the heart
The heart Intro: The heart is a muscular organ and is responsible fore pumping blood around the body, and on average the human heart beats at 72 beats per minute. When looking at the heart (see diagram) it is important to remember that the left and right side are reversed (due to the way we are looking at it). The right side of the heart deals with deoxygenated blood and pumps it into the lungs. The left side of the heart deals with oxygenated blood, and pumps it around the entire body. The lower chambers of the heart is know as the ventricles and is more muscular and stronger than the upper chambers, known as the atria. This is because a large volume of blood is pumped from the ventricles up through the atria and around the body. It is important to maintain a healthy heart, as it reduces the risk of developing high blood pressure and cholesterol levels, as well as developing heart disease. By eating healthy and doing regular exercise we are able to reduce theses factors as well as reducing stress levels too. Main: The heart is a muscular organ that it part of the cardiovascular system. It is located between the lungs, behind the sternum and is approximately the size of a fist. The heart is protected by a membrane called the pericardium which surrounds the heart and secretes a fluid that reduces friction when the heart beats. The atria's job is to receive blood
The history, development and use of the light and electron microscope
The history, development and use of the light and electron microscope History of light microscope Observing objects in detail greater than the naked eye was very interesting to people at early stage. This led to the construction, in the 16th century, of a magnifier composed of a single convex lens, and this, in turn, led to the eventual development of the microscope. The most famous early pioneers in the history of the microscope are Digges of England and Hans and Zcharias Janssen of Holland. But it was Antony van Leeuwenhoek who became the first man to make and use a real microscope. Leeuwenhoek ground and polished a small glass ball into a lens with a magnification of 270X, and used this lens to make the world's first optical microscope. Because it had only one lens, Leeuwenhoek's microscope is now referred to as a single-lens microscope. Its convex glass lens was attached to a metal holder and was focused using screws. The light microscope system was invented in the seventeenth century. This type of microscope incorporates more than one lens so that the image magnified by one lens can be further magnified by another. Today, the term "microscope" is generally used to refer to this type of compound microscope. Since its invention, the light microscope has made tremendous progress and help figure out many biological molecules. Using a light microscope that he had
The Electromagnetic Spectrum
The Electromagnetic Spectrum The electromagnetic spectrum is the collective name for all types of radiation. Radiation is energy that travels around in waves. The electromagnetic spectrum goes from the waves with the lowest energy to those with the highest energy. Radio Waves Radio waves have the longest wavelengths in the electromagnetic spectrum. They can be from as long as a football to as long as a football pitches. Radio waves carry signals from devices from one place to another invisibly through the air. Radio waves are used for many different jobs: ? In Medicine - radio waves are used to transmit the pattern of a heartbeat through a monitor at a patient's home to a nearby hospital. They are also used to radio the condition of a patient from an ambulance to a hospital. Radio waves are used in medicine when paramedics are dispatched to the scene where they are needed. The hospital can tell the paramedics the condition of the person so that the paramedics can prepare a medical treatment kit. ? In Industry - used mainly in the transportation business. Radio waves can also be used to provide communication on construction sites. ? In Science - radio waves from outside the earth are detected using in radio telescopes. Radio waves are picked up when they hit the antenna of the radio telescope. The wave then goes to the tuner, then to the amplifier, and finally to the
The effect of caffeine on heart rate
Core Practical 1.1 the effect of caffeine on heart rate Aim: The aim of this experiment is to investigate the effect of different concentrations of caffeine on the heart rate of Daphnia (water fleas). Hypothesis: I predict that the concentration of caffeine will affect the heart rate. I believe this will be directly proportional to each other. For example, as concentration of caffeine in the blood increases, the heart rate of the daphnia will also increase. Caffeine is a drug that is classed as a stimulant because it stimulates the body's systems. It increases the activity of the neurotransmitters in your body which speeds up your heart rate, thus blood is pumped faster around the body. Variables: The dependant variable being observed and measured was the number of heart beats per minute of the Daphnia (water flea).The independent variable in this experiment was the concentrations of caffeine 0.5%, 0.6%, 0.7%, 0.8%, 0.9% and 1%. Fair Testing: To make it a fair test: we kept the timing the same for each condition; the environment for the daphnia were kept the same; the type daphnia was kept the same. This made the results valid as caffeine was the only variable that was manipulated in the experiment. Ethics: Since this experiment involves living organisms, ethical issues were raised. Consideration has been taken into account and the following guidelines were used:
Specialised Cells
