Chapter 2 Key Terms

Question 1

How does myelin help speed the propagation of the action potential down the axon?

Answer 1

Myelin insulates axons, allowing faster action potential propagation via saltatory conduction.

Question 2

Why is the action potential referred to as “all-or-none?”

Answer 2

It either occurs fully or not at all. Once the threshold is reached, the cell fires.

Question 3

What function would be compromised if the precentral gyrus were lesioned?

Answer 3

Damage to the precentral gyrus would affect motor control, leading to paralysis or
impaired voluntary movements

Question 4

What about the superior temporal gyrus?

Answer 4

Damage to the superior temporal gyrus would affect language comprehension and
auditory processing.

Question 5

What about the calcarine sulcus (primary visual cortex)?

Answer 5

Damage to the calcarine sulcus would affect visual processing, potentially causing
blindness.

Question 6

What cytoarchitectural arrangement does all of the cerebral cortex have in common?

Answer 6

The cortex generally has six distinct layers.

Question 7

What cytoarchitectural variations exist within the cerebral cortex?

Answer 7

Variations include differences in thickness, size, density, and cell type.

Question 8

Why is the thalamus called the “gateway to the cortex?” Name two nuclei in the thalamus and briefly explain their function.

Answer 8

The thalamus is a relay from the peripheral sense organs to the cortex. The LGN
processes visual input, and the MGN processes auditory input.

Question 9

What is meant by the term “topographic map” in the context of neuroanatomy? Give three examples of topographic maps in the cortex. Why are these representations considered topographic?

Answer 9

A topographic map refers to an orderly spatial representation of sensory or motor
information. Examples include the body map in the somatosensory cortex, the visual map in the visual cortex, and the tonotopic map in the auditory cortex. Neighboring neurons represent neighboring parts of sensory space.

Question 10

Is this sentence true: “The gray matter in the brain is the cerebral cortex and the white matter is everything else?” If not, give an example of a gray matter structure that is not part of the cerebral cortex.

Answer 10

No, the thalamic nuclei, such as the LGN within the midbrain, contain gray matter.

Question 11

What is the difference between the central nervous system and the peripheral nervous system?

Answer 11

The CNS consists of the brain and spinal cord. The PNS consists of all nerves branching
out from the CNS.

Question 12

What is the difference between the somatic and autonomic peripheral nervous
system?

Answer 12

The somatic nervous system controls voluntary movements and transmits sensory
information, while the autonomic nervous system regulates involuntary body functions such as heart rate and respiration.

Question 13

What is the function of glial cells in the nervous system?

Answer 13

Glial cells provide structural support, speed up neuronal signaling through myelination,
regulate the extracellular environment, and participate in immune defense.

Question 14

How does the neuron doctrine differ from the reticular theory?

Answer 14

The neuron doctrine, proposed by Ramon y Cajal, states that the nervous system
comprises discrete individual cells (neurons), whereas the reticular theory suggested it
was a continuous interconnected network.

Question 15

What are the differences between astrocytes, oligodendrocytes, and microglial cells?

Answer 15

Astrocytes maintain the blood-brain barrier and ion balance, oligodendrocytes
myelinate axons in the CNS, and microglial cells act as the brain’s immune defenders.

Question 16

What is the role of dendritic spines in neuronal communication?

Answer 16

Dendritic spines increase the surface area of dendrites, allowing neurons to form more synaptic connections and facilitate synaptic strength modulation

Question 17

An electrical pulse that is sent down the axon via electrical transduction/ a brief change in the polarity of the electrical charge across the membrane.

Answer 17

Action Potential

Question 18

Neurons that input to the CNS/ sensory input to the CNS; carries sensory input through the dorsal root into the spinal cord.

Answer 18

Afferent

Question 19

Back

Answer 19

Posterior

Question 20

back/posterior

Answer 20

Caudal

Question 21

Rostral

Answer 21

front/anterior

Question 22

Inferior

Answer 22

Bottom

Question 23

Dorsal

Answer 23

top of the brain/ back of the body

Question 24

Ventral

Answer 24

Bottom of the brain/ front of the body

Question 25

Medial

Answer 25

middle

Question 26

Lateral

Answer 26

Sides

Question 27

Anterior

Answer 27

Front

Question 28

Superior

Answer 28

Top

Question 29

A network of regions in the brain that process complex info and support higher-order cognitive functions, such as language, perception, and thought

Answer 29

Association cortex

Question 30

Tube-like nerve fiber that transmits signals to other neurons

Answer 30

Axon

Question 31

A detailed representation of the brain's cerebral cortex. There are 52 distinct regions.

Answer 31

Brodmann's map

Question 32

He developed a staining technique to visualize individual neurons; he proposed reticular theory saying that our neurons system was a continuous, interconnected network.

