Chapter 3 (Neurophysiology)

Question 1

neurophysiology

Answer 1

The study of the life processes of neurons

Question 2

polarized

Answer 2

Exhibiting difference in electrical charge between the inside and outside of the cell.

Question 3

ion

Answer 3

An atom or molecule that has acquired electrical charge by gaining or losing one or more electrons

Question 4

anion

Answer 4

a negatively charged ion, such as a protein or chloride ion

Question 5

cation

Answer 5

a positively charged ion, such as a potassium or sodium ion

Question 6

intracellular fluid

Answer 6

Also called cytoplasm. The watery solution found within cells.

Question 7

extracellular fluid

Answer 7

The fluid in the spaces between cells (interstitial fluid) and the vascular system

Question 8

cell membrane

Answer 8

The lipid bilayer that ensheathes a cell

Question 9

microelectrode

Answer 9

An especially small electrode used to record electrical potentials in living cells.

Question 10

resting potential

Answer 10

A difference in electrical potential across the membrane of a nerve cell during an inactive period.

Question 11

millivolt (mV)

Answer 11

A thousandth of a volt.

Question 12

ion channel

Answer 12

A pore in the cell membrane that permits the passage of certain ions through the membrane when the channels are open

Question 13

potassium ion (K+)

Answer 13

a potassium atom that carries a positive charge because it has lost one electron.

Question 14

selective permeability

Answer 14

The property of a membrane that allows some substances to pass through, but not others.

Question 15

diffusion

Answer 15

The spontaneous spread of molecules untili a uniform concentration is achieved.

Question 16

electrostatic pressure

Answer 16

The propensity of charged molecules or ions to move, via diffusion, toward areas with the opposite charge

Question 17

sodium-potassium pump

Answer 17

The energetically expensive mechanism that pushes sodium ions out of a cell, and potassium ions in.

Question 18

sodium ion (Na+)

Answer 18

A sodium atom that carries a positive charge because it has lost one electron

Question 19

equilibrium potential

Answer 19

The point at which the movement of ions across the cell membrane is balanced, as the electrostatic pressure pulling ions in one direction is offset by the diffusion force pushing them in the opposite direction.

Question 20

axon hillock

Answer 20

The cone-shaped area on the cell body from which the axon originates

Question 21

hyperpolarization

Answer 21

An increase in membrane potential (the interior of the neuron becomes even more negative).

Question 22

depolarization

Answer 22

A decrease in membrane potential (the interior of the neuron becomes less negative).

Question 23

local potential

Answer 23

An electrical potential that is initiated by stimulation at a specific site, which is a graded response that spreads passively across the cell membrane, decreasing in strength with time and distance

Question 24

threshold

Answer 24

The stimulus intensity that is just adequate to trigger an action potential at the axon hillock

Question 25

action potential

Answer 25

Also called spike. A rapid reversal of the membrane potential that momentarily makes the inside of the membrane positive with respect to the outside

Question 26

all-or-none property

Answer 26

The fact that the size (amplitude) of the action potential is independent of the size of the stimulus.

Question 27

afterpotential

Answer 27

The positive or negative change in membrane potential that may follow an action potential

Question 28

voltage-gated Na+ channel

Answer 28

A Na+ selective channel that opens or closes in response to changes in the voltage of the local membrane potential; it mediates teh action potential

Question 29

refractory

Answer 29

temporarily unresponsive or inactivated

Question 30

absolute refractory phase

Answer 30

A brief period of complete insensitivity to stimuli

Question 31

relative refractory phase

Answer 31

A period of reduced stimulation during which only strong stimulation produces an action potential

Question 32

conduction velocity

Answer 32

The speed at which an action potential is propagated along the length of an axon (or section of peripheral nerve).

Question 33

myelin

Answer 33

The fatty insulation around an axon, formed by glial cells. This sheath boosts the speed at which nerve impulses are conducted.

Question 34

node of Ranvier

Answer 34

A gap between successive segments of the myelin sheath where the axon membrane is exposed.

Question 35

saltatory conduction

Answer 35

The form of conduction that is characteristic of myelinated axons, in which the action potential jumps from one node of Ranvier to the next.

