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80 Cards in this Set
- Front
- Back
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Define: Metabolism
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Chemical reactions occuring in the body
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What is the correct term for the breakdown of molecules into water, CO2, and ENERGY?
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Catabolism
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What process results in the manufacture of large molecules, using energy?
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Anabolism
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Name the undigestible, substance which remains in the GI tract as dietary fibre, softens faeces, and contributes to bowel health
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Cellulose
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Name 3 monosaccharides
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glucose, fructose and galactose
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Monosaccharides are converted to glucose here
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Liver
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This acts as fuel for cells
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Glucose
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What are the average carbohydrate requirements for humans?
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Approx 4.5 grams per kg bodyweight per day
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What are complex carbohydrates commonly called?
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Starches
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What are monosaccharides?
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Simple carbohydrates
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List 3 sources of starch
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potatoes, pastas, rice, bread, beans , peas.
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List 3 sources of monosaccharides
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table sugar, sweet foods, fruits.
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What problems can be caused by carbohydrate deficiency?
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fatigue, protein catabolism for energy, imbalance of water and electrolytes
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What is glucose used for?
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Energy
Glycogenesis (“generating glycogen”) Conversion to fatty acids then triglycerides (when glycogen stores are full, at about 400-500 grams) |
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What is the energy source for cell respiration?
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Glucose is the preferred energy source. It is “clean burning” - it can be broken down to CO2 and H2O if Oxygen is available
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Describe the process of glycolysis
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Glucose has 6 carbon atoms
Split to 2 molecules of pyruvic acid (3C’s each) Cytoplasm 2 ATP No Oxygen: anaerobic |
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Describe the process of aerobic respiration
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Occurs if O2 is available
i. Decarboxylation: turn the 3C pyruvic acid into a CO2, and acetyl CoA (2 C’s on a carrier) ii Citric Acid Cycle (CAC) : uses acetyl CoA Produces more CO2 Joins H onto carriers |
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Describe the electron transport system
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Extracts the energy from the electrons
Passes them down a series of compounds called cytochromes Occurs in Mitochondria Produces water Aerobic Respiration makes another 34 ATP per glucose |
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What is the chemical formula for aerobic respiration
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C6H12O6 + 6O2 -----> 6CO2 + 6H2O +36ATP
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Describe the process of cellular respiration when there isn't enough oxygen
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As much energy is produced aerobically as oxygen permits
Extra energy is produced anaerobically - and for this only step 1 occurs : glycolysis. |
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Describe the products of Glycolysis
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Net 2 ATP produced.
2 x Pyruvic Acid (C3H4O3) produced The Pyruvic Acid is converted to Lactic Acid in order to clear the glycolytic pathway so it can be used again to split more glucose. It is a very fast way to produce energy. Lactic acid accumulates. |
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What is glucose used for?
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Energy
Glycogenesis (“generating glycogen”) About 400 – 500g of glycogen is stored in the body Conversion to fatty acids then triglycerides |
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Describe the control of blood glucose
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Glucose must be in the blood – energy for cells
After a meal, (post prandial, or absorptive state) glucose moves from the dig. tract to the blood – raises blood level It is taken from the blood into the cells (“absorbed”)It has free entry (facilitated diffusion) into liver, kidney and brain tissue - these tissues have as much glucose as they need provided blood flow is adequate and there is glucose in the blood! Other cells (skeletal muscle, adipocytes) need insulin to activate transport proteins for glucose to enter - |
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What is the function of insulin?
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Combines with a protein receptor to allow glucose entry into many cells.
Reduces blood sugar. Promotes glucose metabolism (use) Promotes glycogen storage ~ 150g (liver) ~ 350 g (muscle) promotes excess glucose conversion into fats for storage. |
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Where is insulin produced?
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Endocrine Part of the Pancreas: Islets of Langerhans
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What is the normal level for Glucose Homeostasis?
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4 - 6 mmol.L-1
About 5 grams of glucose in 5 litres of blood |
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Describe the incidence and causes of diabetes mellitus
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2 to 4% or more of the population.
