INTRO TO NEUROSCIENCE EXAM 1
NYGARD CORRECT ANSWERS
What is a membrane potential? What is the resting membrane potential? What is the
value of the resting membrane potential? - Answer-The difference in charge between
the inside and outside of a cell, the value of the neuron membrane at rest, -70mV
A membrane is polarized when it - Answer-carries a charge
How was charge measured in the squid axon? - Answer-Electrodes were placed
inside and outside the cell to measure changes
What are the 2 types of passive ion forces? How do they work? - Answer-
Electrostatic forces: cause a movement of ions based on attraction/repulsion of the
charge of the membrane/other ions
Diffusion: passive movement of ions down concentration gradient to achieve
equilibrium
What are the main ions that exist? Where? - Answer-K+: inside cell
Na+: outside cell
Cl-: outside cell
A-: negatively charged proteins, inside cell
What are the 4 factors contributing to the resting membrane potential? - Answer-1.
Selective permeability of K+
2. K+ diffusion out of the cell following its concentration gradient
3. Electrostatic forces
4. Sodium Potassium Pump(2K+ in, 3Na+ out)
What are ways to test membrane potential? - Answer-Radioactive labeling:
measuring permeability of Na+ and K+, Na+ has 5% that of K+
Changing concentration in extracellular fluid: Increase Na+: no effect
Increase K+: decrease in voltage(hyperkalemia)
What are the graded potentials? - Answer-electrical potentials that degrade over time
Hyperpolarization: more negative
Depolarization: more positive
What is the action potential? - Answer-the electrical impulse that travels down the
axon
always the same size and doesnt degrade in strength(nondecramental)
Amount of times fired determined by strength of depolarizing signals
All or none(when threshold is reached it fires no matter what)
How is the action potential generated? - Answer-1. Nongated K+ channels open and
flow out
2. Depolarizing signals at axon hillock open Na+ channels more and more until
threshold is reached
, 3. Action potential is fired, Na+ channels close at peak of signal
4. K+ channels open and flow until hyperpolarization occurs, then resting membrane
potential reattained
What are refractory periods? What do they do? - Answer-The periods that occur after
an AP is fired before it is easy to fire again
Absolute: impossible for AP to fire, stops AP from going in reverse direction
Relative: hard for AP to fire, if depolarizing signals arent strong enough, AP wont fire
until relative period ends
What is the blood brain barrier? - Answer-Barrier between brain epithelial cells and
brain capillaries(NONFENESTRATED) that help keep substances out of brain,
maintained by astrocytes, only small molecules and lipid soluble molecules can get
through
What are the 3 layers of the meninges? - Answer-Dura mater, arachnoid mater, pia
mater
What is the ventricular system? What are its purposes? - Answer-Where the
cerebrospinal fluid is stored in the brain, it increases bouyancy of the brain allowing it
to be dense but not heavy and it acts as a shock absorber to protect the brain from
injury
What is white and grey matter? Where are they located? - Answer-White matter is
myelinated axons and grey matter is mostly cell bodies and dendrites, the brain has
grey matter on the outside and white matter on the inside and vice versa for the
spinal cord
How many brain and spinal nerves are there? - Answer-12 brain and 31 pairs of
spinal
What are the parts of the brainstem? What are their functions? - Answer-Medulla:
rhythmic breathing
Pons: cerebellum->brainstem and cerebral cortex communication
Midbrain: localization of visual and auditory stimuli
What are the 2 main functions of the cerebellum? - Answer-motor planning and
motor learning
What is the diancephalon? What does it contain? - Answer-Thalamus: sending
sensory and motor signals to cerebral cortex
hypothalamus: bodily functions, homeostasis, and endocrine system through
pituitary gland
What are the sulci and gyri? What do they do? - Answer-They help initiate movement
and higher planning
Sulci: grooves
Gyri: material between sulci
NYGARD CORRECT ANSWERS
What is a membrane potential? What is the resting membrane potential? What is the
value of the resting membrane potential? - Answer-The difference in charge between
the inside and outside of a cell, the value of the neuron membrane at rest, -70mV
A membrane is polarized when it - Answer-carries a charge
How was charge measured in the squid axon? - Answer-Electrodes were placed
inside and outside the cell to measure changes
What are the 2 types of passive ion forces? How do they work? - Answer-
Electrostatic forces: cause a movement of ions based on attraction/repulsion of the
charge of the membrane/other ions
Diffusion: passive movement of ions down concentration gradient to achieve
equilibrium
What are the main ions that exist? Where? - Answer-K+: inside cell
Na+: outside cell
Cl-: outside cell
A-: negatively charged proteins, inside cell
What are the 4 factors contributing to the resting membrane potential? - Answer-1.
Selective permeability of K+
2. K+ diffusion out of the cell following its concentration gradient
3. Electrostatic forces
4. Sodium Potassium Pump(2K+ in, 3Na+ out)
What are ways to test membrane potential? - Answer-Radioactive labeling:
measuring permeability of Na+ and K+, Na+ has 5% that of K+
Changing concentration in extracellular fluid: Increase Na+: no effect
Increase K+: decrease in voltage(hyperkalemia)
What are the graded potentials? - Answer-electrical potentials that degrade over time
Hyperpolarization: more negative
Depolarization: more positive
What is the action potential? - Answer-the electrical impulse that travels down the
axon
always the same size and doesnt degrade in strength(nondecramental)
Amount of times fired determined by strength of depolarizing signals
All or none(when threshold is reached it fires no matter what)
How is the action potential generated? - Answer-1. Nongated K+ channels open and
flow out
2. Depolarizing signals at axon hillock open Na+ channels more and more until
threshold is reached
, 3. Action potential is fired, Na+ channels close at peak of signal
4. K+ channels open and flow until hyperpolarization occurs, then resting membrane
potential reattained
What are refractory periods? What do they do? - Answer-The periods that occur after
an AP is fired before it is easy to fire again
Absolute: impossible for AP to fire, stops AP from going in reverse direction
Relative: hard for AP to fire, if depolarizing signals arent strong enough, AP wont fire
until relative period ends
What is the blood brain barrier? - Answer-Barrier between brain epithelial cells and
brain capillaries(NONFENESTRATED) that help keep substances out of brain,
maintained by astrocytes, only small molecules and lipid soluble molecules can get
through
What are the 3 layers of the meninges? - Answer-Dura mater, arachnoid mater, pia
mater
What is the ventricular system? What are its purposes? - Answer-Where the
cerebrospinal fluid is stored in the brain, it increases bouyancy of the brain allowing it
to be dense but not heavy and it acts as a shock absorber to protect the brain from
injury
What is white and grey matter? Where are they located? - Answer-White matter is
myelinated axons and grey matter is mostly cell bodies and dendrites, the brain has
grey matter on the outside and white matter on the inside and vice versa for the
spinal cord
How many brain and spinal nerves are there? - Answer-12 brain and 31 pairs of
spinal
What are the parts of the brainstem? What are their functions? - Answer-Medulla:
rhythmic breathing
Pons: cerebellum->brainstem and cerebral cortex communication
Midbrain: localization of visual and auditory stimuli
What are the 2 main functions of the cerebellum? - Answer-motor planning and
motor learning
What is the diancephalon? What does it contain? - Answer-Thalamus: sending
sensory and motor signals to cerebral cortex
hypothalamus: bodily functions, homeostasis, and endocrine system through
pituitary gland
What are the sulci and gyri? What do they do? - Answer-They help initiate movement
and higher planning
Sulci: grooves
Gyri: material between sulci
