NEUR200 Exam 1 Review

What does the central nervous system include?

brain and spinal cord

What does the peripheral nervous system include?

neurons outside of the brain and spinal cord

What is the brain responsible for?

cognition, perception, emotion, motivation, motor control, regulation of bodily functions, etc

What does the spinal cord do?

carries sensory and motor information between brain and body

What are the two divisions of the peripheral nervous system?

Somatic and Automatic Nervous System

What is the somatic nervous system responsible for?

sensation and control of skeletal muscles

What are the two divisions of the automatic nervous system?

sympathetic and parasympathetic

What is the sympathetic division of the automatic nervous system responsible for?

arousal, fight or flight, energy expenditure, increased heart rate

What is the parasympathetic division of the peripheral nervous system responsible for?

relaxation, digestion, slowed heart rate

What is the role of cerebrospinal fluid (CSF)?

It provides protection against brain compression, chemical protection, and nutrients to the brain.

What is the meninges?

These are three connective tissue membranes covering and protecting the CNS structures.

What are the three meninges layers?

dura mater, arachnoid mater, pia mater

What arteries supply blood to the brain?

carotid and vertebral arteries

What is the blood brain barrier?

protective mechanism that helps maintain a stable environment for the brain

What is gray matter?

cell bodies

What is white matter?

myelinated axons

What are ventricles of the brain?

fluid filled cavities where metabolic byproducts accumulate and drain into venous circulation

What are tracts?

axon bundles in the CNS

What is the corpus callosum?

a broad band of nerve fibers joining the two hemispheres of the brain.

What are nerves?

bundles of axons in the PNS

What are the ridges in the brain called?

gyri (gyrus)

What are the valleys in the brain called?

sulci (sulcus)

What is the brain stem connected to?

spinal cord

What does the spinal cord control?

automatic and vital functions like respiration and heartache

Where is the cerebellum?

posterior to the brain stem

What does the cerebellum control?

regulation of fine movement, coordination, timing of movements, and postural control

What does medial refer to?

Toward the midline of the body

What does lateral refer to?

away from the midline

What does dorsal refer to?

towards the back or top of head

What does ventral refer to?

toward the belly or down spinal cord

What does anterior refer to?

front of body or up spinal cord

What does posterior refer to?

down spinal cord or back of head

What are glial cells?

support cells of the nervous system

What are the two types of glial cells?

macroglia and microglia

What are astrocytes?

nutritive function, involved in metabolism and neurotransmission

What do oligodendrocytes do?

myelinate CNS axons

What do schwann cells do?

myelinate PNS axons

What do microglia do?

mobilized after injury, infection or disease, help 'clean up'

What does it mean that neurons are polarized?

there is a voltage difference between their environment (extracellular fluid and intracellular fluid)

What is the soma?

cell body of a neuron

What are dendrites?

receives signals from other neurons, conducts impulses TOWARD the body of a neuron

What is the axon?

conducts impulses from the cell body to other cells; moves impulses AWAY from the cell body

What are characteristics of multipolar neurons?

many dendrites and one axon

What are characteristics of unipolar/monopolar neurons?

axon branches off in two directions and acts as both dendrite and axon

What are characteristics of bipolar neurons?

one dendrite and one axon

What does efferent mean?

carries information out

What does afferent mean?

brings information in

At rest, the inside of a nerve cell membrane is about how many mV relative to the outside?

-70 mV

What is the membrane potential?

the voltage difference across a membrane

Why is the resting membrane potential negative?

More Na+ ions pumped out of nerve membrane than K+ in, using ATP.

What are ligand-gated channels?

open and close in response to a specific chemical stimulus

What are voltage-gated channels?

open and close in response to changes in membrane potential

What are mechanoreceptive channels?

open and close in response to mechanical stimulation

What is the direction in which ions flow in and out of the cell determined by?

concentration gradient and how negatively/ positively charged the cell is

Is the more sodium in or outside of the cell at the resting membrane potential?

outside

Is the more potassium in or outside of the cell at the resting membrane potential?

inside

Is there more cloride in or outside of the cell at the resting membrane potential?

outside

Is the more calcium in or outside of the cell at the resting membrane potential?

outside

What does the Nernst Equation used for?

calculating equilibrium potentials of ions

In the Nernst Equation, which concentration is on the top vs bottom?

extracellular on top, intracellular on bottom

What is Na+ equilibrium potential?

