Neurology

Front 1

What are ganglia?

Back 1

A biological tissue mass, most commonly a mass of nerve cell bodies.

Front 2

What are ganglia mostly composed of?

Back 2

Somata and dendritic structures that are bundled or connected together.

Front 3

What is often formed from the interconnection of many ganglia?

Back 3

A complex system of ganglia known as a plexus.

Front 4

What do ganglia often connect?

Back 4

Ganglia are often the intermediary connection between different neurological structures, such as the peripheral and central nervous system.

Front 5

What are the two main types of ganglia?

Back 5

Dorsal root ganglia
Autonomic ganglia

Front 6

What are the nerve fibers that run from the central nervous system to the ganglia in the autonomic nervous system known as?

Back 6

Preganglionic fibers

Front 7

What are postganglionic fibers?

Back 7

Nerve fibers of the autonomic nervous system that run from the ganglia to their effector organ.

Front 8

What are basal ganglia?

Back 8

In the brain, the basal ganglia are a group of nuclei that are interconnected with the cerebral cortex, thalamus, and brainstem. It is associated with a variety of functions such as motor control, cognition, emotions, and learning. It is also known as the basal nuclei.

Front 9

What is a nerve plexus?

Back 9

In vertebrates, a plexus is an area where nerves branch and rejoin. The electrical signals do not mix, rather the fibers travel together while keeping their electrical signals separate. The brachial plexus is an example as it is composed of spinal nerves that enter the upper limbs. In humans the four main plexuses are the cervical plexus, the brachial plexus, the lumbar plexus, and the sacral plexus.

Front 10

What is the dorsal root ganglion? Also called the spinal ganglion.

Back 10

A nodule in the dorsal root that contains the cell bodies of afferent spinal nerves.

Front 11

The dorsal root ganglion are pseudo-unipolar. What does this mean?

Back 11

It is a sensory neuron in the peripheral nervous system. It contains a long dendrite and a short axon that connects to the spinal cord. The dendrite and axon are sometimes referred to as the distal process and the proximal process respectively.

Front 12

In embryological terms, where does the dorsal root ganglion develop from?

Back 12

From neural crest cells.

Front 13

What is the dorsal root?

Back 13

The dorsal root is the afferent sensory root of a spinal nerve. The distal end is known as the dorsal root ganglion

Front 14

Describe the lateral division of the dorsal root.

Back 14

Contains lightly myelinated and unmyelinated axons of small diameter. These transmit pain and temperature sensation from the body

Front 15

Describe the medial division of the dorsal root.

Back 15

Contains myelinated axons of larger diameter than the lateral division. These transmit information of discriminative touch, pressure, vibration, and conscious proprioception, originating from spinal levels C2 through S5.

Front 16

What is the anterior (or ventral) white commissure?

Back 16

A bundle of nerve fibers which cross the midline of the spinal cord, just anterior to the gray commissure.

Front 17

What are afferent neurons?

Back 17

Otherwise known as sensory or receptor neurons, afferent neurons carry nerve impulses from receptor or sense organs to the central nervous system

Front 18

What are efferent neurons?

Back 18

Otherwise known as motor or effector neurons, efferent neurons carry nerve impulses away from the central nervous system.

Front 19

What are autonomic ganglion?

Back 19

Autonomic ganglion are clusters of neuronal cell bodies and their dendrites and are essentially a junction between nerves originating from the central nervous system and autonomic nerves innervating their target organs in the periphery.

Front 20

What are interneurons?

Back 20

Interneurons connect neurons to other neurons within the same region of the brain or spinal cord.

Front 21

All neurons are electrically excitable. What does this mean and how is it maintained?

Back 21

It means they can be stimulated by means of electrical current. Electrical excitability is maintained through voltage gradients that are maintained across their membranes by means of metabolically driven ion pumps and embedded ion channels.

Front 22

In some occasions, astrocytes have been observed turning into neurons due to the fact they are pluripotent. What does pluripotent mean?

Back 22

A pluripotent cell is on that has the ability to differentiate into different cell types.

Front 23

Nerve cell bodies have been shown to have numerous clumps of Nissl substance. What does the prominence of Nissl material indicate?

Back 23

The prominence of the Nissl material indicates that nerve cells are metabolically very active and are involved in large amounts of protein synthesis.

Front 24

What is a Nissl body or Nissl granule?

Back 24

Nissl bodies are large granular bodies found in neurons. These granules are rough endoplasmic reticulum with free ribosomes, and is the site of protein synthesis.

Front 25

Structurally what are neuronal cell bodies supported by?

Back 25

The cell bodies of neurons are supported by a complex meshwork of neurofilaments which are assembled into larger neurofibrils.

Front 26

Do axons or dendrites contain ribosomes?

Back 26

Typical axons almost never contain ribosomes, except for some in the initial segment. Dendrites contain granular endoplasmic reticulum or ribosomes, with amounts diminishing with distance from the cell body.

Front 27

What is a unipolar or pseudounipolar neuron?

Back 27

A neuron where axon and dendrite emerge from the same process.

Front 28

What is a bipolar neuron?

Back 28

Where the axon and a single dendrite are on opposite ends of the soma.

Front 29

What is a multipolar neuron?

Back 29

A neuron that has more than two dendrites emerging from the soma. These can be further divided into Golgi I and Golgi II neurons.

