Brain Basics I - The Membrane

What is the circular structure in the center of the cell body?

Nucleus

What is the name of th structure around the nucleus (circular structure)?

Soma

What are the extensions on the soma (cell body)?

Dendrites

What is the long extension off of the cell body?

Axon

What are the individual sections on the axon (long extension off of the cell body)

Myelin Sheaths

What are the area off of the end of the axon (long extension off of the cell body)?

Axon Terminal

What do dendrites do?

Collect neurotransmitters

What does the axon hillock do?

Initiate action potentials

What do the nodes of ranvier do?

Push action potentials down the axon

What is the flow of information in the neuron?

Electrical to Chemical

On the phospholipid bilayer membrane of the neuron, heads of the phospholipids are ________ and the tails are __________

hydrophobic, hydrophilic

The membrane is _______________, because of the specialized proteins called “ion channels”

selectively permeable to ions

What do dendritic spines do?

Increase the surface area of dendrites

The axon hillock determines if there will be an action potential if enough voltage passes through voltage-gated ion channels

Integration Zone

The axon sends the electrical message with the help of the myelin sheath and nodes of ranvier to make it go faster

Conduction Zone

Taking the electrical signal and releasing the chemical neurotransmitters through the axon terminal

Output Zone

Protects the brain and allow blood to get to it without other substances in the body

Blood Brain Barrier

The BBB is composed of 2 forms of protection _________ and _________ barriers

tight junctions, metabolic (enzymatic)

__________ molecules such as water, Na+, K+, and Cl- can pass through tight junctions in the BBB.

hydrophilic

___________ pass through such as caffeine, ethanol, and nicotine in the Endothelium lipophilic pathway.

Lipid-soluble

Molecules such as creatine, glucose, and vitamins going through the endothelium transport proteins (“Carrier-Mediated”) needs ____________ to pass through.

transport proteins

In the endothelium receptor mediated “transcytosis” a drug need a ___________ to pass through.

receptor

Macromolecules with positive charges can bind to the negative charges on the membrane to pass through.

Adsorptive Transcytosis

Hypertension, radiation, infection, trauma, ischemia, inflammation, and pressure ______ the blood brain barrier.

open

The BBB ______ fully developed at birth.

is not

The weak spot in the BBB, Postrema “Chemical Trigger Zone” triggers _______

vomiting

At rest a neuron has a membrane potential of _____

70 mV

______ the cell is more negative than _______ the cell

Inside, outside

Electrically charged molecules

Ions

Cations are ________ charged and found outside of the cell.

positively

Anions are _________ charged ions and found inside of the cell.

negatively

_______ carry negative charges

Proteins

_____ can move through the neutral membrane through channels

Ions

Use ligand that binds to a neurotransmitter (or drug!) to open and close

Ligand-gated Channels

Ligand finds its home in its binding site on the protein, causes a conformational change resulting in a pore opening to allow passage of a specific ion

Direct Gated Ionotropic Receptors and Channels

Are Direct Gated Ionotropic Channels or Indirect Gated Channels faster?

Direct Gated Ionotropic Channels

When a ligand binds to its receptor, it triggers a G-protein (secondary messenger) to open the channel

Indirect Gated (Metabotropic) Channels

Open and close depending on the voltage of the cell

Voltage-Gated Channels

Voltage-Gated Channels determine if enough voltage passes through the membrane to cause an ______ __________

Action Potential

Use energy to move ions across their concentration gradient (opposite charge)

Pumps

Open all the time, K+

Leak Channels

Which types of channel helps to maintain resting membrane potential?

Leak Channels and Pumps

Pufferfish containing Tetrodotoxin (TTX) and red algae containing Saxitoxin (SXT) which then consumed by shellfish block ____________ as well as cone snails containing conus toxin block _____________ which both cause paralysis and death.

Voltage-Gated Sodium Channels, Voltage-Gated Calcium Channels

Which channel is responsible for reaching threshold in the membrane for an action potential?

Ligand (neurotransmitter) -Gated Channels

Neurotransmitters can bind to their ligand-gated receptor to cause local membrane potential changes called ________ and ________

EPSPs, IPSPs

Action potential causes the release of ________ from the presynaptic membrane.

neurotransmitters

________ __________ bind to their receptor and cause an influx of ______ into the postsynaptic membrane resulting in an EPSP (depolarization)

Excitatory neurotransmitters, cations

More _____ = more likely to fire and action potential

EPSPs

_________ ____________ cause an influx of _____ into the postsynaptic membrane resulting in an IPSP (hyperpolarization)

Inhibitory neurotransmitters, anions

More _____ = less likely to fire an action potential

IPSPs

Voltage-Gated Sodium Channels open to allow sodium influx

Depolarization

Voltage-Gated Sodium Channels inactivating and Voltage-Gated Potassium Channels opening for K+ to efflux

Repolarization

Voltage-Gated Potassium Channels stay open longer driving the cell to be more negative than at rest

Hyperpolarization

_____ pumps and ___ leak channels restore membrane potential

Na/K, K