Chemical messengers released from axon terminals that bind receptors on a receiving cell are called neurotransmitters.
Missing Word
neurotransmitters
Neurotransmitters are chemical messengers stored in vesicles of the axon terminal and released into the synapse. Many nervous system drugs act by changing their release, breakdown or receptor binding.
Category: Neurons and Synapses
Question 2
The basic functional unit of the nervous system, which carries electrical impulses, is the neuron.
Missing Word
neuron
The neuron, or nerve cell, is the basic unit of the nervous system. It has a cell body, dendrites that receive signals and an axon that sends them.
Category: Neurons and Synapses
Question 3
The junction where a nerve cell passes a signal to another cell is called a synapse.
Missing Word
synapse
A synapse is the point of communication between a neuron and another neuron, muscle cell or gland cell. It includes the presynaptic terminal, the cleft and the postsynaptic membrane.
Category: Neurons and Synapses
Question 4
The fatty insulating layer that wraps many axons and speeds impulse conduction is the myelin sheath.
Missing Word
myelin
Myelin is a lipid-rich layer formed by glial cells around axons. It allows impulses to jump between gaps and travel faster; its loss slows conduction.
Category: Neurons and Synapses
Question 5
Clusters of nerve cell bodies located outside the central nervous system are called ganglia.
Missing Word
ganglia
Ganglia are groups of nerve cell bodies in the peripheral nervous system. Autonomic pathways relay through ganglia, where preganglionic neurons release acetylcholine onto nicotinic receptors.
Category: Nervous System Divisions
Question 6
The largest part of the brain, split into right and left hemispheres, is the cerebrum.
Missing Word
cerebrum
The cerebrum is the largest part of the brain and handles thought, memory, speech, sensation and voluntary movement. Its two hemispheres are joined by the corpus callosum.
Category: Brain and Spinal Cord
Question 7
The spinal cord is cushioned and protected by cerebrospinal fluid.
Missing Word
cerebrospinal
Cerebrospinal fluid surrounds the brain and spinal cord, cushioning them and helping maintain their chemical environment. It is the fluid sampled in a lumbar puncture.
Category: Brain and Spinal Cord
Question 8
The five vertebrae of the lower back, labeled L1 through L5, make up the lumbar region of the spine.
Missing Word
lumbar
The lumbar region lies between the thoracic and sacral regions and contains vertebrae L1 to L5. Its spinal nerves supply the lower abdomen and legs.
Category: Brain and Spinal Cord
Question 9
The nerve that arises from the cervical spinal cord and controls the diaphragm is the phrenic nerve.
Missing Word
phrenic
The phrenic nerve arises from cervical spinal nerves and supplies the diaphragm, the main muscle of breathing. A high cervical cord injury can therefore impair breathing.
Category: Brain and Spinal Cord
Question 10
The cranial nerve that carries most parasympathetic output to the heart, lungs and digestive organs is the vagus nerve.
Missing Word
vagus
The vagus nerve is the tenth cranial nerve and carries most parasympathetic signals to the thoracic and abdominal organs. Vagal stimulation slows the heart and increases digestive activity.
Category: Nervous System Divisions
Question 11
The division of the autonomic nervous system that prepares the body for fight or flight under stress is the sympathetic division.
Missing Word
sympathetic
The sympathetic division raises heart rate and blood pressure, dilates the bronchi and pupils, and slows digestion during real or perceived stress.
Category: Nervous System Divisions
Question 12
Nerves that release acetylcholine as their neurotransmitter are described as cholinergic.
Missing Word
cholinergic
Cholinergic nerves release acetylcholine, which acts on nicotinic and muscarinic receptors. Nerves that release norepinephrine are called adrenergic.
Category: Autonomic Receptors
Question 13
Acetylcholine receptors on the target organs of the parasympathetic system, such as the heart, smooth muscle and glands, are muscarinic receptors.
Missing Word
muscarinic
Muscarinic receptors are the cholinergic receptors on parasympathetic target organs. Their stimulation slows the heart, increases secretions and contracts smooth muscle of the gut and bladder.
Category: Autonomic Receptors
Question 14
Pupil constriction caused by parasympathetic stimulation is called miosis.
Missing Word
miosis
Miosis is constriction of the pupil, produced when muscarinic stimulation contracts the iris sphincter muscle. Its opposite, pupil dilation, is mydriasis.
Category: Autonomic Receptors
Question 15
The anticholinergic drug applied as a transdermal patch behind the ear to prevent motion sickness is scopolamine.
Missing Word
scopolamine
Scopolamine blocks muscarinic receptors in the vestibular pathways and vomiting center. Its patch is placed on hairless skin behind the ear, and dry mouth and drowsiness are common adverse effects.
Category: Autonomic Drug Classes