2 common causes (both have genetic involvement) 1) Loss of beta cells (usually autoimmune disease mechanism) no insulin produced: needs to be replaced – Type 1: Insulin Dependant (IDDM). 2) Loss of response to insulin - uptake is impaired – Type 2 : Non Insulin Dependant DM (NIDDM) |
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Type 1 Diabetes
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About 10% of DM
was called “juvenile onset” DM requires insulin injections future treatments may include insulin/amylin dual treatment. Hormone levels must match food. Adjusted for each individual. |
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Describe hypoglycemia
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Too much insulin/ not enough food
Nerve cells run short of energy tired, listless, appear drunk …. Could become comatose. Need sugar to give energy to neurones. |
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Describe the causes and consequences of hyperglycemia
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Too little insulin/ too much food
glucose in blood but not being removed Cellular dehydration due to osmosis Lacking energy Glucose “spills out” in urine taking water with it (osmosis) |
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What are the long term complications of Diabetes Mellitus?
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Deterioration of epithelial cells lining blood vessels.
Blindness Kidney damage Poor circulation in distal limbs - poor wound healing, even tissue death and gangrene can occur. Elevated blood lipids due to increased fat metabolism ---> fatty plaque deposits (atheroma) worsening the condition of vessels… |
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Carbohydrates are eaten in the form of
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Monosaccharides (simple sugars)
Disaccharides: Maltose (Glucose + Glucose, Lactose (Glucose + Galactose, Sucrose (Glucose + Fructose) Polysaccharides |
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The polysaccharide that we can’t break down
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Cellulose
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Carbohydrate Digestion requires
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Salivary amylase (mouth)
Pancreatic amylase (SI) Intestinal Juice enzymes (SI) |
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Describe steroids
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Water and lipid soluble.
Absorbed by diffusion through cell membranes without digestion |
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Describe fats
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are mostly triglycerides.
Not water soluble – need bile salts to emulsify fats to disperse them in water to enable the enzyme lipase to break them down. |
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What are vitamins?
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Small biologically active organic molecules that must be supplied in small amounts in the diet.
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Describe vitamin absorption
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As they are small they Do NOT require digestion:
Fat soluble vitamins A,D,E and K: Dissolve in fat droplets in the digestive tract. Transported close to the epithelium Absorbed by diffusion. Water soluble vitamins: C and B group Also absorbed by diffusion. |
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Describe Vitamin B12
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A water soluble vitamin
Too large to easily absorb by diffusion. Intrinsic Factor (IF) from parietal cells binds Vitamin B12. IF triggers endocytosis in the terminal ileum, absorbing the Vitamin B12. Bacteria in the large intestine synthesise some K and B vitamins, which the large intestine absorbs |
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Describe Minerals
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Absorbed as electrolytes (ions in solution)
Some ions such as Na+, Cl- are actively absorbed (active transport) from the small intestine. Others such as K+ moves by passive diffusion. Most electrolytes reaching the small intestine are absorbed, and the body later uses, saves or excretes them as necessary. |
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Describe Iron (Fe) Absorption
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Absorption of iron and calcium is limited by the body’s need for them.
Iron is actively transported into the mucosal epithelial cells Stored bounds to ferritin protein The epithelial cells are shed, iron is lost if not required. If liver iron levels fall iron is released, transported in bloodby another protein – transferrin Known as the “iron barrier” |
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Why is Calcium (Ca) important?
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Important for muscle and nerve functioning, bone strength.
Vitamin D completes the structure of Ca transport proteins Low Ca levels in blood cause PTH (ParaThyroid Hormone) to be released This activates the transport proteins: Ca is absorbed. |
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Define: Recommended Nutrient Intakes (RNI)
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Recommended Daily Intake (RDI) (Australia)
Recommended Dietary Allowance (RDA) (USA) Daily Reference Value (DRV) (UK) Set at an estimated value so that 97.5% of the population will be assured of obtaining enough to avoid a deficiency (malnutrition) of that nutrient. |
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For which process is this the formula?
