Neurons and the Nervous System

Question 1

motor neuron

Answer 1

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

Question 2

sensory neuron

Answer 2

neurons that carry incoming information from the body’s tissues and sensory receptors to the brain and spinal cord

Question 3

interneuron

Answer 3

neurons within the brain and spinal cord; they communicate internally and process information between the sensory inputs and motor outputs

Question 4

neuron

Answer 4

a nerve cell; the basic building block of the nervous system

Question 5

dendrite

Answer 5

a neuron’s often bushy, branching extensions that receive and integrate messages, conducting impulses toward the cell body

Question 6

axon

Answer 6

the segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands

Question 7

myelin sheath

Answer 7

a fatty tissue layer segmentally encasing the axons of some neurons; it enables vastly greater transmission speed as neural impulses hop from one node to the next

Question 8

synapse

Answer 8

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft

Question 9

threshold

Answer 9

the level of stimulation required to trigger a neural impulse

Question 10

all or nothing response

Answer 10

a neuron’s reaction of either firing (with a full-strength response) or not firing

Question 11

neuortransmitter

Answer 11

chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse

Question 12

central nervous system

Answer 12

the brain and spinal cord

Question 13

peripheral nervous system

Answer 13

the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body

Question 14

automatic nervous system

Answer 14

the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms

Question 15

sympathetic nervous system

Answer 15

the division of the autonomic nervous system that arouses the body, mobilizing its energy

Question 16

parasympathetic nervous system

Answer 16

the division of the autonomic nervous system that calms the body, conserving its energy