Biological Foundations of Behavior Flashcards
What are the two classifications of neurons according to the number of dendrites?
Bipolar: one dendrite Multipolar: many dendrites
What role does kinesin play in neurons?
Kinesin, a motor neuron, drives anterograde movement (soma to axon terminal) of vesicles and organelles along micro tubules in axons
What happens when kinesin is inhibited?
The axon will atrophy
What is the role of the Na+/K+ pump in neurons?
Helps maintain the negative resting membrane potential
How does the Na+/K+ pump help maintain the negative membrane potential?
Uses direct active transport: exergonic hydrolysis of ATP coupled with endergonic transport of Na/K ions (3 Na+ out and 2 K+ in)
What does it mean when a neuron is described as polarized?
Negative in the inside, positive in the outside
What is the resting membrane potential in neurons?
Establishes a negative charge along the interior of axons
What occurs when an action potential disturbs the membrane potential?
A wave of depolymerization of the plasma membrane travels along the axon It is a change in the membrane potential from the -70 mV resting membrane potential to less negative, or even positive, potential
What happens below the resting membrane potential?
The voltage-gated sodium channels are closed
What happens when the membrane potential is reached
The Na+/K+ channels are opened fully
What effect does the opening of these voltage-gated sodium channels have on the cell?
The positively charged sodium ions flow down their concentration gradient This makes the interior of the cell less negatively charged, or even positively charged
What effect does the opening of these voltage-gated sodium channels have on the cell’s membrane potential?
Depolarizes the section of membrane to about +35 mV before inactivating
What is the function of the voltage-gated sodium channels?
In response to change membrane potential (from -70 mV to a threshold potential of -50 mV), these ion channels open to allow sodium ions to flow down their gradient into the cell and depolarize that section of membrane
What is the threshold potential?
About -50 mV
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What is the equilibrium potential?
The membrane potential at which the driving force of gradients do not exist There is no net movement of ions across the membrane Specific for a particular ion
What is the Nernst equation?
E: equilibrium potential for the ion R: universal gas constant T: temperature (K) F: Faraday’s constant (96,500 –) [X]: concentration of the ion
What can the resting membrane potential of -70 mV be attributed to?
There are a large number of K+ leak channels (A membrane that is completely permeable to K+ has a potential of -90 mV, the K+ equilibrium potential) There are a few Na+ leak channels (A membrane that is completely permeable to Na+ has a potential of +35 mV, the Na+ equilibrium potential)
What type of impulse is the action potential?
Electrochemical impulse
What is the resting membrane potential?
Electric potential across the plasma membrane, with the interior of the cell negatively charged with respect the exterior of the cell approximately -70 mV
What are the two primary membrane proteins that are required to establish the resting membrane potential?
1) Na+/K+ Pump 2) Potassium Leak Channels
What are glial cells?
Specialized, non-neuronal cells that typically provide structural and metabolic support to neurons They maintain a resting membrane potential, but do not generate action potentials
What are the five types of glial cells and where are they located?
PNS: Schwann Cells CNS: Oligodendrocytes, Astrocytes, Microglia, Ependymal cells
What is the functions of Schwann cells (PNS) and Oligodendrocytes (CNS)?
Form myelin, which increases the speed of conduction of action potential along the axons
What are the functions of Astrocytes (CNS)?
Guide development Regulate synaptic communication via regulation of neurotransmitter levels
What is the function of Microglia (CNS)?
Remove dead cells and debris
What is the function of Ependymal cells (CNS)?
Produce and circulate cerebrospinal fluid
What are the key proteins involved in the propagation of action potentials?
Voltage-gated sodium channels that are located in the plasma membrane of the axon
