Tag: muscle contraction

• Active sites for myosin are present on actin which are masked by troponin in resting state. When  Ca++ level increases it leads to the binding of calcium with a subunit of troponin on actin(thin) filaments and thereby remove the masking of active sites for myosin.
  
• Utilizing the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge. 
• This pulls the attached actin filaments towards the centre of ‘A’ band.
  
•  The ‘Z’ line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction.
• When EDTA  injected into muscles combines with Ca ++ and prevents the binding of calcium with troponin and slows down contraction.
• So, the correct answer is 'Slows down contraction'. 
  

The skeletal system provides the necessary framework and leverage for muscles to act upon, enabling faster and more efficient locomotion in vertebrates.

A gliding joint is the simplest of the synovial joints. Gliding joints are found between the carpal bones and between the tarsal bones.

• Acetylcholine is the neurotransmitter used at the neuromuscular junction, it is the chemical that motor neurons of the nervous system release in order to activate muscles when acetylcholine is released when the neural signal reaches motor end plate. 
• Repeated activation of muscle induces processes resulting in decreased performance (fatigue) as well as enhanced performance (potentiation).  Lactic acid is formed and accumulated in the muscle under conditions of high energy demand, rapid fluctuations of the energy requirement and insufficient supply of O2. Hence,  Repeated activation of the muscle can lead to lactic acid accumulation.

• The source of energy that is used to power the movement of contraction in working muscles is adenosine triphosphate (ATP).
• ATP is considered as the energy currency of the cell.
• Hence In a hurdle race, what is the major energy source of the leg muscle ATP. It helps in muscle contraction that facilitates running in the race.
• So, the correct answer is 'ATP'.

During muscle contraction, the A - band with a length of 1.85 micrometers does not undergo any contraction. However, the I-bands and the H-zone shorten. This causes the Z lines to come closer together. So, the correct answer is 'The width of A-band remains constant'.

• In the hurdle race, a person requires energy production faster than our bodies can adequately deliver oxygen. 
• In those cases, the working muscles generate energy anaerobically. This energy comes from glucose through a process called glycolysis, in which glucose is broken down or metabolized into a substance called pyruvate through a series of steps.
•  When oxygen is limited, the body temporarily converts pyruvate into a substance called lactate, which allows glucose breakdown and thus energy production to continue.
•  The working muscle cells can continue this type of anaerobic energy production at high rates for one to three minutes, during which lactate can accumulate to high levels.