110 Questions
Which term did Robert Hooke use to describe the repeating units he observed in thin slices of cork?
Cells
Who proposed the cell theory in 1839?
Theodor Schwann
Which discipline of biology widely accepted the cell theory by the second half of the nineteenth century?
Botany
What did proponents of the reticular theory believe constituted the working unit of the nervous system?
Reticulum
Who made important contributions to science including the discovery of the Golgi apparatus?
Camillo Golgi
What is the Golgi apparatus responsible for?
Processing proteins
When were individual neurons first visualized by Golgi staining?
Late nineteenth century
What did contemporary students of neurobiology find surprising about the acceptance of the cellular organization of the nervous system?
It was accepted in the early twentieth century
What did neurobiologists of the early twentieth century believe nerve cells were linked together by?
Reticulum
What did neuroscientists who supported the reticular theory consider as the working unit of the nervous system?
Reticulum
What was Golgi's greatest contribution?
Inventing the Golgi staining method
What happens when neural tissue is soaked in a solution of silver nitrate and potassium dichromate using the Golgi staining method?
The tissue becomes visualized against an unstained background
What is the reticular theory?
The theory that neuronal processes fuse to form a reticulum
Who refuted the reticular theory?
Santiago Ramón y Cajal
What did the neuron doctrine propose?
Neurons communicate through synaptic contact
What did Golgi's staining method enable for the first time?
Visualization of individual neurons
What did Ramón y Cajal use to refute Golgi's theory?
The Golgi staining method
What did Ramón y Cajal state about Golgi's work?
Golgi's work consisted of two separate parts
What did Golgi think about dendritic trees?
They fuse together to form a reticulum
Who were the most influential neurobiologists of their time?
Camillo Golgi and Santiago Ramón y Cajal
What is the elementary unit of nerve impulses called?
Action potential
What do neurons use to convey the intensity of signals being delivered?
Frequency of action potentials
What term is used to describe membrane potentials that can change in continuous values?
Graded potentials
Where are synaptic potentials usually produced in a neuron?
Dendritic spines
What determines whether, when, and how frequently a neuron will fire action potentials?
Synaptic potentials
Where is the site of action potential initiation in most neurons?
Axon initial segment
What is the process called when neurotransmitters diffuse across the synaptic cleft and bind to their receptors on the postsynaptic neurons?
Synaptic transmission
What happens at electrical synapses to transmit information between neurons?
Ion flow across gap junctions
What triggers the release of neurotransmitters at chemical synapses?
Action potentials
What do neurotransmitters bind to on the postsynaptic neurons to produce synaptic potentials?
Synaptic receptors
Which of the following is the physical basis of information flow within neurons?
Electrical signals
What did Luigi Galvani's discovery in the late eighteenth century involve?
Application of electric current to frogs
What is the membrane potential?
The electrical potential difference across the neuronal membrane
What is the resting state of neurons?
More negatively charged inside the cells
How do neurons relay information through nerve impulses?
By changing the membrane potential
What did studies of muscle contraction in response to electrical stimulation of motor nerves suggest?
Different stimulus strengths produce the same type of muscle contraction
When did the development of amplifiers for electrical signals occur?
1920s
What type of neurons did Edgar Adrian and co-workers measure nerve impulses from?
Sensory neurons
What did quantitative studies of sensory stimuli provide important clues about?
The relationship between sensory stimuli and membrane potential
What principle became clearer with the development of amplifiers for electrical signals?
The all-or-none conduction principle
What is the elementary unit of nerve impulses called?
Action potentials
What is the most widely used means to convey signal intensity throughout the nervous system?
Frequency of action potentials
What are membrane potentials that can change in continuous values called?
Graded potentials
Where are graded potentials induced by sensory stimuli produced?
Peripheral endings of sensory neurons
Which type of potentials are produced at the postsynaptic sites in response to neurotransmitter release?
Synaptic potentials
What determines the size of graded potentials?
