Synaptic Transmission and the Neuromuscular Junction

Question 1

What is a synapse

Answer 1

a specialized gap region that permits a neuron (or

nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell

Question 2

What is the difference between chemical and electrical synapses

Answer 2

eletric direct electrical continuity by gap junctions.

indirect chemical neurotransmitter that diffuse to other cell.

Question 3

what is a gap junction made of?

Answer 3

vlakke arrays of connexons, each consisting of 6 connexin monomers.

Question 4

how do the multiple connexons physically conncted two cells.

Answer 4

via multiple aqueous channels

Question 5

What two kind of chemical syapses are there

Answer 5

ionotropic and metabotropic

Question 6

What is the agonist of electrical and chemical synapses?

Answer 6

electrical none

chemical e.g ACh

Question 7

membrane proteine of electrical synapse

Answer 7

connexon

Question 8

membrane proteine of chemical synapse

Answer 8

ionotropic, receptro/channels

metabotropic: receptro/G protein

Question 9

delay in transmission for each type of synapse

Answer 9

electrical, instant
ionotropic 1ms
metabotropic seconds to minutes

Question 10

What kind of nerve is the vagus nerve and what does it do?

Answer 10

parasympathetic, produces a substance (ACh) responsible for depression of the heartbeat.

Question 11

is ACh inhibitory or excitatory?

Answer 11

both

Question 12

what are reciprocal synapses?

Answer 12

pass electrical current with equal efficiency in both directions

Question 13

what are rectifying synapses?

Answer 13

Allow current only in one direction.

Question 14

how can intrinsic rectification be altered?

Answer 14

gap junctions composed heterotypic channels

Question 15

what are heterotypic channels?

Answer 15

a gap junction that is composed of two hemichannels, each made up of a different connexin monomer.

Question 16

are chemical synapses reciprocal or rectifying?

Answer 16

rectifying

Question 17

are chemical channels one or unidirectional for signal propogateion adn why?

Answer 17

unidurectional, because presynaptic cell can produce retorgade sygnaling molecules and receptors on presynaptic membrane can inhibit or facilitate the realse of a transmitter.

Question 18

How do vescular transporters concentrate neurotransmitters inside?

Answer 18

energy on an H+ electrocehmical gradient

Question 19

what does a increase of intracellular Ca2+ do at the presynapse

Answer 19

triggers the fusion of synaptic vesicles with the presynaptic membrane

Question 20

How is the process of chemical synapses terminated?

Answer 20

enzymatic destruction of the transmitter (e.g., hydrolysis of ACh by ace­tylcholinesterase), (b) uptake of transmitter into the presynaptic nerve terminal or into other cells by Na + -dependent transport systems, or (c) diffusion of the transmitter molecules away from the synapse.

Question 21

what are ligands.

Answer 21

agonists

Question 22

what is the difference between ionotropic receptors and metabotropic receptors?

Answer 22

ionotropic aganist gated ion channels.

metabotropic. receptors coupled to G protein.

Question 23

what are the subunits of a G protein?

Answer 23

α and βγ subunits

Question 24

what do the α and βγ subunits produced by the Activation of a metabotropic G protein–linked receptor?

Answer 24

they iniate a wide variety of cell responses by direct interaction with either ion channel proteins or other second-messenger effector proteins.

Question 25

what is the nicotonic AchR

Answer 25

ionotropic receptor

Question 26

what is the muscarinic AchR?

Answer 26

metabotropic recptor at the atrial parasympathetic synapse of the heart

Question 27

what does the activation of Muscarinic receptor do

Answer 27

activates the G protein, which opens an inward rectifier K+ channel, or GIRK. which leads to hyperpolarisation which leads to inhibition of cardiac excitation.

Question 28

what does does the activation of the nictonic receptor do?

Answer 28

opens the AChR channel resulting in increase of permabilkty of NA and K., which leads to muscle contraction.

Question 29

what does Acetylcholinesterase do?

Answer 29

breaks down acetylcholine.

Question 30

what is a motor unit.

Answer 30

all the muscle fibers innervated by the axon from one motor neuron

Question 31

what is the end plate?

Answer 31

neuromuscular junction

Question 32

Where is the neuromuscular junction?

Answer 32

synaptic contact with a muscle fiber.

Question 33

What are boutans

Answer 33

bulb-shaped ending that finally contact the muscle fiber.

Question 34

what do the postjunctional folds do

Answer 34

increase increase surface area of muscle plasma.

Question 35

what is the basal lamina

Answer 35

a extracellualr matrix in the synaptic cleft containing various proteins that mediate adhesion of the neuromuscular junction and play important roles in synapse development and regeneration.

Question 36

what and where is AChE and what does it do

Answer 36

acetylcholinesterase in basal lamina , hydroplyses ACh to choline and acetate.

