Ch 4: Neural Conduction And Synaptic Transmission

Question 1

Membrane potential

Answer 1

Difference in electron charge between inside and outside cell

Question 2

Resting membrane potential

Answer 2

Inside neuron is negative with respect to outside

Resting membrane about -70 mV

Membrane polarized (carries a charge)

Question 3

Ionic basis of resting potential (even distribution)

Answer 3

Factors contributing to even distribution. Of ions

• random motion: particles move down their concent. Gradient
• electrostatic pressure: like repels like, opposites attract

Question 4

Ionic basis of resting potential (uneven distribution)

Answer 4

Factors contributing to uneven distribution

• selective permeability to certain ions
• sodium-potassium pump

Question 5

Ionis contributing to resting potential

Answer 5

Na+
Cl-
K+
Negative charged proteins within neuron

Question 6

Neural membrane

Answer 6

Passive and active factors that influence the dist. Of Na, K, Cl ions across neural membrane

Neuron is prepared to respond to strongly and rapidly to stimulus

Question 7

Postsynaptic potential (psp)

Answer 7

Neurotransmitters bind at postsynaptic receptor

Depolarization: making membrane less negative

Hyperpolarization: making membrane potential more negative

Question 8

Generation of action potential

Answer 8

One Epsp not enough to cause neuron to fire

Threshold of activation near axon hillock to generate firing

Integration of Psp and Epsp result in a potential of -65 mV to generate AP

Question 9

Integration

Answer 9

Adding and combining a number of individual signals into one overall signal

Question 10

Spatial summation

Answer 10

Integration of events at different places

Question 11

Temporal summation

Answer 11

Integration of events at different times

Question 12

Sodium and potassium channels

Answer 12

Opening and closing of voltage activated Na and K channels during the 3 phases of action potential: rising, repolarization, Hyperpolarization

Question 13

Action potentials

Answer 13

1. Occur in axons
2. Any simulation beyond there’s hold = same AP
3. In neuron all AP are equal in size and shape

Question 14

All or none law

Answer 14

Size and shape of AP is independent of intensity of stimulus that initated it

Question 15

Refractory periods

Answer 15

Absolute: impossible to imitate another AP

Relative: harder to imitate another AP

Limit rate of firing and prevent backward movement of AP

Question 16

Psp

Answer 16

Decremental
Fast
Passive (energy not used)

Question 17

AP

Answer 17

Nondecremental
More slow
Passive and active (use Atp)

Question 18

Axonal conduction of AP

Answer 18

Passive conduction along each mylin segment to next node ranvier

New AP generated at each node

Mylinated axon: instant, faster than nonmylinated

Question 19

Structure of synapse

Answer 19

Axodendrite: most common. Synapse onto dendrite spines

Directed synapse: site of release and contact are close proximity

Non directed: site of release and contact are spereated by some distance

Question 20

7 steps of NT action

Answer 20

1. NT synthesized from enzymes
2. NT stored in vesicles
3. NT that leak are destroyed by Enzymes
4. AP vesicles to fuse with presynaptic membrane and release NT into synapse
5. released NT molecules bind with autorec.
6. released NT bind to postsynaptic receptors
7. released NT are deactivated by reuptake or enzymatic degradation

Question 21

Synthesis of proteins

Answer 21

Small NT are synthesized in bouton and packaged in vesicles

Large NT synthesized in cell
Body by ribosomes and transported by Microtubules

Question 22

Release of NT

Answer 22

Exocytosis: NT release
Arrival of AP at terminal opens voltage activated Ca channel

Entry of Ca causes vesicles to fuse with terminal membrane and release their contents

Question 23

Release and diffusion of NT

Answer 23

Usually 2 or 3 NT released from each neuron

Question 24

Ligand

Answer 24

Molecule that binds to another

A NT is a ligand of its receptor

Question 25

Ionotropic receptors

Answer 25

Associated with ligand activated ion channels NT binds and an associated ion channel opens/ closes If Na+ channels opened for example EPSP occurs If K+ channels open for example IPsP occurs

Question 26

Metabolic receptors

Answer 26

Associated with signal Effects slower, longer lasting, more diffuse, more varied, 1. NT 1st messenger binds 2. G protein subunit breaks away 3. Ion channel open/ close or a 2nd message me 3. 2nd messenger wide variety effects

Question 27

Postsynaptic receptors

Answer 27

On terminal at tip of an axon 2 types 1. Autoreceptor: sensitive to the NT released by terminal bouton acts as negative feedback 2. Hetereorecpetor: responds to chemical other than the NT released by terminal bouton

Question 28

Reuptake

Answer 28

Scoop up and recycle NT

Question 29

Enzymatic degradation

Answer 29

A NT broken down by enzymes

Question 30

Seretonin

Answer 30

Mood and temperature regulation, aggression, sleep cycles

Question 31

Glutamate

Answer 31

Main excitatory NT, participates in relay sensory info and learning

Question 32

GABA

Answer 32

Main inhibitory NT

Question 33

Norepinephrine

Answer 33

Brain arousal and other functions like mood hunger and sleep

Question 34

Anandamide

Answer 34

Pain reduction, increases in appetite

Question 35

Acetylcholine

Answer 35

Muscle contraction (PNS) cortical arousal (CNS)

Question 36

Dopamine

Answer 36

Motor function and reward

Question 37

Amino acid NT

Answer 37

Found at fast acting directed synapses in CNS Glutamate and GABA Aspertate and glycine

Question 38

Monoamines NT

Answer 38

Effects tend to be diffused Atecholamines: synthesized from tyrosine (dopamine, norepinephrine, epinephrine) Indolamines: synthesized from tryptophan (serotonin)

Question 39

Unconventional NT

Answer 39

Soluble gases: exsist only briefly (nitric acid and carbon monoxide) Retrograde transmission: backwards communication Endadcannabinoids: anandamine is 1 of 2 known Endo.

Question 40

Agonists

Answer 40

Increase or facilitate activity (nicotine) Inc. synthesis of NT Inc. # NT molecules by destroying degrading enzymes Inc. release of NT molecules from terminal bouton

Question 41

Antagonistic

Answer 41

Decrease or inhibit activity Blocks synthesis of NT Cause NT to leak from vesicles and be destroyed Blocks the release of NT from terminal bouton Activates autoreceptors and inhibit NT release Drug is a receptor blocker. Binds to postsynaptic receptors and blocks effect of NT