Key area 8- Energy Systems in Muscle Cells

Question 1

What happens during vigorous exercise?

Answer 1

.The muscle cells do not get sufficient oxygen to support the electron transport chain
.Therefore, pyruvate is converted to lactate. This conversion involves the transfer of hydrogen ions from the NADH produced during glycolysis to pyruvate in order to produce lactate. This regenerates the NAD that is needed to maintain ATP production through glycolysis
.Lactate accumulates in the muscles, causing muscle fatigue, and an oxygen debt builds up
.The oxygen debt is repaid when exercise is complete

Question 2

What happens during the recovery period?

Answer 2

.Breathing rate and heart rate remain higher than normal to ensure that sufficient oxygen is transported to the cells
.A sufficient concentration of oxygen in the blood allows respiration to provide the energy needed to convert lactate back to pyruvate and glucose in the liver.

Question 3

What are the two types of muscle fibres?

Answer 3

.slow-twitch muscle fibres
.fast-twitch muscle fibres

Question 4

What are slow twitch muscle fibres?

Answer 4

.Contract relatively slowly
.Sustain contractions for longer
.Rely on aerobic respiration to produce ATP
.Have many mitochondria
.Large blood supply
.High concentration of the oxygen storing protein myoglobin
.Major storage fuel is fats
.Useful for endurance activities such as long-distance running, cycling or cross country

Question 5

What are fast-twitch muscle fibres?

Answer 5

.Contract relatively quickly
.For short periods of time
.Generate ATP through glycolysis only
.Few mitochondria
.Lower blood supply
.Low concentration of myoglobin
.Major storage fuel is glycogen
.Useful for activities such as sprinting or weightlifting

Question 6

What is myoglobin?

Answer 6

.It is found in the proteins of the muscle cell with the function to store oxygen

Question 7

What do athletes show?

Answer 7

.They show distinct patterns of muscle fibres that reflect their sporting activities