nervous system Flashcards
Define neuroscience, nervous systems, and neurons
the study of the nervous system
circuits of neurons that integrate internal and external info
cells that send/receive electrical/chemical systems
How do neurons and nervous systems differ in association with species complexity?
as the species becomes more complex, so does the system
What is the CNS? What is the PNS?
central nervous system: brain and spinal chord, interprets sensory information
peripheral nervous system: all of the external nerves from CNS and connects it to rest of the body
What are the parts of a neuron? What do they do? List them in order of the direction in which an electrical signal would typically travel down a neuron
dendrites: receive signals from other neurons
soma (body): contains nucleus and other organelles needed from neuron to function
axon: transmits electrical signals to other neurons
order: dendrites, soma, axon
What are glial cells? Name 3 and describe what they do
non-neural cells that provide protection and support for neuron
Astrocytes: These are the most abundant type of glial cell in the brain. They are star-shaped cells that provide physical and nutritional support to neurons
Oligodendrocytes: These are glial cells that produce myelin, a fatty substance that wraps around axons to insulate them and speed up the transmission of electrical signals.
Schwann cells: These are glial cells that produce myelin in the peripheral nervous system
What disease is associated with myelin degeneration?
multiple sclerosis, body’s immune system attacks body’s own myeline sheath
What type of signals travel down neurons? What type of signals typically travel between neurons?
electrical signals, chemical signals
Describe the 3 types of neurons found in the CNS and PNS and how they can work
together to regulate behavior
sensory neurons: give sensory input
interneurons: talk to other neurons
motor neurons: elicit a response
info enters sensory neurons first, than interneurons interpret it, motor neurons put a response
Which type of neuron is affected by Lou Gehrig’s disease?
motor neuron
What does the squid have to do with neuroscience? Are neurons similar in squid and
other animals?
electrical properties of neurons are similar across species
Define membrane potential; Define resting potential
membrane potential: across plasma membrane, every cell has voltage where inside of cell is relatively negative to outside
resting potential: the membrane potential of a neuron that is not transmitting signals
How are K+ and Na+ ions distributed within and outside a neuron that is at its resting membrane potential? What is meant by selective permeability?
at resting potential the cell is more negative inside than outside, ion channels are closed when a neuron is at rest
channels only let in K+ or Na+
Define the resting membrane potential in terms of millivolts (mV), K+, Na+, and the sodium-potassium pump.
resting membrane potential ranges from -40mV to -90mV
the sodium potassium pump helps maintain the unequal changer on both sides by pumping our sodium and bringing in K+
Explain the concentration and electrical gradients and the pressure they place on K+ and Na+ ions. Which pressure is more powerful for K+ in a neuron at rest?
the concentration gradient and the electrical gradient act in opposition to each other
at rest, concentration gradient is stronger than electrical gradient, K+ tends to leak out of cell and leave negative residue making it more negative inside
Under what circumstances are ions actively transported across the membrane? Under what conditions are they passively transported?
passive transport when moving down the concentration gradient, so from a higher electrical concentration to a lower one
active is vice versa, can be achieved through sodium-potassium pump
What is a voltage-gated ion channel?
a channel where electrical signals from other neurons cause ion channels to open
Explain hyperpolarization and depolarization in terms of the membrane potential and
ion channels involved
hyper-polarization: an increase in magnitude of membrane potential, inside more (–), makes it less likely to react action potential
depolarization: a decrease in reduction magnitude of membrane potential, inside more positive, more likely to reach action potential
What is meant by graded potentials?
magnitude of change in membrane potential changes with strength of stimulus
What happens when a depolarization crosses the “threshold potential”?
neuron fires
Define action potential. How are action potentials different from graded potentials?
brief all or none depolarization of neuron’s plasma membrane
there is not varying, all or nothing
Explain each step of the action potential (i.e., at each step what is happening with the membrane potential? What is happening with ions and ion channels?)
- resting state: Na+ and K+ channels are closed
- Depolarization: Na+ channels open and Na+ diffuses in cell
- Rising phase: many Na+ channels open, Na+ rushes into cell
- Falling phase: K+ channels open
- undershoot: K+ slowly closing, Na+ inactivated
- restoration of resting potential: K+ channels close
When during the action potential does positive feedback come into play?
rising phase, as more Na+ enters, the sodium channels open in response and more Na+ rushes in
When during the action potential is a neuron refractory and why?
rising phase, the Na+ channels open for depolarization, guaranteeing that the cycle can’t proceed until it reaches action potential
How do different toxins affect ion channels (tetrodotoxin, alpha and beta toxins, apamin)? How are these toxins used?
Tetrodotoxin: blocks Na+ channels an used for self-defense
Alpha and beta toxins: shifts opening and closing of Na+ channels, used to capture prey
apamin: blocks k+ channels, used for defense
