GOOD biopsych exam 2

Action Potential

A rapid rise and fall in voltage or membrane potential across a cellular membrane.

Excitatory Postsynaptic Potential (EPSP)

A postsynaptic potential that makes the neuron more likely to fire an action potential.

Inhibitory Postsynaptic Potential (IPSP)

A postsynaptic potential that makes the neuron less likely to fire an action potential.

Temporal Summation

The process by which multiple signals are summed over time to produce a stronger effect.

Spatial Summation

The process by which multiple inputs are summed across different locations simultaneously.

Charles Scott Sherrington

A neurophysiologist known for his work on reflexes and the concept of summation in neurons.

Nociception

The sensory process that provides signals that trigger pain.

TRP Receptors

Transient Receptor Potential (TRP) channels, a group of ion channels located in the cell membrane, which are activated by various stimuli.

Neural Integration

The process by which multiple inputs are combined at the neuron to determine the final output.

Axon Hillock

The part of a neuron where action potentials are initiated.

Neurotransmitter

Chemical messengers that transmit signals across synapses from one neuron to another.

Summation

The process of adding together multiple inputs to determine whether a neuron will fire.

Resting Potential

The polarized state of a neuron when it is not actively firing an action potential.

Neuronal Threshold

The level at which a depolarization causes a neuron to fire an action potential.

Synapse

The junction between two neurons, where neurotransmitters are released.

GABA

Gamma-aminobutyric acid, a primary inhibitory neurotransmitter in the brain.

Excitation

The process of increasing the likelihood that a neuron will fire an action potential.

Inhibition

The process of decreasing the likelihood that a neuron will fire an action potential.

Spinal Cord

The part of the central nervous system that conducts signals between the brain and the rest of the body.

Pain Pathways

Neural pathways involved in the transmission of nociceptive signals to the brain.

Cerebral Cortex

The part of the brain responsible for processing sensory information and higher brain functions.

Dendrites

Tree-like extensions of a neuron that receive signals from other neurons.

Somatic Nervous System

The part of the nervous system responsible for voluntary movements and reflexes.

Peripheral Nervous System

The part of the nervous system that connects the central nervous system to the limbs and organs.

Blood Brain Barrier (BBB)

A selective barrier that prevents certain substances in the bloodstream from entering the brain, while allowing others to pass.

Circumventricular organ

Areas of the brain where the blood-brain barrier is weak, allowing for the detection of hormones and other substances in the bloodstream.

Heroin vs. Morphine Potency

Heroin is more potent than morphine due to its higher ability to cross the blood-brain barrier.

Korsakoff’s syndrome

A chronic neurocognitive disorder primarily caused by thiamine deficiency, often associated with alcohol misuse.

Cell membrane

A biological membrane that separates and protects the interior of all cells from the external environment.

Ion Channels

Proteins that allow ions to pass through the cell membrane, can be classified as passive, voltage-gated, or ligand-gated.

Sodium-Potassium Pump

A protein that actively transports sodium out of the neuron and potassium into the neuron, maintaining resting potential.

Hyperpolarizing stimulation

A type of stimulation that makes the inside of the neuron more negative compared to the outside.

Depolarizing stimulation

A type of stimulation that makes the inside of the neuron less negative or more positive.

Action Potential

A rapid, temporary change in a neuron's membrane potential that propagates along the axon.

Absolute refractory period

A time during which a neuron cannot fire another action potential, regardless of stimulation.

Relative refractory period

A time following an action potential during which a neuron can fire again only if the stimulus is strong enough.

Myelin sheath

A fatty layer that insulates the axon of neurons, speeding up the transmission of action potentials.

Nodes of Ranvier

Gaps in the myelin sheath that facilitate the rapid conduction of action potentials along myelinated axons.

Multiple Sclerosis

A disease where the immune system attacks the myelin sheath of neurons, leading to communication problems between the brain and the rest of the body.

Inhibitory Postsynaptic Potential (IPSP)

A hyperpolarizing change in the postsynaptic neuron, making it less likely to fire an action potential.

Excitatory Postsynaptic Potential (EPSP)

A depolarizing change in the postsynaptic neuron, making it more likely to fire an action potential.

Synapse

A junction between two neurons, where neurotransmitters are released to transmit signals.

Charles Scott Sherrington

A neurologist who provided early evidence for the existence of synapses based on reflex arc data.

Reflex Arc

The neural pathway that controls a reflex action; involves sensory, intrinsic, and motor neurons.

Neurotransmission

The process of communication between neurons across a synapse.

