Define the following terms:
$(1)$ Intercalated disc
$(2)$ Neuromuscular junction

(N/A) $(1)$ Intercalated disc: These are specialized cell-to-cell junctions that connect adjacent cardiac muscle cells. They facilitate the rapid transmission of electrical impulses,allowing the heart muscle to contract as a single functional unit (syncytium).
$(2)$ Neuromuscular junction: This is the chemical synapse formed between a motor neuron and a muscle fiber. It is the site where the neurotransmitter (acetylcholine) is released to initiate muscle contraction.