Explain the process of respiration in detail.

We can consider Respiration as the physiological definition or the biochemical definition.

Explanation:

Physiological definition:

Respiration in this case is the movement of oxygen from the outside environment to the cells within tissues, and the transport of carbon dioxide in the opposite direction.

Steps:

1. Inhalation (breathing in) which is active movement and the oxygen enters.

2. There is a pulmonary gas exchange. It takes place between the air in the alveoli and the blood in the pulmonary capillaries.

3. Intern gas exchange in cells.

3. Exhalation (breathing out) is usually a passive process, CO2 goes out of the body.

Biochemical definition:

Refers the metabolic process placed in cells by which an organism obtains energy (in the form of ATP and NADPH) by oxidising nutrients and releasing waste products. During all the sequence the six-carbon sugar molecule glucose is converted to carbon dioxide and water in the presence of oxygen to give 36 to 38 molecules of ATP (the energy). Cellular respiration we are defining happens in the presence of oxygen.

Steps: (all this sequence occur in the mitochondria)

1. Glycolysis (in prokaryotic and eukaryotic). It's sequence of 10 chemical reactions that break down a glucose molecule into two pyruvate (pyruvic acid) molecules.

2. The bridge reaction. In here there's no ATP production. Two pyruvate molecules that come from glycolysis are transformed into two molecules of acetyl coenzyme A (acetyl CoA), with two molecules of CO2 as a metabolic waste.

3. The Krebs cycle (oxygen dependent pathway). It has eight steps catalyzed by eight different enzymes. The result of this process is only 4 ATPs, but a lot of NADH that will be very useful in the electron transport chain.

4. The electron transport chain (oxygen dependent pathway). NADH carry electrons from Hydrogen and they go to an electron transport chain. The result is 32 ATPs for every glucose.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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