Answer 32

Camillo Golgi

Question 33

The arrival of the action potential at the axon terminal leads to depolarization of the terminal membrane, causing voltage-gated Ca2+ channels to open. The opening of these channels triggers small vesicles containing neurotransmitters to fuse with the membrane at the synapse and release the neurotransmitter into the synaptic cleft. The neurotransmitter diffuses across the cleft and, on reaching the postsynaptic membrane, binds with specific receptors embedded in it.

Answer 33

Chemical Transmission

Question 34

Deals with balance, maintaining posture, walking, and performing coordinated movements. It clings to the brainstem at the level of the pons. Damage to it causes movement to be uncoordinated and halting, and it may not be able to maintain balance.

Answer 34

Cerebellum

Question 35

The difference in concentration of a substance between two areas/ ions moving through the membrane from an area of high concentration to an area of low concentration.

Answer 35

Concentrated Gradient

Question 36

crosses over/ opposite side

Answer 36

Contralateral

Question 37

Ipsilateral

Answer 37

same side

Question 38

Coronal

Answer 38

Cut that gives an anterior/posterior section (or rostral/caudal cut)

Question 39

Sagittal

Answer 39

Cut that gives a left and right section (lateral or medial cut)

Question 40

Axial

Answer 40

aka horizontal; gives a dorsal and ventral section (or inferior/superior section)

Question 41

52 areas; study of the structure of cells in the CNS. Involves examining the arrangement, density, and type of cells in the CNS's tissues.

Answer 41

Cytoarchitecture

Question 42

Receives input from other neurons; branching extensions of the neuron

Answer 42

Dendrite

Question 43

Reduce or remove the polarization of; making the membrane potential becomes less negative, making it more likely to fire an action potential; resting potential goes from -70mV to -55mV.

Answer 43

Depolarize

Question 44

process of movement of molecules under a concentration gradient

Answer 44

Diffusion

Question 45

The outermost of the 3 meninges; it is a tough outer layer

Answer 45

Dura Mater

Question 46

Neurons that output from the CNS/ motor input from the CNS to the organs; carries motor outputs through the ventral root away from the spinal cord

Answer 46

Efferent

Question 47

Caused by each k+ ion carries one unit of positive charge out of the neuron as it moves across the membrane.

Answer 47

Electrical gradient

Question 48

The electrical potential difference across a cell membrane that balances the concentration gradient of an ion; the electrical potential difference across the cell membrane that exactly balances the concentration gradient for an ion.

Answer 48

Equilibrium Potential

Question 49

Nerve cel bodies/ non-neuronal cells of the brain and nervous system.

Answer 49

Glia

Question 50

A technique that uses silver nitrate and potassium chromate to stain neurons in the nervous tissue; invented by Camillo Golgi.

Answer 50

Golgi Stain

Question 51

A rounded ridge on the surface of the brain's cerebral cortex; gyri are made of gray mater/ the crowns of the folded tissue that are visible on the surface of the cerebral cortex

Answer 51

Gyrus

Question 52

mostly made up of nerve cell bodies and dendrites; layers of the cerebellum that is composed of neuronal cell bodies.

Answer 52

Gray Matter

Question 53

Hodgkin-Huxley Cycle

Answer 53

1. When a neuron reaches a certain threshold, voltage-gated sodium channels open. 2. Sodium flows into the neuron, which depolarizes it further. 3. The depolarization opens more sodium channels, which causes even more depolarization. 4. The cycle continues until the membrane potential reaches the sodium equilibrium potential. 5. Potassium channels open, allowing potassium to flow out of the neuron. 6. This repolarizes the membrane potential, returning it to its resting state.

Question 54

Change in a cell's membrane potential that makes it more negative; increasing the polarization/ decreasing firing of the action potential

Answer 54

Hyperolarize

Question 55

Molecules or atoms that have either a positive or negative electrical charge.

Answer 55

Ion

Question 56

He classified cortical areas based on cytoarchitecture; Brodmann's areas.

Answer 56

Korbinian Brodmann

Question 57

Receives info from the ganglion cells of the retina and sends axons to the primary visual cortex.

Answer 57

LGN (lateral geniculate nucleus)

Question 58

Part of the brain that process visual info, such as color, motion, and form; located in the posterior part of the brain relative to the parietal and temporal lobes. It holds the visual association area, the visual cortex.

Answer 58

Occipital Lobes

Question 59

Part of the brain that processes sensory info, stores memories, understands language, and processes auditory info; located behind ears, it is anterior to the occipital lobe and posterior to the frontal lobe. It holds the auditory associations areas, auditory and olfactory cortex.

Answer 59

Temporal Lobes

Question 60

Part of the brain that controls behavior, emotions, and many cognitive functions; located directly behind the forehead, the anterior part of the brain, anterior to the parietal lobe. It holds the primary motor cortex, the premotor cortex.

Answer 60

Frontal lobes

Question 61

Part of the brain processes sensory info, including touch, pain, and temperature.

Answer 61

Parietal lobes

Question 62

The ability of a cell membrane to control what passes in and out of the cell; can change because the membranes have ion channels that are capable of changing their permeability for a particular ion.

