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54 Cards in this Set
- Front
- Back
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What is the first law of thermodynamics? |
The total energy in a system is constant: it cannot be created or destroyed but only converted. |
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How do humans utilize the first law of thermodynamics? |
We convert chemical energy stored in food to mechanical energy. |
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What is the equation for energy intake and energy expended? What has to be taken into account? |
E(intake)= E(expended) + E(stored) E(expended)= BMR +activites Some energy is lost in sweat, faeces and urine. |
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From the E(intake) equation what can be said? |
If E(intake) is greater than E(expended) it is stored as fat. |
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How can weight loss be achieved? |
-Reducing energy intake -Increasing activity -Increasing BMR |
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When does exercise work for weight loss? |
When paired with dietary cotroll |
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How can the energy content of food be measured? |
Bomb calorimetry |
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What are Atwater factors? |
The energy contained in certain fuels that has been adjusted for other losses in the body. |
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What is the calculation for E(intake) using Atwater factors? |
E(intake)= Chemical compound x Atwater factor For each compound and add them together. |
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What is direct calrorimetry? How may this be done? |
The measurement of the energy expenditure of a person by measuring the heat they give off. Whole body calrorimetry |
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What is indirect calrorimetry? How may this be done? |
Where measurements of CO2 or O2 production is used to determent energy expenditure. Measured using a respriometer |
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What is Graves disease? What are the symptoms? What does it do to the BMR? |
Hyperthyroidism. Anitbodies produced against the thyroid hormone receptor which causes it to be broken down and increase thyroxine (and fuel breakdown) Hot, shaking and weight loss Increases it |
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What is Hypothyroidism? What are the symptoms? What does it do to the BMR? |
Antibodies destroy the thyroid gland which leads to low levels of thyroxine. Cold, depression and poor memory Decreases it. |
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How does the salivary gland take part in digestion? |
Digestion of carbohydrates start here. The saliva contains mucous and amylase which start carb digestion. Mucous is a glycoprotein that aids in the movement of food down the digestive tract. |
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What does the stomach do in digestion? |
Stores, mixes food with gastric juices and slowly release chyme into the into the intestines |
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What does the stomach secret during digestion? |
Acid, pepsinogen (for digesting proteins) and a protective mucous lay (to prevent self digestion) |
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What are the two cells of the stomach we covered and what do the secret (and what do they do)? |
-Mucous cells secret mucous (protective layer) -Parietal cells secret protons (aid in digestion and pepsinogen activation) There needs to be a very fine balance between H+ secretion (so pepsinogen is still activated) and mucous secretion (protection of the tissue) |
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What does the pancreas do in digestion? |
It secrets digestive enzymes such as amylases, lipases and proteases. |
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What does the liver do in digestion? |
Synthesizes bile salts/acids (which are stored in the gall bladder) that are important for fat digestion. |
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What are the two main phases of digestion? |
-Hydrolysis of the bonds connecting monomers -Absorption of the products from the gut to he body |
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Describe the break down of starch (Amylose). |
Amylases break the 1,4 glycosidic bonds inmaltose/isomaltose after repeated attacks. Maltose is then broken down into 2 glucose units and absorbed into the intestinal villi. This is all done at the intestinal brush border. |
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What is lactose intolerance? |
A genetic disorder that cause a lactase deficiency and an inability to break down lactose. This causes bloating, flatulence and diarrhea due to fermentation by bacteria and villi cell wall damage. |
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What are the two glucose transporters in the microvilli? Which part do they sit in and what type of transport do they use? |
SGLT-1 in the outer part (glucose/Na+ symport) and GLUT-2 in the inner part (passive diffusion) into the blood |
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Why is fructose potentially harmful to humans? |
It bypasses a lot of digestive processes (it even has a different delivery system in different cells to glucose) |
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What is Coeliacs disease? |
A small intestine disease which results in the body reacting against wheat protein and antibodies against transglutaminase. Results in flattened villi, malabsorption of nutrients and gastrointestinal symptoms. |
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What do dietary proteins do (4)? |
