Final answer:
Nerve and muscle cells are termed excitable tissues due to their unique ability to generate and propagate electrical impulses, or action potentials, and release neurotransmitters to communicate swiftly and respond to stimuli. Neurons are specialized for signal transmission, while muscle cells can visibly contract upon receiving nerve impulses. These features are central to the roles they play in the nervous and muscular systems.
Step-by-step explanation:
Nerve and muscle cells are classified as excitable tissues because they possess the ability to generate and propagate electrical impulses, known as action potentials. These cells communicate and respond rapidly to stimuli owing to their sophisticated electrochemical properties. In the case of neurons, these impulses are biochemically linked to the release of neurotransmitters, which cross synapses to reach other neurons or muscle cells, thus influencing their activity. Similarly, muscle cells can be triggered by nerve impulses to contract, a fundamental action in movement and bodily function.
Neurons, as the main functional units of the nervous system, are specialized for rapid signal transmission. They operate by discharging these neurotransmitters at synapses, which can then bind to receptors on other nerve or muscle cells, inducing a change in membrane potential and generating a downstream effect. Nerve and muscle cells share the unique characteristic of excitability, which provides the physiological basis for sensation, thought, movement, and the myriad of activities coordinated by the nervous system.
Muscle cells, including skeletal, cardiac, and smooth muscles, also exhibit excitability. Each type responds characteristically to electrochemical signals, with skeletal muscle cells being voluntarily controlled, cardiac muscle cells beating involuntarily and rhythmically, and smooth muscle cells controlling involuntary movements in various parts of the body.