Chapter 2 Flashcards
Neurons
cells that convert sensory information into the brain, carry out operations, and transmit commands to the body
Bipolar neuron
dendrites on one side, receive info, cell body, and then the axon terminals which send info to other cells
- sensory
Motor Neurons
carries commands to the muscles and organs
- sent away from CNS
Sensory Neurons
carry info from the body and outside world into the brain and spinal cord
Interneurons
- majority of neutrons
- neurone which connect one neutron to another in the same part of the brain or spinal cord
Cell Membrane
- phospholipid bilayer
- has a hydrophilic head and a hydrophobic tail
- decides what gets in and what doesn’t
- has proteins floating around that act as a channel, choose what comes in and out
Polarization
a state in which there is a difference in electrical charge between the inside and outside of the neutron
- due to selective permeability
Voltage
measure of the difference in electrical charge between two points
Resting Potential
- difference in charge between inside and outside of membrane of a neuron at rest
- on average, -70mV
Ions
atoms that have lost or gained elections
Postive Ions
Na+, K+
Negative
Cl-, A-
Force of Diffusion
tendency of ions to move through membrane to the less concentrated side
Electrostatic Pressure
force where ions are prelude from similarly charged, attracted to oppositely charged
Sodium Potassium Pump
large protein molecules that move sedum ions through cell membrane to outside, potassium ions back inside
- uses up a lot of energy
- accounts for about 40% of your neurone energy
Ion Channels
gated pores in the membrane formed by proteins; limit the flow on ions into and out of the cell
- can be chemically gated or electrically
Chemically Gated
neurotransmitter or hormones must bind for the channel to open
- the right one must bind or else it won’t open
Electrically Gated
will stay closed unless there is a change in electrical potential of the membrane
Excitatory
increase the likelihood of depolarization
Inhibitory
decrease the likelihood of depolarization
Local Potential
- partial depoloarlization
- polarity in an area shifts toward zero when disturbed
- “graded potential”
Action Potential
abrupt depolarization of membrane that allows neurone to communicate
- huge amount of Na+ coming into the cell
- ungraded
Hyperpolarization
when the cell is too negative, below resting potential
Refractory Period
break for the neuron
- cannot immediately fire again
All-or-none Law
occurs at full strength or does not occur at all
Non-Decremental
as it travels down the axon, it does not loose strength
- length of the axon doesn’t matter, the strength of the action potential does not change
Absolute Refractory Period
sodium ion channels are unresponsive to further stimulation
- resting
- 1-2 ms
Relative Refractory Period
sodium ion channels could support another action potential, but potassium channels are still open
- don’t really want to open
- 2-3 ms after the absolute refractory period
Rate Law
axon encodes stimulus intensity not in the size of it’s action potential but in it’s firing rate
Glial Cells
cells that provide a number of supporting functions to neurons
Myelin
fatty tissue that wraps around an axon to insulate it
- keeps cell seperate from extracellular fluid and other neurons
Nodes of Ranvier
gaps in the myelin sheath
Saltatory Conduction
a form of transmission in which action potentials appear to jump from node to node
Benefits of Myelin Sheath
- reduces capacitance (slows movement of ions down the axon)
- signal regeneration at nodes of Ranvier
- use less energy
Capacitance
electrical effect of the membrane,
Oligodendrocytes
- glial cells which produce myelin in the brain and spinal cord
- almost 75% of glial cells in the brain are oligodendrocytes
Schwann Cells
glial cells which produce myelin in the rest of the nervous system
Radial Glia
during the fetal development they form “scaffolds” that guide new neurons to their destinations
Microglia
provide energy to neurons and respond to injury and disease by removing cellular debris
Astrocytes
trigger the formation of seven times as many connections in neurons
Synapse
the connections between two neurons
Synaptic Cleft
the small gap which separates neurons so they are not in direct physical contact at the synapse
Presynaptic
transmitting neuron
Post Synaptic
receiving neuron
Vesicles
membrane-enclose bubbles at axon terminals which store neurotransmitters
Ionotropic Receptors
receptors which forth ion channel and open quickly to produce the immediate reactions
Metabotropic Receptors
receptors which open channels indirectly through a second messenger
Partial Depolarization
depolarization which is excitatory and facilitates the occurrence of an action potential
Hyper polarization
increased polarization which is inhibitory and makes an action potential less likely to occur
Excitatory postsynaptic potential (EPSP)
when receptors open sodium channels to produce a partial depolarization of the dendrites and cell body
Inhibitory postsynaptic potential (IPSP)
when receptors open potassium channels, chloride channels, or both to produce a hyper polarization of the dendrites and cell body
Spatial Summation
combines potentials occurring simultaneously at different locations on the dendrites and cell body
Temporal Summation
combines potentials arriving a short time apart, from either the same or separate inputs
Reuptake
transmitters taken back into the terminals by transporter proteins where they are repackaged into vesicles for reuse
Presynaptic Excitation
increases the presynaptic neutrons release of neurotransmitters onto the postsynaptic neuron
Presynaptic Inhibition
decreases the presynaptic neutrons release of neurotransmitter onto the postsynaptic neuron
Autoreceptors
receptors on presynaptic terminals which sense amount of transmitter in cleft
Dale’s Principle
erroneous belief that a neuron was capable of releasing only a single transmitter
Corelease
partial vesicle opening
Neural Codes
varied intervals between spikes in nerve signals
Neural Networks
groups of neurons that function together
Human Connectome Project
large-scale, multi- university effort to map brai’s circuits
