Exam 1 Flashcards
If the inactivate gates of the Na+ channels were hindered so that they couldn’t close as fully and reliably as normal, then the following is the most likely effect:
a) the rising phase of the action potential would be slower
b) the falling phase of the action potential would be slower
c) resting membrane potential would hyperpolarize
d) the absolute refractory period would be shorter
Answer
b) the falling phase of the action potential would be slower
The current that brings the membrane potential back to rest following the peak of an EPSP is:
a) the voltage-gated potassium current
b) the voltage-gated sodium current
c) the leak current
d) the Na/K pump current
Answer
c) the leak current
All voltage-gated channels have gates. The fastest of all the voltage gates associated with the action potential is the _______ gate on the voltage-gated _____ channel.
The gate most responsible for determining the length of the relative refractory period of the action potential is
the _______ gate on the voltage-gated ______channel.
Answer
All voltage-gated channels have gates. The fastest of all the voltage gates associated with the action potential is the (activation) gate on the voltage-gated ( Na+ ) channel.
The gate most responsible for determining the length of the relative refractory period of the action potential is
the (activation) gate on the voltage-gated ( K+ ) channel.
The driving force for an ion increases as the difference between the membrane potential
and the _______ of that ion is increased.
Multiplying the driving force by the ________ of that ion yields the current of that ion.
Answer
The driving force for an ion increases as the difference between the membrane potential and the (equilibrium potential) of that ion is increased. Multiplying the driving force by the (conductance (or g)) of that ion yields the current of that ion.
This kind of synapse doesn’t involve the use of any neurotransmitter _________.
Answer
This kind of synapse doesn’t involve the use of any neurotransmitter ( electrical or gap junction ) .
Vesicles containing __________ are made in the soma and transported to the synaptic terminal.
Answer
Vesicles containing peptides or neuropeptides or proteins or peptide neurotransmitters are made in the soma and transported to the synaptic terminal. (*give 1 point for “neurotransmitters”)
Name a type of glial cell that provide myelin for axons in the brain: ________ .
Name a glial cell that regulates the extracellular environment in the brain: ______ .
Answer
Name a type of glial cell that provide myelin for axons in the brain: ( oligodendrocytes or oligodendroglia (NOT Schwann cells—they are not in the brain) ) .
Name a glial cell that regulates the extracellular environment in the brain: ( astrocytes ) .
The relative concentrations of _______ outside and inside of the membrane mostly determines Vrest, as it is the ion that has the greatest passive permeability with respect to the membrane.
Answer
The relative concentrations of ( K+ ) outside and inside of the membrane mostly determines Vrest, as it is the ion that has the greatest passive permeability with respect to the membrane.
- Define the term “neuron doctrine” and describe one piece of evidence that lent support for this theory when it was formulated in the late 1800s-early 1900s.
it was formulated in the late 1800s-early 1900s. Elementary structural (cellular) component of the brain and elementary signalling mechanism of the brain. Use of Golgi stain (silver nitrate) produced first images of individual cells in brain tissue. Ramon y Cajal used these images to create detailed drawings of how cells compose elements of the nervous system.
- In describing myelination of axons, your textbook mentions the important fact that wider axons (ie, larger diameter axons) can afford to have the nodes of Ranvier (the gaps between myelin on an axon) spaced at longer intervals, so that the segments of axon that are myelinated are longer. Explain why wider axons can afford such increased distances between the nodes of Ranvier.
The nodes of Ranvier allow a recharging of the AP via the voltage gated channels that are otherwise not available in the myelinated segments. Relative to the total current of the AP, the current that leaks out of an axon through a myelinated segment is proportionally smaller in a wider axon due to the decreased internal resistance (ri) of the wider (larger diameter) axon. Because of this, the relative decrease in voltage from one node to the next is diminished, allowing extra length from node to node before a critical drop below AP threshold is reached.
What is behavioral neurobiology?
The study of nerve cells and associated cells and the way they are organized into functional circuits that process information and mediate behavior
What are the historical orgins of neuroscience?
Trepanning
700 BC in Rural France found 120 skulls where 40 had trepanning holes
trepenation is a process where holes are bored into the skull to cure for headaches and mental disorders. The skulls had holes in them but showed they were healed, and not used to kill the person.
