Extracellular Buffers

Question 1

Sodium bicarbonate (baking soda) - what evidence is there?

Answer 1

Evidence of ergogenic aid, especially in allout exercise 30s-10min.
e.g 200-400m swimming.

Na HCO2

Question 2

what are the side effects of taking sodium bicarbonate? How much is recommended?

Answer 2

200-300mg/lg

Stomach discomfort or gastro intestinal problems.

-can be prevented by consuming with carbohydrates.

Question 3

What does bicarbonate do?

Answer 3

• helps to buffer/remove hydrogen ions in the blood.

Question 4

What are the two redox reactions associated with producing energy ?

Answer 4

Reduction reaction = pyruvate gains 2 electrons, producing lactate.

Oxidation reaction = lactate loses 2 electrons, producing pyrvate.

what reactions are these more specifically? (perplexity) - when in strenuous exercise oxygen becomes inadequate, causing reductio reaction. in recovery, when oxygen supply is adequate lactate loses 2 electrons, oxidising back to pyruvate.

Question 5

what % of glycolysis forms atp. is It still useful?

Answer 5

5%

high concentrations of glycolytic enzymes and the speed of these reactions provide significant energy for intense muscle action.

Question 6

Examples that rely heavily on ATP generated by glycolysis

Answer 6

sprinting at the end of the mile run,
performing all-out from start to finish in the 50- and 100-m swim,
routines on gymnastics apparatus,
sprint running races up to 200 m.

Question 7

explain hydrogen release in glycolysis:

Answer 7

two pairs of hydrogen atoms are stripped from glucose and electrons pass to NAD+ to from NADH.

high intensity = energy demand exceeds oxugen supply of rate of use. - hydrogen joined to NADH cannot be oxidised at sufficient rate.

Continued release of anaerobic energy in glycolysis depends on NAD+ availability for oxidising phosphogylceraldehyde.

Question 8

How is lactate formed under anaerobic glycolysis?

Answer 8

NADH combines with pyruvate to form lactic acid catalysed by lactate dehydrogenase (LDH) = reversible reaction.

Lactic acid forms in muscle, diffuses into blood for buffering, lactate accumulation in blood increases blood acidity (lowering pH), increased acidity inhibits enzymes involved in energy transfer and muscle contractile machinery.

Question 9

What is buffering?

Answer 9

Endogenous systems to control pH homeostasis:

Question 10

What is intracellular buffering?

Answer 10

-Organic and inorganic phosphates,
-Bicarbonate,
-Histidine containing dipeptides
-active transport of H+ ions out of muscle into blood.

Question 11

What is extracellular buffering?

Answer 11

Lactate-proton transporters i.e. monocarboxylate transporter 1 (MCT1) and 4 (MCT4)

Once H+ are extracellular BUFFERING occurs via circulating bicarbonate (HCO3)

Highly efficient process under normal physiological conditions
Quickly overwhelmed by H+ accumulation during exercise, particularly HIGH INTENSITY

bicarbonate can be excreted by being being reduced into carbonic acid, into co2 and h20. ###