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31 Cards in this Set
- Front
- Back
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Amylase |
The enzyme which starch is broken down by |
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Lipase |
The enzyme which lipids are broken down by |
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Endopeptidases |
Hydrolyses peptide bonds within a protein |
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Exopeptidases |
Hydrolyse peptide bonds at the ends of protein molecules, removing single amino acids. |
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Dipeptidases |
Work specifically on dipeptides. |
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Bile Salts |
Produced by the liver and emulsify lipids to increase the surface area. |
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Micelles |
Monoglycerides and fatty acids stuck to the bile salts. Help the products of lipid digestion to be absorbed. |
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How are monosaccharides absorbed? |
Glucose and Galactose - Active transport via co-transporter Fructose - Facilitated diffusion |
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What do co-transporters help absorb? |
Glucose, galactose and amino acids. |
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How are monoglycerides and fatty acids absorbed across the ileum epithelium? |
Micelles can constantly break up and reform to release monoglycerides and fatty acids. Whole micelles are not taken up across the epithelium. Monoglycerides and fatty acids are lipid-soluble so can diffuse directly across the cell membrane. |
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What is the role of haemoglobin? |
To carry oxygen around the body |
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What does an oxygen dissociation curve show? |
How saturated the haemoglobin is with oxygen at any given partial pressure. |
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How are arteries adapted? |
Thick and muscular walls with elastice tissue to stretch and recoil as the heart beats to help maintain a high pressure. Folded epithelium allowing it to stretch |
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What are arterioles? |
Arteries divided into smaller vessels. |
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How are veins adapted? |
Wider lumen with little elastic or muscle tissue. Contain valves to stop the blood flowing backwards. Blood flow is helped by the contraction of the body muscles surrounding them. |
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What are capillaries and how are they adapted? |
Arterioles branched into smaller vessels. Found near cells in exchange tissues so there's a short diffusion pathway. Walls are only one cell thick. Large number of capillaries which increases surface area. |
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What is tissue fluid? |
Surrounds cells in tissues, made from small molecules that leave the blood plasma. Doesn't contain red blood cells or big proteins. |
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How does pressure filtration work? |
At the start of the capillary bed, near the arteries, the hydrostatic pressure is greater in the capillaries than in the tissue fluid. Fluid is forced out of the capillaries. As the fluid leaves the hydrostatic pressure reduces in the capillaries so pressure is much lower at the venule end, water re-enters the capillaries. Excess fluid is drained into the lymphatic system. |
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Name structures A - H |
A - Pulmonary Artery B - Aorta C - Vena Cava D - Pulmonary Vein E - Right Atrium F - Semi-lunar Valve G - Atrio-ventricular Valve H - Left Ventricle |
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Atheroma |
A fibrous plaque formed from the build up and hardening of white blood cells, lipids and connective tissue |
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How does an atheroma affect the artery it's in? |
It partially blocks the lumen of an artery and restricts blood flow |
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Aneurysm |
A balloon-like swelling of the artery caused by the formation of artheromas. Blood travelling through a weakened artery at high pressure causes the inner layers of the artery to push through the outer elastic layer. |
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Thrombosis |
The formation of a blood clot. An atheroma plaque can rupture the endothelium of an artery damaging the artery wall and leaving a rough surface. Platelets and fibrin can accumulate at the site and form a blood clot. |
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Myocardial Infarction |
If a coronary artery becomes completely blocked an area of the heart muscle will be cut off from its blood supply so it will receive no oxygen. |
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What are the risk factors for cardiovascular disease? |
High blood pressure - increases risk of damage to the artery walls High blood cholesterol and poor diet - Cholesterol is one of the main constituents of the fatty deposits that form atheroamas Cigarette smoking - CO combines with haemoglobin and reduces the amount of oxygen available to tissues. Reduces the amount of antioxidants in the blood |
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What are risk factors that can't be controlled? |
Having a genetic predisposition to coronary heart disease or having high blood pressure as a result of another condition e.g diabetes. |
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Cohesion Tension Theory |
Water evaporates at the top of the xylem, creating tension, which pulls more water into the leaf. Water molecules are cohesive so the whole column of water in the xylem moves upwards. Water then enters the stem through the roots. |
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What factors affect transpiration rate? |
Light Intensity, Temperature, Humidity and Wind |
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Mass flow Hypothesis |
Source - Active transport actively loads the solutes from companion cells into the sieve tubes, lowering the water potential in the sieve tubes so water enters by osmosis, creating a high pressure. Sink - Solutes are removed to be used up, increasing the water potential inside the sieve tubes so water leaves by osmosis, lowering the pressure in the sieve tubes Flow - There is a pressure gradient from the source to the sink, pushing solutes along the sieve tubes |
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Evidence for the mass flow hypothesis |
1. If a ring of bark is removed from a tree a bulge will form above the ring which has a higher conc of sugars than below because sugars cant move past the area (downward flow of sugars). 2. Using aphids it can be found out that sap flows out quicker near the leaves than further down. 3. A radioactive tracer can be used to track the movement of organic substances 4. If a metabolic inhibitor is put into the phloem, then translocation stops. |
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Objections to the mass flow hyposthesis |
1. Sugar travels to many different sinks not just the one with the highest water potential 2. The sieve plates would create a barrier to mass flow. A lot of pressure would be needed for the solutes to get through. |
