Amount of heat required to heat 1 litre of water by 1 degrees c
What is catabolism?
Large molecules broken down to small ones e.g. glycogen to glucose to use
(NOTE: releases energy - ATP)
What happens to pyruvate after glycolysis?
In the absence of oxygen pyruvic acid is converted to lactic acid. In the presence of oxygen pyruvic acid passes into the mitochondrian to enter the TCA cycle and the electron transport chain. Because Acetyle Co Enzyme A and then 36 ATP.
What naturally increases during pregnancy?
Early in pregnancy fat stores increase these are used later as an energy supply
What happens during lipid catabolism?
Lipolysis
Breaking down fat for fuel:
glycerol -> glycolysis
fatty acids -> Acetyle Co enzyme A -> TCA Cycle
What is glycogenolysis?
Breakdown of glycogen into glucose
How are vitamins obtained?
From meat and veg
How does insulin lower blood glucose?
Increases entry of glucose into cells (increases carriers for facilitated diffusion)
Stimulating glycogenesis
Stimulating protein and fat synthesis
Inhibiting gluconeogenesis
What are the sources of cholesterol?
Egg yolks, cream, shellfish, organ meats and other meats
Name the essential amino acids?
isoleucine leucine lysine methionine phenylalanine threonine tryptophan valine
Are lipids water soluble?
No
What is cholesterol useful for in the body?
For hormones and plasma membranes
What does diabetes mellitus have to do with ketones?
Lack of insulin leads to increased breakdown of fats and amino acids and can result in ketoacidosis
Where is glucocorticoids released from?
Released by adrenal cortex
Where are incomplete proteins found?
In plant sources e.g. beans
What happens during the absorptive processes?
Mainly anabolic processes
Which nutrients are important post partum?
Iron (blood loss), calcium (breast feeding) and vit d (breast feeding)
Give some examples of minerals?
Calcium, phosphorous, iron, magnesium, manganese, chlorine, folate and other electrolytes
What proportion of LDLs is protein and fat?
Low protein High Fat
What is the GDA of protein?
45-60g/day depending on physiological state, age and sex
Which mineral requirement increase during pregnancy?
Calcium Folate Zinc Iodine Iron
What percentage of the adult body is lipids?
Male body fat 15% Female body fat 25%
How are carbohydrates catabolysed?
Glucose is used to form ATP by glycolysis or the TCA cycle
In the presence of oxygen what the ATP yioeld from the flycolysis of one glucose?
38 molecules of ATP
Are ketones used by the body?
Yes, some cells use ketone bodies for energy (heart and kidney)
What does HBA1C?
Glycated hemoglobic tells wether diabetes is controlled well - tells of hypers not hypos
What is an incomplete protein?
Incomplete proteins lack one or more essential amino acids
What is anabolism?
Small molecules joined together to form complex structure e.g. glucose stored as glycogen
(NOTE: it uses energy)
What happens in protein catabolism?
Amino acids can enter the TCA cycle. First they must be deaminated by removed of NH2 (amino group). The NH2 because NH3 (ammonia) a toxic substance that is converted to urea by the liver and then excreted in the urine
Where do nearly all carbohydrates come from?
Plants
What is the aim of the post absorptive state?
To prevent blood glucose falling
What are the effects of fibre?
Absorbs water into intestines, softening the stool Provides bulk so speeds up transit time
What vitamins are synthesized by the body?
Vitamins D and K
What are lipoproteins made up of?
Core of cholesterol and triglycerides (lipids from diet) Outer coating of proteins and phospholipids
What is important during gestational diabetes?
Frequent monitoring of plasma glucose levels
What is glucose tolerance test?
Fast overnght, before and after 75g glucose load (or random)
What are best form of carbohydrates and why?
Polysaccharides (complex carbs) as they are more complex to break down, so they are broken down slower which is better for us
What processes allow blood glucose homeostasis?
