Question

neurons
neurons, also called nerve cells, are highly specialized to transmit messages (nerve impulses) from one part of the body to another. although (1 ) differ structurally from one another, they have many common features (figure 7.4). all have a cell body, which contains the nucleus and one or more slender processes extending from the cell body.
cell body
the cell body is the (2 ) center of the neuron. its transparent nucleus contains a large nucleolus. the cytoplasm surrounding the nucleus contains the usual organelles, except that it lacks centrioles (which confirms the amitotic nature of most neurons). the rough er, called nissl (nisl) bodies, and neurofibrils (intermediate filaments that are important in maintaining cell shape) are particularly abundant in the cell body.
processes
the armlike processes, or fibers, vary in length from microscopic to about 7 feet in the tallest humans. the longest ones in humans reach from the lumbar region of the spine to the great toe. neuron processes that convey incoming messages (electrical signals) toward the cell body are dendrites (dendritz), whereas those that generate nerve (3 ) and typically conduct them away from the cell body are axons (aksonz). neurons may have hundreds of branching dendrites (dendr = tree), depending on the neuron type. however, each neuron has only one axon, which arises from a conelike region of the cell body called the axon hillock.
an occasional axon gives off a collateral branch along its length, but all axons branch profusely at their terminal end, forming hundreds to thousands of axon terminals. these terminals contain hundreds of tiny vesicles, or membranous sacs, that contain chemicals called neurotransmitters (review our discussion of events at the neuromuscular junction in chapter 6). as we said, axons transmit nerve impulses away from the cell body. when these impulses reach the axon terminals, they stimulate the release of (4 ) into the extracellular space between neurons, or between a neuron and its target cell.
each axon terminal is separated from the next neuron by a tiny gap called the synaptic (si-naptik) cleft. such a functional junction, where an impulse is transmitted from one neuron to another, is called a synapse (syn = to clasp or join). although they are close, neurons never actually touch other neurons. you will learn more about (5 ) and the events that occur there a bit later.

1. neurotransmitters 2. synapses 3. neurons 4. metabolic 5. impulses

1. synapses 2. neurons 3. metabolic 4. impulses 5. neurotransmitters

1. impulses 2. neurotransmitters 3. synapses 4. neurons 5. metabolic

1. metabolic 2. impulses 3. neurotransmitters 4. synapses 5. neurons

1. neurons 2. metabolic 3. impulses 4. neurotransmitters 5. synapses

Explanation:

1. Neurons can vary structurally, so "neurons" fits (1).
2. The cell - body is the metabolic center of the neuron, so "metabolic" for (2).
3. Axons generate nerve impulses and conduct them away from the cell - body, so "impulses" for (3).
4. When impulses reach axon terminals, neurotransmitters are released, so "neurotransmitters" for (4).
5. The functional junction where an impulse is transmitted is a synapse, so "synapses" for (5).

Answer:

1. neurons 2. metabolic 3. impulses 4. neurotransmitters 5. synapses