Chapter 2: Structure and Function Flashcards
Neurons
Nerve cells, basic unit of the brain
Glial cells
Serve various functions in the nervous system, providing structural support and electrical insulation to neurons and modulating neuronal activity
Three main types of glial cells
Astrocytes, microglial cells, and oligodendrocytes
Astrocytes
Large glial cells with round or radially symmetrical forms; they surround neurons and are in close contact with the brain’s vasculature
Blood-brain barrier (BBB)
Created by astrocytes between the tissues of the central nervous system and the blood
The BBB restricts the diffusion of microscopic objects (such as most bacteria) and large hydrophilic molecules in the blood from entering the neural tissue, but it allows the diffusion of small hydrophobic molecules, such as oxygen, carbon dioxide, and hormones.
Myelin is formed by _______ in the central nervous system and _______ in the peripheral.
oligodendrocytes, Schwann cells
Microglial cells
phagocytes that devour and remove damaged cells. Unlike many cells in the central nervous system, microglial cells can proliferate even in adults (as do other glial cells)
Presynaptic
The neuron’s axon’s output synapses make connections onto other neurons or targets
Postsynaptic
Other neurons make a connection at input synapses onto their dendrites or elsewhere on the receiving neuron
Neurons communicate with other neurons and cells at specialized structures called _______.
synapses
The electrical gradient across a neuron’s membrane results from the _______.
asymmetrical distribution of ions
What makes a molecule a neurotransmitter?
It is synthesized by and localized within the presynaptic 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 for it.
When artificially applied to a postsynaptic cell, it elicits the same response that stimulating the presynaptic neuron would.
Tachykinins
(brain-gut peptides, which are peptides secreted by endocrine cells and enteric neurons in the GI tract and also neurons in the central nervous system). This group includes substance P, which affects vasoconstriction and is a spinal neurotransmitter involved in pain.
Neurohypophyseal hormones
Oxytocin and vasopressin are in this group. The former is involved in mammary functions and has been tagged the “love hormone” for its role in pair bonding and maternal behaviors; the latter is an antidiuretic hormone.
Hypothalamic releasing hormones
This group includes corticotropin-releasing hormone, involved in the stress response; somatostatin, an inhibitor of growth hormone; and gonadotropin-releasing hormone, involved with the development, growth, and functioning of the body’s reproductive processes.
Opioid peptides
This group is named for its similarity to opiate drugs, and these peptides bind to opiate receptors. It includes the endorphins and enkephalins.
Other neuropeptides
This group includes peptides that do not fit neatly into another category, such as insulins, secretins (e.g., glucagon), and gastrins.
Action potential (p. 31)
A rapid depolarization and repolarization of a small region of the membrane on the neuron’s output via its axon caused by the opening and closing of ion channels.
Amygdala (p. 50)
Collections of neurons anterior to hippocampus in the medial temporal lobe, involved in emotional processing
Association cortex (p. 61)
Part of neocortex that involves signals from different inputs (not jsut sensory or motor)
Autonomic nervous system (p. 40)
involved in controlling the involuntary action of smooth muscles, the heart, and various glands
Axon (p. 27)
The axon is a single process that extends from the cell body.
This structure represents the output side of the neuron. Electrical signals travel along the length of the axon to its end, the axon terminals, where the neuron transmits the signal to other neurons or other targets.
Axon collaterals (p. 27)
Some axons branch to form axon collaterals that can transmit signals to more than one cell.
Axon hillock (p. 32)
A part of the cell body of a neuron where the membrane potential’s are summer before being transmitted down the axon.