Question 37

where are the vesicles produced

Answer 37

the cell bodies of motor neurons in the spinal cord.

Question 38

how are the vesicels translocated to the nerve terminal

Answer 38

by microtubule-mediated process of fast axonal transport

Question 39

what is choline acetyltransferase

Answer 39

enzyme that syntheses ACh from choline and acetyl outside the vesicle.

Question 40

What does the ACh-H exchanger do

Answer 40

moves ACh inward the vesicle and H+ out

Question 41

how is the process of the ACH-H exchanger driven?

Answer 41

vesicular proton electrochemical gradient (positive voltage and low pH inside), which is produced by the vacuolar-type H pump.

Question 42

is vacuolar-type H pump passive or acxtive?

Answer 42

active, uses ATP

Question 43

what are active zones

Answer 43

regions where vesicles fuse and ach is released

Question 44

where are the most AChRs at neuromuscular joints

Answer 44

at the tops of postjunctional folds.

Question 45

is the delevery of neurotransmitters to a location precise

Answer 45

yes

Question 46

what is EPP

Answer 46

end plate potential

Question 47

To what is the revarsal potential of end plate current close?

Answer 47

0mV

Question 48

to what are AChR permeable

Answer 48

NA, K and Ca, not anions

Question 49

What happens to Vm when nicotinic AChR channels open?

Answer 49

V m shifts to a value between E K (approximately −80 mV) and E Na (approximately +50 mV).

Question 50

what kind of potential is EPP

Answer 50

excitory postsynaptic potential.

Question 51

Whata re hyperpolarizing postsynaptuc responses called?

Answer 51

inhibtory postsynaptic potentials.

Question 52

serotonin and glutamate are .. selective | and glycine and GABA are ... selective

Answer 52

serotonin and glutamate are cation selective | and glycine and GABA are anion selective

Question 53

what are depolarizing postsynaptic responses called

Answer 53

excitatory postsynaptic potentials.

Question 54

What is dendrotoxin

Answer 54

K+ antagonist

Question 55

what is tetanus and botulinum toxin

Answer 55

proteine toxins made by bacteria, ACh release antagonist

Question 56

what is physostigmine and DFP

Answer 56

acetylcholinesterase antagonist

Question 57

what is nicotine en acetylcholine

Answer 57

AChR channel agonist

Question 58

what is d -tubocurarine and a-Bungarotoxin

Answer 58

AChR channel antagonist

Question 59

what is tetrodotoxin, Saxitoxin and u-conotoxin

Answer 59

Muscle Na channel antagonist

Question 60

what is ω-conotoxin

Answer 60

peptide toxin, Ca2+ channel antagonist

Question 61

what is tetrodoxotin en Saxitotoxin

Answer 61

small guanidinium neurotoxins of neuronal Na+ channel antagonist

Question 62

how does dendrotoxin facilitate ACh release?

Answer 62

Because it block K+ so the memrbane cant repolarise and more Ca2+ enters the cell.

Question 63

What does tetanus do.

Answer 63

increase of muscle tension, (begint met kaak). these toxins inhibit synaptic transmission at the spinal cord, neurons that would normale inhibit muscle contraction.

Question 64

what does botulism cause

Answer 64

paralysis of skeletal muscle, and a vierty of symptoms that are related to inhibition of cholinergic nerve endings in the autonomic nervous system.

Question 65

what anatgonist is used to treath muscle spams.

Answer 65

botuliism

Question 66

what antagonist is used to threath strabismus (a condition in which both eyes cannot focus on the same object because of abnormal hyperactivity of particular eye muscles).

Answer 66

botulism

Question 67

what is botox and how long does it last

Answer 67

botulinium toxin, smooth wrinkles by local paralysis of facial muscles. to 6 months

Question 68

what are carbamycholine and succinylcholine and what is difference with normale stof

Answer 68

agonist AChR | resistent to AChE so prolonged effect.

Question 69

what molecule is used for sugery and why

Answer 69

succinycholine, to prevent excitation because of inactivation of Na channels.

Question 70

what leads to desensitization of the AChR

Answer 70

agonising, a AChR for a long time.

Question 71

how can d-Tuborcurarine be cured

Answer 71

increase in concentration of the natural agonist ACh by binding competition. which can be produced indirectly by an inhibitor of AChE such as neostigmine

Question 72

what is pancuronium

Answer 72

stronger agonist of AChR than d-tubocuraine, used for surgery.

Question 73

what is the difference between organophosphorus compounds and physostigmine/Neostigmine

Answer 73

organophosphorus is irreversible anti AChE drug

Question 74

what are anatoxin and fasciculin?

Answer 74

natural organophosphorus (inhibitor of AChE)