C16H32O2 + 23O2 ---> 16CO2 + 16H2O + 129 ATP |
Metabolising Fat
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For which process is this the formula?
C6H12O6 + 6O2 -----> 6CO2 + 6H2O + 36 ATP |
Metabolising Glucose
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Explain 4 factors that control energy intake:
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Metabolic needs:
*Low blood sugar stimulates eating behaviour (hunger). *High fat stores causes adipose cells to release leptin, a hormone which suppresses hunger, stimultes fat use, suppresses glucose use. habit psychological factors What is available |
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What do we call chains of amino acids?
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Proteins
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List 6 essential amino acids
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tryptophan, methionine, valine, threonine, phenylalanine, leucine, isoleucine, lysine,
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List 4 factors for protein use
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The all or none rule
Energy balance Nitrogen balance Hormonal Controls |
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What is the 'all or none rule' for protein synthesis?
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All the necessary amino acids must be present. If one kind of amino acid is not available in the cell cytoplasm, protein synthesis stops – and none of the amino acids can then be used. Amino acids are not stored – they are absorbed, proteins are made and any excess amino acids are broken down and processed into other things.
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Explain the role of energy balance in protein synthesis
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The body requires energy first
– everything stops without energy present, and cells will die. If there is not sufficient energy available from glucose (first choice) or fats (second choice) then protein will be broken down for energy, rather than being used for protein synthesis. Existing proteins will even eventually be broken down to keep the energy coming. |
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Explain the role of nitrogen balance in protein synthesis
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The amine part of amino acids contain Nitrogen, and accounts for some 16% of protein by weight. When the body is in nitrogen balance N intake will be equal to loss.
A Positive Nitrogen Balance occurs when the body is making more protein than it is breaking down and excreting – e.g. during growth (children, pregnant women) and repair (after illness and injury) NET PROTEIN SYNTHESIS. A Negative Nitrogen Balance occurs when more protein is broken down than is being used in protein synthesis – as in illness, injury and starvation. NET PROTEIN LOSS. |
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Explain the role of Hormonal Controls in protein synthesis
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Growth Hormone secreted during childhood will stimulate protein synthesis.
Sex hormones also promote protein synthesis, cause growth spurt during adolescence. Stress hormones (released in the body’s emergency (Fight or Flight) response: eg adrenaline and cortisol can cause protein breakdown to provide energy |
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Define: First Class (complete) protein
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Animal products: Meats, eggs, dairy products.
Contain all essential amino acids. |
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Define: Incomplete (2nd Class) Protein
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Plant protein: Nuts, grains, fruits. Always missing at least one essential amino acid.
Must be eaten as mixtures - complementing each other. |
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Explain Protein Metabolism
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Amino acids are used to make required proteins
Amino acids that are not used are removed from the blood by the liver and broken down. Protein is not stored at all for re-use. Surplus a.a. are deaminated. Proteins made by the body are built for performing specific tasks. They are only broken down to supply energy as a last resort |
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List 5 Protein Nutritional Deficiency Symptoms:
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Restriction of growth in children
Mental deficiency in infants Anemia Hunger Oedema Loss of appetite Fatigue Diarrhoea |
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What is Phenylketonuria (PKU)?
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The gene coding for the enzyme that breaks down phenylalanine (an amino acid) is defective. No enzyme is produced.
When eaten the amino acid levels build up – can reach toxic levels, causing damage to the developing brain. A low phenylalanine diet has to be eaten – remember this is an essential amino acid so they have to eat some, but not too much! |
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Identify dietary sources of fats
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Saturated fats: triglycerides mostly from animal sources – in meat, dairy products.
Unsaturated fats (oils): are present vegetable and fish oils. |
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Why are fats an essential part of the diet?
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Energy source
For absorption of fat soluble vitamins For cell membrane synthesis Linoleic acid - cannot be made in the body – it is an essential nutrient |
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What is the dietary requirement for fat in humans?
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In order to meet dietary requirements 20% of our energy needs to come from fats.
