THE NEURONS Flashcards
number of neurons in the human brain
100 billion neurons
Carry information to the cell body from other neurons
dendrites
Contains nucleus
cell body (Soma)
Carries information to the next cell
axon
Insulates the axon and speeds up the neural impulse
myelin sheath
Tiny gap between neurons
synaptic space (synaptic cleft)
Enlarged area at the end of an axon
terminal button
Composed of the terminal button of one neuron, the synaptic space, and the dendrites or cell body of the receiving neuron
the synapse
Sacs in terminal button that release chemicals into synaptic space
synaptic vesicles
Chemicals released by synaptic vesicles
neurotransmitters
Location on receptor neuron for specific neurotransmitter
receptor sites
the microscopic gap that serves as a communications link between neurons
synapse
Carry information from sensory systems to the brain; Also referred to as afferent
sensory neurons
Carry information from the brain to muscles and glands; also referred to as efferent
motor neurons
Carry information between other neurons
interneurons
carry messages from the receptors to the CNS
sensory neurons
carry messages from the CNS to muscles and glands
motor neurons
are located in the CNS and are the link between sensory and motor neurons
interneurons
- Cells that insulate and support neurons
- Create the myelin sheath
- Remove waste products
- Provide nourishment
- Prevent harmful substances from entering the brain
glial cells
Nothing is happening. The gates are closed and the positive ions are on the outside with the negative ions on the side of the cell.
resting potential
a brief electrical charge that travels down an axon
Action potential (neural impulse)
when the inside of the neuron is negatively charged relative to the outside (resting potential)
polarization
when the electrical charge of a cell moves toward zero
depolarization
the time it takes for the positive ions to be pumped out
refractory period
the level of stimulation required to trigger a neural impulse
threshold
A shift in the electrical charge in a tiny area of a neuron
graded potentials
Many subthreshold depolarizations are added together to produce an action potential
summation
- A neuron either fires or it does not
- When it does fire, it will always produce an impulse of the same strength
- Intensity of a stimulus is seen by the frequency of action potentials
all or none law
A junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron.
synapse
This tiny gap is called the
synaptic gap or cleft
Chemicals released from the sending neuron travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing it to generate an action potential.
neurotransmitters
Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of ____. This process applies the brakes on neurotransmitter action.
reuptake
Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism.
lock and key mechanism
mimicking or impersonating naturally occurring neurotransmitters, like a hairpin picking a lock, a___ are able to unlock a cell to produce an effect
agonist
working in the opposite way, they block the receptor, like jamming glue into a keyhole so that it may be not opened
antagonists
- Released at the neuromuscular junction
* Plays an important role in arousal and attention
acetylcholine
- Affects neurons associated with voluntary movement and pleasure
- Play a role in learning, memory, and emotions
- Implicated in Parkinson’s Disease and Schizophrenia
Dopamine
- Found throughout the brain
- Appears to sets an “emotional tone”
- Affects mood, hunger, sleep, and arousal
- Low serotonin level are implicated in depression
- Some antidepressant drugs raise serotonin
serotonin
- Reduce pain by inhibiting or “turning down” neurons that transmit pain information
- “runner’s high”
endorphins
- Helps control alertness and arousal
* Undersupply can depress mood
norepinephrine
- A major excitatory neurotransmitter; involved in memory
* Oversupply linked to seizures, tremors, and insomnia
GABA (gamma-aminobutyric acid)
Most psychoactive drugs (and toxins) work by blocking or enhancing synaptic transmission
psychopharmacology
- Blocks release of ACh at the neuromuscular junction, causing paralysis
- “Botox” is a botulism toxin used to prevent facial muscles from making wrinkles
botulism
- Can stun or kill prey quickly
* Block ACh receptors causing paralysis
curare
- Block dopamine receptors
* Reduces schizophrenic hallucinations
antipsychotic medications
Increases the release of excitatory neurotransmitters by blocking the inhibitory neurotransmitter adenosine
caffeine
- Prevents the reabsorption of dopamine
* Leads to heightened arousal of entire nervous system
cocaine
- The brain can be changed, both structurally and chemically, by experience
- Rat studies show that an “enriched” environment leads to larger neurons with more connections
- Has also been shown in humans
- Recent research has uncovered evidence of neurogenesis, or the production of new brain cells, in human brains
Neural plasticity
