Question

1. Describe the energy requirements and metabolism of the various skeletal muscle types (slow oxidative and fast glycolytic).

2.Explain how human activities are changing the carbon cycle, and describe biological responses to those changes such as changes in phenology.

Answer 1

There are three types of skeletal muscles, among them 2 type of skeletal muscles fibre need to be discussed here as per the question.

Energy requirements and metabolism of SO and FG:- Slow oxidative(SO) fibers contract relatively slowly and use aerobic respiration ( oxygen and glucose) to produce ATP. Fast glycolytic (FG) fibres have relatively fast contractions and primarily use anaerobic glycolysis.

The primary metabolic pathways used by a muscle fibres determines whether the fibre is classified as oxidative or glycolytic. If a fibre primarily produce ATP through aerobic pathways, then it is classified as oxidative. More ATP can be produced during each metabolic cycle, making the fibre more resistant to fatigue. Glycolytic fibres primarily create ATP through anaerobic glycolysis, which produces less ATP per cycle. As a result glycolytic fibres fatigue at a quicker rate.

SO fibres have structural elements that maximize their ability to generate ATP through aerobic metabolism. These fibers contain many more mitochondria than the glycolytic fibres , as aerobic metabolism, which uses O2 in the metabolic pathways, occurs in the mitochondria. SO fibres possess a large number of mitochondria and are capable of contracting for longer periods because of the large amount of ATP they can produce, but they have a relatively small diameter and do not produce a large amount of tension. SO fibres are extensively supplied with blood capillaries to supply O2 from the red blood cells in the bloodstream. The SO fibres also possess myoglobin, an O2 carrying molecule similar to O2 carrying haemoglobin in the red blood cells. The myoglobin stores some of the needed O2 within the fibre themselves. All of these features allow SO fibres to produce large quantities of ATP, which can sustain muscle activity without fatiguing for long periods of time. Infact the SO fibres can function for maintaining posture, isometric contractions, stabilizing bones and joints but do not require large amount of energy. They do not produce high tension, thus they are not used for powerful , last movements that require high amounts of energy and rapid cross-bridge cycling.  

Fast glycolytic (FG) fibres primarily use anaerobic glycolysis as their ATP source. They have a large diameter and possess high amounts of glycogen, which is used in glycolysis to generate ATP quickly to produce high levels of tension . Because of their reliance on anaerobic metabolism, these fibres do not possess substantial number of mitochondria, a limited capillary supply, or significant amounts of myoglobin, resulting in a white colouration for muscles containing large numbers of these fibres. FG glycolytic fibres fatigue quickly, permitting them to only be used for short periods. However , during these short periods, FG fibres are able to produce rapid, forceful contractions to make quick, powerful movements. ATP provides the enery for muscle contraction.

**Dear students as per rules I have to do only one question. To get the all questions answers please post that questions separately. Please like and support. Thank you.