Core body temperature: 37 oC
When the body‘s core temperature increases or decreases by only a few degrees, the body must find a way to alter the temperature. It does this by utilising Poiseuille’s law. This means that if, for example, the core body temperature rises by too much the blood vessels will dilate to allow more blood to flow to the surface of the body in order for the excess heat to escape.
The volume of blood in the vessels near the surface of the skin will rise because the tube will dilate, using Poiseuille’s law, if the radius increases by 5% the volume of blood will increase by 20%.
When an individual gets out of a hot bath, they might feel dizzy and have palpitations, this is because the body temperature has risen too much, the heart pumps the blood faster so that it can get to the body surface faster to be cooled down, the blood pressure increases so that the blood can be pushed into the smaller blood vessels. The person feels dizzy probably because the blood vessels near the internal organs such as the lungs or brain have constricted in order to protect them from the high temperatures, during this time these organs will have a reduced blood supply.
Too hot?
Initially the body responds to heat by sweating and by circulating blood closer to the skin's surface by dilating the blood vessels in order to lower the core body temperature, this works by circulating the blood close to the surface so that it can loose the excess heat.
In the first instance Heat rash will appear. This is an early signal of potential heat stress. Heat syncope, which is dizziness or fainting whilst standing in the heat for long periods. Heat cramp painful cramps or spasms in the legs, arms, or abdomen. Heat exhaustion results from the reduction of body water content or blood volume. The individual may suffer with all or any of the following symptoms: heavy sweating, flushed, or pale skin, weakness, dizziness, nausea, rapid and shallow breathing, headache, vomiting, or fainting.
Too cold?
Blood vessels close to the surface of the body constrict, so that cold air does not cool the blood down too much the body will also use other mechanisms such as sending the muscles into spasm (shivering), therefore not reach the internal organs such as the heart and brain when it returns. In the event of the core temperature dropping to low (below 35 oC) an individual will become hypothermic. If exposed to the cold for too long and the blood vessels having been constricted the tissue will become ischaemic and die, this is called frostbite, which mainly affects the ears, nose, fingers and toes, in milder cases it causes chilblains, in extreme cases it can lead to thrombosis and dry gangrene.
C)
Calculate the amount of glucose required to make half a litre of a molar solution of glucose.
The molecular formula for glucose is
C6H12O6
180.156 g of glucose equals 1 mole of glucose
To make a one molar solution of glucose you would add 180.156 grams of glucose (1m) and add 1000ml of water making a litre of a molar glucose solution, divide this by two leaving ½ a litre of molar glucose solution.
D)
Write the following chemical reaction equations in symbols and balance them
- Hydrogen peroxide decomposing into water and oxygen.
Hydrogen peroxide = H2O2
Water = H2O
Oxygen = O2
2H2O2 → 2H2O + O2
- Magnesium and oxygen into magnesium oxide.
Magnesium = Mg
Oxygen = O2
Magnesium oxide = MgO
Mg + O2 → 2MgO
- Sodium hydroxide and hydrochloric acid into sodium chloride and water.
Sodium hydroxide = NaOH
-
Sodium = Na
-
Oxygen = O2
-
Hydrogen = H
Hydrochloric acid = HCl
-
Hydrogen = H
-
Chloride = Cl
Sodium chloride = NaCl
-
Sodium = Na
-
Chloride = Cl
Water = H2O
NaOH + HCl → NaCl + H2O
E)
What can affect the rate of a chemical reaction?
Temperature
When temperature affects the rate of a chemical reaction it usually speeds it up. This happens because the heat makes the particles move at a faster rate and therefore the reaction happens much faster.
Concentration
When there is a higher concentration of a substance the chemical reaction will either increase or decrease depending on the substance. e.g. A higher concentration of hydrogen peroxide to Catalase will increase the rate that the H2O2 Is broken down
Particle Size
Catalysts
Experiments
1) Diffusion of ink in water at different temperatures
Describe the experimental method and results. Use the Kinetic theory of matter to explain the results.
Molecules move from an area in which they are highly concentrated to an area in which they are less concentration in a process called diffusion. This process describes the movement of molecules through air, a liquid, or in and out of a cell. It continues until the system reaches a state of equilibrium in which the molecules are randomly distributed throughout the whole system.
Apparatus:
5 glasses of water
ink
a dropper
Observations
At first, the molecules of ink are close together in the cold water, as the water temperature is increased the water molecules and the ink molecules bump into each other much more, as the water molecules have more energy, and become mixed. The water turns blue quicker. There are many factors that will affect the rate of diffusion. Kinetic energy is frequently measured by temperature. Molecules in a higher temperature system will diffuse more quickly because they have more energy and move more quickly.
2) Osmosis of water into a raisin
Hypotonic: A low solute concentration
Hypertonic: A high solute concentration
Apparatus:
Raisins
A drinking glass
Stopwatch
A raisin was placed in a glass of water and left for five minutes; it began to plump out and became a more smooth oval shape, rather than a shrivelled and wrinkly oval.
The water in the glass is hypotonic, a low solute concentration, therefore it will move into the raisin, which is hypertonic, where the concentration of solute is high. This means that a state of equilibrium is met. In the body red blood cells for example, cannot survive in a state of hyper/hypotonicity if the concentration out side the cell is too high they will swell and burst (haemolyse), if the concentration is too low they will shrivel up (rather like the raisin in the experiment).
Observations and Comments:
I would like to have done this experiment using higher and lower concentration of solutions rather than just tap water. It would have been interesting to see if anything else might happen other than equilibrium being reached.
3) The effectiveness of Catalase as a catalyst.
The Breakdown Of Hydrogen Peroxide In The Presence Of Catalase
Hydrogen peroxide will breakdown to oxygen and water in the presence of Catalase.
Apparatus
Hydrogen peroxide
In quantities of 4, 8,12, 16 and 20 vols.
A potato
A cork borer
A stopwatch
A ruler
Rubber tubing and a glass tube
A bung
A water bath
A measuring cylinder
5 tubes of potato 10mm in diameter were bored from a potato using a cork borer. 5 disks of 1mm thick were cut from each tube. 25ml of hydrogen peroxide was then measured and added to the flask. Care was taken to view the flask from the side to ensure correct measurement. 5 pieces of potato were placed in to the flask. The experiment was then repeated for different vols of Hydrogen peroxide.
Measurements
Observations
In the flask it was clear that a reaction was taking place by the observation of bubbles of oxygen gas being released creating a fizzing effervescent reaction, rather like a soluble aspirin. From this experiment I can conclude that a higher concentration of H2O2 will cause a faster reaction between the H2O2 and the Catalase. The higher the concentration of Hydrogen Peroxide the more oxygen is given off in the decomposition.
Factors that may have affected the experiment:
1) I was restricted by time, it would have been better to have left the experiment to work for longer.
2) The rate of reaction could be affected by movement, i.e. if the flask containing the potato and Hydrogen Peroxide was moved it would have increased the rate of decomposition.
3) A certain amount of user error can be attributed to the experiment as I was working alone it was quite difficult to keep the equipment still, therefore keeping an accurate amount of water in the tube that was measuring the oxygen was quite tricky.
References
Books:
Brooker.C., Human Structure and Function (se), Mosby, 1998, London
Marieb.E., Human anatomy and physiology (se), Benjamin Cummings,1992, USA
Bailliere’s Nurses Dictionary 23rd edition Harcourt 2000
Journals:
Websites:
http://newton.dep.anl.gov/askasci/bio99/bio99317.htm
http://www.bham.lib.al.us/tech/sciencefair.htm
UNIT 3 BTEC National Diploma Health Studies 27/04/2007
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