3) Nerve Cells & Communication Flashcards
Name the type of cells in the nervous system
Nerve cells
- Sensory
- Motor
- Interneuron
Glial cells
- Astrocytes
- Oligodendrocyte
Neuron
- Nerve cell specialized for communication
- Differ in shape and size depending on function and location
- Contains genetic material like other cells
What are the parts to a neuron?
Dendrites - receives signals
Axons - sends signals
Soma
- Cell body
- Central region that manufactures and renews cell components / molecules
- Contains nucleus where proteins are made
How does a neuron differ from other cells?
- Has electrified membrane that enables exchange of electrical & chemical signals
- Are not easily replaceable or interchangeable
- Each neuron acquires unique functions and connections based on experiences
What are glial cells?
Plays a role in the formation of myelin and the blood-brain barrier
“Glue”
Protects neurons
Responds to injury
Removes debris
Facilitates communication among neurons
Enhances learning and memory
Astrocyte
- The most abundant glial cell, especially in blood-brain barrier
- Communicate with neurons, increase accuracy of transmission
- Help control blood flow in brain
- Vital role in development of embryo
- Involved in thought, memory, immune system
Which glial cell plays a crucial role in the blood brain barrier?
astrocytes
What is the blood-brain barrier?
Protective shield of blood vessels that insulate brain from infection/intruders
Lots of astrocytes
Security system of brain, ensures that our knowledge, thoughts, & abilities remain intact
Oligodendrocyte
Type of glial cell that produces myelin sheath in brain and spinal cord (CNS)
Promotes new connections among nerve cells
Releases chemicals that help healing
which glial cell produces the myelin sheath?
oligodendrocyte
which glial cell plays a vital role in the development of embryo, and helps control blood flow in the brain?
astrocyte
which glial cell promotes new connections and helps with healing?
oligodendrocyte
what is the name of the most abundant glial cell?
astrocyte
myelin sheath
Glial cells wrapped around axons that act as insulators of neuron’s signal
Speeds up transmission of electrical signals down the length of axon
Gaps called nodes that allow signal to jump along
Sclerosis
Degrading myelin sheath, so signals and messages can’t travel reliably
Results in symptoms like coordination problems
What are the two ways that neurons communicate?
- action potential
- within cell process, electrical - synapse
- between cell process, chemical
what is the electrical communication in neurons?
action potential transmit info WITHIN neurons
Neurons respond to neurotransmitters by generating electrical activity
What is the basis of all electrical responses / action potentials in neurons?
uneven distribution of charged particles across neuron membrane
what is the neuron membrane & what is on either side?
impermeable membrane with channels for ions to move thru
Outside: lots of Na
Inside: lots of K
what is membrane potential?
diff in charge between inside & outside cell
(inside minus outside)
Resting potential
No NTs acting on neuron, not stimulated
Electrical charge difference (-70mV) across neuronal membrane
There are more negative particles inside of neuron than outside
Outside cell = extracellular = 110mV
Inside cell = intracellular = 40 mV
Explain the concept of concentration gradient
ions move from high concentration to low concentration until balanced
Threshold of excitation
membrane potential or level of depolarization necessary to trigger an action potential
Threshold of excitation
membrane potential or level of depolarization necessary to trigger an action potential
Action potential & when it occurs
Wave of electrical impulse/signal that travels down the axon to synapse, triggers the release of NTs
Happens when charge inside neuron reaches high enough level relative to outside
Massive, momentary reversal of membrane from -70mV to +50mV
“All or none” response
what is the universal language of neurons in all animals? aka how neurons communicate?
action potential
How does the action potential work?
Originate in trigger zone near cell body
Positive particles flow into and out of axon quickly
Inside charge end up at slightly more negative than resting value
Shifts in charge produce a release of electricity
Triggers release of NTs when it reaches axon terminal
What are the 5 phases of the action potential?
- Resting state
- Depolarization
- Rising phase
- Falling phase
- Undershoot or Refractory period
Which gates are open in resting state of the action potential?
Na closed
K closed
Inside -, outside +
Which gates are open in depolarization state of the action potential?
Na opens a bit, enters so that cell is less polar (less charged, becoming more positive)
K closed
Inside -, outside +
Which gates are open in rising state of the action potential?
Na open more, rushes in cuz concentration gradient (less Na on inside)
K still closed
Inside +, outside -
Which gates are open in falling state of the action potential?
Na closed
K open, leaving to outside
(cuz less K outside and lots of + charge on inside)
Inside -, outside +
Which gates are open in undershoot or refractory period of the action potential?
Na closed
K open, still leaving
Inside -, outside +
Membrane is hyperpolarized, can’t fire again during this point
Absolute refractory period
Brief time during which another action potential is impossible
Limits the maximal firing rate
Action potential can only happen once the membrane has reset to resting potential
More limiting on long axons
Unmyelinated vs myelinated transmission
unmyelinated: slower since action potentials along entire axon
myelinated: faster cuz less action potentials happening, only at nodes
oligodendrocyte vs schwann cells
oligo myelinate CNS
Schwann myelinated PNS
neurotransmission
chemical communication of info AMONG neurons
NTs bind with receptor sites on dendrites after release into synapse
Lock and Key!
describe the lock and key analogy
in neurotransmission, receptor sites (lock) recognize specific types of NT (key)
Neurotransmitters
Chemical messengers specialized for communication between neurons
Either excite or inhibit postsynaptic neuron
Specific types often found in specific “pathways” or regions of brain
What does exciting/inhibiting a neutron mean?
