1-neurons and action potentials and all that yucky stuff Flashcards
glial cells (glia)
- outnumber neurons 10:1, traditionally thought to play a supportive role to neurons
- physically and metabolically
- provide scaffolding on which the nervous system is built
- help neurons line up closely with each other to allow neuronal communication
- insulation for neurons
- transport nutrients and waste products
- mediate immune responses
neurons
- interconnected information processors that are essential for all of the tasks of the nervous system
Dendrites
receives information and transport it to the cell body
- recieve neurotransmitters and report to nucleus with an excitatory or inhibitory charge
- create action potential!!
neuronal membrane:
acts as a boundary that controls what substances enter and leave the neuron.
keeps extracellular and intracellular fluid separate
cell body (soma)
core of the neuron which maintains the cell and ensures it is working effectively, collects and processes information
axon
transmits information form one part of the neutron to the other
Node of Ranvier
gaps in the myelin sheath which facilitates a more efficient and quick conduction of action potentials.
Oligodendrocytes
-
one type of glial cell. The role of these cells is to support neurons in the brain.
- Oligodendrocytes specifically maintain the myelin sheath in the central nervous system.
myelin sheath
helps info travel down axon faster, surrounds the neuron in layers of its proteins and fat, made of glial cells
Axon/terminal buttons
Send the signal to the next neutron. The terminal buttons contain synaptic vesicles that are packed with neurotransmitters.
synapse
gap between two neurons
resting potential:
- the state of readiness of the neuron membrane between signals
-70 millivolts
state of the cell during the resting state?
- in resting state, sodium (Na+) is higher concentrations outside the cell, so it will tend to move into the cell once gates are open
- potassium (K+) is more concentrated inside the cell and will tend to move out of the cell once gates are open
- inside of the cell is negatively charged compared to the outside!!
threshold of exitation
- 50 millivolts
Vesicles
filled with neurotransmitters, releases neurotransmitters into the synapse
gates
pick up neurotransmitters, NT are the key to the gate!
electrochemical event
neuronal communication
all-or-none phenomenon
either you have not enough signal, or enough and BOOM ACTION POTENTIAL
action potential!! process!!
- neuron recieves signal at dendrites!! state changes abruptly!!
- gates open on the neuronal membrane
- allows NA+ ions, propelled by both charge and concentration differences to move into the cell
- internal charge of the cell becomes more positive!!
- if charge reaches a certain level (threshold of excitation) action potential begins!!
- -55 mv
- at the peak! sodium gates close and potassium gates open
- it pumps out not only the potassium ions but the sodium as well
- positively charged potassium ions leave, the cell begins repolarization
- first, it hyperpolarizes, becoming slightly more negative than the resting potential
- then it levels off, getting the potassium back in, returning to the resting potential
- moves like a wave—some of the sodium ions that enter the cell diffuse to the next section of the axon
- raising the charge past the threshold of excitation and triggering a new influx of sodium ions
- moves all the way down the axon to the terminal buttons
How neurotransmitters are transmitted across a synapse
- once NT are released into the synapse, they travel across the small space and bind with corresponding receptors on the dendrite of an adjacent neuron
receptors
proteins on the cell surface where NT attach, vary in shape, different shapes matching different neurotransmitters
- NT and receptor have a **lock-and-key** relationship!!
- specific NT fit specific receptors like how a key fits a lock
Once the neurotransmitters are delivered?
- excess NT in the synpase drift away, broken down into inactive fragments
- reabsorbed in a process known as reuptake
- NT being pumped back into the neuron that released it, in order to clear the synapse
- clearing the synapse provides a clear “on” and “off”
- regulates the production of NT
- NT being pumped back into the neuron that released it, in order to clear the synapse
EXCITATORY
neurotransmitters that INCREASE the positive charge!!
- dopamine—mood/sleep/learning
- norepinephrine—fight/flight, concentration
- glutamate—memory/learning
- acetylcholine—muscle/memory
INHIBITORY
neurotransmitters that DECREASE positive charge!!
- serotonin—mood/sleep
- GABA—sleep/anxiety
- Endorphins—pain/pleasure
acetylcholine
involved in muscle action, memory
potential effect on behaviour: increase arousal, enhanced cognition
beta-endorphin
involved in pain, pleasure
potential effect on behaviour: decreased anxiety, decreased tension
dopamine
involved in mood, sleep, learning,
potential effect on behaviour: increased pleasure, suppressed appetitie
Gamma-aminobutyric acid
involved in brain function, sleep
potential effect on behaviour: decreased anxiety, decreased tension
glutamate
involved in memory, learning
potential effect on behaviour: increased learning, enhanced memory
norepinphrine
involved in heart, intestines, alertness
potential effect on behaviour: increased arousal, suppressed appetitite
serotonin
involved in mood, sleep
potential effect on behaviour: modulated mood, suppressed appetitie
agonist
INCREASES the function of an NT by mimicking and NT at the receptor site
antagonist
DECREASE OR INHIBIT the function of a neurotransmitter
reuptake inhibitors
- prevent unused NT from being transported back to the neuron
- leaves more NT in the synapse for a longer time, increasing its effects
