Lab Four Flashcards
What is skeletal muscle?
Excitable tissue where an action potential is generated along the plasma membrane of muscle cells, controlled by the motor neurons coming from the CNS.
What is a Neuromuscular Junction?
A specialized synapse in motor neurons that release a neurotransmitter (acetylcholine) that causes a muscle action potential that simulates the contraction of a muscle cell.
What do muscle neurons excite in vertebrates?
Muscle fibers (contractions).
What do muscle neurons do in invertebrates?
Both excitatory and inhibitory reactions, depending on the neurotransmitter released and receptor it binds to.
What do Antagonistic Muscle Groups do?
Cause movement of limbs due to the coordination of contraction and relaxation of the muscles, and can be responsible for changes in limb position.
What does an Electromyogram (EMG) do?
Records muscle activity by the electrical activity associated with skeletal muscle APs on the surface of the body. A non-invasive way to assess muscle function.
What do Skeletal Muscles contain?
Specialized receptors that convey information about muscle length, tension, and pressure to the CNS.
What are Muscle Spindles?
The mechanosensory receptors responsible for providing information about the length, or rate of change of length, of a muscle. Arranged in parallel with muscle fibres and are stretched when an external force stretches the muscle.
What is a Stretch (Myotatic) Reflex?
When the stretching of a muscle causes excitation of its muscle spindles and results in a reflex contraction of the muscle.
What do Stretch Reflexes contain?
Large diameter sensory axons and contain a small number of synapses to result in minimal time delay from stretching to contraction; a monosynaptic pathway.
What is the Patellar Reflex?
The thigh muscle group responsible for extension of the lower leg. The quadriceps muscles insert on the patellar tendon and act in concert to extend the lower leg.
What does the strength of a striated muscle contraction depend on?
The amount of electrical activity in the muscle.
What are Motor Neurons?
The innervate the groups of muscle fibres, a single motor neuron has a branched axon.
What is a Motor Unit?
The motor neuron and the nuscle fibres it innervates.
What happens when a motor unit undergoes an action potential?
All of the associated muscle fibres are stimulated and contract.