Answer 62

Membrane permeability

Question 63

an insulated layer,or sheath that forms around nerves, including those in the brain and spinal cord. It insulates axons from each other, preventing signal interference. It also speeds up conduction enabling efficient long-distance communication.

Answer 63

Myelin

Question 64

Receive, integrate and transmit info in the brain. There are 3 types: sensory, interneurons/relay neurons, and motor. It is one of the 2 main cell types in the nervous system.

Answer 64

Neuron

Question 65

The process by which neural stem cells divide and differentiate into neurons and glial cells; the process of cell division that creates new neurons in the brain.

Answer 65

Neuronal Proliferation

Question 66

Describe the steps of Neuronal Proliferation

Answer 66

1. Neural stem cells differentiate into neurons and glial cells 2. progenitor cells divide symmetrically to create proliferative units. 3. progenitor cells divide asymmetrically to create stem cells and neurons. 4. Neurons move/migrate to their final destinations

Question 67

A chemical substance/ a body's chemical messengers. They are the molecules used by the nervous system to transmit messages between neurons or from neurons to muscles.

Answer 67

Neurotransmitter

Question 68

What are the four identifiers of a neurotransmitter?

Answer 68

1. It is synthesized by and localized within the pre-synaptic neuron and stored in the presynaptic terminal before release. 2. It is released by the presynaptic neuron when action potentials depolarize the terminal (mediated primarily by Ca2+) 3. The postsynaptic neuron contains receptors specific to it. 4. When artificially applied to a postsynaptic cell, it elicits the same response that stimulating the presynaptic neuron would.

Question 69

A relatively compact arrangement of nerve cell bodies and their connections.

Answer 69

Nucleus

Question 70

Refers to when neurons' axon output synapses make connections onto other neurons or targets.

Answer 70

Presynaptic

Question 71

Refers to when neurons make a connection at input synapses onto their dendrites or elsewhere on the receiving neurons.

Answer 71

Postsynaptic

Question 72

Neurons with a pyramid-shaped cell body that is found in the cerebral cortex, hippocampus, and amygdala; highly polarized neurons found in the cerebral cortex, serving as the main excitatory neuron. It plays a crucial role in cortical output.

Answer 72

Pyramid cell

Question 73

He is known for establishing the neuron, or nerve cell, as a basic unit of nervous structure; he proposed the neuron doctrine that states the nervous system is composed of individual cells called neurons, which communicate with each other at specialized junctions called synapses/ each neuron functions as an autonomous unit within the nervous system.

Answer 73

Ramon y Cajal

Question 74

A molecule inside or on the surface of a cell that binds to a specific substance and causes a specific effect in the cell.

Answer 74

Receptor

Question 75

The absolute refractory period refers to the time after an action potential when a cell cannot generate another action potential. A relative refractory period follows an absolute refractory period; the neuron can generate action potentials, but only with longer-than-normal depolarizing.

Answer 75

Refractory Period

Question 76

aka resting membrane potential; the voltage difference across the neuronal membrane in the resting state, is typically about -70 mV inside.

Answer 76

Resting Potential

Question 77

The rapid method by which nerve impulses move down a myelinated axon with excitation occurring only at nodes of Ranvier

Answer 77

Saltatory Conduction

Question 78

aka cell body; contains the nucleus, which acts as the cell's control center, integrating incoming signals and generating the output signal.

Answer 78

Soma

Question 79

Occurs when stimuli are applied at the same time, but in different areas, with a cumulative effect upon membrane potential.

Answer 79

Spatial summation

Question 80

The crevices of the cortical sheet; increases surface area and divides the brain into regions.

Answer 80

Sulcus

Question 81

A specialized structure where two neurons came into close contact so that chemical or electrical signals can be passed from one cell to the next.

Answer 81

Synapse

Question 82

The transfer of a signal from the axon terminal of one neuron to the next neuron.

Answer 82

Synaptic transmission

Question 83

A complex process which describes how neurons integrate the receiving inputs from thousands of presynaptic neurons before the generation of a nerve impulse.

Answer 83

Synaptic integration

Question 84

It occurs when multiple action potential signals fire down the axon hillock of a single neuron to be received by the synapse of another neuron.

Answer 84

Temporal summation

Question 85

When the membrane reaches -55mV, leading to the fire, an action potential/ the minimum level of energy or depolarization is required to trigger a response.

Answer 85

Threshold

Question 86

Refers to the orderly spatial representation of sensory or motor info. Ex: somatosensory cortex, retinotopic map, tonotopic map in the auditory cortex.

Answer 86

Topographic Maps

Question 87

Allows action potentials to regenerate itself; proteins that allow certain ions to pass through cell membranes. They open and close in response to changes in the cell's membrane potential.

Answer 87

Voltage-gated channels

Question 88

Layers of the cerebellum that consist of axons and glial cells.

Answer 88

White matter