Answer:
B. Synaptic vesicle—neurotransmitter—ion channels—end plate potential
Explanation:
When an impulse reaches the synaptic knob, it stimulates the vesicles to move towards the pre-synaptic membrane releasing the acetylcholine(neurotransmitter). This transmitter substance makes the membrane permeable. The transmitter substance then diffuses across the synaptic cleft to the post-synaptic membrane which then becomes depolarised. Sodium ions from cleft then flow through the post-synaptic membrane into the post-synaptic knob causing an action potential at this point. This action potential is then transmitted as a nerve impulse along the neurone. End-plate potential is a change in electrical potential that is chemically induced at the motor neurone leading to muscle contraction because a nerve impulse has reached the nerve endings.
A synovial joint is surrounded by a two layer <em>joint capsule</em> which encloses a fluid filled space called the <em>synovial cavity</em>. The outer layer of this structure consists of <em>dense connective tissue</em> which is continuous with the periosteum of each bone. The outer layer may be reinforced by <em>ligaments</em> which are bundles of collagenous fibers. Some of these bundles are part of the capsule while other are located outside of the capsule. By definition, the structures, such as some ligaments, that are located outside the capsule are called <em>accessory structures</em>. The inner layer of the joint capsule is the <em>synovial membrane</em>, consisting of loose connective tissue. The inner lining of the joint capsule secretes a fluid called <em>synovial fluid</em>. This fluid is viscous, and moistens and lubricates the surfaces within the joint capsule