-Supply AA's to make body proteins -Essential AA's -A source of nitrogen for purines and pyrimidines -Carbon skeleton can be used as a metbolite |
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What is Kwashikhor? What are the symptoms? |
Acute childhood protein malnutrition, their diet does not supply enough essential AA's. Presents as a pot belly, muscle wasting and swollen feet. |
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Why do we need to eat a variety of foods? |
Because not all have the right mix of AA's |
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Protein digestion has a higher risk of self digestion than carbohydrate digestion. True or False? |
True |
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What is protein digestion regulated by and why? |
Polypeptide hormones to release the enzymes only when needed and decrease the risk of self digestion |
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Protein enzymes are secreted ready to go from the pancreas. True or False? |
False: They are secreted as Zymogens to decrease the risk of digestion of the pancreas |
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How are protein enzymes kept specific? |
They only cleave next to certain side chains. |
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What are the stages of protein digestion? What are the enzymes involved? |
-Endopeptidase attack the peptide bonds within the chain -Exopeptidases attack the peptide chain at the ends (Aminopeptidases at the N-terminus and Carboxypeptidases at the C-terminus) |
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Describe pepsinogen activation. |
Disruption of electrostatic interactions at a low pH leads to the revealing of the active site. An increase in H+ cause conformation changes in the enzyme. Activated pepsinogen can also go and act on others to activate them. |
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How are di and tri-peptides absorbed? Who are they done in and why? |
Via H+ contransport by PepT1 Babies and young because they need colestrum |
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What are the 5 main AA transporters? |
-Neutral -Basic -Acidic -Glycine -Proline -Hydroyxproline |
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What is pancreatitis? |
In appropriate zymogen activation which results in digestion of the pancreas |
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What causes ulcers? |
Stomach and intestinal mucousal layer breakdown |
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What is cystic fibrosis and what causes it? |
Thick mucousal secretions that stop the movement of pancreatic enzymes. A mutation in the CFTR gene |
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Briefly describe nucleic acid absorption. |
They undergo hydrolysis in the stomach, intestinal nucleases hydrolyses phosophodiester bonds between nucleoside and the nucleoside are then absorbed via nucleoside transporters. |
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What are bile salts made from? |
Cholesterol |
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Briefly describe what bile salts do. |
They are secreted into the small intestine in response to cholecystokinin. They surround hydrophobic molecules and allow them to move through aqueous environments and interact with aqueous enzymes They act as powerful detergents They form Micelles with TAG's (emulsify) |
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What are the 2 main bile salts? |
Glycocholic acid and Taurocholic acid |
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Why can bile salts intercat with lipids and enzymes at the same time? |
They have a hydrophobic and hydrophillic side |
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Briefly describe how enzymes interact with a Micelle? |
They bind to the lipid/aqueous interface and hydrolyse the TAG's fatty acids at positions 1 and 3 to form FFA's and 3-Monoacylglycerol |
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What happens to the MAG's and FFA's after absorption? |
They are resysnthesised to TAG's by hydrolysis in the Endoplasmic Recticulum. They are then taken to the Golgi and the membrane |
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What are lipoproteins and what is their basic strucure? |
They are structures that transport lipids around the body. It stabbilises the lipids and makes them soluable They consist of TAG's and esterified cholesterol surrounded by phosopholipids, appoproteins and un-esterified cholesterol |
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What are the 4 main classes of lipoproteins? |
-Chylomicrons -VLDL -LDL -HDL |
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The denser the lipoprotein the more the TAG's. True or false? |
False: Higher density means less TAG's |
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What to chylomicrons carry? |
Exogenous lipids |
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What do VLDL and LDL carry? |
Endogenous lipids |
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How are chylomicrons secreted and made? |
From TAG's and other lipids combined with apoB in the endoplasmic recticulum They are secreted from the intestinal cells and enter the blood stream via the lymphatic system |
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What is familial C2 defficency? |
A deffect in ApoC2 gene which results in FA deposits under the skin and heart attacks due to defects in chylomicron processing |
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What is familial Hypercholesterolaemia? |
A form of hyperlipidaemia caused by a defect in the LDL receptor gene causing LDL levels to be 2-3x higher than usual |
