The Brain (Kapitel 3) Flashcards
(39 cards)
What is the difference between an ‘anion’ and a ‘cation’?
An ‘anion’ is a negatively charged ion, such as a protein or chloride.
An ‘cation’ is a positively charged ion, such as potassium (k+) or sodium ion.
A ‘resting membrane potential’ can be described as?
A difference in electrical potential across the membrane of a nerve cell during an inactive period.
Where can the ‘lipid bilayer’ be located, and what does it consist of?
It is the structure of the neuronal cell membrane, which consists of two layers of lipid molecules, within which float various specialized proteins, such as receptors.
Explain the function of the ‘sodium-potassium pump’.
The sodium-potassium pump, is the energetically expensive mechanism that pushes sodium (Na+) ions out of the cell, and potassium (K+) ions in.
Explain what ‘Action Potential’ is.
Action potentials are very brief large changes in neuronal polarization, which are propagated at high speed along the axon. The information that a neuron sends to its postsynaptic targets is encoded in patterns of these action potentials.
Action potential is created by the movement of sodium ions (Na+) into the cell, trough channels in the membrane.
What is the relation and difference between hyperpolarization and depolarization?
Hyperpolarization is an increase in membrane potential (the interior of the neuron becomes even more negative). This is in opposition to depolarization where there is a reduction in membrane potential ((the interior of the neuron becomes less negative). So, depolarization of a neuron brings its membrane potential closer to zero (mV).
Name a “Na+ selective channel that opens or closes in response to changes in the voltage of the local membrane potential - it mediates the action potential”
The voltage-gated Na+ Channel
Frank Oceans most recently released album is called?
‘Blond’.
What is meant by the ‘all-or-none property’ of the action potential?
The amplitude (size) of the action potential is independent of stimulus magnitude. It turns out that information is encoded by changes in the frequency of action potentials rather than in their amplitude.
What happens when the ‘treshold’, at about -40Mv, is reached?
Voltage gated Na+ neurons channels open causing a rapid change of polarity (the action potential). Shortly after, the Na+ channels close automatically; gated K+ channels open, repolarizing and even hyperpolerizing the cell (afterpotential).
An absolute refractory phase is..
.. a brief period of complete insensitivity to stimuli (following the action potential).
What is the difference between ‘conduction velocity’ and ‘saltatory conduction’?
Whereas ‘the conduction velocity’ refers to the speed at which an (un-myelinated) action potential is propagated along the length of the axon, ‘the saltatory (latin, saltare = to leap or jump) conduction’ refers to the conduction that is characteristic of myelinated axons, in which the action potential jumps from one Node of Ranvier to the next.
The saltatory is often way faster, than the conduction velocity itself.
Is it true, that an..
Excitatory postsynaptic potential causes hyperpolarization?
No, excitatory postsynaptic potential (EPSP) causes depolarization in the postsynaptic neuron.
Is it true, that an..
Inhibitory postsynaptic potential (IPSP) causes hyperpolarization?
Yes, exactly that.
The function of inhibitory postsynaptic potential (IPSP) is..
.. To decrease the probability that the postsynaptic neuron will fire an action potential.
Complete the following sentence:
“Whether a neuron fires an action potential at any given moment is decided by the balance between..”
”.. The number of extatory and the number of inhibitory signals that it is receiving”.
Hvad kalder man en etnisk person, som styrer et fly?
En pilot.
Explain the ‘spatial summation’, compared to the ‘temporal summation’ in/on the cellbody.
Spatial (rumlig?) summation refers to the summation at the axon hillock of postsynaptic potentials from across(!) the cell body. If this summation reaches threshold, an action potential is triggered.
Temporal (tid?) summation, on the other hand, refers to the summation of postsynaptic potentials that reach the axon hillock at different times. The closer in time that potentials occur, the more complete the summation.
Finish the sentence:
“This summation of potentials from different physical locations across the cellbody is called..”
”.. spatial summation”.
Finish the sentence:
“If too much time passes between EPSPs, each will..”
”.. fade away before the next occurs, and the neuron will never fire”.
How does glial cells play a role in synaptic transmission?
They increase the strength of the postsynaptic potential, overlying the presynaptic terminal and thereby preventing neurotransmitter from leaking out of the synaptic cleft.
What happens during ‘Exocytosis’?
Exocytosis is the fusion of vesicles with the presynaptic membrane, which releases transmitter into the cleft. The process is facilitated by influx of Ca2+. Typically, an action potential causes the ‘exocytosis’ of several hundred vesicles at a time.
What is the function of autoreceptors on the presynaptic neuron?
Transmitter bind to autoreceptors in the presynaptic membrane. This helps to adjust the concentration of neurotransmitter in the presynaptic neuron.
What is acetylcholine (ACh)?
A neurotransmitter; produced and released by parasympathetic postganglionic neurons, by motorneurons, and by neurons throughout the brain.