Excitatory Postsynaptic Potential (EPSP)

A graded depolarization that makes a neuron more likely to fire an action potential.

Inhibitory Postsynaptic Potential (IPSP)

A graded hyperpolarization that reduces the likelihood of a neuron firing an action potential.

Temporal Summation

The phenomenon where repeated stimuli applied over a short time at the same location can produce a response.

Spatial Summation

The cumulative effect of multiple synaptic inputs from different locations on a neuron that may produce an action potential.

Local Potentials

Graded and decremental electrical signals that occur when a neuron is stimulated.

Action Potentials

All-or-none electrical signals that travel down an axon; they are nondecremental.

Resting Potential

The difference in charge across the neuron membrane when the neuron is not sending a message, typically between -55 to -70 mV.

Action Potential

The electrical signal of the neuron when it is stimulated, initiated at the axon hillock and traveling down the axon.

Axon Hillock

The region of the neuron where action potentials are initiated.

Phospholipid Bilayer

A double layer of phospholipid molecules that makes up the cell membrane, acting as a barrier to most water-soluble substances.

Selectively Permeable

The property of the cell membrane that allows certain molecules to pass through while blocking others.

Ion Channels

Proteins in the cell membrane that allow specific ions to enter or exit the neuron.

Sodium-Potassium Pump

A membrane-bound protein complex that pumps sodium ions out of and potassium ions into the neuron.

Concentration Gradient

The difference in concentration of ions across the membrane that drives the movement of ions.

Electrical Gradient

The difference in charge across the membrane, affecting the movement of ions.

Diffusion

The movement of ions from an area of higher concentration to an area of lower concentration.

K+ Channels at Rest

Potassium channels that are open, allowing K+ ions to leak out of the neuron.

Na+ Channels at Rest

Sodium channels that are closed, preventing Na+ ions from entering the neuron.

-70 mV

Common measurement for resting potential in neurons, indicating a more negative charge inside the neuron compared to outside.

Uneven Ion Distribution

The state where there is a different concentration of ions inside and outside the neuron, crucial for creating resting potential.

Hydrophobic Molecules

Molecules that do not mix with water; can pass through the phospholipid bilayer easily (e.g., O2, CO2).

Blood Brain Barrier

A barrier discovered by Paul Ehrlich around 1900 that separates the circulatory system from the brain.

Selectively Permeable

A property of the Blood Brain Barrier allowing only certain substances to cross, such as O2, CO2, and small uncharged fat-soluble molecules.

Energy Dependent Active Transport

Mechanisms that allow glucose and some large amino acids to cross the Blood Brain Barrier.

Circumventricular organs

Structures in the brain that allow communication between the brain and the bloodstream.

Neurotrophic factors

Proteins that support the growth, survival, and differentiation of neurons, relevant in conditions like Alzheimer's disease.

Korsakoff’s syndrome

A neurological disorder associated with thiamine deficiency affecting glucose utilization in the brain.

Glucose and Metabolism

Neurons primarily use glucose in metabolic pathways with O2; glucose is derived from diet and conversion of other fuels.

PET Scan

A method to measure glucose as indices of brain activity.

Know what the blood brain barrier (BBB) is.

The BBB is the barrier between the circulatory system and the brain. Discovered by Paul Ehrlich, around 1900. Brain needs BBB because it has a weak immune system. BBB minimizes the loss of neurons (more neurons cannot be made)

Know what can pass through the blood brain barrier without the use of energy and know what substances need to be to be actively (using energy) moved across the blood brain barrier using transport molecules.

without the use of energy: O2, CO2, & small uncharged fat soluble molecules

actively moved (with energy): glucose and some large amino acids cross via energy dependent active transport

Know what the circumventricular organ is and know why we need to have weaknesses in some parts of the blood brain barrier.

Circumventricular organs are areas where the BBB is weakened.

We need leaky regions in some parts of the brain so that the brain can monitor our blood contents to regulate physiology and tell us if we need to vomit. The pineal and pituitary glands secrete hormones that get into the bloodstream thanks to the leaks in the BBB.

Know why heroin is more potent than morphine (this has to do with blood brain barrier permeability).

Heroin is 3x more potent than morphine because it is fat soluble, so it goes straight through the blood brain barrier.

Know what the primary fuel (energy source) for neurons is.

Glucose in a metabolic pathway with O2

Know the cause and symptoms of Korsakoff's syndrome.

Cause: due to lack of thiamine (this kills neurons in the brain)

Symptoms: can't remember things and can't create new memories

Know what the cell membrane is and what it is composed of.