Edwin Smith Papyrus
first surgical manuscript understanding that trauma to head affects behavior. In Ancient Egypt there was a belief that the thoughts, feelings, memories are based in the heart. The brain tissue was often removed from people when they died, but the heart preserved.
Manuscript as some idea of trauma in the skull and brain affecting the bodily functions. It states that the side of the skull damage is the same as the side of bodily injury.
However typically this is the opposite.
What were the early conceptual models of neuroscience?
Natural philosophy - study of reality which deviates from traditional study of thought
animism in ancient times - moving things possess spirits, including humans. After it was disproved, still used later to describe human behavior
It follows that if humans possess spirits or souls, what is the relationship of soul to brain
“mind-body” question?
What are the 4 crucial ideas for the study of neuroscience? (list only)
brain hypothesis
neuron doctrine
ventricular hypothesis
localization vs distribution
Explain the inital brain versus cardiac hypothesis debate and the general order of figures involved in theorizing about brain function
Aristole and the Greeks - heart is the seat of the soul and intellect, brain is the cooling center for the body. The rational temperament of humans is explained by the large cooling capacity of the brain.
Hippocrates (remember medicine) - assigned mental function and emotion to the brain. Brain is a source of healthy and disordered behavior. He believed in a humoral theory of psychology and bodily health. Fluids course through people in different amounts in different ways, and the balance is important for maintaining the functioning of the brain. The 4 humors are blood, yellow bile, black bile, and phlegm.
Aristotle, Hippocrates, Galen, Vesalius, Descartes
What are the differences between Aristotle and Hippocrates in their view of neural function?
Aristole and the Greeks - heart is the seat of the soul and intellect, brain is the cooling center for the body. The rational temperament of humans is explained by the large cooling capacity of the brain.
Hippocrates (remember medicine) - assigned mental function and emotion to the brain. Brain is a source of healthy and disordered behavior. He believed in a humoral theory of psychology and bodily health. Fluids course through people in different amounts in different ways, and the balance is important for maintaining the functioning of the brain. The 4 humors are blood, yellow bile, black bile, and phlegm.
What were Vesalius’s views on the neural function?
Andreas Vesalius (father of anatomy) - added more detail to the structure of the brain with his drawings.
- Did not like Galen and his study of animals
- Most places forbade human dissections, so he travelled, stole bodies
- Hydraulic theory of the brain - Saw the function units of the brain to be liquid containing ventricles rather than grey and white matter
- Refuted the Galen belief that Animal spirit flows down the ventricles through hollow nerves in the body
- No physical outlet through the skull and searched for flow routes that for example funnel brain phlegm into nostrils
What were Galen’s views on neural activity?
Fluid comes from the ventricles and goes to the brain in the hollow fluid filled chambers.
He touched the bumps on the cortex and noticed the “give” and impressions and assumed the cortex processes sensory information (actually repository for memory, sensation and perception).
He touched the cerebellum and found no impressions and assumed it controlled movements (true!)
Animal spirit flows down the ventricles through hollow nerves in the body
What was Descartes response?
Descartes Response - mathematician and philosopher provided a philosophical model to account for the “mind-body” problem called “dualism”
- Mind and body are separate
- Body consists of physical matter, mind does not
- People possess intellect and soul
- That of beasts is controlled by the brain in humans but the unique mental capabilities (mind) is a spiritual entity that receives sensations and command movements via the pineal gland
- Pineal gland is the seat of rational thought, sensation, imagination, memory
Mind Body Problem
- Does the mind control the body? Is sensory input or motor output controlled by the soul? Where does the soul rest? Is the soul physical?
- Given that the eyes and ears were windows to the soul, trauma to the head could knock someone out, and it was considered that the soul resides in the head
What is the mind-body problem?
Mind Body Problem
- Does the mind control the body? Is sensory input or motor output controlled by the soul? Where does the soul rest? Is the soul physical?
- Given that the eyes and ears were windows to the soul, trauma to the head could knock someone out, and it was considered that the soul resides in the head
difference between the CNS and PNS
CNS - spinal cord and brain
PNS - neurons outside the spinal cord and brain
Who were the figured involved in the location vs distribution of function in the brain theory?
Franz Gall -phrenologist
Fritsch and Hitzig - stimulated areas of primary cortex
Alternatives
Flourens - experimental ablations ==> tissue non specific aggregate theory
Galvani - muscles contracted, brain conducts electricity
Bell and Magendie - 2 nerve paths efferent (CNS) and afferent (PNS)
Who was Franz Gall?
