Chap 4: Neural Conduction & Synaptic Transmission

Question 0

Microelectrodes

Answer 0

Their tips are less than 1000th of a millimeter in a diameter much too small to be see by the naked eye

Question 1

Membrane potential

Answer 1

The difference in electrical charge between the inside and the outside of a cell

Question 2

Resting membrane potential

Answer 2

When both electrode tips are in the extracellular fluid, the voltage difference between them is zero

Question 3

Resting potential

Answer 3

In its resting state with the -70 mV charge built up across its membrane a neuron is said to be polarized

Question 4

Ionic basis of the resting potential

Answer 4

Like all salts in solution the salts in neural tissue separate into positively and negatively charged particles called ions

Question 5

Concentration gradients

Answer 5

That is, they are more likely to move from areas of high concentration to areas of low concentration than vice versa

Question 6

Electrostatic pressure

Answer 6

Any accumulation of charges, positive or negative in one area tends to be dispersed by the repulsion among the like charges in the vicinity and the attraction of opposite charges concentrated elsewhere

Question 7

Neurotransmitter

Answer 7

Which diffuse across the synaptic clefts and interact with specialized receptor molecules on the receptive membranes of the next neurons in the circuit

Question 8

Depolarize

Answer 8

The receptive membrane (decrease the resting membrane potential, from -70 to -66 mV

Question 9

Hyperpolarize

Answer 9

Increase the resting membrane potential from -70 to -72 mV

Question 10

Excitatory post synaptic potentials (EPSPs)

Answer 10

Known as post synaptic depolarization, they increase the likelihood that the neuron will fire

Question 11

Inhibitory postsynaptic potentials (IPSPs)

Answer 11

Known as postsynaptic hyperpolarization, they decrease the likelihood that the neuron will fire

Question 12

Graded responses

Answer 12

The amplitudes of EPSPs & IPSPs are proportional to the intensity of the signals that elicit them

Question 13

Axon hillock

Answer 13

The conical structure at the junction between the cell body and the axon, but they are actually generated in the adjacent section of the axon

Question 14

Threshold excitation

Answer 14

If the sum of the depolarizations and hyperpolarizations reaching the section of the axon adjacent to the axon hillock at any time is sufficient to the dispel arise the membrane

Question 15

Action potential (AP)

Answer 15

Is massive but momentary lasting for 1 millisecond reversal of the membrane the potential from about -70 to +50 mV

Question 16

Integration

Answer 16

Adding or combing a number of individual signals into one overall signal

Question 17

Temporal summation

Answer 17

Shows how post synaptic potentials produced in rapid succession at the same synapse sum to form a greater signal

Question 18

Voltage activated ion channels

Answer 18

Ion channels that open or close in response to changes in the level of the membrane potential

Question 19

Refractory periods

Answer 19

Th

Question 20

Refractory periods

Answer 20

There is a brief period of about 1 to 2 milliseconds after the initiation of an action potential during which it is impossible to elicit a second one

Question 21

Relative refractory period

Answer 21

The period during which it is possible to fire the neuron again, but only by applying higher than normal levels of stimulation

Question 22

Antidromic conduction

Answer 22

When electrical stimulation of sufficient intensity is applied to the terminal end of an axon, an action potential will be generated and will travel along the axon back to the cell body

Question 23

Orthodromic conduction

Answer 23

Axonal conduction in the natural direction from cell body to terminal buttons

Question 24

Nodes of ranvier

Answer 24

The gaps between adjacent myelin segments

Question 25

Saltatory conduction

Answer 25

It's the transmission of action potentials in myelinated axons

Question 26

Dendritic spines

Answer 26

Nodules of various shapes that are located on the surfaces of many dendrites Also common are axosomatic synapses-synapses of axon terminal buttons on somas (cell bodies)

Question 27

Directed synapses

Answer 27

Supynapses at which the site of neurotransmitter release and the site of neurotransmitter reception are in close proximity

Question 28

Nondirected synapses

Answer 28

Are synapses at which the site of release is at some distance from the site of reception

