Neurons, Synapses and Signaling Flashcards
What does the CNS consist of? PNS?
CNS: brain and spinal cord
PNS: Cranial nerves, spinal nerves, and ganglia that originate outside the CNS
Where are action potentials created? Where are neurotransmitters released?
Axon hillock
Axon terminal
Look at this picture and have an understanding of the structures of neurons.
:)
What are the 3 stages of information processing of the nervous system?
- Sensory input (PNS)
- Integration (CNS)
- Motor output (PNS)
Describe the function of sensory neurons, interneurons, and motor neurons.
Sensory neurons - Sensors detect stimuli (internal or external) and transmit impulse along these towards CNS
Interneuron - these are in the brain and receives input from sensory neurons and integrate the information.
Motor neuron - motor output leaves brain through these and triggers muscle or gland activity.
Is the inside of a neurons charge a net positive or negative?
Negative
What is the difference in voltage across the membrane called?
Membrane potential
What does the membrane potential have to do with message transmitting?
Messages are transmitted as changes in membrane potential.
What is the resting potential of a neuron? (membrane potential of neuron not sending signals)
between -60 to -80 mV
What are the two ions whose concentrations primarily determine the resting potential? How are these gradients maintained? Does this require energy?
K+ and Na+
sodium/potassium pumps control this gradient, ATP is required to run these.
Are there also ion channels that allow for Na and K to feely move across the membrane? What quantity of each of these are open in a resting cell?
YES
Generally in a resting neuron has MANY open K+ channels and a FEW open Na levels.
What is importnat to the formation of the membrane potential? Why?
The diffusion of K+ out of the cell
As K+ diffuses out of the cell the anions within the cell contribute to the negative charge inside.
What is the purpose of gated ion channels?
These open or close in response to stimuli to change the membrane potential.
What is the difference between hyperpolarization and depolarization?
Hyper - increase in magnitude of the membrane potential, making the inside of the membrane MORE NEGATIVE.
Depolarization - A reduction in the magnitude of the membrane potential, making it LESS NEGATIVE.
What are graded potentials?
These are changes in the polarization where the magnitude of change varies with the strength of the stimulus.
What channels open during depolarization?
voltage gated Na+ channels open and Na+ flows in which results in further depolarization, which leads to further Na+ channels to open and more Na+ to flow in,
Eventually the change is massive enough to trigger an action potential.
What must the membrane voltage cross before an AP occurs?
The THRESHOLD, usually -55 in mammalian neurons.
Once an AP is triggered, does the strength of the contributing stimulus have any effect on the magnitude of the AP?
What is this called?
NO
The all-or-none response
What is the definition of an AP?
Signals that carry information along axons.
What are the 5 stages of an action potential?
- Resting
- Depolarization
- Further depolarization
- Repolarization
- Hyperpolarization
What gives the graphing of an AP its shape?
The movement of ions through their voltage-gated channels
Can a neuron perform many APs per second?
YES
What is the refractory period?
This is the period after an AP in which a second AP cant be initiated.
This is caused by temporary inactivation of Na+ channels
How does an AP travel along the axon?
The neighboring region is depolarized, and the AP cant travel backwards due to the refractory period of the portion of the axon behind it, only allowing the AP to travel in one direction.
WHICH IS TOWARDS THE SYNAPTIC TERMINALS