How did he contribute to the localization of function in the brain?
Franz Gall (late 1700s)- German physician and proponent of phrenology.
- Phrenology - is a pseudoscience which involves the measurement of bumps on the skull to predict mental traits.
- Different psychological functions located in different parts of the brain (love, anger, secretiveness)
- First localization approach to neural function
- Over 200 areas of brain localized for different aspects of personalitY
- Measured bumps on the skull (cranioscopy) as indicators of the brain tissue
- People paid for head readings and were interested in personality
- Mostly false predictions but language correct (tramau around left eye - difficulty speaking)
What did Fritsch and Hitzig show?
Fritsch and Hitzig
Stimulated areas of primary cortex via electrode and saw specific types of movements in different parts of the body
Movement always on opposite sides of body from stimulation
Who proposed an alternative to the localization approach?
Flourens - 19th Century french physiologist
- Preformed experimental ablations
- Determined areas responsible for breathing, heart rate, purposeful movement, visual and auditory reflexes
- Largest contribution for the “aggregate field” theory of the brain function - tissue non specific
- Cerebellum does play a role in the coordination of movement and is involved in sensation and perception
- Critiqued phrenology = shape of skull is not correlated with the brain
What did Galvani contribute?
Galvani -
Muscles can be contracted when stimulated electrically and brain itself can generate electricity
Bidirectional suggested, nerve fibers can operate independently
What did Charles Bell and Francois Magendie research?
Charles Bell and Francois Magendie
- Before nerves attach to the spinal cord, fibers divide into 2 branches
- Tested if roots carry information in different directions by cutting each root and seeing the consequences
- Bell-magendie law ⇒ afferent and efferent information carried through separate nerve paths
- Efferent - motor division transmits impulses from CNS out to peripheral organs to cause effect or action
- Spinal nerve roots contain only motor fibers
- Afferent - sensory division transmits impulses from peripheral organs to the CNS
- posterior roots only sensory fibers and nerve impulses are conducted in only one direction in each case
- Efferent - motor division transmits impulses from CNS out to peripheral organs to cause effect or action
- Conclusion - within each nerve is a mixture of many wires where some go to brain or spinal cord and others into muscles. Motor fiber transmission is one way. Fibers are mostly bundled.
What is the reticular theory versus neuron doctrine?
Reticular theory - brain is a syncytium (a single cell or cytoplasmic mass containing several nuclei, formed by fusion of cells or by division of nuclei)
Neuron doctrine - the neuron is an anatomical unit in addition to the glia. The neuron is an elementary and structural unit of neuroscience
Who was Golgi?
What did he discover?
Camillo Golgi - discovered that nerve cells could be stained with silver nitrate visualized against yellow background (see some around 15%)
Revised to accept neuron theory and hung into reticular theory
Described nervous system as a continuous single network
lGolgi recognized that dendrites are separate processes that end freely and do not “anastomose” (connect between adjacent tubes)
Who was Ramon y Cajal? What did he study?
Ramon y Cajal - made drawing of nerve cells based on Golgi stains
Believed in neuron doctrine
Provided evidence for the discontinuity of the nervous system
Axons and their dendrites end separately and large individual neurons
Who was the novel prize awarded to in 1906 and what was the controversy? How was it resolved?
Nobel Prize in 1906 awarded jointly to Golgi and Cajal in recognition of their work on the nervous system
Debate between Golgi (brain is continuous matter) and Cajal (independent neurons)
Brain composed of functional units - neurons and glia ⇒ Cajal correct
Conformed by electron microscopy in 1950s
2 ways that neurons function as signalling elements?
Structural - connected to responsive muscles that are connected to sensory organs, computational signals
Functional - high speed signals via action potentials
which glial cells mylinate in the CNS and which in the PNS
oligodendrocytes in the CNS
schwann cells in the PNS
what are apical, basal, distal dendrites?
What is the soma?
what are recurrent collaterals?
What is the terminal?
apical - top dendrites
basal - bottom dendrites
distal dendrites - away from center
soma - where dendrites eminate and axon stems
recurrent collaterals - comes back to neuron
terminal - where NT is released
what is the length constant?
The length constant describes the rate of exponential decay of membrane voltage as a function of distance from the location where current is injected
