NP1A Flashcards
(36 cards)
Neurons are the building blocks of circuits, like segments of wire that can be connected in multiple ways to drive….(4 things)… and coordinate these responses with sensory input
Motor function
Release hormones
Regulate immune functions
Metabolic functions
The __________ is a long extension of the neuron cell body
Axon
The junction between circuit components is called the _________
Synapse
The __________ may be located at one end, receiving signals on processes known as dendrites
Cell body
_________ allow input from many different circuits
Dendrites
The axon varies in ______ and can be as long as several feet
Lenght
How do we transmit a signal over the length of the cell?
Establishing a charge across the plasma membrane (i.e. create polarized membranes). Then trigger depolarization on one end of the cell.
Depolarization will spread as a wave over the length of the axon and will trigger release of neurotransmitters upon reaching the end of the axon.
How do we establish a membrane charge?
Establish high intracellular concentrations of K+ using ion pumps, but then let some of that K+ leak out of the cell, down its concentration gradient, through small channels that le K+ pass but not accompanying negatively charge molecules that normally balance the charge. These negatively charged molecules are larger (proteins). The result is excess of negative charge on the inner aspect of the membrane and an excess of positive charge on the outside. The membrane charged and is said to have a resting potential.
The resting potential is
-90 mV
__________________ establishes the intracellular concentration of K+ by exchanging +
ATP-dependent Na+ K+ pump
Two ______ are brought in and three ______ are from the cell
K+ , Na+
This pump requires ATP and defines the energy requirements of nervous system function
ATP-dependent Na+ K+ pump
_____________ allow a small amount of K down its concentration gradient, leaving the large behind.
Potassium leak channels
(True/False) Potassium leak channels allow extracellular Na+ to enter
False, leak channel does not allow extracellular Na+ to enter
We initiate _______________ by allowing extracellular Na to flow back into the cell, down its concentration gradient, eliminating the negative charge. The process is know as “initiating an action potential”
Depolarization
The sodium-potassium pump is initially open on the ______________ side of the cell
intracellular
It is common for many cells to have far more ____________ leakage channels than __________ leakage
potassium, sodium
Positive potassium ions that travel out of the cell contribute to a more ___________ charge inside the cell
negative
Neurons have a Na+ gate that is closed when the membrane voltage is -90 to -50 mV, but above -50 mV the gate pops open, allowing Na+ to enter along its concentration gradient. The gate is thus known as a __________________
voltage gated Na channel
What causes the change in a resting potential of -90 mV to the -50 mV (more positive) that causes the voltage-gated Na channel to open?
specialized nerve endings in skin, joints, and in visceral organs elicit pain responses to mechanical, chemical and thermal insults, and these insults have the effect of reducing membrane charge to the point of activating (opening) the voltage gated Na channels
__________________ can reduce membrane charge to elicit an action potential
Neurotransmitters
The __________ charge causes the opening of voltage-gated Na channels in adjacent areas such that the depolarization spreads as a wave across the cell
positive
How do we repolarize so that we can send another signal? (three steps)
close the gate that is letting Na in, let more K+ out of the cell down its concentration gradient (and do it fast), and re-establish the high intracellular K+ and low intracellular pump and action of the K+ leak channels
Neurons require abundant ____________ to support ATP production
oxygen
