Module 3

Question 1

graded potentials; dendrite and cell body are ___ and ___ summed together

Answer 1

spatially and temporally

Question 2

what happens when EPSP and ISPS are summed

Answer 2

action potential

Question 3

Gray (1731) proposed

Answer 3

electricity may be a messenger that spreads info in the nervous system

Question 4

Galvani discovered

Answer 4

electrical stimulation produced behviour

Question 5

Fritsch and Hitzig demonstrated

Answer 5

electrical stimulation of the neocortex causes movement

Question 6

bartholow (1874) was the first research to

Answer 6

describe the effects of human brain stimulation

Question 7

T/F neurons convey information as a wave

Answer 7

true

Question 8

what is an electrical potential

Answer 8

electrical charge measured in volts (ability to do work)

Question 9

cations are __ charged ions

Answer 9

+ve

Question 10

anions are __ charged ions

Answer 10

-ve

Question 11

what 3 factors influence the movement of anions and cations in/out of cells

Answer 11

Diffusion
Concentration gradient
Voltage gradient

Question 12

how does equilibrium potential work

Answer 12

• Efflux of chloride ions down the chloride concentration gradient is counteracted by the influx (inward flow) of chloride ions down the chloride voltage gradient.
• Equilibrium occurs when the concentration gradient of chloride ions on the right side of the membrane is balanced by the voltage gradient of chloride ions on the left.
• At equilibrium, the concentration gradient is equal to the voltage gradient

Question 13

inside of the membrane at RMP is ___ mV

Answer 13

-70

Question 14

what 4 particles take part in RMP

Answer 14

1.) Na+
2.) Cl-
3.) K+
4.) A-

Question 15

what 2 particles have a higher [] in the cell

Answer 15

K+ and A-

Question 16

what are graded potentials

Answer 16

• if the concentration of any of the ions across the unstimulated cell membrane changes, the membrane voltage changes.
  -These graded potentials are small voltage fluctuations across the cell membrane

Question 17

what happens during hyperpolarization

Answer 17

• Increase in electrical charge across a membrane (more negative).
• Usually due to the inward flow of chloride ions or outward flow of potassium ions.

Question 18

what happens during depolarization

Answer 18

• Decrease in electrical charge across a membrane (more positive)
• usually due to inward flow of Na+

Question 19

Hyperpolarization and depolarization typically take place on ___ and the __

Answer 19

neuron dendrites and soma membrane

Question 20

what are the 3 channels that underlie graded potentials

Answer 20

1.Potassium (K+) channels.
For the membrane to become hyperpolarized, its extracellular side must become more +ve, which can be accomplished with an outward movement, or efflux, of K+ ions.
2.Chloride (CI−) channels.
Even though chloride ions can pass through the membrane, more ions remain on the outside than on the inside, so an influx of Cl- ions due to decreased resistance to Cl− flow can result in brief increases of Cl− inside the cell.
3.Sodium (Na+) channels.
Depolarization can be produced if normally
closed sodium channel gates open to allow an influx of sodium ions. Evidence that potassium channels have a role in hyperpolarization comes from the fact that the chemical tetraethylammonium (TEA), which blocks potassium channels, also blocks hyperpolarization. The involvement of sodium channels in depolarization is indicated by the

Question 21

who researched how the cell bodies of large motor neurons integrate an enormous array of inputs into a nerve impulse

Answer 21

John Eccles + students (1965)

Question 22

what are excitatory postsynaptic potentials (EPSP)

Answer 22

brief depolarization of a neuron membrane in response to stimulation

more likely to produce action potential

Question 23

what are inhibitory post synaptic potentials (IPSP)

Answer 23

brief hyperpolarization of a neuron membrane in response to stimulation

less likely to produce an action potential

Question 24

EPSPs are associated with the opening of

Answer 24

sodium channels (allows Na+ influx)

Question 25

IPSPs are associated with the opening of

Answer 25

potassium channels (allows efflux of K+) or chloride channels (allows efflux of Cl-)

Question 26

Temporal summation is

Answer 26

when EPSP (or IPSP) pulses occur at approximately the same TIME on a membrane are summed

Question 27

spatial summation is

Answer 27

when EPSP (or IPSP) pulses occur at approximately the same PLACE on a membrane are summed

Question 28

how long does an action potential last

Answer 28

~ 1 millisecond

Question 29

what are the steps of an action potential

Answer 29

- Both sodium and potassium voltage-activated channels are attuned to the threshold voltage of about −50 mV. - The voltage-activated sodium channels respond more quickly than the potassium channels. - Sodium channels have two gates. Once the membrane depolarizes to about +30 mV, one of the gates closes. - K+ channels open more slowly refractory period

Question 30

what is a nerve impulse

Answer 30

Propagation of an action potential on the membrane of an axon.

