Lab 4: Skeletal Muscle Physiology Flashcards
Skeletal Muscle:
is an excitable tissue in that an action potential (AP) is generate along the plasma membrane of muscle cells.
How is the skeletal muscle AP generated?
Controlled by Motor Neurons originating from the Central Nervous System.
What does a motor neuron release and where does it release it?
Release a neurotransmitter (acetylcholine) at a specialized synapse called a neuromuscular junction (or motor endplate)
What does the release of acetylcholine cause?
causes a muscle AP that will stimulate contraction of the muscle cell.
What is the difference of motor neurons in vertebrates and invertebrates?
In vertebrates motor neurons always excite muscle fibers. However for invertebrates motor neurons can be both excitatory or inhibitory depending on the neurotransmitter released and receptor it binds to.
Movement of limbs is generally accomplished by…
coordinating the contraction and relaxation of antagonistic muscle groups.
what knowledge has important clinical implications in the development of effective rehabilitation treatments for muscle disease, brain and spinal cord injuries?
Understanding the roe of sensory information and reflex arcs in walking and in other locomotory tasks in humans.
Electrical acitivty associated with skeletal muscle APs can be recorded from…
the surface of the body.
The recording of muscle activity is called an
electromyogram (EMG) and is accomplished by placing recording electrodes on the skin overlying the muscle group under study.
Muscle Spindles:
The mechanoreceptory receptors responsible for providing information about the length or the rate of change of the length of a muscle. Muscle spindles are arranged in parallel with muscle fibers and are stretched when an extrenal force, such as a tendon tap, stretches the muscle.
The stretching of a muscle causes…
Excitation of its muscle spindles and results in a relfex contraction of the muscle. The reflex response is know as a stretch reflex.
Stretch reflexes involve — —- —- —- and contain a — — – —- — — —.
large diameter sensory axons/ small number of synapses in the circuit.
Stretch reflexes have what kind of pathway?
monosynaptic pathway because the sensory afferent nerves from the muscle spindles enter the spinal cord and synapse directly with motor neurons rather than with interneurons.
The calf muscle group is composed of
Gastrocnemius and the soleus which lies underneath the gastrocnemius. The gastrocnemius and soleus merge at the base of the calf and are joined to the achilles tendon by rough connective tissues.
The EMG taken from the calf muscle will primarily reflect muscle activity from the
gastrocnemius.