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Describe fat storage
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Fat is an energy store
Other food sources (carb, protein) can be turned into fat for long term storage. There is no limit to how much fat can be stored in the body Fat distribution: Visceral fat: round organs of the trunk – dangerous Abdominal fat: visible |
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Lipid Metabolism is used for
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energy production
gluconeogenesis. energy storage Ketone bodies |
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What happens to energy from Triglycerides?
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Glycerol Portion:
converted to pyruvic acid and enter the CAC Fatty Acid Portion: broken off in 2 carbon chunks, joined to CoA, enters CAC |
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Fatty Acids are used for...
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1x 6C fatty acid can produce 44 ATP – a higher energy output than glucose.
Most cells can use these directly for energy, especially skeletal muscle . (Neurones and RBC need glucose.) |
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What is Gluconeogenesis?
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The glycerol portion (3C unit) can be used to make glucose
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Describe fatty acid breakdown.
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Fatty Acid breakdown is fast – faster than the CAC can process it.
Acetyl CoA builds up and forms Acetoacetyl CoA, (4 C’s) this cant be uses by cells. It is sent to the liver which turns it into Ketone bodies. |
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What are ketone bodies?
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Formed when a lot of fat is being used for energy.
Acetoacetic acid Hydroxybutyric Acid Acetone Used by cells for energy Some is lost in urine, acetone on breath. Ketosis, Acidosis. |
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What are structural lipids
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Fats used to make important functional compounds within the body:
e.g. phospholipids in cell membranes myelin, prostaglandins |
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Describe lipid transport
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Fats do not dissolve readily in water – they are hydrophobic – and the body has to take special measures to transport them. Problems with this transport or excessive amounts of transported fat can lead to cardiovascular disease.
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What are Chylomicrons?
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Fat droplets from intestines
Made soluble in water by phospholipids, proteins, cholesterol Distribute fats around the body to the adipose tissues. Leave intestines by fluid drainage in lymphatics (bypassing the liver). |
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Describe Very Low Density Lipids
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Exported from the liverContain fat made from excess carb or protein
Very large Deliver the fat to tissues |
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Describe low density lipids
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VLDL becomes LDL after the triglyceride is delivered
Now rich in cholesterol, which is also delivered to tissues “bad cholesterol” |
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Describe High Density Lipids
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collects cholesterol from the tissues, returns it to the liver for excretion
“good cholesterol” |
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What is cholesterol?
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Blood lipids are often collectively referred to as “cholesterol”.
Best referred to as Lipoproteins (which specify the form in which the cholesterol is being carried in the blood) High levels of LDL are associated with cardiovascular risk. (“Bad cholesterol”) |
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Describe disease risk associated with lipids
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Risk is best assessed by comparing the ratio of HDL to LDL or total fats Greater than 2:1 LDL:HDL indicates elevated disease risk.
1:3 HDL:Total fat – ideal 1:5 HDL:Total fat - borderline 1:5+ HDL:Total fat - concern |
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Describe Fat Storage
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Fat is constantly moved around the body by lipoproteins - not just stored until needed!
Location: subcutaneous adipose (50%) mesenteries (10-15%) around the kidneys (12%). |
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Define LEPTIN
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Adipose tissues secrete a hormone called LEPTIN. This signals the brain to suppress appetite and increase metabolic rate, and encourage the cells to mobilise and use fat for energy
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What is the function of vitamins?
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Function to complete protein structure and functionality
Many are co-enzymes others are activate proteins in other ways – e.g. visual pigments (Vit A), activating Calcium transport proteins (Vit D) |
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Describe the role of minerals in nutrition
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Inorganic, smaller than vitamins
Some required in relatively large amounts (macronutrients) e.g. (Na, Cl, Ca, K) these are important as electrolytes (see the earlier section on water and electrolyte balance) Others are required in small amounts (micronutrients, trace elements) e.g. Co, Cu, Cr, Fl, Fe, I, Mn, Mb, Se, Zn and largely function as coenzymes. (Fe completes haemoglobin structure, Iodine completes thyroid hormone structure) |
