Task 2 Flashcards
neurons
cells that are specialized for the reception, conduction and transmission of electrochemical signals
unipolar neuron
a neuron with one process extending from its cell body
multipolar neuron
a neuron with more than two processes extending form its cell body
bipolar neuron
a neuron with two processes extending from its cell body
interneurons (schakelneuronen)
neurons with a short or no axon. Function is to integrate the neural activity within a single brain structure.
nuclei
Clusters of cell bodies in the central nervous system
ganglia
Clusters of cell bodies in the peripheral nervous syste,
nucleus has two different meanings
- it is a structure in the neuron cell body
2. it is a cluster of cell bodies in the CNS
tracts
bundles of axons in the CNS
nerves
bundles of axons in the peripheral nervous system
Kinds of glial cells
- Oligodendrocytes
- Schwann Cells
- Microglia
- Astrocytes
Schwann cells function
- increase speed and efficiency of axonal conduction.
- guide axonal regeneration (regrowth) after damage
4 neuroanatomical techniques
- Golgi Stain - using nitrate and dichromate to view the silhouettes of a few neurons.
- Nissl Stain - using cresol violet to estimate the number of cellbodies in an area
- Electron Microscopy - provides information about the details of neuronal structures
- neuroanatomical tracing techniques- to trace the paths of axons by injecting chemicals in a specific brain area.
membrane potential
the difference in electrical charge between the inside and the outside of a cell
resting potential
steadily membrane potential (inside the cell) of -70 mV
sodium-potassium pumps
natrium-kalium pumps: Transport / exchange 3 Na ions inside the neuron for 2 Ka ions outside the neuron
neurotransmitter may depolarize the receptive membrane
from -70 to -67mV
neurotransmitters may hyperpolarize the receptive membrane
from -70 to -72 mV
Excitatory Postsynaptic Potentials –> EPSPs
are postsynaptic depolarizations, who increase the likelihood that the neuron will fire
Both EPSPs and IPSPs are graded responses
amplitude of the potentials are proportional to the intensity of the signals that elicit them (weak signals–> small postsynaptic potentials)
Two characteristics of the transmission of the Postsynaptic potentials
- rapid
- the transmission is decremental ( the potential decreases in amplitude as they travel trough a neuron)
action potentials are generated:
in the adjacent (aangrenzend) section of the axon
threshold of excitation
the action potential is elicited when the depolarization of the neuron reaches -65mV
All-or-none responses
action potentials occur to their full extend or don’t occur at all. ( EPSPs and IPSPs on the other hand, have different levels of responding)
Neurons integrate postsynaptic potentials in 2 ways:
- spatial summation: 2 EPSPs tegelijkertijd versterken elkaar, 1 EPSPs en 1 EPSPs tegelijkertijd cancel each other out.
- temporal summation: postsynaptic potentials produced in rapid succession at the same synaps increase/decrease the signal
voltage-activated channels
ion channels that open or close in response to changes in the level of the membrane potential
absolute refractory period
a brief period after the initiation of an action potential during which it is impossible to elicit another one
relative refractory period
the period during which it is possible to fire the neuron again, but only applying higher-than-normal levels of the stimulation. ( Not possible to create a second separate stimulation in this period)
conduction of an AP along an axon differs from the conduction of EPSPs/IPSPs in 2 ways:
- conduction of Aps along an axon is non decremental, and IPSPs and EPSPs are decremental.
- APs are conducted more slowly than postsynaptic potentials
orthodromic conduction
axonal conduction in the natural direction: from the cell body to the terminal buttons
antidromic conduction
Action potential that travels from the terminal end of an axon along the axon to the cell body
nodes of Ranvier
the gaps between adjacent myelin segments
quality of myelination
it increases the speed of axonal conduction
saltatory conduction
the transmission of APs in myelinated axons
Conduction in interneurons is typically
passive and decremental (different than cells with long axons)
neuron doctrine
the hypothesis that the brain is composed of separate cells that are distinct structurally, metabolically and functionally
mitochondrion
a cellular organelle that provides metabolic energy for the cell’s processes
cell nucleus
(Cell kern) the spherical central structure of a cell that contains the chromosomes
ribosomes
structures in the cell body where genetic information is translated to produce proteins
dendrite
receptive surfaces of the neuron
axon
carries action potentials from the cell body to other neurons
cell body
soma
axon collateral
a branch of an axon from a single neuron
axon terminal
synaptic bouton, end of an axon which forms a synapse on a neuron
motor neuron
A nerve cell that transmits motor messages, stimulating a muscle or gland
sensory neuron
A neuron that is directly affected by changes in the environment (light, odor, touch)
interneuron
A neuron that is neither a sensory or motor neuron. It receives input from and sends output to other neurons
arborization
the elaborate branching of the dendrites in some neurons
