1.The aim of the practical:
The aim of this practical is to study the characteristics of skeletal muscles in vitro, such as super-position, précis of stimuli, helpful influence of contraction and tetanus.
During the practical the effect of neuromuscular inhibitors on muscle contraction and persuasion as well as temperature, loading and muscle length on skeletal muscle contraction will be determined.
2. Introduction:
A conscious decision must be made for muscle activity/contraction to take place. Because of this, skeletal muscles are also known as voluntary muscles since they are in charge of the somatic nervous system.
The onset of an action potential encourages the release of acetylcholine from the working neuron. This happens once a mindful decision has been made and an action potential is sent from the brain through motor neurons to the muscle.
An action potential is generated within the muscle fibre, which in turn causes the release of calcium ions from the terminal cisternae of the sarcoplasmic reticulum. The acetylcholine that binds to these receptors on the motor end plate and then influences the fibres permeability to sodium ions causes this action potential.
The calcium ions bind to the troponin of the thin filaments, which cause the tropomyosin to detach from the filamentous actin. The myosin heads of the thick filaments move to the closest active sites on the filamentous actin through the use of adenosine triphosphate.
Here the myosin heads bind to the active sites on the filamentous actin and pull the actin filaments towards the M line of the sarcomere. When this happens uniformly throughout the muscle, the muscle will contract (Martini et al. p52-63)
3. The Myogram
The myogram, or muscle curve is a graphic representation of the velocity and intensity of a single isotonic contraction. It is divided into three sections; the latent period, the contraction period and the relaxation period.
1. The Latent Period (lasts ±2...