PNB 2XB3
sodium potassium pump - ✔️✔️enzyme that transports 3 sodium to the outside, and it
transports 2 potassium to the inside using the hydrolysis of ATP - creates more sodium
outside and more potassium inside and creates a concentration gradient
Midline, ipsilateral and contrelateral - ✔️✔️line separating left and right of the entire
nervous system - ipsilateral means the same side of something and contralateral means
the opposite side of something
Nissl stain showed (Nissl) - ✔️✔️Nissl used basic dyes (cresyl violet, thionine) to stain
the ER (RNA in the nucelus) to reveal cell bodies
Nissl Stain - ✔️✔️piece of neural tissue is treated with a Nissl Stain solution that will
dye the cell bodies of neurons - there are areas of varying density called cell layers
(usually 6)
Neurons - ✔️✔️cells with an axon that produce action potentials, are enclosed in a lipid
bilayer membrane and contain organelles, but have unique morphology and they are
electrically excitable - action potentials are not unique to neurons (muscle cells produce
them too)
how many neurons are in the brain and what is the power of the brain - ✔️✔️100 billion
neurons, and it is about 20W
how large are neurons - ✔️✔️10 microns
Central Nervous System (CNS) - ✔️✔️all the parts within bone (spinal cord, thalamus,
brainstem, cortex...)
Peripheral Nervous System (PNS) - ✔️✔️not within bone (peripheral nerves)
brainstem - ✔️✔️includes the medulla, midbrain, and the pons
spine - ✔️✔️cervical, thoracic, lumbar, and sacral sections with each vertebrae
numbered - can then be used to classify which parts of the skin&nerves come from
where
Dendrites - ✔️✔️receive signals/neurotransmitters from neighbouring neurons (input) -
not all neurons have dendrites but most do
,Axons - ✔️✔️send the signals to other neurons (output) - axons will often branch into
many pathways, but only one will come off of the cell body
Action potentials - ✔️✔️rapid increases and then decreases of voltage along the action
potential (caused by rapid depolarization to the threshold)
Astroc Neuroscience - ✔️✔️study of the neurons and nervous systems
ytes (CNS) - ✔️✔️glial cells that maintain ionic environment
oligodendrocites and schwann cells - ✔️✔️glial cell that forms myelin around neurons
Microglia - ✔️✔️glial cells that scavenge cellular debris
cerebrospinal fluid (CSF) - ✔️✔️aqueous saline solution surrounding neurons that
contains sodium, potassium, chloride, and other ions in solution
neuronal membrane - ✔️✔️impermeable to the movement of ions, but ions can cross
by either ion transporters and ion channels
Ion transp Nissl stain showed (Broadmann) - ✔️✔️found that different areas of the
cerebral cortex had distinct cytoarchitectonic (density of neurons) appearances (52
cortical areas, now called broadmann's areas) - evolutionailly older cortex will have
fewer layers
orters - ✔️✔️active transporters (enzymes) that use energy to actively move selected
ions against concentration gradients to create ion concentration gradients
Ion channels - ✔️✔️do not use energy and they allow ions to diffuse down a
concentration gradient and are selectively permeable to only certain ions
neuronal membrane permeability (at rest) - ✔️✔️primarily permeable to potassium
because the membrane contains leak potassium ion channels, allowing potassium to
diffuse out of the cell, which makes the inside of the cell negative when potassium flows
out of the cell
equalibrium potential - ✔️✔️The potential at which the net flow of an ion would be zero
due to electrostatic and diffusion forces being equal and opposite - still movement, but
no net movement
,Diffusion of potassium - ✔️✔️when potassium diffuses out of the cell down its
concentration gradient (outside of the cell)
Electrostatic force of potassium - ✔️✔️as potassium diffuses out, the inside becomes
progressively more negative, and the positive potassium is attracted to the inside
Nernst equation - ✔️✔️allows us to calculate the equilibrium potential (Ex) for a
particular ion (X) using the electric charge, the outside concentration and the inside
concentration
equilibrium potentials for potassium and sodium - ✔️✔️EK is around -84, ENa is
around +67
Membrane potential at rest is most similar to - ✔️✔️neuron is primarily permeable to
potassium, so the resting potential is close to EK, but is not the same as the neuron is
still somewhat permeable to other ions
neuraxis - ✔️✔️axis of the nervous system - in humans, the neuraxis curves at the
brain
Neuraxis before curving - ✔️✔️dorsal is behind, ventral is infront, caudal is down, and
rostral is up
Neuraxis after curving - ✔️✔️dorsal is up, ventral is down, caudal is back, and rostral is
front
General axis - ✔️✔️superior is above, inferior is below, anterior is infront of, and
posterior is behind
Decussate, medial and lateral - ✔️✔️to cross over to the other side of the brain, medial
is near the midline and lateral is far from the midline
Proximal and distal - ✔️✔️Proximal is close to the point of reference and distal is far
from the point of reference
Efferent and Afferent - ✔️✔️Efferent is projecting away from reference and afferent is
projecting towards reference
coronal plane - ✔️✔️separates the front of the brain from the back (vertical axis)
sagittal plane - ✔️✔️separates the left from the right (vertical)
, horizontal plane - ✔️✔️separates the top from the bottom (horizontal)
midsagittal plane and parasagittal plane - ✔️✔️divides the in the middle, divides into
quarters
4 rules of the nervous system - ✔️✔️1. symmetry
2. localization of function
3. Contralaterality
4. Topography
Symmetry of the nervous system - ✔️✔️when looking at a coronal section, we can see
that the brain is mostly bilaterally symmetric (right is mostly the same as the left)
Localization of Function - ✔️✔️different parts of the nervous system have different
specialized functions, like how the different lobes in the brain all have different functions
Contralaterality in the brain - ✔️✔️each side of the nervous system controls the
opposite side of the body and each side of the physical field activates the opposite side
of the brain
Topography in the nervous system - ✔️✔️there is a "map" of the body on different
areas of the brain based on where each area controls
electric potential - ✔️✔️when the concentration of charged ions varies on either side of
the membrane
how was it determined that potassium is a main contributor to the membrane potential –
✔️✔️When we record the membrane potential while altering how much potassium is in
the bath around the neuron (altering concentration gradient), we find that as the
potassium concentration in the bath rises, the resting membrane potential becomes
more positive
Goldman Equation (GHK) - ✔️✔️calculates Vm based on the concentrations and
relative permeabilities of all ions crossing the membrane, which reflects the ratio of
internal to external concentrations of all ions and their permeability coefficients - still a
slight discrepancy due to the sodium potassium pump
permeability of ions - ✔️✔️Typically, PK:PNa:PCl = 1:0.04:0.45
"Feeling" - ✔️✔️Sensory stimuli evoke electrical impulse (action potentials) that travel
to the brain where the stimulus is perceived - proven by local anestesia, stroke, and
electrical brain stimulation
