We investigated the density of mock blood in order to see the effect of exercise and altitude on the blood's efficiency at carrying the oxygen around the body.

Biology Coursework James Batchelor

Introduction

We investigated the density of mock blood in order to see the effect of exercise and altitude on the blood’s efficiency at carrying the oxygen around the body.

We tested out three mock blood samples. Sample A, the control sample, represents the blood of a normal, healthy adult male who lives at sea level. Sample B represents blood taken from the same male after he has undergone six months regular aerobic exercise. Sample C represents blood taken from the same male after he has spent three months undergoing aerobic training at high altitude.

The relative density of protein-carrying fluids, such as blood, can be determined by measuring the rate at which drops of ‘blood’ fall under gravity through copper (II) sulphate solution, since a layer of copper proteinate forms around each drop, preventing the dispersal of the ‘blood.’

Research

Red Blood Cells - red blood cells are the primary carriers of oxygen to the cells and tissues of the body. The biconcave shape of the cell is an adaptation for maximizing the surface area across which oxygen is exchanged for carbon dioxide. Its shape and flexible plasma membrane allow the red blood cell to penetrate the smallest of blood capillaries.

The red blood cells are round discs, concave on two sides, and approximately 7.5 thousandths of a millimeter in diameter. In humans, and most other mammals, the mature red blood cell contains no nucleus; in some vertebrates, it is oval, and nucleated. Haemoglobin, a protein in the red blood cells, is the most prevalent of the special blood pigments that transport oxygen from the lungs to the body cells, where it picks up carbon dioxide for transport back to the lungs to be expired.

Haemoglobin - Haemoglobin is the most prevalent of the special blood pigments that transport oxygen; it is present in all but the least complex of animals. It participates in the process by which blood carries required nutrients to the cells and transports their waste products to the excretory organs. Haemoglobin also carries oxygen from the lungs or gills, where blood is oxygenated, to body cells. When saturated with oxygen it is called oxyhaemoglobin. After haemoglobin releases oxygen to the body tissues, it reverses its function and picks up carbon dioxide, the principal product of tissue respiration, for transport to the lungs, where it is expired. In this form, it is known as carboxyhaemoglobin.

Haemoglobin is a protein that is contained entirely in the red blood cells, amounting to perhaps 35 per cent of their weight. To combine properly with oxygen, the red blood cells must contain adequate haemoglobin; this, in turn, depends on the amount of iron in the body. The organism derives its store of iron by absorption from the gastrointestinal tract. The organism conserves and constantly reuses the supply of iron. A deficiency of haemoglobin caused by a lack of iron leads to anaemia.

Haemoglobin carries more than 20 times its volume of oxygen. It combines so firmly with carbon monoxide that it can no longer combine with oxygen; this causes asphyxiation. After a life of perhaps 120 days, red blood cells are destroyed in the spleen or, in the course of circulation, their haemoglobin is broken into its constituents, including iron, which enters new blood cells formed in the bone marrow. When blood vessels rupture, as in an injury, the red cells are released and escape into tissue, where they are broken down. The haemoglobin is converted into bile pigments, the colour of ...

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Alterations in the structure of haemoglobin can lead to life-threatening illnesses. The most important of these conditions is sickle-cell anaemia, which involves a hereditary change in one of the amino acids that make up haemoglobin. The thalassaemias are a group of hereditary diseases of similar origin.

Hypoxia

Hypoxia is the term for a lack of oxygen. This can be caused by many things, including living and training at high altitudes. In this situation, the body tries to maximize the delivery of oxygen to the tissues, by way of aerobic respiration. This increases the heart rate. After a few days at altitude, water is absorbed from the circulation, concentrating to the Red Blood Cells. Finally, after a few more weeks, the kidneys secrete erythoprotein, which increases production of Red Blood Cells from the bone marrow.

Physical Training

Doing physical exercise or training increases the need for haemoglobin. The total blood volume is increased, probably because blood plasma increases. Thanks to this increase in volume, the Haemoglobin concentratiotn is usually unchanged.