Both strength of input stimuli and sensitivity of postsynaptic neurons
Which type of neurons do not fire action potentials at all?
Retinal neurons
Where are synaptic potentials usually produced in a neuron?
Dendrite tree
What facilitates action potential production by the postsynaptic neuron?
Excitatory inputs
What triggers the release of neurotransmitters at chemical synapses?
Action potentials
Which scientist discovered that the nervous system uses electrical signals to propagate information?
Luigi Galvani
What is the term used to describe the electrical potential difference across the neuronal membrane?
Membrane potential
What do neurons in the resting state have compared to the extracellular environment?
More negatively charged
What did quantitative studies of sensory stimuli provide important clues about?
How information is relayed through nerve impulses
What principle became clearer with the development of amplifiers for electrical signals in the 1920s?
All-or-none conduction principle
What type of neurons did Edgar Adrian and his co-workers measure nerve impulses from?
Somatosensory neurons
What is the physical basis of information flow within neurons?
Electrical signals
What triggers the release of neurotransmitters at chemical synapses?
Nerve impulses
What did studies of muscle contraction in response to electrical stimulation of motor nerves suggest?
An elementary nerve impulse underlies different stimulus strengths
What do sensory neurons convey information about?
Touch, pressure, and pain
What is the physical basis of information flow within neurons?
Electrical signals
What did Luigi Galvani's discovery in the late eighteenth century involve?
The discovery of muscle twitches in frogs
What did studies of muscle contraction in response to electrical stimulation of motor nerves suggest?
The presence of elementary nerve impulses
What is the term used to describe the electrical potential difference across the neuronal membrane?
Membrane potential
What is the resting state of neurons?
The state of low electrical activity
Where are graded potentials induced by sensory stimuli produced?
Dendrites
What determines the size of graded potentials?
The intensity of the stimulus
What do sensory neurons convey information about?
Sensations
What facilitates action potential production by the postsynaptic neuron?
Neurotransmitters
Who made important contributions to science including the discovery of the Golgi apparatus?
Camillo Golgi
Which concept of modern neuroscience is the presence of an elementary unit of nerve impulses that axons use to convey information across long distances?
Action potential
What do neurons use to convey the intensity of signals being delivered?
Frequency of action potentials
What are membrane potentials that can change in continuous values called?
Graded potentials
What type of potentials are produced at the postsynaptic sites in response to neurotransmitter release by presynaptic partners?
Synaptic potentials
What type of potentials are induced at the peripheral endings of sensory neurons by sensory stimuli?
Receptor potentials
What do most neurons in the vertebrate retina use to transmit information instead of action potentials?
Graded potentials
Where are synaptic potentials usually produced in a neuron?
Dendritic spines
What is the eventual purpose of synaptic potentials in most neurons?
To transmit information to postsynaptic target neurons
Where is the site of action potential initiation typically located?
Axon initial segment
What triggers the release of neurotransmitters at chemical synapses?
Action potentials
What is the term used to describe the membrane potentials that can change in continuous values?
Graded potentials
What is the main purpose of synaptic potentials in most neurons?
To produce action potentials
Where are synaptic potentials usually produced in a neuron?
Dendritic spines
What triggers the release of neurotransmitters at chemical synapses?
Action potentials
What is the elementary unit of nerve impulses called?
Action potential
What do graded potentials depend on?
The strength of the input stimuli
What is the main purpose of action potentials in neurons?
To transmit information across long distances
What is the site of action potential initiation typically located?
Axon initial segment
Which scientist discovered that application of an electric current could produce muscle twitches in frogs?
Luigi Galvani
What is the term used to describe the distribution of positive and negative charges on each side of the neuronal membrane?
Membrane potential
What did studies of muscle contraction in response to electrical stimulation of motor nerves suggest?
An all-or-none conduction principle
What did the development of amplifiers for electrical signals in the 1920s make possible?
Recording nerve impulses from single axon fibers
What type of neurons did Edgar Adrian and his co-workers measure nerve impulses from?