Question 31

what is myelin

Answer 31

- made by oligodendroglia in the CNS - made by Schwann cells in the PNS. - Speeds up neural impulse; energetically cheaper

Question 32

what are nodes of ranvier

Answer 32

- Part of an axon that is not covered by myelin. - Tiny gaps in the myelin sheath. - Enables saltatory conduction

Question 33

what saltatory conduction

Answer 33

speeds up singaling

Question 34

Loewi (1921) is known for

Answer 34

Frog heart experiment; first isolation of a chemical messenger. Acetylcholine (first neurotransmitter discovered in somatic nervous system) + epinephrine (adrenaline) and norepinephrine later on

Question 35

what are nuerotransmitters

Answer 35

- Chemical released by a neuron onto a target with an excitatory or inhibitory effect. - Outside the CNS, many of these chemicals circulate in the bloodstream as hormones (have distant targets, action slower than that of a neurotransmitter).

Question 36

NEUROTRANSMISSION IN FIVE STEPS

Answer 36

1.) neurotransmitter is synthesized - axon terminal or soma 2.) neurotransmitter packaging and storage - origin = peptide, lipid, gas and/or ions 3.) neurotransmitter release - action potential at terminal opens voltage Ca channels - Ca enters the terminal and binds to protein calmodulin, forming complex - complex causes some vesicles to empty their contents into the synapse and other to empty it ___ 4.) receptor site activation - neurotransmitter diffuses across synaptic cleft to activate receptors on postsynaptic membrane (transmitter-activated receptors, ionotropic receptor, metabotropic receptor, auto-receptor, quantum) 5.) neurotransmitter inactivation - removed from receptor sites and from the synaptic cleft. inactivation done in 4 ways; (1) diffusion (2) degradation (3) reuptake (4) astrocyte reuptake

Question 37

what is a gap junction

Answer 37

- contains connexin proteins on adjacent cell membranes to connect to from hemichannels (allows ions to pass between) - can open/close - eliminate brief information flow delay - allow glial cells and neurons to exchange functions and selectivity for specific size molecules - allow for dual chemical and electrical synaptic transmission

Question 38

traits of excitatory synapse

Answer 38

- typically on dendrites - round vesicles - dense material on membranes - wide cleft - large active zone

Question 39

traits of inhibitory synapse

Answer 39

- typically on soma - flat vesicles - sparse material on membranes - narrow cleft - small active zone

Question 40

what's the criteria to be a neurotransmitter

Answer 40

1.) carry a message from one neuron to another by influencing the voltage on the postsynaptic membrane 2.) change the structure of a synapse 3.) communicate by sending messages in opposite direction. these retrograde messages influence the release or reuptake of transmitters on the presynaptic side

Question 41

5 classes of neurotransmitters

Answer 41

1.) small-molecule transmitters 2.) peptide transmitters 3.) lipid transmitters 4.) gaseous transmitters 5.) ion transmitters

Question 42

what does a second messenger do

Answer 42

- Binds to a membrane-bound channel, causing the channel to change its structure and thus alter ion flow through the membrane. - Initiates a reaction incorporating intracellular (within the cell) protein molecules into the cell membrane, leading to formation of new ion channels. - Binds to sites on the cell’s DNA to initiate or cease the production of specific proteins

Question 43

These are embedded membrane protein with a binding site for a neurotransmitter but no pore.

Answer 43

metabolic receptors

Question 44

acetylcholine synthesis

Answer 44

- Two enzymes combine the dietary precursors of ACh within the cell, and a third breaks them down in the synapse for reuptake. - Acetylcholine synthesis Choline Acetate -Breakdown of acetylcholine Enzyme: acetylcholinesterase (AChE)

Question 45

amine synthesis

Answer 45

- Sequential synthesis of three amines - A different enzyme is responsible for each successive molecular modification in this biochemical sequence of amine neurotransmitters. - The precursor chemical is tyrosine. - The enzyme tyrosine hydroxylase changes tyrosine into L-dopa, which other enzymes convert first into dopamine, then into norepinephrine, and finally into epinephrine.

Question 46

5-HT synthesis

Answer 46

- Amine transmitter serotonin (5-HT, for 5-hydroxytryptamine) Synthesized from the amino acid L- tryptophan (abundant in pork, turkey, milk, and bananas, among other foods). - Serotonin Plays a role in regulating mood and aggression, appetite and arousal, respiration, and pain perception.

Question 47

amino acid transmitter synthesis

Answer 47

- Amino acid transmitters are workhorses of the brain because so many synapses use them. Glutamate (Glu): Amino acid neurotransmitter; typically opens Na+ and Ca2+ channels and therefore excites neurons. Gamma-aminobutyric acid (GABA): Amino acid neurotransmitter; typically opens Cl– channels and therefore inhibits neurons

Question 48

Purine synthesis

Answer 48

- Synthesized as nucleotides (molecules that make up DNA and RNA). - Purine adenosine triphosphate (ATP) Consists of a molecule of adenine attached to a ribose sugar molecule and three phosphate groups. - Removal of the three phosphate groups leaves adenosine (neurotransmitter) Plays a central role in promoting sleep, suppressing arousal, and regulating blood flow to various organs through vasodilation.

Question 49

lipid transmitters

Answer 49

Phytocannabinoids - Obtained from the hemp plants Cannabis sativa and Cannabis indica. - Used medically and recreationally for thousands of years. - Many constituents of cannabis, including THC and cannabidiol (CBD) isolated and their chemical structure determined early in the twentieth century. - Research on physiological and psychological effects of THC is ongoing.