Biology and Neuroscience Flashcards
What are the two main divisions of the nervous system
CNS and PNS
What does the CNS consist of
Brain and spinal cord
What does the PNS consist of
All the nerves in the body that are not the brain/spinal cord
What are the 3 roles of your nervous system:
- Receives information from world and our own body
- Analyze and interprets the information
- Uses the information to send out messages
What are the two important cells of the nervous system
Neurons and Glia Cells
What are neurons
the basic unit of communication in the nervous
What is the communication process between neurons called
Its an electrochemical process.
Describe the 3 steps a neuron takes to communicate
- When it wants to communicate, it fires by sending an electrical impulse (aka action potential)
- The action potential causes the release of neurotransmitters
- The release of neurotransmitters deliver the message from one neuron to another
What are the 8 important structures of the neuron
- Soma
- Dendrites
- Axon
- Axon terminals
- Terminal buttons
- Myelin Sheath
- Synapse
- Synaptic Cleft
What is the soma and what is its role
The cell body of a neuron. It contains the nucleus and DNA. It manufactures everything the neuron needs to survive
What are the 2 roles of dendrites
- they increase the surface area of the soma without taking up too much space
- Receive messages from other neurons
What is an axon and what is its role
Its a thin tube in the neuron. It carries the electrical impulse
What is an axon terminal and what is its role
Its a part of the axon in the neuron. It carries the action potential (electrical impulse) until it reaches the terminal buttons
What are the terminal buttons and what are their roles
little nobs at the end of axon branches in a neuron. They release neurotransmitters when the action potential reaches them
What is a myelin sheath and what is its role
a white fatty-like substance on the axon of a neuron. It speeds up the transmission of the information.
What is a synapse
the place where neurons need to communicate
What is a synaptic cleft
a little gap at the synapse between two neurons. It is where the communication happens.
What is a presynaptic neuron
the neuron that sends out messages
What is a post synaptic neuron
a neuron that receives messages
Why are Glial Cells called ‘Nannies of the neurons’
They provide neurons with everything they need to survive: protection, insulation, nutrition, clean after them
What are the 4 types of glial cells
- Oligodendrocytes 2. Schwann Cells 3. Astrocytes 4. Microglia
What are Oligodendrocytes and Schwann Cells both involved in
the production, laying down, and repair of the myelin sheath
What is the difference between Oligodendrocytes and Schwann Cells
Oligodendrocytes repair the myelin sheath in the central nervous system and Schwann Cells repair the myelin sheath outside the brain and spinal cord
What is the function of microglia and astrocytes?
They both form the immune system of the brain
What percent of a neuron is water?
80%
What is intracellular fluid?
fluid dissolved inside neuron
What is extracellular fluid?
fluid outside the neuron
What are the 3 dissolved chemicals in neurons?
Na+ (sodium), Cl- (chloride), K+ (potassium)
What is happening with the dissolved chemicals inside a neuron when the neuron is AT REST?
When neuron is at rest, there is a higher concentration of negative neurons on the inside. There is a higher concentration of positively charged ions on the outside.
What does a inhibitory message mean to the neuron?
Not to fire. Not to produce an active potential
How will an inhibitory message keep the neuron from not firing?
message will change the concentration of ions to make it MORE negative inside the neuron. As a result, neuron is less likely to fire
What does it mean when a neuron is hyperpolarized?
the inside is made MORE negative than normal. it will be less likely to fire.
What does an excitatory message mean to the neuron?
Instructs the neuron to fire. To produce an action-potential
How will an excitatory message get the neuron to fire?
It will change the concentrations of the inside of the neuron to be LESS negative. As a result, it is more likely to fire
What does it mean when a neuron is depolarized?
When the inside is LESS negative than normal. More likely to fire.
At what charge will a neuron most likely to fire at?
About -50 mv
What are the nodes of Ranvier in a neuron and why are they there?
they are gaps in the myelin sheath that covers the axons. Ions use them to get in and out of the neuron
Explain the movement of ions in the neurons during an inhibitory response
Chloride (Cl-) channels open which causes an influx of chloride ions in the neuron. When this happens, there is an excess of negative ions inside the neuron, making the neuron more negative (hyperpolarized)
Explain the movement of ions in the neurons during an excitatory response
Sodium (Na+) channels open, causing sodium channels to rush into the cell. This increase the amount of positive ions in the neuron, causing it to be less negative (depolarization)
What is the threshold of excitation and how is it reached?
Its about -50mv. Its the electrical charge that the neuron must get to for it to fire. It is achieved through depolarization.
What is resting potential?
Around -70mv. Its the electrical charge that a neuron rests at.
After a neuron is fired, it has to go back to resting membrane potential. How does it return?
AFTER sodium channels open and sodium has rushed inside cell, potassium channels open. Potassium (K+) ions start leaving the neuron. Potassium ions leaving = less positive ions inside cell = less positive charge = back to resting potential
What is a refractory period?
During this period, the neuron will not fire when stimulated. The membrane is hyperpolarized.
What are the 7 steps of a presynaptic neuron firing?
- Presynaptic neuron decides to send a message to another neuron. It fires, producing an action potential.
- Action potential travels down the axon until it reaches the terminal buttons
- It goes inside the terminal buttons, where it reaches the terminal neurons.
- When it arrives at the terminal neurons, the synaptic vesicles attach the the membrane of the neuron.
- Synaptic vesicles burst open and release neurotransmitters into synaptic gap.
- Neurotransmitters cross the gap and attach to receptor sites of the synaptic neurons
- Once they attach to receptor sites, they send the message to the postsynaptic neurons.