Block II - Neurophysiology Flashcards
4. Hodgkin-Huxley Model 5. Synapses and neurons 6. Central and autonomic nervous systems 7. Sensory systems
Under what condition can a voltage across the membrane be clamped?
Ec = Ei - Eo
What is the purpose of the voltage-clamp?
Removal of the capacitive current or determination of the ionic current flux across biological membrane
In the H-H equation, what number of power of the exponential function is the best fit for the time-dependant change of potassium conductance?
4
What letter is used to describe the rate of change of inactivation of sodium conductance in H-H equation?
h
In the H-H equation, what number of power of the exponential function is the best fit for the time-dependant change of activation of sodium conductance?
3
*What letter is used to describe the rate of change of activation of potassium conductance in H-H equation?
n
* study entire equation
m3h gx(E-Ex) in H-H resembles:
Na current (see variables present)
What does the patch clamp allow us to do for the first time in history of science?
To monitor the living function of a single protein molecule
Who invented patch clamp technology?
Neher E, Sakman B
Does patch clamp share the same principle of voltage clamp?
Yes. Patch clamp is voltage clamp applied on a single mammalian cell
*Letter h represents the opening probability of Na channel inactivating gate. What change of voltage causes the channel to activate (h -> 0)?
Depolariztion
* study curve of polarization
*What cells are responsible for myelination?
Oligodendrocytes (CNS) and schwann cells (PNS)
Which channels mediate transmitter release at the presynaptic terminal?
Ca channels
- Describe the progression of how ions flow during the action potential curve
*
What is the order of types of synapse in terms of fasted to slowest?
Gap junction, ligand-gated, g-protein-coupled
What is the main fast inhibitory transmitter in the nervous system?
GABA
- What is the structure circled in the picture?
Thalamus, diencephalon
* look at picture or just memorize this
What are the neurotransmitters of the preganglionic neuron and the postganglionic neuron of the sympathetic nervous system?
Acetylcholine, norepinephrine
What nervous system’s function is referred to as “fight or flight?”
sympathetic nervous system
What are the functions of the cerebellum?
Movement, posture, balance
Is the autonomic nervous system voluntary or involuntary?
Involuntary
How many types of synapse does the autonomic nervous system consist of?
Two - cholinergic and adrenergic
Sensory afferents that cross immediately when entering the spinal cord carries ___ info and ascends which pathway?
pain and temperature; spinothalamic tract
What is the only sensory info that doesn’t first synapse in the thalamus before reaching the cortex?
Olfactory
Where does the tonotopic organization of the auditory system originate from?
Basilar membrane
How is the depolarization of taste cells in response to the salt mediated?
Na ions flowing through an amilioride-sensitive Na channel
What are the types of the sensory receptor cells of the visual system?
Rods (dark) and cones (color)
What is the equilibrium potential of an ion dependent on?
Valence of the ion, temperature, intra- and extracellular concentration of the ion
What is the main excitatory neurotransmitter in the brain?
Glutamate
In general, by which root do the sensory afferents enter and motor efferents exit the spinal cord?
Sensory afferents enter dorsally, motor efferents exit ventrally
What makes cerebrospinal fluid?
Choroid plexus
What are the function of cranial nerve X (Vagus nerve)?
The vagus nerve is responsible for such varied tasks as heart rate, gastrointestinal peristalsis, sweating, quite a few muscles in the mouth (such as speech and keeping larynx open for breathing)
What is the area of the body or visual space that when stimulated leads to activity in a primary sensory neuron called?
Receptive field
After crossing the medulla, ascending sensory info travels in what structure to reach the thalamus?
Medial lemniscus
What ion in the endolymph surrounding cilia of the hair cells generates endocochlear potential?
High K concentration
What kind of shape change of the lens in near-sited vision?
Rounded
What is the intensity of a sensory stimulus encoded by?
The frequency of action potentials fired
What is the dark current (depolarizing current) in photo sensory cells mediated by?
A continual influx of Na ions
What is the neurotransmitter of postganglionic neurons in the parasympathetic nervous system?
Acetylcholine
Most sensory info synapses in what structure where neurons then send axons on to the cortex?
Thalamus
What causes congenital birth defects such as anencephaly and spin bifid a?
Failure of the neural tube to close
What current is responsible for repolarizing the cell during action potential?
A slow-onset and continuous outward K current
If the capacitance of a membrane is increased, it will have what effect on the time course (i.e. time constant) of membrane response to current pulses?
Increase
What factors will influence the threshold for two-point discrimination sensory tasks?
Receptor density, size of receptive field and lateral inhibition
What is the cellular response to light falling on a photoreceptor?
Hyperpolarize and refrain from releasing transmitter in amounts corresponding to the light intensity
What is the function of cholinesterase inhibitors?
The inhibition of break-down of acetylcholine in the synaptic cleft
Reuptake of autonomic monoamine neurotransmitter is an important physiological regulation on synapse function. List three mechanisms that mediate the reuptake of these neurotransmitters
- Serotonin transporter (SERT) blocked by selective serotonin reuptake inhibitors (SSRI)
- norepinephrine transporter (NET) blocked by tricyclic antidepressant (TCA)
- dopamine transporter (DAT), blocked by amphetamines
Cocaine blocks all three
What is the function Wernicke’s area and Broca’s area of the cerebral cortex?
Wernicke: understanding of written and spoken language
Broca: production of language