Question 36

postsynaptic potential

Answer 36

A local potential that is initiated by a stimulation at a synapse, which can vary in amplitude, and spreads passively across the cell membrane, decreasing in strength with time and distance.

Question 37

EPSP

Answer 37

A depolarizing potential in the postsynaptic neuron that is caused by excitatory presynaptic potentials. EPSPs increase the probability that the postsynaptic neuron will fire an action potential.

Question 38

synaptic delay

Answer 38

The brief delay between the arrival of an action potential at the axon terminal adn the creation of a post-synaptic potential.

Question 39

IPSP

Answer 39

A hyperpolarizing potential in the postsynaptic neuron that is caused by inhibitory connections. IPSPs decrease the probability that the postsynaptic neuron will fire an action potential.

Question 40

chloride ion (Cl-)

Answer 40

A chlorine atom that carries a negative charge because it has gained one electron.

Question 41

spatial summation

Answer 41

The summation of postsynaptic potentials that reach the axon hillock from different locations across the cell body. If this summation reaches threshold, an action potential is triggered.

Question 42

temporal summation

Answer 42

The summation of postsynaptic potentials that reach the axon hillock at different times. The closer in time the potentials occur, the more complete the summation is.

Question 43

synaptic vesicle

Answer 43

A small, spherical structure that contains molecules of neurotransmitter

Question 44

calcium ion (Ca2+)

Answer 44

a calcium atom that carries a double positive charge because it has lost two electrons

Question 45

ligand

Answer 45

a substance that binds to receptor molecules, such as a neurotransmitter or drug that binds postsynaptic receptors

Question 46

acetylcholine (ACh)

Answer 46

A neurotransmitter that is produced and released by parasympathetic postganglionic neurons, by motoneurons, and by neurons throughout the brain.

Question 47

curare

Answer 47

a neurotoxin that causes paralysis by blocking ACh receptors in muscle.

Question 48

bungarotoxin

Answer 48

A neurotoxin, isolated form the venom of the banded krait, that selectively blocks ACh receptors.

Question 49

agonist

Answer 49

A molecule, usually a drug, that binds a receptor molecule and initiates a response like that of another molecule, usually a neurotransmitter

Question 50

antagonist

Answer 50

A molecule, usually a drug, that interferes with or prevents the action of a neurotransmitter

Question 51

cholinergic

Answer 51

Referring to cells that use ACh as their synaptic transmitter.

Question 52

degradation

Answer 52

The chemical breakdown of a neurotransmitter into inactive metabolics

Question 53

acetylcholinesterase (AChE)

Answer 53

An enzyme that inactivates the transmitter ACh

Question 54

reuptake

Answer 54

The process by which release transmitter molecules are taken up and reused by the presynaptic neuron, thus stopping synaptic activity.

Question 55

transporter

Answer 55

A specialized receptor in the presynaptic membrane that recognizes transmitter molecules and returns them to the presynaptic neuron for reuse.

Question 56

knee jerk reflex

Answer 56

A variant of the stretch reflex in which stretching the tendon beneath the knee leads to an upward kick of the leg

Question 57

electroencephalogram (EEG)

Answer 57

A recording of gross electrical activity of the brain via large electrodes placed on the scalp.

Question 58

event-related potential (ERP)

Answer 58

Also called evoked potential. Averaged EEG recordings measuring brain responses to repeated presentations of a stimulus. Components of the ERP tend to be reliable because the background noise of the cortex has been averaged out.

Question 59

epilepsy

Answer 59

A brain disorder marked by major, suden changes in the electrophysical state of the brain that are referred to as seizures.

Question 60

seizure

Answer 60

an epileptic episode

Question 61

grand mal seizure

Answer 61

A type of generalized epileptic seizure in which nerve cells fire in high-frequency bursts, usually accompanied by involuntary rhythmic contractions of the body

Question 62

petit mal seizure

Answer 62

Also called absence attack. A seizure that is characterized by a spike-and-wave EEG and often involves a loss of awareness and inability to recall events surrounding the seizure.

Question 63

complex partial seizure

Answer 63

In epilepsy, a type of seizure that doesn't involve the entire brain, and therefore can cause a wide variety of symptoms

Question 64

aura

Answer 64

In epilepsy, the unusual sensations or premonition that may precede the beginning of a seizure.