Exam 2 Flashcards
Permeability of the membrane before, during, and after an AP
Before, K+ is much greater
During, Na is much greater
After, K+ is high once again
What keeps the membrane potential near Ek at rest
Leaky K+ channels
Long QT syndrome
Takes longer to repolarize after the action potential
Glucose-sodium cotransporter
Two sodium for every glucose molecule, can get 10,000 fold conc. gradient for glucose
Most important countertransporter in the body and why
Na/H exchanger, cell pH is basic because protons are constantly pumped out using sodium
Digitalis (oubain)
inhibits the Na/K ATPase, causing reverse operation of the Na/Ca exchanger, raising cytoplasmic Ca2 and producing a more powerful heart contraction
Voltage sensor
Polar element within a membrane that moves to one side or another based on charge
3 regions of a pore module
Selectivity filter, cavity, and gating
Are there synapses in sensory ganglia
No
Afferent vs. efferent
Afferent (towards a source), sensory
Efferent (away from a source), motor
Where are pseudounipolar neurons found
Exclusively in sensory ganglia in the PNS, single short process bifurcates into two other processes
Axon hillock and rough ER
It has no Nissl substance
MAP’s
Microtubules-associated proteins that compartmentalize the neuron
What part of a neuron is lost with age
Dendritic spines
Anterograde neuronal transport
Kinesis, 400 mm a day
There is also slow, diffusive transport (enzymes and neurotransmitter precursors)
Neurofibrillary tangles
Caused by tau protein that causes crosslinking of microtubules in alzheimers, down’s etc.
Retrograde axonal transport
Mediated by dynein, recycles substances, can take up toxins and viruses
Oligodendrocyte
Makes CNS myelin, multiple axons
Microglia
CNS macrophage, smallest cell, derived from monocytes
Proliferate to site of CNS injury, determine survival of a tissue graft
Astrocytes
Ensheath the synapse, store glycogen
Foot processes make the blood-brain barrier
Most common glial cells in the CNS
Proliferate to injuries and form an astroglial scar
Are similar to neurons but are not polarized
GFAP
Glial Fibrillary Acidic Protein, expresses by astrocytes
Ependymal cells and tanycytes
Other two glial CNS cells
Satellite cells
Microenvironment around a ganglion, pathway for metabolic exchange
Schwann cells
Make all PNS myelin
Guillane-Barre syndrome vs. MS
MS is CNS myelin disorder, Guillane barre is PNS myelin
What myelin proteins cause compaction of schwann cell myelin
P0 and MBP (Myelin Basic Protein)
Are nodes of ranvier larger in the CNS or the PNS
Larger in the CNS, making saltatory conduction more efficient
Neuregulin
Signal that causes myelination, derived from axon size
Wallerian degeneration
Anterograde degeneration, axon degenerates distal to the cut, cell body undergoes retrograde chromatolysis
Molecules that cause lack of CNS regrowth
Nogo, MAG, and OMgp
Epineurium
Connective tissue around surface of entire nerve
Perineurium
Blood nerve barrier, surrounds each fascicle of nerve fibers
Endoneurium
Surrounds each nerve cell and is made of collagen and reticular tissue
Cystic Fibrosis
Mutation in CFTR, mucus in lungs cannot trap bacteria
ASL
Airway surface liquid, below the sticky mucus that cilia beat out of the lungs, 8 microns high
Passage of CL from lumen of the lungs
Can be paracellular or transcellular, follows sodium, net effect is a pumping of NaCl from the apical to the basolateral membrane, and water follows, dehydrating the ASL
CF heterozygote advantage
May mae you more resistant to cholera-induced diarrhea
Cholera mechanism
Activates the CFTR regulatory domain, ion channel always opened and dehygration occurs
Cholera and glucose treatment
Sodium glucose transporter causes water to obligatorily come with the glucose, counteracting the loss in the cholera
What can the reflex arc at the patellar tendon be used to detect
pre-eclampsia
Why does AP depolarization not go backwards
Sodium channels remain inactivated (cannot reopen) and the voltage gated potassium channels are slow to close
Myelin and capacitance
Myelin decreases the effective membrane capacitance
how does a chemical synapse work
Depolarization opens voltage gated calcium channels
Ca ions bind to SNARE proteins, vesicles fused with the membrane and Ach is released
Botulin toxin
Blocks the vesicle fusion process by cleaving SNARE proteins that are required
High Safety Factor
Endplate potential brinds the membrane potential to the AP threshold every time
How many nuclei do smooth muscle have
1
Electrical isolation properties of the different muscle cells
Skeletal muscles are isolated electrically, cardiac and smooth muscles are connected to neighboring cells (smooth can sometimes be isolated)
Satellite Muscle Cells
Closely associated with muscle fibers, can be reactivated at any time, re-enter the cell cycle, and generate new cells to fuse into
Tend to have totallly condense chromatin
When are the nuclei of muscle cells centrally located
When the fiber is damaged
A band
The extent of the thick myosin filaments
H band
Parts of the myosin band where there is no actin present
I band
Parts where only actin is present
M line
Narrow dark line in the center of the A band, L line is the narrow light line next to the M line on each side
Z band
High density of protein on the edge of each sarcomere
Myomesin
Proteins in the M band that bind the thick myosin filaments together
Myosin II
The myosin that is found in muscle, made up of 2 essential light chains, 2 regulatory light chains, and 2 heavy chains
In what part of myosin does phosphorylation occur
At the end motor domains, on the regulatory lgith chains
Actin and Myosin and polarization
The actin filament is polarized, unlike the myosin filament.
the pointed end of actin is the minus end, while the barbed end is the plus end
Tropomodulin
Capping protein that regulates acin polymerization and depolymerization at the pointed end of the actin filament
CapZ
Capping protein that regulates actin polymerization and depolymerization at the barbed end
Titin
Elastic protein that forms connections between Z discs and myosin filaments
Myosin and actin in the absence of ATP
Bind tightly, rigor mortis
When does the power stroke occur
As phosphate is released. When ADP dissociates, myosin minds to actin again
Tetanus
Completely fused twitches
Also a bacteria - cleaves synaptobrevin which blocks the release of inhibitory NT’s, permitting unopposed neural stimulation