Skeletal muscle lab
Lab 3 – Skeletal Muscle Physiology
Introduction
Skeletal muscles are composed of hundreds to thousands of individual cells, each doing their share of work in the production of force. As their name suggests, skeletal muscles move the skeleton. Skeletal muscles are remarkable machines; while allowing us the manual dexterity to create magnificent works of art, they are also capable of generating the brute force needed to lift a 100-lb. sack of concrete. When a skeletal muscle from an experimental animal is electrically stimulated, it behaves in the same way as a stimulated muscle in the intact body, that is, in vivo. Hence, such an experiment gives us valuable insight into muscle behavior.
The Motor Unit and Muscle Contraction
A motor unit consists of a motor neuron and all of the muscle fibers it innervates. Motor neurons direct muscles when and when not to contract. A motor neuron and a muscle cell intersect at what is called the neuromuscular junction. Specifically, the neuromuscular junction is where the axon terminal of the neuron meets a specialized region of the muscle cell’s plasma membrane. This specialized region is called the motor end-plate. An action potential (depolarization) in a motor neuron triggers the release of acetylcholine, which diffuses into the muscle plasma membrane (also known as the sarcolemma). The acetylcholine binds to receptors on the muscle cell, initiating a change in ion permeability that results in depolarization of the muscle plasma membrane, called an end-plate potential. The end-plate potential, in turn, triggers a series of events that results in the contraction of a muscle cell. This entire process is called excitation-contraction coupling.
We will be simulating this process in the following activities, only instead of using acetylcholine to trigger action potentials, we will be using electrical shocks. The shocks will be administered by an electrical stimulator that can be set for the precise voltage, frequency,
Introduction
Skeletal muscles are composed of hundreds to thousands of individual cells, each doing their share of work in the production of force. As their name suggests, skeletal muscles move the skeleton. Skeletal muscles are remarkable machines; while allowing us the manual dexterity to create magnificent works of art, they are also capable of generating the brute force needed to lift a 100-lb. sack of concrete. When a skeletal muscle from an experimental animal is electrically stimulated, it behaves in the same way as a stimulated muscle in the intact body, that is, in vivo. Hence, such an experiment gives us valuable insight into muscle behavior.
The Motor Unit and Muscle Contraction
A motor unit consists of a motor neuron and all of the muscle fibers it innervates. Motor neurons direct muscles when and when not to contract. A motor neuron and a muscle cell intersect at what is called the neuromuscular junction. Specifically, the neuromuscular junction is where the axon terminal of the neuron meets a specialized region of the muscle cell’s plasma membrane. This specialized region is called the motor end-plate. An action potential (depolarization) in a motor neuron triggers the release of acetylcholine, which diffuses into the muscle plasma membrane (also known as the sarcolemma). The acetylcholine binds to receptors on the muscle cell, initiating a change in ion permeability that results in depolarization of the muscle plasma membrane, called an end-plate potential. The end-plate potential, in turn, triggers a series of events that results in the contraction of a muscle cell. This entire process is called excitation-contraction coupling.
We will be simulating this process in the following activities, only instead of using acetylcholine to trigger action potentials, we will be using electrical shocks. The shocks will be administered by an electrical stimulator that can be set for the precise voltage, frequency,