+60 mV

What is K+ equilibrium potential?

-90 mV

What is Cl- equilibrium potential?

-65 mV

What does it mean when an ion is at its equilibrium potential?

the electrical force across the membrane exactly balances the chemical (concentration) force, resulting in no net movement of that ion

What is permeability?

how readily ions can cross channels

What is conductance?

measure of the rate of ion movement across the cell membrane (flux)

What is flux?

ionic movement across the cell membrane

What is the Goldman equation used for?

estimating membrane potentials, given the permeability of each ion

At rest, is Na+ permeability high or low?

very low

At rest, is K+ permeability high or low?

high

At rest, is Cl- permeability high or low?

low to moderate

At rest, do Na+ electrical and concentration gradient agree?

yes

At rest, do K+ electrical and concentration gradient agree?

no; electrical wants K+ to come in while concentration wants K+ out

Will concentration gradient or electrical gradient 'win'?

concentration

What is Excitatory Post Synaptic Potential (EPSP) caused by?

influx of cations or efflux of anions; depolarization

What is depolarization?

membrane potential is more positive

What is Inhibitory Post Synaptic Potential (IPSP) caused by?

influx of anions or efflux of cations; polarization

What is polarization?

membrane potential is more negative

What is an example of EPSP?

Glutamate Mediated Excitation

How does Glutamate Mediated Excitation work?

- glutamate binds to glutamate receptor (AMPA)

- AMPA receptors have sodium channels

- AMPA sodium channel does not open until glutamate binds (ligand gated)

- when glutamate binds, sodium permeability opens and sodium enters cell

- this depolarizes the membrane

What is an example of IPSP?

GABA Mediated Inhibition

How does GABA Mediated Inhibition work?

- GABA binds to GABA receptor (GABA-A)

- GABA-A receptors have chloride channels

- GABA-A chloride channel does not open until GABA binds (ligand gated)

- when GABA binds, chloride permeability opens and chloride enters cell

- this polarizes the membrane

EPSPs decay over ______ and _______?

space and time

What does it mean that EPSPs are graded?

strength varies and it is proportional to the size of stimulus

Are action potentials graded?

No, they are all or nothing

Why are action potentials all or nothing?

due to the interaction between the voltage-gated sodium channels and the membrane potential

What is the threshold for neurons?

-50 mV

What is the threshold for an action potential?

minimum membrane potential (around -50 mV) that must be reached to trigger an action potential

Where are action potentials initiated?

axon hillock

What is special about the axon hillock?

it has a high density of voltage gated sodium channels, making it the most sensitive place for generating an action potential

What is the window of time called when neurons cannot fire an action potential?

refractory period

What is the absolute refractory period?

voltage-gated sodium channels become inactivated shortly after opening; Na+ channels are physically blocked even if they are open sodium cannot get through

What is the relative refractory period?

When an action potential can occur if a stimulus is strong enough

What is myelin?

fatty insulating layer

What are two functions of myelin?

Insulates axons and increases speed of nerve transmission

What are the Nodes of Ranvier?

gaps in myelin sheath along the axon

How do the Nodes of Ranvier act in myelinated regions?

speed up the transmission of the impulse by forcing it to 'jump' across the gaps along the axon

How is the transmitter released to send a signal?

- when the action potential reaches the terminal, voltage gated calcium channels open and calcium enter the terminal

- once calcium enters terminal, neuron releases the transmitter

- signal is sent!

What is neural representation?

the way in which properties of the outside world manifest themselves in the neural signal (e.g. different spiking rates for different stimuli)

What are the three ways neurons code information?

rate coding, population coding, and temporal coding