Question 29

Neuropeptides

Answer 29

Are short amino acid chains comprising between 3 and 36 amino acids, in effect they are short proteins

Question 30

Synaptic vesicles

Answer 30

Small molecule neurotransmitter are typically synthesized in the cytoplasm of the terminal button

Question 31

Coexistence

Answer 31

When neurons contain two neurotransmitter

Question 32

Exocyctosis

Answer 32

The process of neurotransmitter release When a neuron is at rest, synaptic vesicles that contain small molecule neurotransmitters tend to congregate near sections of the presynaptic membrane that are particularly rich in voltage activated calcium channels

Question 33

Receptors

Answer 33

Is a protein that contains binding sites for only particular neurotransmitters and it can influence only those cells that have receptors for it

Question 34

Ligand

Answer 34

Any molecule that binds to another

Question 35

Receptor subtypes

Answer 35

The different types of receptors to which a particular neurotransmitter can bind

Question 36

Ionotropic receptors

Answer 36

Are those receptors that are associated with ligand activated ion channels

Question 37

Metabotropic receptors

Answer 37

Are those receptors that are associated with signal proteins and G proteins

Question 38

Second messenger

Answer 38

The subunit may move along the inside surface of the membrane and bind to a nearby ion channel thereby inducing an EPSP or IPSP or it may trigger the synthesis of a chemical

Question 39

Autoreceptors

Answer 39

Are metabotropic receptors that have two unconventional characteristics

Question 40

Enzymatic degradation

Answer 40

Reuptake is the more common of the two deactivating mechanisms The majority of neurotransmitter once released are drawn back into the presynaptic

Question 41

Acetylcholinesterase

Answer 41

One of the few neurotransmitters for which enzymatic degradation is the main mechanism of synaptic deactivation

Question 42

Gap junction

Answer 42

Are narrow spaces between adjacent neurons that are bridged by fine tubular channels called connexins that contain cytoplasm

Question 43

Amino acid neurotransmitters

Answer 43

Glutamate, aspartate, glycine, and gamma aminobutyric acid GABA

Question 44

The three classes of conventional neurotransmitter

Answer 44

The amino acids, the monoamines, and the acetylcholine

Question 45

Acetylcholine

Answer 45

Is a small molecule neurotransmitter that is in one major respect like a professor who is late for a lecture

Question 46

Soluble gas neurotransmitter

Answer 46

Includes nitric oxide and carbon monoxide, these neurotransmitters are produced in the neural cytoplasm and immediately diffuse through the cell membrane into the extracellular fluid and then into nearby cells

Question 47

Endocannabinoids

Answer 47

Are neurotransmitters that are similar to delta 9 tetrahydrocannabinol

Question 48

Pituitary peptides

Answer 48

Contains neuropeptides that were first identified as hormones released by the pituitary

Question 49

Hypothalamic peptides

Answer 49

Contains neuropeptides that were first identified as hormones released by the hypothalamus

Question 50

Brain gut peptides

Answer 50

Contains neuropeptides that were first discovered in the gut

Question 51

Opioid peptides

Answer 51

Contains neuropeptides that are similar in structure to the active ingredients of opium

Question 52

Miscellaneous peptides

Answer 52

Is a catch all category that contains all of the neuropeptide transmitters that do not fit into one of the other four categories

Question 53

Agonists

Answer 53

Drugs that facilitate e effects of a particular neurotransmitter

Question 54

Antagonists

Answer 54

Drugs that inhibit the effects of a particular neurotransmitter

Question 55

Receptor blockers

Answer 55

Bind to postsynaptic receptors without activating them and in so doing block the access of the usual neurotransmitter

Question 56

Atropine

Answer 56

Which is the main active ingredient of belladonna is a receptor blocker that exerts its antagonist effect by binding to muscarinic receptors

Question 57

Botox

Answer 57

A neurotoxin released by a bacterium often found in spoiled food, is another nicotine antagonist

Question 58

Endogenous

Answer 58

Occurring naturally within the body opioids have been discovered Enkephalins means in the head Endorphins which is a contraction of endogenous morphine