Changes in the Brain Flashcards
What are the building blocks of the Central Nervous System?
Neurons
What are neurons?
Cells that are responsible for receiving and transmitting electrochemical information
What are dendrites doing?
Receiving information from other neurons and sensory receptors
What is the axon doing?
It carries neuron’s messages to the other body cells
What do the terminal buttons of the axon do?
They form junctions with other cells and release chemicals called neurotransmitters
What does the cell body do?
It receives information from dendrites and if enough stimulation is received, the message is passed to the axon
What does the myelin sheath do?
It covers the axon of some neurons to insulate and help speed neural impulses
What is the grey matter in the brain?
Grey matter consists of neuronal cell bodies and their dendrites
- Unmyelinated - cell bodies and dendrites
- This is where information processing happens! Sensation, perception, voluntary movement, learning, speech, cognition, etc…
- The cell bodies are responsible for our unique ability to think and reason
What percentage of the brain is grey matter?
40%
What is the white matter in the brain?
Consists of the long axons of neurons that transmit impulses to more distant regions of your brain and spinal cord.
- White matter’s role is to provide communication between different grey matter areas and between grey matter and the rest of your body.
What percentage of the brain is white matter?
60%
What is it called when a neuron is at rest?
The resting potential
What happens during resting potential?
sodium (Na+)is more highly concentrated outside the cell in the extracellular fluid, whereas potassium (K+)is more highly concentrated inside the cell. Other molecules, such as chloride (Cl-) and other negatively charged proteins (-) (brown squares), contribute to a positive net charge in the extracellular fluid and a negative net charge in the intracellular fluid
- negative charge within the cell, positive outside the cell
What is an action potential?
a neural impulse that carries information along the axon of a neuron)
What happens during an action potential?
During the action potential, the electrical charge across the membrane changes dramatically (depolarization), such that the inside of the cell becomes + charged
This results in the release of chemicals that serve to communicate with surrounding cells
- The cell goes from a negative charge to positive because the cell membrane was disrupted
- The cell wants to go back to its negative net charge and will do things to get rid of the positive chemicals and this is what the action potential is
How does neural communication occur?
Between neurons, communication occurs through transmission of neural information across a synapse by neurotransmitters
What is a synapse?
The space that exists where communication between cells can occur
How do neurotransmitters act like lock and key?
- Receptors and neurotransmitters act like a lock-and-key system.
- Just as it takes the right key to open a specific lock, a neurotransmitter (the key) will only bind to a specific receptor (the lock)
- If the neurotransmitter is able to work on the receptor site, it triggers “changes“ in the receiving cell
What are some of the basic neurotransmitters?
- Acetylcholine
- Dopamine
- GABA
- Glutamate
- Glycine
- Norepinephrine
- Serotonin
What is dopamine?
The neurotransmitters that produces feelings of pleasure when released by the brain reward system.
Dopamine usually has multiple functions depending on where in the brain it acts.
It is usually inhibitory.
- Highest as a teenagers
What is serotonin?
A neurotransmitter involved in many functions including mood, appetite, and sensory perception.
In the spinal cord, serotonin is inhibitory in pain pathways
True or False: The effects of neurotransmitters are simple
FALSE.
They are compliated
What determines if an action potential occurs or not?
Receiving neurons receive multiple messages from other neurons. These multiple messages then determine if an action potential occurs or not.
True or False: The basic structure of the brain has been laid out during prenatal development
TRUE
What can looking at the brain tell us?
- Some axons can connect to individual neurons more than a dozen times, while some connect only once
- These multiple connections could indicate memories or skills that have been “strengthened” by repeated use
Just something to know
Note how the axon terminals of sending neurons almost completely cover the cell body of the receiving neuron (these axons come from MANY different neurons!)
Why aren’t adolescent brains like adult brains?
it will take years of “fine tuning” before the brain functions in the same way as an adult and has adult-like microstructure
What is synaptogenesis?
Once in place, neurons start to make connections
Send out projections to nearby neurons
Rapid period of synapse formation begins, contributing in part to growth of grey matter
- the creation of synapses
- you create a lot of synapses but you don’t need all of them
How can the brain be made more efficient with grey matter changes?
- Cortical thickness decreases (because synapses are decreasing)
- Synapses rearranged and pruned
- Greater efficiency
True or False: Young children’s brain work harder and less efficiently than adults
TRUE
- Having all those synapses is expensive
How can the brain be made more efficient with white matter changes?
- Myelination increases
- Greater connectivity
- Greater efficiency
- White matter increases, not as many synapses, but these synapses have better communication
How does the brain figure out which synapses to prune?
Active synapses likely take up neurotrophic factor that maintains the synapse
Inactive synapses get too little neurotrophic factor to remain stable
- Use it or lose it