The site where most processes involved in neuronal preservation and functioning are triggered. Maintains electrical gradient necessary for signaling. Covers entire neuron. Selectively permeable.

composed of 2 layers of fat and phosphate molecules (phospholipid bilayer)

Know what can and cannot pass through the cell membrane without the use of protein ion channels and pumps.

O2 & CO2 go right through

small uncharged fat soluble molecules - water, glycerol, urea, ethanol - go right through (not as quickly as gasses though)

Charged molecules cannot go through - Na, K, Chloride (Cl), Calcium (Ca), Hydrogen (H)

Ion channels and pumps are ________.

proteins

Know the difference between ion channels and pumps, and know the difference between passive, voltage-gated, and ligand (transmitter)-gated ion channels.

Pumps use energy to move ions, while channels do not.

Passive ion channels are always open.

Voltage-gated ion channels open when the membrane potential changes to a specific voltage, closed at some voltages and opened at other voltages.

Ligand-gated ion channels open when a neurotransmitter binds to the protein

Know the different ion channels and pumps (and their characteristics) that play a role in the resting potential and action potential of neurons.

Sodium-Potassium Pump: moves Sodium out and Potassium in. ALWAYS RUNNING!

State of ion channels at resting potential:

K+ passive channels are always open.,

Na+ channels are not

Results in a slow steady leak of K+ out of the neuron down its concentration gradient

Know where NA+, K+, and A- ions are more concentrated (inside or outside of the neuron) when the neuron is at rest.

Na+ is more concentrated outside of the neuron.

K+ and A- are more concentrated inside of the neuron.

Know what the resting potential is and be able to explain why it is important that neurons have a resting potential.

The resting potential is the -55 to -70 mv difference in charge when the neuron is not sending a message.

It is important because it is needed in order for an action potential to be produced. A stored up difference in charge across the membrane makes an action potential possible.

Be able to explain how concentration forces effect the distribution and movement of ions across the neuronal cell membrane.

Ions move from an area of high concentration to an area of low concentration.

Diffusion (concentration) forces work to equalize the concentration of ions across the membrane

Be able to explain how electrical forces effect the distribution and movement of ions across the neuronal cell membrane.

Electrical gradient is the gradient that develops because of the difference in charge across the membrane. Opposite charges ATTRACT and Like charges REPEL.

Be able to explain which ions are moved across the membrane (and in which direction) with each cycle of the sodium-potassium pump.

With each cycle, 3 sodium ions exit the cell and 2 potassium enter.

Be able to describe the experiments using squid giant axons that were conducted to figure out how an action potential could be produced using electrical stimulation of a neuron/axon.

Hodgkin & Huxley experimentally studied action potentials. They used squid because their axons are bigger than typical axons, making electrical stimulation of the axon much easier. They placed electrodes in the middle of the axon in order to artificially start an action potential. Two potentials occur. One will roll to the soma where it will die, and the other will travel toward the nerve terminal.

Hyperpolarizing stimulation:

making the inside of the axon more negative than it was at rest

Depolarizing stimulation:

making the inside of the axon more positive than it was at rest

Graded/local potentials:

- can sum together local potentials

- caused by opening of transmitter(ligand)-gated channels only

vs. Action potentials:

- cannot be summed together

- caused by opening of voltage-gated channels

- cannot be graded (proportional)

- all or none

Know what the threshold potential is, and what happens when you depolarize a neuron and reach this potential.

Threshold Potential: the level to which a membrane potential must be depolarized to in order to start an action potential

when you depolarize a neuron and reach this potential, an action potential occurs.

Be able to define Action Potential.

brief depolarization of the axon that provides the basis for conduction of information along the axon

Be able to explain the chain of events that occurs when an action potential is electrically stimulated that cause the upswing (depolarization phase) and the downswing (repolarization phase) of the action potential.

The upsweep is due to sodium entry. Once the threshold potential is hit, voltage-gated sodium channels open quickly. Voltage-gated potassium channels begin to open, slowly. When voltage-gated sodium channels open, sodium will go in because it is attracted to the negativity. Sodium changes shape before going into the refractory period. At the peak of the action potential, there is a lot of permeability, sodium (and potassium) leaves and the action potential returns to the resting potential.

Know what tetrodotoxin (TTX), and local anesthetics like Novocaine do to stop action potentials from occurring.

Block voltage-gated channels

Know what the absolute refractory period is, and why it occurs.

The absolute refractory period is a period of time where it is impossible for the cell to send more action potentials. This is due to the gating mechanism of the voltage-gated sodium channels. After a period of being open, the channels close and are inactivated.