Fundamentals and Structure of the Nervous System

Comprehensive fill-in-the-blank practice flashcards covering nervous system anatomy, neurophysiology, membrane potentials, synaptic transmission, neurotransmitters, brain structures, and clinical neuroimaging cases.

The three overlapping functions of the nervous system are sensory input, integration, and __________.

motor output

The motor division of the peripheral nervous system is subdivided into the somatic nervous system and the __________ nervous system.

autonomic

The most abundant and versatile glial cells in the central nervous system, which anchor neurons to capillaries and mop up leaked potassium ions, are __________.

astrocytes

In the central nervous system, defensive cells that transform into specialized macrophages to phagocytize microorganisms and neuronal debris are __________.

microglial cells

Ciliated glial cells that line the central cavities of the brain and spinal cord to circulate cerebrospinal fluid are __________.

ependymal cells

In the central nervous system, myelin sheaths are formed by __________, which can wrap around up to $60$ axons at once.

oligodendrocytes

In the peripheral nervous system, the bulge containing the nucleus and most cytoplasm of a Schwann cell external to the myelin sheath is called the outer collar of __________ cytoplasm.

perinuclear

A cluster of neuron cell bodies located in the central nervous system is called a(n) __________, whereas a cluster in the peripheral nervous system is called a ganglion.

nucleus

A bundle of axons located in the central nervous system is called a(n) __________, whereas a bundle in the peripheral nervous system is called a nerve.

tract

In healthy neurons, microtubules are small tubes composed of tubulin that are structurally stabilized by __________ molecules.

tau

Retrograde axonal transport moves substances toward the cell body using the ATP-dependent motor protein __________.

dynein

Pathogens such as rabies, polio, and herpes simplex viruses, as well as __________ toxin, use retrograde axonal transport to reach the neuron cell body.

tetanus

Neurons with two processes—one axon and one dendrite—found only in special sense organs such as the retina and olfactory mucosa are classified structurally as __________ neurons.

bipolar

Ohm's law describes the relationship between current ($I$), voltage ($V$), and resistance ($R$) through the formula __________.

$$I = \frac{V}{R}$$

The resting membrane potential of a typical neuron is approximately __________.

$$-70\,mV$$

The resting membrane potential is stabilized against ion leakage by the sodium-potassium pump, which ejects __________ $Na^+$ ions from the cell for every two $K^+$ ions transported in.

$$3$$

A change in membrane potential where the inside becomes less negative, moving closer to $0\,mV$, is termed __________.

depolarization

Short-lived, localized changes in membrane potential that decay with distance are called __________ potentials.

graded

During the depolarizing phase of an action potential, the opening of voltage-gated __________ channels creates an explosive positive feedback cycle.

$$Na^+$$

The repolarizing phase of an action potential is caused by the inactivation of $Na^+$ channels and the opening of voltage-gated __________ channels.

$$K^+$$

The period from the opening of $Na^+$ channels until they begin to reset, during which a neuron cannot respond to another stimulus, is the __________ refractory period.

absolute

In myelinated axons, action potentials are generated only at the myelin sheath gaps in a rapid process known as __________ conduction.

saltatory

Nerve fibers that have the largest diameter, thick myelin sheaths, and conduct impulses at speeds up to $150\,m/s$ belong to Group __________.

A

The autoimmune disease characterized by immune destruction of central nervous system myelin sheaths into nonfunctional scleroses is __________.

multiple sclerosis

During synaptic transmission at a chemical synapse, depolarization of the axon terminal triggers the opening of voltage-gated __________ channels.

$$Ca^{2+}$$

The rate-limiting step of neural transmission, lasting approximately $0.3\text{--}5.0\,ms$, is known as __________.

synaptic delay

Binding of an excitatory neurotransmitter to a postsynaptic membrane causes local depolarization known as a(n) __________.

EPSP (excitatory postsynaptic potential)

Inhibitory postsynaptic potentials (IPSPs) are generated by the opening of chemically gated ion channels permeable to either $K^+$ or __________.

$$Cl^-$$

When a single presynaptic neuron fires in rapid succession to produce additive postsynaptic potentials close in time, it is called __________ summation.

temporal

The principal inhibitory neurotransmitter in the brain that plays a critical role in presynaptic inhibition is __________.

GABA (gamma-aminobutyric acid)

The major excitatory neurotransmitter of the brain, known as the 'stroke neurotransmitter' because excessive release leads to excitotoxicity, is __________.

glutamate

The plane of section illustrated here, which divides the brain into anterior and posterior parts, is the __________ plane.

coronal

The plane of brain section depicted in this diagram, separating structures into left and right sections, is the __________ plane.

sagittal

In MRI Case 2, the glioblastoma resected in a 54-year-old woman was situated within the left __________ gyrus of the primary motor cortex.

precentral

In MRI Case 9, a 56-year-old hypertensive patient experienced left-sided sensory loss due to an acute ischemic lacunar stroke in the right __________.

thalamus

In MRI Case 10, a tumor infiltrating the __________ caused the patient to develop severe daytime sleepiness and obesity.

hypothalamus

In MRI Case 14, posttransplant lymphoproliferative disorder (PTLD) presented as a $25\text{-mm}$ mass in the __________ oblongata of the brainstem.

medulla

Neuronal hyperexcitability during generalized seizures can result from a lowered threshold for $Na^+$ channels and activation of __________ channels.

T-type $Ca^{2+}$

The cerebral hemispheres form the superior part of the brain and account for __________ percent of total brain mass.

$$83\%$$

The left and right cerebral hemispheres are separated from each other along the midline by the median __________ fissure.

longitudinal

The cerebral white matter tracts that connect corresponding gray areas between the two hemispheres are called __________ fibers.

commissural

The primary somatic motor cortex is characterized by large neurons called __________ cells, whose long axons form the corticospinal tracts.

pyramidal

The specialized motor speech area located anterior to the inferior region of the premotor cortex is __________ area.

Broca's

The sensory cortex responsible for conscious awareness of taste is the gustatory cortex, located in the __________.

insula

The association area involved in the comprehension and understanding of written and spoken language is __________ area.

Wernicke's

Deep within the cortical white matter lie the masses of gray matter shown here, which include the caudate nucleus and lentiform nucleus, collectively termed the __________.

corpus striatum (basal nuclei)

The egg-shaped diencephalic structure that sorts, edits, and relays ascending sensory impulses to the cerebral cortex is the __________.

thalamus

The main visceral control center of the body that regulates body temperature, water balance, and pituitary secretions is the __________.

hypothalamus

The circled endocrine structure located on the dorsal surface of the diencephalon is the __________, which secretes melatonin.

pineal gland

In the midbrain, visual reflex centers coordinating eye and head movements are located in the __________ colliculi of the corpora quadrigemina.

superior

Cranial nerves V (trigeminal), VI (abducens), and VII (facial) have their origin in the __________ of the brainstem.

pons

The brain structure operating subconsciously to coordinate voluntary muscular movements, posture, muscle tone, and balance is the __________.

cerebellum