Somatosensory neurons
What is the physical basis of information flow within neurons?
Electrical signals
What do sensory neurons convey information about?
Touch, pressure, and pain
Which scientist discovered that application of an electric current could produce muscle twitches in frogs?
Luigi Galvani
What is the term used to describe the transient changes of the membrane potential that propagate electrical signals in neurons?
Nerve impulses
What did studies of muscle contraction in response to electrical stimulation of motor nerves suggest?
An elementary nerve impulse underlies different stimulus strengths
Who systematically measured nerve impulses from somatosensory neurons that convey information about touch, pressure, and pain to the spinal cord?
Edgar Adrian
What principle became clearer with the development of amplifiers for electrical signals in the 1920s?
All-or-none conduction principle
What do sensory neurons convey information about?
Touch, pressure, and pain
What is the physical basis of information flow within neurons?
Electrical signals
Which concept of modern neuroscience is the presence of an elementary unit of nerve impulses that axons use to convey information across long distances?
The concept of action potentials
What is the term used to describe membrane potentials that can change in continuous values?
Graded potentials
Where are synaptic potentials usually produced in a neuron?
At the dendritic spines
What is the main purpose of synaptic potentials in most neurons?
To determine whether the neuron will fire action potentials
Where is the site of action potential initiation typically located in neurons?
At the initial segment of the axon
How is information transmitted between neurons at electrical synapses?
Through ion flow across gap junctions
What triggers the release of neurotransmitters at chemical synapses?
Action potentials
What is the most widely used means to convey signal intensity throughout the nervous system?
Action potentials
Study Notes
Cell Theory and Nervous System
- Robert Hooke used the term "cell" to describe the repeating units he observed in thin slices of cork.
- In 1839, Matthias Jakob Schleiden and Theodor Schwann proposed the cell theory.
- By the second half of the nineteenth century, the cell theory was widely accepted in the discipline of biology.
Golgi Apparatus and Neurobiology
- Camillo Golgi made important contributions to science, including the discovery of the Golgi apparatus.
- The Golgi apparatus is responsible for processing and modifying proteins synthesized by the cell.
- Golgi staining enabled individual neurons to be visualized for the first time in 1873.
- Golgi's greatest contribution was the development of the Golgi staining method.
Reticular Theory and Neuron Doctrine
- The reticular theory believed that the working unit of the nervous system was a continuous network of nerve fibers.
- Santiago Ramón y Cajal refuted the reticular theory and proposed the neuron doctrine, which states that nerve cells are separate units.
- The neuron doctrine proposed that neurons are independent units that communicate with each other through synapses.
Neurotransmission and Action Potentials
- Neurotransmitters are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron, producing synaptic potentials.
- The release of neurotransmitters is triggered by the arrival of an action potential at the presynaptic terminal.
- Synaptic potentials are usually produced in the dendrites of a neuron.
- The site of action potential initiation is typically located at the axon hillock.
Membrane Potentials and Signal Transmission
- The membrane potential is the electrical potential difference across the neuronal membrane.
- In the resting state, neurons have a higher concentration of potassium ions and a lower concentration of sodium ions than the extracellular environment.
- Graded potentials are induced by sensory stimuli and can change in continuous values.
- Action potentials are the elementary unit of nerve impulses that axons use to convey information across long distances.
Early Neuroscientists and Contributions
- Luigi Galvani's discovery in the late eighteenth century involved the use of electrical signals to propagate information in the nervous system.
- Edgar Adrian and co-workers measured nerve impulses from somatosensory neurons.
- Santiago Ramón y Cajal used his staining method to refute Golgi's theory and proposed the neuron doctrine.
- Ramón y Cajal and Golgi were the most influential neurobiologists of their time.
Test your knowledge on the history of neurobiology with this quiz! Explore the discovery of individual neurons and the initial skepticism surrounding the cellular organization of the nervous system.
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