Hypothesis

My null hypothesis is that there will be no significant difference between the results of mock blood A and mock blood B, and no significant difference between mock blood A and mock blood C.

My hypothesis is that Sample C will be quicker at passing through the copper sulphate solution the quickest, since the blood adapts after being at high altitudes for a long time so that it can pass through the body quicker.

I also predict that B will be quicker than A but not C at descending through the copper sulphate solution. This is because sample B was taken after exercise, which affects the density, but A was not so the density will be ordinary, and C was taken after exercise at higher altitudes, making it denser than B, meaning it will pass more quickly.

Method

First, we mixed some copper sulphate solution. We did this by adding 24g of copper sulphate powder to a litre of water, and shaking this until the powder was completely dissolved, creating copper sulphate solution.
We then filled a measuring cylinder with this solution until the liquid level was well above 100cm3. We then took a syringe full of Mock Blood Sample A and dropped a drop of blood just above the liquid level.
As the drop of blood descended through the water, we timed how long it took for the drop to descend between 100cm3 and 10cm3 on a stopwatch.
We then repeated this another 19 times with sample A in order to collect 20 results. We then did the same experiment 20 times for Sample B and 20 times for Sample C.

To make this a fair test, we used the same copper sulphate solution for each test and the different measuring cylinders for each mock blood sample. We also used a different syringe for each mock blood sample. These measures were taken to prevent cross-contamination and ensure the accuracy of our results.

Results

Analysis of Results

The null hypothesis is that there will be no significant difference between the results of A and B, and the results of A and C.

The Mean

Mean= the sum of the results, divided by the number of the results.

The mean of the tests on sample A was 10.18 seconds

10.03 + 7.60 + 6.47 + 10.29 + 8.84 + 8.89 + 14.16 + 11.78 + 10.84 + 9.94 + 10.64 + 10.95 + 10.70 + 11.07 + 9.80 + 10.26 + 10.31 + 11.09 + 6.50 + 12.58 = 203.6

203.6 divided by 20 = 10.18

The mean of the tests on sample B was 9.03 seconds

9.37 + 11.31 + 8.00 + 8.21 + 9.60 + 9.17 + 9.70 + 10.74 + 12.21 + 10.57 + 9.27 + 8.84 + 10.01 + 8.65 + 8.78 + 9.31 + 8.14 + 8.82 + 6.94 + 8.88 = 180.6

180.6 divided by 20 = 9.03

The mean of the tests on sample C was 7.46 seconds

7.11 + 6.07 + 8.40 + 7.89 + 6.80 + 6.80 + 7.40 + 6.49 + 7.95 + 7.24 + 6.14 + 7.11 + 9.74 + 8.46+ 6.75 + 6.05 + 7.41 + 6.78 + 8.63 + 10.02 = 149.2

149.2 divided by 20 = 7.46

The Standard Deviation

The Standard Deviation is the square root of the sum of the results squared minus the sum of the results squared divided by the number of results, divided by the number of results. [That makes no sense.]

The standard deviation for the Sample A test was 44.37359125

(1.) Sum of results squared = 203.6 x 203.6 = 41452.96

(2.) (1.) divided by number of results= 41452.96 divided by 20 = 2072.648

(3.) (1.) minus (2.) = 41452.96 – 2072.648 = 39380.312

(4.) (3.) divided by number of results = 39380.312 divided by 20 = 1969.0156

(5.) The square root of (4.) = 44.37359125

The standard deviation for the Sample B test was

(1.) Sum of results squared = 180.6 x 180.6 = 32616.6

(2.) (1.) divided by number of results= 32616.6 divided by 20 = 1630.818

(3.) (1.) minus (2.) = 32616.6 – 1630.818 = 30985.782

(4.) (3.) divided by number of results = 30985.782 divided by 20 = 1549.2891

(5.) The square root of (4.) = 39.3610099

The standard deviation for the Sample C test was

(1.) Sum of results squared = 149.2 x 149.2 = 22260.64

(2.) (1.) divided by number of results= 22260.64 divided by 20 = 1113.032

(3.) (1.) minus (2.) = 22260.64 – 1113.032 = 21147.608

(4.) (3.) divided by number of results = 21147.608 divided by 20 = 1057.3804

(5.) The square root of (4.) = 32.51738612

The t-Test

To compare sample A (x1) with sample B (x2)