Glycogenesis
Glycogenolysis
Gluconeogenesis
What is fibre?
Animal or plant carbohydrate that resists digestion
Where is glycogen found?
Found only in small amount in cooked meats
What 3 things prevent blood glucose falling during post absorptive state?
Glucagon
Adrenaline
Glucocorticoids (cortisol, cortisone)
What happens to insulin during absorptive state?
Insulin is secreted by beta cells (in islets of langerhans) of pancreas
What happens where there are to many ketone bodies?
Ketoacidosis
Name the disaccharides?
Sucrose which is glucose and fructose Lactose which is glucose and galactose Maltose which is 2x glucose
What is the disadvantage of eating plant products?
Must be combined to ensure all amino acids are provided
What are special about water soluble vitamins?
Can’t be stored by the body
Where is adrenaline released from?
Released by sympathetic nervous system and adrenal medulla
What happens during lipid anabolism?
Fatty acids and glycerol -> triglycerides
Lipogenesis - triglycerides formed from amino acids and glucose
What is the advantage of eating animal products?
They provide other nutrients (vitamins and minerals etc)
What is increased transit time associated with?
Decreased bowel cancer in some studies
What are the types of diabetes mellitus?
Type 1 (insulin dependence)
Type 2 (non-insulin dependence)
What are the uses of carbohydrates?
Converted to energy (e.g. neurons and RBCs which depend on glucose) Form structural components of other molecules (e.g. glycoproteins) Provides energy stores (glycogen in liver, excess converted and stored as fat)
What is the conversion between kcal and kj?
1kcal=4.184kj
What is a micro-nutrient?
Nutrients required in small amounts
Describe the absorptive metabolic state?
Up to 4 hours after a meal and mainly anabolic processes
Where are minerals found?
Veg, milk, eggs, meat, fish and shellfish
What do chylomicrons do?
Transport triglycerides and cholesterol from small intestine to liver and adipocytes via lymphatic vessels
What is your daily requirement of fibre?
24g/day
What are the sources of unsaturated fats?
Nuts, seeds and most vegetable oils
What does glucagon do?
Stimulates glycogenolysis, gluconeogenesis and lipolysis
Describe the postabsorptive metabolic state?
From 4 hours after meal to next meal, no absorption occuring, mainly catabolic processes
What do glucocorticoids do?
Stimulate gluconeogenesis
What causes diabetes mellitus?
Stress
Viral
Environmental
Genetic
Diet
What happens in lipid catabolism?
Lipolysis (breaking down fat for fuel)
Glycerol –> glycolysis
fatty acids –> acetyle co enzyme a –> TCA cycle
Name some non-essential amino acids?
Glutamine Tyrosine
How do we get nutrients?
Nutrients are provided by the food we eat
What proportion of HDLs is protein and fat?
High protein Low fat
What are disaccharides?
Monosaccharides joined together, usually glucose + something
What do LDLs do?
Transport cholesterol to tissues e.g. blood vessels
What is basal metabolic rate?
Energy release required to support vital organs at rest (12hr fasting in warm environment)
What is gluconeogenesis?
Synthesis of glucose from amino acids
What do all carbohydrates generate?
Glucose
What to vitamins do in metabolic activities?
Act a co-enzymes and carry out many other functions
What happens in protein anabolism?
Amino acids used to form new proteins
Why don’t type 2 take insulin?
Because they’re insulin resistant, cells aren’t responding to it
What are the risk factors for gestational diabtes?
BM 30kg/m2
Previous big baby
Cose relative with diabetes
Previous gestational diabetes
Fill in the blanks
What is the average basal metabolic rate?
2000kcal/day for women, 2500kcal/day for men
What nutrients are used for growth, repair or maintenance?
Carbohydrates, proteins, fats, minerals, vitamins and water
When are ketones produced?
When too much acetyl co enzyme A enters the TCA cycle (during fat and protein breakdown in liver) acetyl co enzyme a is converted into ketone bodies
