Neurobiology (Exam 1)

Question 1

Membrane Potential

Answer 1

• Voltage difference across the membrane (v or mv)
• Arises from unequal distribution of ions
• Changes w/ selective movement of ions across the membrane
• Rate of ion movement is proportional to the difference between membrane and equilibrium potential (driving force)
  
  • The larger the difference, the stronger the driving force

Question 2

Equilibrium Potential

Answer 2

• Membrane potential when the net flow of an ion is zero
• When concentration gradient and electrochemical gradients are equal and opposite to one another

Question 3

What is the resting membrane potential of neurons?

Answer 3

~70mV

Question 4

Resting Membrane Potential

Answer 4

• Relies heavily on K+ leak current
• Neurons maintain concentration gradients via active transport
• Na/K pump, leaky channels, and ions all contribute to this

Question 5

Graded Potentials

Answer 5

• Short distance signals that occur in dendrites and cell bodies
• Vary in magnitude and duration
  
  • Based on strength of stimulus
• Created by ligand-gated channels
• Decay over short distances

Question 6

Action Potentials

Answer 6

• Long distance all-or-none signals that maintain the same magnitude, duration, and amplitude
• Move from the axon hillock to axon terminal only
  
  • Due to the inactivation of voltage-gated Na+ channels
• Weak stimulus leads to a low frequency of action potentials
• Strong/supra-threshold stimulus leads to high frequency of action potentials

Question 7

Types of Neurons

Answer 7

Multipolar, bipolar, unipolar, efferent, afferent, interneuron

Question 7

Steps of Neurotransmitter Release

Answer 7

1. Voltage-gated Ca2+ channels open, Ca2+ flows into the cell and pushes vesicles toward the plasma membrane
2. Ca2+ ions change the conformation of SNARE proteins, which causes the vesicles to fuse with the plasma membrane
3. Neurotransmitter is released and binds to receptor on post-synaptic cell

Question 8

Multipolar

Answer 8

Several processes off of cell body

Question 9

Bipolar

Answer 9

Two processes off of cell body

Question 10

Unipolar

Answer 10

One process off of cell body + branches

Question 10

Efferent Neuron

Answer 10

• Carries info from CNS to PNS
• Motor neuron (multipolar)

Question 11

Afferent Neuron

Answer 11

• Carries info from PNS to CNS
• Sensory neuron (unipolar)

Question 12

Interneuron

Answer 12

• Carries info from one neuron to another
• Multipolar

Question 13

Temporal Summation

Answer 13

Converts a rapid series of weak pulses from a single source into one large signal

Question 14

Spatial Summation

Answer 14

Several weak signals from different locations into one large signal

Question 15

Types of Neurotransmitters

Answer 15

• Amino acids
• Neuropeptides
• Biogenic amines
• Acetylcholine

Question 16

Ionotropic Receptors

Answer 16

• Receptors + channel is the same protein
  
  • Neurotransmitter binds, channel opens, ions flow through

Question 16

Inhibitory Neurotransmitters

Answer 16

Generates IPSPS (hyperpolarization)

Question 17

Excitatory Neurotransmitters

Answer 17

Generates EPSPS (depolarization)

Question 18

What causes depolarization (action potential graph)?

Answer 18

Ligand-gated channels open at threshold, Na+ enters

Question 18

Metabatrophic Receptors

Answer 18

• Receptor + channel are different proteins
  -Neurotransmitter binds + activates pathway to open a separate channel

Question 19

What enables the transition from absolute to relative refractory period?

Answer 19

Opening of the inactivation gate

Question 20

Absolute Refractory Period

Answer 20

Time during which no new AP can occur, occurs from onset of AP until the end of Na+ channel inactivation

Question 21

What causes repolarization (action potential graph)?

Answer 21

Voltage-gated K+ channels open and K+ leaves

Question 22

What results from hyper-polarization (action potential graph)?

Answer 22

Voltage gated K+ channels close

Question 23

Relative Refractory Period

Answer 23

When a larger depolarization is needed to reach the threshold due to hyper-polarization

Question 24

Neuron

Answer 24

• Fundamental unit of the nervous system
• Uses changes in membrane potential to communicate signals across long distances

Question 25

What Quickens the Action Potential Conduction Velocity

Answer 25

• Quicker when the axon is heavily myelinated
• Quicker when the axon has a large diameter
  - Current spreads farther + decays slower

Question 26

Dendrites Function

Answer 26

Receives information from other neurons

Question 27

Rough ER Function

Answer 27

Protein synthesis

Question 28

Cell Body (soma) Function

Answer 28

Keeps cell functional

Question 29

Axon Hillock Function

Answer 29

Generates impulse in the neuron

Question 30

Myelin Sheath Function

Answer 30

Increases speed of signal

Question 31

Nodes of Ranvier Function

Answer 31

APS jump between these (saltatory conduction)

Question 32

Axon Function

Answer 32

Transfers signals to other cells; stimulus must surpass threshold potential here

Question 33

Axon terminal Function

Answer 33

Forms junctions with other cells

Question 34

Synapse Function

Answer 34

Transmits info; neurotransmitter carries message to next cell