GCSE Edexcel Additional Biology : Respiration

gcse science edexcel biology B2 Respiration

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What is Respiration?

- Definition : breathing, the bodily process of inhalation and exhalation; the process of taking in oxygen from inhaled air and releasing carbon dioxide by exhalation

- In scientific terms, it is the process of breaking down glucose to release energy, which goes on in every cell

It is used to things like :

 -break down larger molecules like protiens

- contract muscles

- maintain a steady body temperature 

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Types of Respiration

There are two types of Respiration.

Aerobic (with air) and Anaerobic (without air)

The word equation for aerobic respiration is :

Glucose + Oxygen---> Carbon Dioxide + Water (+Energy)

Aerobic respiration is the simple an efficient way of releasing energy from glucose.

Anaerobic respiration happens without oxygen. It happens when not enough oxygen is available. It does not release as much energy as aerobic, and is useful for emergencies only. You tend to use it when you exercise because when you exercise you respire more.

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More on Types of Respiration

When you do really vigorous exercise like sprinting, your body can't supply oxygen to your muscles quickly enough, so they start to respire anaerobically.

However, you cannot use anaerobic respiration for too long as it produces a build up of lactic acid in your muscles, which is painful and can cause a cramp. 

An advantage is that at least you can keep using your muscles for a while longer.

After the use of anaerobic respiration, when you have stopped exercising you have an oxygen debt.

An oxygen debt is just a lack of oxygen that you didn't manage to get to your muscles in time. To repay the debt you have to breathe hard for a while, then you stop to get oxygen into your muscles to convert the painful lactic acid to harmless CO2 and Water. These can be displayed on graphs.

Units for interpreting data : breaths/min or beats/min

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-The circulatory system carries glucose, oxygen and co2 around the body in the blood. 

-Glucose needed for respiration comes from breaking down food in the digestive system.

-The oxygen comes from air breathed into the lungs. CO2 is breathed out

-The smallest blood vessels in the body are the capillaries. All the cells in body have capillaries nearby to supply them with glucose and oxygen, and to take away the waste CO2

- All these substances move between the cells and the capillaries by a process known as diffusion

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Diffusion Continued

Diffusion in scientific terms, is the movement of particles from an area of higher concentration to an area of lower concentration.

It's the gradual movement of particles to where there are lots of them to where there are fewer.

Its the natural tendency of stuff to spread out

 When cells respire they use up oxygen and glucose, so the concentration of these inside the cells is low . The concentrations of these substances in the blood is higher, so they diffuse fro the capillaries into the cells

When cells respire they produce lots of co2 so the concentration of this in the cells is high. This means carbon dioxide diffuses from the cells into the blood, where the concentration is lower.

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  • It is the diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal

  • Osmosis is the movement of water molecules across a partially-permeable membrane down a water potential gradient
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Heart and Breath Rate Monitoring

- Professional athletes measure their heart and breathing rate, as well as temperature by training

- You can measure heart rate during exercise by taking your pulse, by putting 2 fingers on the inside of your wrist or neck, and counting the number of pulses in one minute.

- You can measure body temp with a thermometer, and breathing rate by counting breaths

- Body temps go up during exercise, because increased respiration releases more heat energy

- Digital monitors can be used to measure as well, recording electronically instead of counting. This has advantages as digital recorders dont lose count or miss a beat like humans

- Changes can be monitored continuously, instead of having to stop or start taking a pulse

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Former Member

took a lot of time to do..but worth it



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