Saturday, 17 December 2011

2.24a Sources of Food

Recall sources and describe functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, and the mineral ions calcium and iron, water and dietary fibre as components of the diet.

There are a number of different types of grass which having flowered, forms seeds. These seeds are forms of starch provides most of the carbohydrates of our diets, for example, rice and wheat. Another well known source of carbohydrate which are the root tubers of the potatoes. Which is also stored starch and that is a form of carbohydrate. Carbohydrate provides us energy through the process of respiration.

Animal  proteins is a well known source of protein and animals such as cows, fishes, pigs, chicken form a large part of the world's protein diet. Plants provide protein through the form of beans or seeds. Protein is associated with growth and repairing cells.

From animals such as cows you would get fat but from animals such as fishes you would get oil and from plants we would get things such as oils, for example, palm oil, sun flower oil. These are associated with stored energy and also insulation.

Wednesday, 7 December 2011

2.5 Elements in biological molecules

Recall the chemical elements present in carbohydrates, proteins and lipids (fats and oils).

The elements present in a carbohydrate is Carbon, Hydrogen and Oxygen (CHO). The simple molecule in carbohydrates are sugars and the larger molecules are the polysaccharites e.g. starch.

The elements present in a protein is Carbon, Hydrogen, Oxygen and Nitrogen (CHON). The simple molecules of proteins are amino acids and the larger molecules are proteins itself.

The elements present in lipids are Carbon, Hydrogen, Oxygen (CHO). Lipids can be split into two categories - the fats and the oils.

Even though lipid and carbohydrates consists of the same elements, the structure is very different from one another. 

2.66 Circulation

Recall the general plan of the circulation system to include the blood vessels to and from the heart, the liver and the kidneys.

Let's start of with some revision:
When blood comes out of the heart it is an artery. When blood comes in the heart its in an vein. The word for lung in biology is pulmonary. The word for liver is hepatic. The word for kidney is renal.

Description: Blood leaves the right ventricle and enters the lungs through the pulmonary artery, then the blood leaves the lungs and enters the left atrium of the heart through the pulmonary vein. Blood then leaves through the major artery - the aorta - through the left ventricle. The Aorta then branches out to the liver and this smaller blood vessels travels through the liver but is still travelling from the heart which is called the hepatic artery. A branch of the aorta travels to the kidney and since this branch is carries blood to the kidney it's called renal artery. Blood returns to the heart through a blood vessel which is called the vena cava. Blood in the liver travels through the capillary and through a vein called hepatic vein. The vein leaving the kidney is called the renal vein.

Tuesday, 6 December 2011

2.65b Blood Vessels

Describe the structure of arteries, veins and capillaries and understand their roles.

The artery is carrying blood in high blood pressure. The walls of the artery is fairly thick, containing muscles. The lumen would be narrow which carries the blood. The muscle contracts and we can see this 'maintains' the blood pressure.

The capillary is the sight of exchange. The capillary walls are very thin (one cell thick) this capillary will have a diameter of a red blood cells.

The vein returns the blood to the heart under low pressure. So although the veins are large, the vein will have a large lumen so the pressure is kept low (low resistance). We can also find that they have valves to stop blood from flowing down.

2.65a Blood vessels

Describe the structure of arteries, vein and caprillaries and understand their roles.

Arteries take blood away from the heart and the high in the arteries are under high pressure. Blood is delivered to another part of the body.

All veins take blood to the heart. Veins take blood which are under low pressure. Blood in veins returns from the organ.

Between the vein and the artery the blood vessel travels through the organ and where the contents of the organ and exchanged with the blood. The blood vessels in the organ are called carpillary. Substance goes into and out of the cell e.g. Oxygen in, Carbon Dioxide out.

264 Heart Output

Understand that the heart rate changes during exercise and under the influence of adrenaline.

Excercising involves muscle contractions and this muscle contract requires energy, this energy is produced by increased levels of muscle cell respiration. So the muscle cell needs more oxygen and the removal of carbon dioxide. By increasing heart rate we can supply more blood and therefore more oxygen and we can remove more carbon dioxide.

 By increasing the output of the heart, more blood is sent to the heart and more carbon dioxide is moved to be excreted by the lungs. The heart can also be influenced by hormones and the particular hormone is adrenaline; this is produced in the adrenal glands which sits on top of the kidney.

This travels to the heart through the blood stream and increases in heart rate. The stimulus for the production includes fear, anxiety, danger. This results in an increase in heart rate. A faster beating heart sends more oxygen and glucose to the body so that they can have more movement or exercise

Friday, 2 December 2011

2.63c Coronary Arteries

Describe the structure of the heart of how it functions.

Heart muscles get its blood supply through the coronary artery. The coronary artery is a branch of the Aorta. So the Aorta leaves the heart and branches to form the coronary artery which takes nutrients such as glucose and oxygen to the heart. The coronary artery is the red blood vessels sweeping across the surface of the heart.
Because of a number of factors including dietary fats, the coronary arteries can become blocked.
If the central part (lumen) becomes blocked the heart would receive less nutrients and less oxygen. This blockage could be a partial blockage which reduces blood flow. A patient suffering from this will suffer from this is experience Angina (heart pain). A serious version of this would be where the coronary artery will completely blocked which is called Myocardial Infarction. If the coronary artery is blocked than all the heart cells supplied by the coronary artery will be deprived or oxygen and nutrients. The cells in that part will begin to die and this is what is better known as a heart attack; when severe this can lead to death. Coronary bypass is where the surgeon re-route the blockage using a extra blood vessel. 

2.63b Heart Function

Describe the structure of the heart and how it functions

Cardiac Cycle = Heart Beat
A normal human heart beat would be around 60 beats per minute (bpm).
Which is one beat per second so the cycle is taking one second.

In the diagram it shows the heart in its Diastole (relaxed) state, all three valves are closed here (semi-lunar valve, bicuspid valve and tricuspid valve)
In this diagram, the heart is still in the state of diastole which means that it is still relaxed, but the atrium is filled with blood this time. This is because the veins (the pulmonary vein and the vena cava) are bringing blood back into the heart. All three valves are still closed.
In the diagram below, the bicuspid and tricuspid valves had opened. The reason for this is because the pressure in the atria is larger than the pressure in the ventricles. So the ventricles fill with blood and a final contraction of the atria and forces blood down the ventricles and stretches the walls of the ventricle and fill up the final volume of the ventricles.
In the fourth diagram, the valves have closed again including the semi-lunar valve. We have contraction of the walls of the ventricle which is also called systole. In which the heart is contracting, which increases the pressure of the blood in the ventricles. Since the ventricle pressure is greater than the atria pressure the valves are now closed. This causes what is known as the first heart sound.'lup'  The semi-lunar valve are still closed, so the blood there are under increasing pressure since it can't escape.
In the fifth stage, the ventricle pressure is larger than the artery pressure so that the semi-lunar valve have both opened. What happens is we eject the pulse of blood into the artery (pulmonary artery and the aorta).
In the last stage, the heart has returned to the state of diastole. The arterry pressure is greater than the ventricle pressure which means the semi-lunar valve both closes together. This causes the second heart sound. 'dup'