Increase or decrease likelihood of firing action potential
Concentration of NT is controlled by what 3 things?
- Autoreceptors
- Reuptake
- Degrading enzymes
Autoreceptors
when too high concentration of NT, this binds to presynaptic cell to signal it to stop releasing the NT
Reuptake
recycling mechanism of NTs, a continually occurring process where pre synaptic vesicle reabsorb NTs
Degrading enzymes
enzymes that are released into synapse to break down NTs, regulating NT concentration
Glutamate
Excitatory NT
Enhanced learning and memory
Relay sensory info
ex/ MSG in food
What are the two most common neurotransmitters in the CNS?
Glutamate and GABA
Schizophrenia is caused by too much of what NT?
glutamate, toxic to receptors
GABA
Inhibitory NT
Learning, Memory, Sleep
Anti anxiety drugs would bind to what NT receptors?
GABA
Drugs target what NT to treat anxiety disorders, insomnia, depression, or epilepsy?
GABA
Acetylcholine
Can inhibit or excite depending on where it’s released
Arousal, attention, memory, sleep
Alzheimer’s: neurons with this NT are slowly destroyed = memory loss
Those with Alzheimer’s do not have enough of which NT?
acetylcholine
Acetylcholine plays what role in the PNS?
Voluntary muscle control
Internal organs
Acetylcholine plays what role in the brain?
Regulation of attention / arousal
Learning & Memory
Sleep & dreaming
Dopamine
NT that regulates motivation & pleasure
Emotional arousal
Motor behavior
which NT plays a large role in addictions like gambling?
dopamine
which NT plays a large role in addictions like gambling?
dopamine
serotonin
NT that regulates sleep & wakefulness
Appetite, social behavior, sexual desire
Norepinephrine
NT involved in states of heightened awareness of dangers in envo
Increases alertness, arousal, attention
which two NT regulate mood, sleep, and memory?
serotonin and norepinephrine
endorphins
Naturally occurring pain killer
Acts within
- pain pathways to reduce pain
- emotional centers of brain to elevate mood
EPSP
Excitatory Post Synaptic Potential
Depolarize postsynaptic membrane
Increase likelihood that postsynaptic neuron will fire
Ex/ from -70mV to -67mV
IPSP
Inhibitory Post Synaptic Potential
Hyperpolarize postsynaptic membrane
Decreases likelihood that postsynaptic neuron will fire
Ex/ from -70 to -73mV
an action potential can be generated by simultaneous _____
EPSPs
synaptic vesicles
Spherical sac containing neurotransmitters
Amount of neurotransmitters is regulated by the cell
synapse
Space between two connecting neurons where messages are transmitted chemically
Consists of synaptic cleft
synaptic cleft
Gap into which neurotransmitters are released from axon terminal
Axon doesn’t actually touch dendrites
Receptor Site
Location that uniquely recognizes a NT
Psychoactive Drugs
Interact with neurotransmitter systems, affecting mood, thinking, arousal, behavior, etc
most drugs impact some aspect of ____ in the following ways _____
neurotransmission
- impact receptor binding
- influence concentration of NT in cleft
agonists vs antagonists
agonists increase or mimic effect of NT (opiates)
antagonist block effect of NT (botox)
Neural Plasticity
Ability of nervous system to change over time, continually!
ex/ response to damage
Abilities like language, jealousy, morality, aren’t fixed or predetermined
What is our super power, as humans?
adaptability!
Development is most flexible during ____
early development
Our brains don’t mature fully until?
early adulthood
4 main ways of brain development
- growth of dendrites & axon
- synaptogenesis
- pruning
- myelination
Pruning
Death of some neurons or retraction of axons to remove unuseful connections
Organizes neurons, which enhance communication (process info more efficiently with fewer neurons)
In the brain, learning results in the formation of what?
new synapses and more connections
- the brain changes as we learn
Potentiation
strengthening existing connections
What are the two ways we learn?
potentiation and forming new connections
Structural plasticity
changing shape of neurons is critical for learning
ex/ more dendrites when exposed to richer envo
Neurogenesis
Creation of new neurons in adult brain
Importance: can possibly induce nervous system to heal itself even in adulthood
Controversial, first found in animals
- potentially involved in learning
stem cells
have capacity to differentiate into more specialized cell,
but becomes permanent after choosing a direction
(muscle, blood, neuron)
What type of cell is important in treating diseases, such as gene therapy?
stem cells can replace damaged cells
gene therapy = providing replacement genes
controversy of embryonic stem cell research
potential for treating serious diseases
(cancer, alzheimers)
VS
they are a early form of human life
