Exam I Flashcards
Neuroanatomical Division:
Saggital
Neuroanatomical Division:
Horizontal
Neuroanatomical Division:
Coronal
Neuroanatomical Division:
Anterior/Rostral
The frontal section of the brain closest to the face, nose, and mouth.
Neuroanatomical Division:
Posterior/Caudal
The rear section of the brain closest to the back of the head.
Neuroanatomical Division:
Superior/Dorsal
The upper section of the brain closest to the top of the head.
Neuroanatomical Division:
Inferior/Ventral
The lower section of the brain closest to the neck.
Types of Neurons: Monopolar
a neuron from which only a single process leaves the cell body; this single process then divides close to the cell body into a trunk to supply the branching dendrites for incoming signals and an axon for outgoing signals
Types of Neurons: Bipolar
a neuron from which two processes leave the cell body; in this neuron, the dendritic tree emerges from one end of the cell body, while the axon emerges from the opposite end; the dendritic branching of bipolar neurons is typically limited, and the axons of such neurons are usually short in length
Types of Neurons: Multipolar
a neuron from which multiple branches leave the cell body; the many dendrites of the multipolar neuron allow for extensive integration of information coming from many other neurons; the axons of such neurons are usually long, allowing this integrated information to affect distant regions of the nervous system
True or False:
Neurons make up the majority of the cells in the brain
False. Glia make up most of the cells in the brain.
True or False:
Microglia have similarities to macrophages
True. Microglia can phagocytose pathogens.
Why are bullet wounds to the brainstem so often fatel, whereas bullet wounds to the frontal lobe of the cerebral cortex can often be survivable?
- Brainstem controls respiration
- Frontal lobe controls motor planning and complex behavior.
Which kind of glial cell is involved in potassium uptake around neuronal axons
Astrocyte.
What is the function of oligodendrocytes?
Myelin formation in the central nervous system.
Cajal stated the “Principle of Dynamic Polarization.” What did this principle assert?
This asserted that information flows from dendrites to nerve terminal via the axon.
What method or technique would you use for measuring the individual responses of 50 neurons simultaneously?
Multi-electrode Method or Dye Method
What method or technique would you use for showing that the cerebral cortex has layers where neuronal cell bodies are in high density
Nissel Stain
What method or technique would you use for demonstrating that the protein actin is localized at the tip of a growing axon?
GFP tag or antibody labeling.
What method or technique would you use for measuring the membrane potential of a living cell?
Intracellular electrode, Voltage-Sensitive Dye
Why does fMRI take much longer than magnetoencephalography (MEG) to localize neuronal activity to a particular region of the brain?
Because it detects blood flow charges, not electrical activity directly.
In the knee-jerk response reflex, the flexor muscle reflex, how many neurons are involved in the pathway that mediates this relaxation and what are they called?
- Sensory Neuron
- Interneuron
- Motor Neuron
Fill in the blanks:
A voltage clamp is a circuit that measures ____________ while keeping the _______________________ at a fixed value that the experimenter determines.
A voltage clamp is a circuit that measures CURRENT while keeping the MEMBRANE POTENTIAL at a fixed value that the experimenter determines.
The sodium ion concentration outside a squid giant axon is 435 mM whereas the sodium ion concentration outside a mammalian axon is 100 mM. Despite this difference, the maximum peak amplitude of action potentials in both axons is the same, about +50 mV. Explain why the greater external sodium concentration outside a squid axon does not lead to a greater peak amplitude of the squid axon’s action potential. In your explanation you must refer to specific equation(s) that describe the relationship between ion concentrations and the forces that move ions across a membrane.
- [Na+]I is also greater inside a squid axon than inside a mammalian axon.
- Keeping in mind the Nernst Equation (ENa = RT/F ln(Co/Ci), the ratio is the same for the squid and the mammal.
- If ENa is the same, than the peak of the action potential will also be the same.
A neuronal membrane contains only voltage-gated calcium channels and leakage chloride channels. Draw the LABELED circuit model for the membrane. You must show which side of the battery is positive.
There needs to be:
- Cm to show the capacitor of the membrane
- ECl with the negative side on the opposite side of the resistor for chloride
- ECa with the positive site on the opposite side of the resistor for calcium
- GCl next to the positive terminal for ECl
- GCa next to the negative terminal for ECa
You are investigating a neuron that has a resting potential of around -80 mV, rather more negative than usual. You suspect that the neuron’s leakage ion channels (which determine its resting potential) are much more permeable to potassium ions than to chloride ions. Briefly describe an experiment (method, results, conclusion – with labeled graphs if you want) that would allow you to verify this suspicion. You can isolate the neuron and alter the composition of the saline solution surrounding it and you can impale it with a single micropipette and measure Vm
- Impale neuron with the micropipette and measure Vm
- Increase [K+]o to various levels to measure the Vm at each level of [K+]o
- Plot Vm vs log[K+]o
- If slope approaches 58 mV/10 x [K+]o, then Vm follows Ek and cell is mostly permeable to K+
- Repeat with [Cl-]o—Vm should not change much with [Cl-]o and should not follow ECl
Explain in terms of the forces that move ions why the action potential never exceeds +60 mV?
+60 mV is ENa and at ENa, the positive Vm repels any more net Na+ influx and so Na+ influx slows down and stops and so Vm reaches ENa but does not depolarize further and equilibrium is reached.
Principal of Dynamic Polarization
- Information flows in a consistent way in each neuron
- From dendrites to nerve terminals via axons
Principal of Connectional Specificity
- NO cytoplasmic connection between neurons
- Nerve cells do NOT form random networks
- Each cell makes precise connections with neurons via synapses
Glial Cell Functions
- Regulate environment around nerve cell
- Take up NTs released from nerve terminals
- Defend the brain and/or spinal cord from injury or infection
- Can direct neuronal growth
- Glial Stem cells can proliferate and differentiate into new glial cells, or sometimes into new neurons
- 10 to 50 times more glia than neurons in BRAIN