Basal ganglia (p. 50)
Collection of nuclei bilaterally located beneath the anterior portion of lateral ventricals
5 nuclei: caudate, putamen, globus pallidus, subthalamic nucleus, substantia nigra
action selection, action gating, reward-based learning, motor prep, timing, task switching, and more
Brainstem (p. 46)
Region of the nervous system that contains groups of motor and sensory nuclei, nuclei of widespread modulatory neurotransmitter systems, and white matter tracts of ascending sensory info and descending motor signals
Medulla, pons and cerebellum, and midbrain
Central nervous system (CNS) (p. 40)
The brain and spinal cord
Central sulcus (p. 54)
Divides frontal and parietal lobes
Cerebellum (p. 42)
“Little brain”
Coordination and movement
Cerebral cortex (p. 42)
Layered sheets of neurons over the forebrain
Commissure (p. 42)
White matter tracts that cross from left to right of CNS or vise versa
Corpus callosum is the largest
Corpus callosum (p. 42)
Fiber system composed of axons that connect the cortex of the two cerebral hemispheres
Largest white matter structure
Cytoarchitectonics (p. 54)
Brodmann used the micro anatomy of cells and their organization to subdivide the cortex into 52 regions
Can seem unsystematic and is not standardized
Dendrites (p. 26)
Dendrites are branching extensions of the neuron that receive inputs from other neurons.
Depolarization (p. 32)
A change in the membrane potential in which the electrical current inside the cell becomes less negative. 
Electrical gradient (p. 30)
A force that develops when a charge distribution across the neuronal membrane develops such that the charge inside is more positive or negative than the one outside. Electrical gradient result from a symmetrical distributions of ions across the membrane. 
Electrotonic conduction (p. 31)
The small electrical current produced by the EPSP is passively conducted through the cytoplasm of the dendrite, cell body, and axon.
Passive current conduction is called electrotonic conduction or decremental conduction: “decremental” because it diminishes with distance from its origin—the synapse on the dendrites, in this case.
Equilibrium potential (p. 32)
The membrane potential at which given an ion has no net flux across the membrane. (Ions in = ions out)
Frontal lobe (p. 53)
Contains motor and prefrontal cortex
Gray matter (p. 42)
Regions of the nervous system that contain primarily neuronal cell bodies. Includes the cerebral cortex basil ganglia a nuclei of the thalamus
Gyrus (p. 52)
Crowns in cortical sheet
Hippocampus (p. 50)
Layered structure in medial temporal lobe, receives inputs and sends projections out to subcortical targets
Involved in learning, memory (spatial locations and episodic memory)
Hyperpolarization (p. 32)
A change in the membrane potential in which the electrical current inside of the cell becomes more negative. With respect to resting potential a hyperpolarized membrane potential is farther from the firing threshold. 
Hypothalamus (p. 49)
Link between nervous system and endocrine system
Chief site for hormone production and control
Floor of 3rd ventricle
Maintains homeostasis
Insula (p. 54)
Part of cortex hidden in sylvian fissure
Also has extensive reciprocal connections with areas associated with emotion, such as the amygdala, medial prefrontal cortex, and anterior cingulate gyrus
As well as with frontal parietal and temporal cortical areas involved with attention, memory, and cognition
Ion channel (p. 28)
Proteins with a pore through the center, and they allow certain ions to flow down their electrochemical and concentration gradients.
Ion pump (p. 28)
Ion pumps use energy to actively transport ions across the membrane against their concentration gradients—that is, from regions of low concentration to regions of higher concentration.
Layer (p. 41)
Neurons are organized in layers, such as in the cerebral cortex
Limbic system (p. 50)
Border around brainstem
Amygdala, orbiofrontal cortex, portions of basal ganglia
Medulla (p. 46)
Brainstem’s most caudal portion
Houses cell bodies of many of the twelve cranial nerves, provides sensorimotor innervations to face, neck, abdomen, and throat and ♡
Controls necessary functions like breathing, heart rate, and arousal
Microcircuit (p. 39)
A small network of localized interconnected neurons that process specific kinds of information. 
Midbrain (p. 48)
Visumotor function
Myelin (p. 25)
Glial cells also form the fatty substance called myelin in the nervous system.
Neocortex (p. 55)
Cortex that contains six cortical layers or that passed through a developmental stage involving six cortical layers
Neural network (p. 39)
A complex Netwerk made up of a long distance connections between various brain regions. Neural networks are macrocircuits composed of multiple embedded microcircuit and they support more complex analysis integrating information processes from many microcircuits
Neurotransmitter (p. 35)
A chemical substance that transmits the signal between neurons at chemical synapses.