Front 30

What are Golgi I neurons?

Back 30

Neurons with long projecting axonal processes. Examples are pyramidal cells, Purkinje cells, and anterior horn cells.

Front 31

What is a Golgi II neuron?

Back 31

A Golgi II neuron is one where the axonal process projects locally, such as in a granule cell.

Front 32

In neuronal signaling, what determines the effect that is produced from the target neuron?

Back 32

They type of receptor that is activated determines the effect produced in the target cell, not the neurotransmitter or source neuron.

Front 33

What are the most common neurotransmitters in the brain?

Back 33

Glutamate and GABA are the most common neurotransmitters in the brain, as well over 90% of neurons use one of the two.

Front 34

What are cholinergic neurons?

Back 34

Neurons that manufacture the neurotransmitter acetylcholine

Front 35

What are the two neuroinhibitors of the CNS?

Back 35

GABA and Glycine

Front 36

What is an endogenous substance?

Back 36

A substance that originates within an organism.

Front 37

What is synaptic plasticity?

Back 37

Synaptic plasticity is the ability of a synapse between two neurons to change in strength. There are several underlying mechanisms that cooperate to achieve synaptic plasticity, including changes in the quantity of neurotransmitters released into a synapse and changes in how effectively cells respond to those neurotransmitters.

Front 38

Due to glutamate's role in synaptic plasticity, what kind of functions in the the brain is it involved with?

Back 38

Glutamate is involved in brain function such as learning and memory.

Front 39

Glutamate does not just function as a point to point transmitter. What other type of neuronal communication is it involved in?

Back 39

Glutamate uses spill-over synaptic cross talk in which summation of glutamate released from neighboring synapses creates extrasynaptic signaling and increased volume transmission.

Front 40

What are excitatory amino acid transporters?

Back 40

Formerly known as glutamate transporters, excitatory amino acid transporters (EAAT) serve to terminate the excitatory neurotransmitter signal by uptake of glutamate from the neuronal synapse into Glia cells. EAAT's are membrane bound pumps that resemble ion channels. After glutamate is released following an action potential, EAAT's quickly remove it from the extracellular space, thereby terminating the synaptic transmission.

Front 41

Where are Glutamate transporters found?

Back 41

They are found on neuronal and glial cell membranes.

Front 42

What serves as the precursor for the inhibitory neurotransmitter GABA?

Back 42

Glutamate serves as the precursor to GABA in GABAergic neurons. The reaction is catalyzed by glutamate decarboxylase (GAD), which is most abundant in the cerebellum and pancreas.

Front 43

Drugs like phenylcyclidine and ketamine produce their dissociative and hallucinogenic effects by doing what?

Back 43

Phenylcyclidine and ketamine act as non-competitive antagonists of glutamic acid at the NMDA receptor.

Front 44

What types of synapses is glutamate often found at?

Back 44

Glutamate is used at the great majority of fast excitatory synapses in the brain and spinal cord. It is also used at most synapses that are modifiable, or capable of increasing or decreasing in strength. These modifiable synapses are thought to be the main memory-storage elements in the brain.

Front 45

GABA is often found at what type of synapses?

Back 45

GABA is used at a great majority of fast acting inhibitory synapses in virtually every part of the brain.

Front 46

Most sedative/tranquilizer drugs act through what?

Back 46

Most sedative drugs act through enhancing the effects of GABA.

Front 47

What acts as the inhibitory neurotransmitter in the spinal cord?

Back 47

Glycine acts as the inhibitory neurotransmitter in the spinal cord.

Front 48

GABA stands for what?

Back 48

GABA stands for gamma-aminobutyric acid.

Front 49

In addition to its role in regulating neuronal excitability, GABA also serves what function in humans?

Back 49

GABA is also directly responsible for the regulation of muscle tone.

Front 50

How does GABA induce an inhibitory effect on nerves?

Back 50

GABA acts at inhibitory synapses in the brain by binding to specific transmembrane receptors on both the presynaptic and postsynaptic neuronal processes. The binding causes ion channels to allow the flow of either negatively charged chloride ions into the cell or positively charged potassium ions out of the cell resulting in a negative change in the transmembrane potential, usually causing hyperpolarization.

Front 51

Acetylcholine is a neurotransmitter most commonly found at what type of neuronal junction in the PNS?

Back 51

Acetylcholine is the neurotransmitter found at the neuromuscular junction connecting motor nerves to muscles.

Front 52

Where is acetylcholine the principal neurotransmitter in the autonomic nervous system?

Back 52

Acetylcholine is the principal neurotransmitter in the autonomic ganglia.

Front 53

What is acetylcholine's function in the CNS?

Back 53

In the CNS, acetylcholine and its associated neurons form a neurotransmitter system called the cholinergic system which tends to cause anti-excitatory actions.

Front 54

At what sites in the autonomic nervous system is acetylcholine released?

Back 54

All pre- and postganglionic parasympathetic neurons; all preganglionic sympathetic neurons; some postganglionic sympathetic neurons.

Front 55

What type of functions does dopamine have in the brain?

Back 55

Dopamine's effect on the brain includes roles in behavior and cognition, voluntary movement, motivation, punishment and reward, inhibition of prolactic production (involved in lactation and sexual gratification), sleep, mood, attention, working memory and learning.