Applied Science

Respiration and the vascular system expained.



Aerobic Respiration

Glucose + Oxygen = Carbon Dioxide + Water + Energy

Anaerobic Respiration

Glucose = Lactic Acid

Why is Respiration so Important?

Growth, sensitivity, nutrition, movement, excretion and reproduction all involve chemical changes that require energy. Respiration provides the energy in the form of ATP, required by these life processes.


  • Muscle contraction
  • Sqimming of spearms
  • nerve impulse transmission
  • active transport

Aerobic respiration takes place in the mitochondria.

Anaerobic takes place in the cytoplasm.

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A molecule of ATP is formed when three phosphate groups are attached to a molecule called adenosine. Energy is required to attach the phosphates, particularly the third.Respiration provides this energy. ATP is produced during respiration. When ATP is broken down, e.g. ATP to ADP (adenosine diphosphate) this energy is released. ATP is used as a means to transfer energy from one process to another. (

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Using Energy

Aerobic respiration goes on only in the presence of oxygen. Anaerobic respiration can take place in the absence of oxygen.

Anaerobic has 2 molecules of ATP per molecules of glucose. Anaerobic has 2 molecules of ATP per molecule of glucose.

Oxygen Debt

The lactic acid produced during anaerobic respiration is transported to the liver. Here it is converted into a 3-carbon compound which can be used to produce ATP when the oxygen balance is rstored. Whilst exercising, the extra oxygen breathed in is used to oxidise the lactic acid formed. ATP is on credit and the extra oxygen is to pay back the oxygen debt.

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The Vascular System

The human heart has 4 muscular chambers. There are two atria (singular atrium) and two ventricles. When you are standing up blood can pass from the right atirum into the right ventricles below it, similarly on the left of the heart. the atrium and ventricle on each side of the heart are separated by a valve - an atriventricular valve. The same thing will happen if you are upside down. This is possible because blood moves under pressure and back flow is prevented by the valves. there are valves at the places where blood enters or leaves the heart.

Double circulation

You can think of the heart as having two functions. These are to pump blood:

  • to and from the lungs to enable oxygen to be picked up and to excrete carbon dioxide - pulmonary circuit
  • to and from the body to meet the needs of the cells in body tissues - the systematic circuit.
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The Vascular System

Contraction of the cardiac muscle in the walls of the atria moves blood past the atrioventricular valves into the ventricles. The tricuspid valve is on the right and bicuspid (also known as the mitral valve) on the left. Ventricular contraction moves blood though the semilunar valves of the pulmonary artery and aorta. In a healthy heart this arrangement keeps oxygenated and deoxygenated blood apart improving the efficiency of the circulatory system.


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