Node of Ranvier (p. 32)
Location at which myelin is interrupted between successive patches of axon, and where an action potential can be generated
Nucleus (p. 41)
Relatively compact arrangement of nerve cell bodies and their connections
Occipital lobe (p. 54)
At back of the brain
Visual info processing
Parietal lobe (p. 54)
Somatosensory cortex, gustatory cortex, and parietal association cortex
Visuomotor orienting, attention, representation of space
Above temporal lobe
Peripheral nervous system (PNS) (p. 40)
Comprised of sensory and motor nerves and associated nerve cell ganglia, located outside the central nervous system
Permeability (p. 29)
Extent to which ions can cross the neuronal membrane
Pituitary gland (p. 49)
Endocrine gland that synthesizes and secretes hormones that aid in regulation of multiple processes to maintain homeostasis, controlled by hypothalamus
Pons (p. 47)
“Bridge” between brain and cerebellum
Responsible for REM
Prefrontal cortex (p. 61)
High-level motor control, planning and executing behavior
Large in humans
Refractory period (p. 32)
The short period of time following an action potential during which the neuron may not be able to generate action potential‘s or may be able to do so only with larger-than-normal depolarizing currents. 
Resting membrane potential (p. 28)
The voltage difference across the neuronal membrane in the resting state is typically about –70 millivolts (mV) inside, which is known as the resting potential or resting membrane potential.
This electrical-potential difference means that the neuron has at its disposal a kind of battery; and like a battery, the stored energy can be used to do work—signaling work
Saltatory conduction (p. 32)
Mode of conduction in myelinated neurons, in which action potentials are generated down the axon only at nodes of Ranvier. Measurement of the propagation of the action potential gives it the appearance of jumping from node to node. 
Somatotopy (p. 58)
Point-for-point representation of the body in the nervous system in the somatosensory cortex
Spike-triggering zone (p. 32)
The location at the juncture of the soma and the axon of a neuron where currents from synaptic inputs on the soma and distant dendrites are summed and where the voltage gated sodium channels are located that can be triggered to generate action potentials that can propagate down the axon
Spine (p. 27)
Most dendrites also have specialized processes called spines, little knobs attached by small necks to the surface of the dendrites, where the dendrites receive inputs from other neurons.
Sulcus (p. 52)
Crevices in cortical sheet
Allow for more surface area to be packed into brain
Neurons are closer because if sulci
Sylvian (lateral) fissure (p. 54)
Divides temporal, frontal, and parietal lobes
Synapse (p. 27)
Transmission occurs at the synapse, a specialized structure where two neurons come into close contact so that chemical or electrical signals can be passed from one cell to the next.
Synapse elimination (p. 67)
Pruning
Synaptic cleft (p. 33)
Gap between neurons at synapses
Synaptogenesis (p. 67)
Formation of synapses
Temporal lobe (p. 54)
Hippocampus, amygdala, high-order vision, representation of conceptual info, linguistics representation, Sylvian fissure, auditory fissure
Below parietal lobe
Thalamus (p. 48)
Divided between the left and right
Bigger than hypothalamus
“Gateway to the cortex”
Threshold (p. 32)
The potential value to which the membrane must be depolarized for an action potential to be initiated
Tract (p. 42)
Bundle of axons in the CNS, formed from the axons in white matter
Ventricle (p. 41)
Any of the four large, interconnected cavities of the brain
Vesicle (p. 33)
Small, intracellular organelle, located in presynaptic terminals at synapses, contains neurotransmitter
Voltage-gated ion channel (p. 31)
A transmembrane ion channel that changes molecular conformation when the membrane potential changes, altering the conductance of the channel for specific ions
White matter
Regions of nervous system composed of axons surrounding myelin. Looks white because of myelin
Sympathetic v Parasympathetic branches
Work in opposition to one another