To calculate the value of t

(1.) Mean 1 minus Mean 2 = 10.18 – 7.463 = 2.717

(2). S1 squared divided by number of results = 2.3732 divided by 20 = 0.11866

(3). S2 squared divided by number of results = 49.43911 divided by 20 = 2.4719555

(4.) (2) plus (3) = 0.11866 + 2.4719555 = 2.59060155

(5.) (1) divided by the square root of (4) = 1.688065632

T = 1.688065632 degrees of freedom = number of results in test A + number of results in test B – 2 = 20 + 20 – 2 = 38

Critical value= 2.024

2.024 > 1.688065632

The critical value is greater than the t value so there is a significant difference between the two sets of results.

To compare sample A (x1) with sample C (x2)

To calculate the value of t

(1.) Mean 1 minus Mean 2 = 10.18 – 9.179 = 1.001

(2). S1 squared divided by number of results = 2.3732 divided by 20 = 0.11866

(3). S2 squared divided by number of results = 2.177179 divided by 20 = 0.10885895

(4.) (2) plus (3) = 0.11866 + 0.1088595 = 0.2275195

(5.) (1) divided by the square root of (4) = 2.098576306

T = 2.098576306 degrees of freedom = number of results in test A + number of results in test C– 2 = 20 + 20 – 2 = 38

Critical value= 2.024

2.024 < 2.098576306

The critical value is lower than the t value so there is not a significant difference between the two sets of results.

Conclusion

The t-test clearly shows that there is a significant difference between the results of mock blood A and mock blood C. This shows that mock blood C is much denser than mock blood A, making it better for carrying oxygen.

At higher altitudes, there is less oxygen. The body, therefore, creates more and more red blood cells, and these carry more haemoglobin, allowing for more oxygen to be carried around the body. The presence of more red blood cells makes the blood denser, or heavier, making it travel through the body faster, allowing for faster and, therefore, more efficient delivery of the blood around the body. Mock blood C is denser since it represents blood taken from a normal, healthy adult after he has spent three months undergoing aerobic training at high altitude. In these conditions, the number of red blood cells would increase dramatically, thus making the blood denser.

The t-test also shows that there isn’t a significant difference between mock blood A and mock blood B, although B is slightly denser than A, since it needs to carry more oxygen.

Exercise creates a larger need for oxygen, since oxygen is being used up much quicker by aerobic respiration. Like at higher altitudes, more red blood cells are created, but not on a scale even close to that of red blood cell production at high altitudes. This will make the blood slightly denser, in order to provide a faster and more efficient delivery of oxygen to the areas that need it, such as the limbs. This is shown by mock blood B, which, though it didn’t become as dense as mock blood C, it did become denser than A.

Evaluation

There were a few faults, mostly unavoidable, with the implementation of the experiment. Firstly, the drops of mock blood dispersed into random shapes as they entered the copper sulphate solution. The different shapes descended through the solution at different speeds. There is no way of controlling this, so the results can never be entirely accurate. Also, there was no way of measuring the distance between the needle and the liquid level before we dropped the blood drop into the solution so there is no way of accurately making sure that the experiment was carried out exactly the same way each time. Finally, though I used the same solution and measuring cylinder for each blood sample, the later results in each experiment could have been affected by the piles of previous blood drops lying at the bottom of the measuring cylinder.

These three faults provided the largest margin of error, but were unavoidable. Aside from these, the implementation was as accurate and fair as I could make it. If I were to do the experiment again, I would, time permitting, find ways of minimalizing these margins of error, e.g. finding some way to measure the distance between the syringe needle and the liquid level.