lecture 2 Flashcards
what are the parts to a neuron
cell body, dendrite, axon hillock, pre-synaptic cell, post-synaptic cell, synapse, myelin sheath
what is the structure of a nerve
many axons in one package - many packages - nerve
what is the white layer around the axon
myelin sheath
where are cell bodies bunched at in a nerve
nucleus (CNS) or ganglion (PNS)
what is a nerve supplied with and what do they do
nutrients, O2, removing waste
what are the three types of glial cells and what do they do
microglia - macrophage - destroy old cells into parts
astrocytes - anchor neurons in place, blood brain barrier
oligodendrocytes (CNS) or schwann cells (PNS) - create myelin sheath (phospholipid bilayer)
what are glial cells
cells that helps the neuron function but is not part of the neuron
how does a myelin sheath form
schwan cells have nucleus, they engulf the axon and wraps itself around it many times
what are the gaps created by myelin sheath called and what type of conduction occurs there
nodes of ranvier, saltatory conduction
where does an AP originate
axon hillock
what is the resting membrane potential of the axon
-70mV
what are axon hillocks and nodes of ranvier rich in
sodium channels
what are the types of synaptic transmissions called and how do they work
electrically - junctions directly connect pre and post synaptic - ions and current flow through
neurotransmitters - vesicles in pre-synaptic cell binds with plasma membrane for exocytosis, neurotransmitters released into the synapse,, bind to receptors, cause Na channels to open, create another AP
what is in the cytosol compared to the ECF during resting membrane potential
cytosol - large anions, high K, low Na, proteins and AA
ECF - high Na, low K
what are the structures used to move ions during an action potential
voltage-gated Na channels, voltage-gated K channels, ATPase pump
where do the majority of the body’s ATP go
ATPase pump
what is the threshold potential voltage
-50mV
what are the parts to an action potential
resting potential, threshold potential, depolarization, repolarization, hyperpolarization
what are the components to the voltage-gated Na channel
activation and inactivation gate
what are the components to the voltage-gated K channel
activation gate
what happens when the membrane approaches the threshold potential
some Na activation gates open, allows for potential to slowly become less negative
what happens when membrane reaches threshold potential
all Na activation gates open –> depolarization
what happens when you reach the peak of depolarization
Na inactivation gates slowly close, activation gates are still open
K activation gates slowly open, K leaves the cell, making cytosol more negative again
membrane begins to repolarize
what happens at the peak of repolarization
K activation gates start to close slowly
Na inactivation and activation gates open slowly
what happens when membrane potential starts to fall below threshold after repolarization
Na activation gates begin to close
what happens at hyperpolarization
ATPase pump moves 3 Na out and 2 K in
how does saltatory conduction work
starts in axon hillock - rich with Na channels
positive charge rushes down axon - node of ranvier, trigger Na channels to open, another Ap generated, positive charge continues to spread
what is an internode
myelinated region where the current passes through
what is the asbsolute refractory period at depolarization
all Na channels are open, there are no more Na channels that can allow for more Na to come in for another AP
what is the absolute refractory period at repolarization
Na activation gates are closed because of high membrane potential - AP increasing potential will further close gates
what is the relative refractory period
after mid repolarization, another AP can be generated
what are the types of chemical synapses
excitatory - cause Na channels to open for new AP
inhibitory - cause Cl channels to open, makes membrane more negative so more stimulus is needed for a new AP
