Chapter 2 Key Terms Flashcards
How does myelin help speed the propagation of the action potential down the axon?
Myelin insulates axons, allowing faster action potential propagation via saltatory conduction.
Why is the action potential referred to as “all-or-none?”
It either occurs fully or not at all. Once the threshold is reached, the cell fires.
What function would be compromised if the precentral gyrus were lesioned?
Damage to the precentral gyrus would affect motor control, leading to paralysis or
impaired voluntary movements
What about the superior temporal gyrus?
Damage to the superior temporal gyrus would affect language comprehension and
auditory processing.
What about the calcarine sulcus (primary visual cortex)?
Damage to the calcarine sulcus would affect visual processing, potentially causing
blindness.
What cytoarchitectural arrangement does all of the cerebral cortex have in common?
The cortex generally has six distinct layers.
What cytoarchitectural variations exist within the cerebral cortex?
Variations include differences in thickness, size, density, and cell type.
Why is the thalamus called the “gateway to the cortex?” Name two nuclei in the thalamus and briefly explain their function.
The thalamus is a relay from the peripheral sense organs to the cortex. The LGN
processes visual input, and the MGN processes auditory input.
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?
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.
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.
No, the thalamic nuclei, such as the LGN within the midbrain, contain gray matter.
What is the difference between the central nervous system and the peripheral nervous system?
The CNS consists of the brain and spinal cord. The PNS consists of all nerves branching
out from the CNS.
What is the difference between the somatic and autonomic peripheral nervous
system?
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.
What is the function of glial cells in the nervous system?
Glial cells provide structural support, speed up neuronal signaling through myelination,
regulate the extracellular environment, and participate in immune defense.
How does the neuron doctrine differ from the reticular theory?
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.
What are the differences between astrocytes, oligodendrocytes, and microglial cells?
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.
What is the role of dendritic spines in neuronal communication?
Dendritic spines increase the surface area of dendrites, allowing neurons to form more synaptic connections and facilitate synaptic strength modulation
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.
Action Potential
Neurons that input to the CNS/ sensory input to the CNS; carries sensory input through the dorsal root into the spinal cord.
Afferent
Back
Posterior
back/posterior
Caudal
Rostral
front/anterior
Inferior
Bottom
Dorsal
top of the brain/ back of the body
Ventral
Bottom of the brain/ front of the body
Medial
middle
Lateral
Sides
Anterior
Front
Superior
Top
A network of regions in the brain that process complex info and support higher-order cognitive functions, such as language, perception, and thought
Association cortex
Tube-like nerve fiber that transmits signals to other neurons
Axon
A detailed representation of the brain’s cerebral cortex. There are 52 distinct regions.
Brodmann’s map
He developed a staining technique to visualize individual neurons; he proposed reticular theory saying that our neurons system was a continuous, interconnected network.
Camillo Golgi
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.
Chemical Transmission
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.
Cerebellum
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.
Concentrated Gradient
crosses over/ opposite side
Contralateral
Ipsilateral
same side
Coronal
Cut that gives an anterior/posterior section (or rostral/caudal cut)
Sagittal
Cut that gives a left and right section (lateral or medial cut)
Axial
aka horizontal; gives a dorsal and ventral section (or inferior/superior section)
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.
Cytoarchitecture
Receives input from other neurons; branching extensions of the neuron
Dendrite
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.
Depolarize
process of movement of molecules under a concentration gradient
Diffusion
The outermost of the 3 meninges; it is a tough outer layer
Dura Mater
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
Efferent
Caused by each k+ ion carries one unit of positive charge out of the neuron as it moves across the membrane.
Electrical gradient
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.
Equilibrium Potential
Nerve cel bodies/ non-neuronal cells of the brain and nervous system.
Glia
A technique that uses silver nitrate and potassium chromate to stain neurons in the nervous tissue; invented by Camillo Golgi.
Golgi Stain
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
Gyrus
mostly made up of nerve cell bodies and dendrites; layers of the cerebellum that is composed of neuronal cell bodies.
Gray Matter
Hodgkin-Huxley Cycle
- When a neuron reaches a certain threshold, voltage-gated sodium channels open.
- Sodium flows into the neuron, which depolarizes it further.
- The depolarization opens more sodium channels, which causes even more depolarization.
- The cycle continues until the membrane potential reaches the sodium equilibrium potential.
- Potassium channels open, allowing potassium to flow out of the neuron.
- This repolarizes the membrane potential, returning it to its resting state.
Change in a cell’s membrane potential that makes it more negative; increasing the polarization/ decreasing firing of the action potential
Hyperolarize
Molecules or atoms that have either a positive or negative electrical charge.
Ion
He classified cortical areas based on cytoarchitecture; Brodmann’s areas.
Korbinian Brodmann
Receives info from the ganglion cells of the retina and sends axons to the primary visual cortex.
LGN (lateral geniculate nucleus)
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.
Occipital Lobes
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.
Temporal Lobes
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.
Frontal lobes
Part of the brain processes sensory info, including touch, pain, and temperature.
Parietal lobes
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.
Membrane permeability
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.
Myelin
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.
Neuron
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.
Neuronal Proliferation
Describe the steps of Neuronal Proliferation
- Neural stem cells differentiate into neurons and glial cells
- progenitor cells divide symmetrically to create proliferative units.
- progenitor cells divide asymmetrically to create stem cells and neurons.
- Neurons move/migrate to their final destinations
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.
Neurotransmitter
What are the four identifiers of a neurotransmitter?
- It is synthesized by and localized within the pre-synaptic neuron and stored in the presynaptic terminal before release.
- It is released by the presynaptic neuron when action potentials depolarize the terminal (mediated primarily by Ca2+)
- The postsynaptic neuron contains receptors specific to it.
- When artificially applied to a postsynaptic cell, it elicits the same response that stimulating the presynaptic neuron would.
A relatively compact arrangement of nerve cell bodies and their connections.
Nucleus
Refers to when neurons’ axon output synapses make connections onto other neurons or targets.
Presynaptic
Refers to when neurons make a connection at input synapses onto their dendrites or elsewhere on the receiving neurons.
Postsynaptic
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.
Pyramid cell
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.
Ramon y Cajal
A molecule inside or on the surface of a cell that binds to a specific substance and causes a specific effect in the cell.
Receptor
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.
Refractory Period
aka resting membrane potential; the voltage difference across the neuronal membrane in the resting state, is typically about -70 mV inside.
Resting Potential
The rapid method by which nerve impulses move down a myelinated axon with excitation occurring only at nodes of Ranvier
Saltatory Conduction
aka cell body; contains the nucleus, which acts as the cell’s control center, integrating incoming signals and generating the output signal.
Soma
Occurs when stimuli are applied at the same time, but in different areas, with a cumulative effect upon membrane potential.
Spatial summation
The crevices of the cortical sheet; increases surface area and divides the brain into regions.
Sulcus
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.
Synapse
The transfer of a signal from the axon terminal of one neuron to the next neuron.
Synaptic transmission
A complex process which describes how neurons integrate the receiving inputs from thousands of presynaptic neurons before the generation of a nerve impulse.
Synaptic integration
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.
Temporal summation
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.
Threshold
Refers to the orderly spatial representation of sensory or motor info. Ex: somatosensory cortex, retinotopic map, tonotopic map in the auditory cortex.
Topographic Maps
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.
Voltage-gated channels
Layers of the cerebellum that consist of axons and glial cells.
White matter
