Atherosclerosis + Blood clotting

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  • Created by: Millie
  • Created on: 04-05-13 18:58

Atherosclerosis steps

  • Damage to the endotheilal lining of an artery (e.g by smoking or high bp)
  • This causes an inflammatory response and white blood cells move into the artery wall, but these cells accumulate cholesterol from the blood and a deposit called an atheroma forms
  • Calcium salts and fibrous tissues build up at the site resulting in plaque formation. 
  • The build up of fibrous tissues means that the arterial wall loses some of its elacticity = hardens 
  • Plaques cause a narrowing of the artery which makes pumping the blood around the body more difficult, resulting in raised BP causing a dangerous positive feedback 
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Blood Clotting steps

1. A cascade of events

2. Damage to a blood vessel.

3. Damage exposes collagen fibre to which platelet attatch and release thromoplastin          ( soluble plasma protein)

4. In the presense of calcium ions and vitamin K thromboplastin converts inactive thrombin into actve thrombin ( enzyme)

5. Active thrombin converts soluble fibrinogen into insoluble fibrin 

6. The insolule fibrin forns a network of fibres, trapping cells and debris to make a clot 

*fibrinogen is a plasma protein 

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Carbohydrates: monosaccharides & disaccharides

Carbs = Carbon,hydrogen and oxygen (CH2O)n

Monosaccharides: Glucose, galactose and fructose

Glucose= Main substance for respiration. Soluble and has an osmotic effect

Glactose= soluble, osmotic effect, has same structure as glucose but the -OH groups are both up.

Fructose = fruit sugar, osmotic effect

Dissacharides. Sucrose =fructose and glucose. lactose= galactose + glucose. Maltose= glucose + glucose. All are soluble

The bonds that link dissacharides together are glycosidic bonds and they are made through condensation reactions ( loss of a water molecule) Hydrolysis breaks the glycosidic bond, adding back a water molecule ( catalyzed by enymes)

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Polysaccharides

Amylose.

Structure = unbranched. Found in starch - energy storage molecule in plants. Made of alpha glucose in tight spirals so it's very compact.1,4 glycosidic links. Insoluble, so no osmotic effect

Amylopectin

Structure = branched. Found in starch - energy storage molecule in plants. Branched alpha glucose molecules - lots of terminal ends so it's digested ( hydrolised) more quickly than amylose. 1,4 & 1,6 glycosidic links. Insoluble, so no osmotic effect.

Glycogen

structure= branched. Energy storage molecule in animals, bacteria and fungi. Brached chains of glucose molecules. Compact, insoluble, no osmotic effect

Note* monosaccharides are easily/ quickly hydrolysed <- sharp rise in blood sugar levels

Di and poly saccharides have to be broken down first <-takes time does not cause sharp rise

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Risk factors for CVD

Gender: Oestrogen gives women some protection from CVD before the menopause. Then the risk in both sexes is about the same

Ageing:Elasticity and width of arteries decrease with age

Smoking: Chemicals in smoke damage arterial lining and also cause them to constrict

Genetic: Some people have a tendency to have high BP and poor cholesterol metabolism/ arteries that are more easily damaged + mutations in genes that affect relative HDL:LDL levels in blood.

High BP:High bp should not be above 140/90 as it can damange arteries

Inactivity:regular exercise reduced the riskof CVD by reducing BP and raising HDL levels

Obesity: increases risk of CVD and developing type II diabetes

Diet: Diets high in sat fat, cholesterol and lipoprotein levels

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Scientific studies

Cohort studies: a group of people are followed over time to see who develops the disease

Case control studies: a group of people who have the disease are compared with a group who do not have the disease

Cohort studies main features: Large no. of people followed, long period of time; monitored to see if they develop the condition under the study; those who develop the condition are put in one groupd and those who do not in another; various risk factors that subjects have been exposed to are looked at ( by interviewing), correlations are searched for.

Case-control studies 

main features: A group with the condition ( cases) is compared with a group who do not have it ( control); past history is investigated to try to identify factors leading to one group having the disease anf the other not; the case goup and control group have to match in age and gender; it's like the classical experiement where independent variables are controlled

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A good study...

The sample has to be representative of the whole population, otherwise the sample could be biased

Variables should be controlled as far as possible when selecting cohort groups or case-control studies . 

Measurement techniques or questions in a questionaire should be standardized

Sample sizes have to be large enough.

If the study can be repeated in different places with different people and the result is still the same each time the study can be said to be valid

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Perceived risk / Actual risk

Own experience often carries more weight than statistics

inability to assess risks well e.g.,  people will smoke as they know that it keeps weight down, but the relative risks of obesity and smoking are not considered

Peer pressure: v. powers esp. in terms of alcohol

The remoteness if the likely consequence : a bag of crips now tastes good now and people are not very likely to thinkofthe possibility of having an incrased risk of a heart attack in 30 years.

Estimating risk :

People with the disease/ total population 

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Perceived risk / Actual risk

Own experience often carries more weight than statistics

inability to assess risks well e.g.,  people will smoke as they know that it keeps weight down, but the relative risks of obesity and smoking are not considered

Peer pressure: v. powers esp. in terms of alcohol

The remoteness if the likely consequence : a bag of crips now tastes good now and people are not very likely to thinkofthe possibility of having an incrased risk of a heart attack in 30 years.

Estimating risk :

People with the disease/ total population 

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Vitamin C ( core practical)

You need to make a calibration curve 1) Make up several vit c concentrations of different, known concentrations.

2) measure out a set volume of DCPIP (at a set concentration) into a test tube

3)Add one of the vitamin c solutions to the DCPIP, drop by drop, using a pipette 

4) gently shake the test tube for a set amount of time after each drop of vitamin C solution is added

5) When the solution turns colourless, record the volume (no. of drops) that has been added

6)Repeat the experiment twice more, with the same solution and take an average of the three readings

7) All other variables should be kept constant e.g temperature

8) Repeat the above procedure with each solution

9) Use the results to make a line graph, showing the volume of vitamin c against its concentration -this is the calibration curve

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