With the aid of annotated diagrams, discuss the relationship between the structure and function in four specialised human cells. By Mark Cannan. Within the human body the cell is the smallest living organism, it is a microscopic package that contains lots of different organelles that are necessary to survive such as mitochondria, nucleus, Golgi body, rough and smooth endoplasmic reticulum, ribosomes, lysosomes, cytoplasm just to name a few. Cells were first discovered by Robert Hooke, an English philosopher in 1665 and from there, a cell theory was formed. Through the improvement and development of microscopic technologies, cells were looked at even closer and separated into two categories, prokaryotic (bacteria) cells and eukaryotic (animal) cells. There are over two hundred different types (in all shapes and sizes) and it is estimated that there are over 50 trillion cells in the human body. Cells reproduce all the time through mitosis to replace damaged or dead cells. http://en.wikipedia.org/wiki/File:Simplified_spermatozoon_diagram.svg (Accessed 30/10/09) The picture above is an illustrated diagram of a spermatozoon cell, otherwise known as a sperm, which is the male reproductive cell. Starting from puberty and leading through to old age, the testes will produce over a thousand sperm cells every second. The sperm goes through a process called spermatogenesis; this is
Analysis Of Commercial Vitamin C Tablets
Experiment 5 Date: 18-10-2005 Analysis Of Commercial Vitamin C Tablets Objective To determine the mass of Vitamin C in 1 pill of Vitamin C tablet. Introduction In this experiment, the concentration of sodium thiosulphate solution is not given. So, we need to standardize it through titration. Sodium thiosulphate reacts with iodine in the following reaction: I2 + 2S2O32- ----------------->2I- + S4O62- After an amount of S2O32- is added, the solution of I2 turns pale yellow. When starch solution is added and more S2O32- is added, the solution reaches its end point, which is colorless. In this way, the molarity of the thiosulphate solution is determined. Vitamin C could be oxidized by iodine in the presence of acid in the following equation: Due to the low solubility of iodine, direct titration of iodine solution and Vitamin C is unsuitable. Then how could the experiment be done? The experiment could be done by adding acidified Vitamin C solution into potassium iodide solution. Then, we add potassium iodate to allow the following reaction to take place: IO3- + 5I- + 6H+ ----------------> 3I2 + 3H2O I2 formed in this reaction could react with the Vitamin C in as mentioned in the above equation. The I2 not yet reacted would then be titrated against thiosulphate solution, like the first equation, to determine its amount. This method is a kind of back titration. It is
Investigation on whether Rubber obeys Hooke's Rule
Investigation on whether Rubber obeys Hooke's Rule Plan Introduction Hooke's Rule states that extension of a material is proportional to the tension force applied to it unless the elastic limit is reached, which is the point at which the material no longer obeys Hooke's Rule. There are only a few materials that obey this rule. In this investigation, we will find out whether rubber obeys Hooke's Rule. We will measure in detail the way in which the extension of a rubber band depends on the tension in the band. This will be done by applying various amounts of weights, as it is a continual variation. Hooke's Rule = F = ke * F = Force in Newtons * k = Spring constant * e = Extension in Centimetres Rubber is a natural polymer which is made up of long chains of molecules which are bent back and forth with weak forces acting between them. As the rubber band is stretched, molecules straighten out and allow the rubber band to become larger. Eventually, as the molecules become fully stretched, the long chains will become parallel to each other and can stretch up to ten times its original length. Extra force will make the rubber band break. If the rubber is not stretched to breaking, once the force is removed the molecules tend to curl back again into their original position because of the attraction and cross-links between adjacent molecules. The return is elastic. Hypothesis I
Properties of Waves.
Properties of Waves There are many different waves including water, sound, light and radio waves. All waves have the same range of properties, they can all be reflected, refracted, totally internally reflected, diffracted or interfere with each other. Waves are repeated oscillations (vibrations) which transfer energy from one place to another. Sound energy in the atmosphere is transferred by the oscillation of air molecules. Movement energy in water waves is transferred by the oscillation of water molecules. Amplitude is the measure of the energy carried by it. Frequency (f) is the number of complete wave cycles per second and is measured in Hertz (Hz). Wavelength (?) is the distance between two successive peaks or troughs and is measured in metres, m. Reflection Light waves travel in straight lines but reflecting them using mirrors can alter their direction. Reflection is the bouncing off of any type of wave from a surface. Reflection can be used to guide a laser past obstacles to a receiver. Shiny surfaces such as mirrors are smooth so reflect all light strongly as all the waves pass in one direction only. Rough surfaces look dull as they reflect light in many different directions causing it to scatter. This is called diffuse reflection. If light waves are reflected, the colour of the surface affects the colour of the reflected ray. Concave surfaces are used
To investigate the effect of temperature on the enzyme catalase.
To investigate the effect of temperature on the enzyme catalase Aim: To investigate the effect of temperature on the enzyme catalase Apparatus Celery extract (catalase) Labels 20 Volume hydrogen peroxide Distilled water 6 100cm beakers 20cm and 50 cm measuring cylinders Balance Stopwatch Trough Clamps & stand 50cm conical flask + bung + tubing + 3 way tap 0cm syringe Beehive shelf Gas syringe Goggles Water bath at 25 & 35°C 250cm beakers & thermometer for water bath Method .Weigh out 1 sample of celery extract of 10g in a conical flask. 2.Place in a water bath at 25°C. 3.Place about 20cm hydrogen peroxide solution in a container in the same water bath. 4.Leave for 10 min to equilibrate. 5.Set up the apparatus as follows: -Fill a trough with water -Fill a measuring cylinder with water and invert in the trough (ensure that no air bubbles are in the water) -Secure the cylinder with a clamp & stand -Position the bung and 3 ways tap to fit on a conical flask, ensure that this can be held in place with a clamp & stand -Put the end of the tubing in the measuring cylinder 6.Make sure that the tap is closed and fill a syringe with 10cm hydrogen peroxide from the water bath. 7.Take the first conical flask containing the celery extract; arrange the apparatus as above and empty the syringe into the flask closing the 3-way tap start the stopwatch.
