How neurons send and receive signals
resting membrane potential
-70mV
ions
-chemical changes cause electrical changes -chemicals in the body are electrically charged
the neuron at rest
-ions move in and out through ion-specific channels -K+ and Cl- pass readily -little movement of Na+ -proteins don't move at all, trapped inside -Na+ is driven by both electrostatic forces and its concentration gradient -K+ is driven in by electrostatic forces and out by its concentration gradient -Cl- is at equilibrium
factors contributing to even distribution of ions (charged particles)
-random motion -electrostatic pressure
factors contributing to uneven distribution of ions
-selective permeability to certain ions -sodium-potassium pumps works constantly to ensure negative charge
dendrites
Branchlike parts of a neuron that are specialized to receive information.
ions contributing to resting potential
Sodium (Na+), Chloride (Cl-), Potassium (K+), and negatively charged proteins (A-)
velocity of axonal conduction
The maximum velocity of conduction in human motor neurons is about 60 meters per second.
integration
adding or combining a number of individual signals into one overall signal
terminal buttons
buttonlike endings of axon branches, release chemicals into synapses
excitatory postsynaptic potentials (EPSPs)
depolarizing
Recording the membrane potential:
difference in electrical charge between the inside and outside of the cell -inside the neuron is negative with respect to the outside -membrane is polarized (carries a charge)
relative refractory period
harder to initiate another action potential
inhibitory postsynaptic potential (IPSP)
hyperpolarizing
absolute refractory period
impossible to initiate another action potential
spatial summation
integration of events happening at different places
temporal summation
integration of events happening at different times
electrostatic pressure
like repels like, opposites attract
depolarization
making the membrane potential less negative
hyperpolarization
making the membrane potential more negative
Generation and Conduction of Postsynaptic Potentials (PSPs)
neurotransmitters bind at postsynaptic receptors, these chemical messengers bind and cause electrical changes
random motion
particles tend to move down their concentration gradient
refractory periods
prevent the backwards movement of APs and limit the rate of firing
axon hillock
the cone-shaped region at the junction between the axon and the cell body
myelin sheath
the fatty insulation around many axons
synapses
the gaps between neurons, across which chemical messages are sent
nodes of ranvier
the gaps between sections of myelin
axon
the long, narrow process that projects from the cell body
cell body
the metabolic center of the neuron; also called the soma
equilibrium potential
the potential at which there is no net movement of an ion - the electrical potential difference that exactly counterbalances diffusion due to concentration differences
cell membrane
the semipermeable membrane enclosing the neuron
decremental graded potential
they become less impactful
conduction of APS
when the threshold is reached, voltage-activated ion channels are opened - all or none - when threshold is reached the neuron "fires" and the action potential either occurs or it does not