chap 9 muscular system II

Question 1

how do the nerves from the brain and spinal cord extend to the skeletal muscle

Answer 1

through the axons

Question 2

what do axons do?

Answer 2

convey electrical signals to muscle cells and initiate contraction

Question 3

what is RMP?

Answer 3

resting membrane potential

like a charged battery ready to do work

Question 4

what is the voltage inside the cell

Answer 4

-70 mV

Question 5

what creates and maintains an imbalance of Na+ and K+?

Answer 5

active transport of Na+/K+ by membrane pump

Question 6

what do CLOSED ion specific gates do?

Answer 6

prevent Na+/K+ from seeking rapid equal concentration adjustments by diffusion

Question 7

other ion specific gates

Answer 7

ligand activated gates

voltage activated ion gates

Question 8

how do ligand activated gates work?

Answer 8

are activated by a ligand landing on the receptor protein of the gate

Question 9

how is ligand released?

Answer 9

due to some signal

Question 10

how do voltage activated ion gates work?

Answer 10

opened by a rapid change in voltage within the cell

Question 11

example of a voltage activated ion gate?>

Answer 11

potassium gate

Question 12

what is depolarization?

Answer 12

reversal of the voltage difference

inside grows less negative

Question 13

how does depolarization work

Answer 13

a stimulus to the cell causes some Na+ ion specific gates to open, causing Na+ to leak into the cell
this creates a voltage change

Question 14

electrical charge for outside Na+

Answer 14

outside + positive

Question 15

electrical charge for inside K+

Answer 15

inside - negative

Question 16

what happens when threshold is reached?

Answer 16

if the stimulus is strong enough to cause sufficient voltage change, Na+ specific voltage gates quickly open completing rapid intense depolarizatikn

Question 17

what happens to the electrical charge during depolarization?

Answer 17

goes from -70mV to +30mV as Na+ move in

Question 18

what happens if threshold is not reached?

Answer 18

no action potential takes place

Question 19

what is action potential?

Answer 19

the rapid changing of membrane potential

Question 20

what is the all or none principle

Answer 20

if the ligand-gated Na+ entry is above threshold, then no more neurotransmitter ligand is necessary to open the rest of the voltage gated channels and complete the action potential

Question 21

repolarization

Answer 21

put membrane back to RMP

Question 22

steps of repolarization

Answer 22

with the abundance of Na+, charge is +30. this trigggers the K+ specific voltage gated channels to open
K+ then rushes out, using laws of diffusion
intracellular environment returns to -70mV, returning to RMP

Question 23

homeostasis

Answer 23

an ion imbalance across the membrane must exist or ions will not move or move as rapidly when gates are opened

Question 24

what help maintain the -70mV during RMP

Answer 24

Na+/K+ pump

Question 25

propagation

Answer 25

spreading of a signal throughout the cell

Question 26

result of propagation

Answer 26

muscle cells contract, nerve cells send impulses

Question 27

what happens if they is repeat stimulation?

Answer 27

action potentials increase the strength of the cell response which results in an increase in strength or duration of contraction in muscle cells

Question 28

synapse

Answer 28

neuromuscular junction | transfer site of motor neuron action potential to skeletal muscle cell action potential

Question 29

what stimulates each muscle fiber

Answer 29

the terminal branch of axon

Question 30

structures of neuromuscular junction

Answer 30

presynaptic terminal synaptic cleft postsynaptic membrane

Question 31

presynaptic terminal

Answer 31

the end | sends the message

Question 32

postsynaptic membrane

Answer 32

"motor end plate" | skeletal muscle cells

Question 33

steps of neuromuscular junction

Answer 33

1. action potential travels down moto neuron membrane to the presynaptic terminal 2. Ca2 specific voltage gates open and Ca2+ diffuses inwards 3. triggers neurotransmitter vesicle release by exocytosis into the synapse 4. result of action potential across the muscle fiber

Question 34

acetylcholine

Answer 34

ACh | is the excitatory NT of the NMJ

Question 35

what happens after the exocytosis into the synapse

Answer 35

ACh ligand binds to ACh receptors on muscle fiber post synaptic membrane activating ligand gate Na+ channels depolarization of the postsynaptic membrane generates action potential

Question 36

what happens to ACh?

Answer 36

ACh is quickly broken down | ACh-> acetic acid + choline

Question 37

purpose of choline

Answer 37

to be reuptaked to more more ACh

Question 38

acetic acid

Answer 38

bad | formed from a variety of metabolic responses

Question 39

enzyme responsible for ACh breakdown

Answer 39

acetylcholineesterase AChE

Question 40

result of action potential across the muscle fiber

Answer 40

excitation-contraction coupling

Question 41

steps after action potential created | excitation-contraction coupling

Answer 41

1) T-tubule invagination takes the sarcolemma depolarization into the S 2) Ca2+ is released internally (200x normal concentration_ 3) Ca2+ binds to the regulatory troponin and exposes myosin binding site 4) myosin head engages and power stroke ensues 5) ATP molecule energy uses to unhook myosin and recock head

Question 42

what do organophosphate pesticides and some nerve gases do?

Answer 42

block the action of AChE | result in transient spastic paralysis

Question 43

spastic transient paralysis

Answer 43

fibers constantly stimulated, unable to relax and eventually fatigue death through respiratory failure importance of protecting populations and workers from sprays

Question 44

why would solders be given syringes of atropine sulfate which blocks postynaptic membrane ACh receptor sites?

Answer 44

??

Question 45

what happens to blocked postynaptic membrane ACh receptors

Answer 45

limits membrane depolarization flaccid paralysis results myasthenia gravis

Question 46

flaccid paralysis

Answer 46

muscles unable to respond

Question 47

myasthenia gravis

Answer 47

your antibodies from response to viral infection damage ACh receptors muscle weakness most survive but end up in coma and require ventilation

Question 48

treatment for myasthenia gravis

Answer 48

neostigmine, which interferes with AChE action, tries to keep whatever ACh is already there

Question 49

recovery stroke

Answer 49

ATP dependent release of myosin head and recocking

Question 50

what is muscle contraction?

Answer 50

produced by many quick repeats of the cycle in each fiber that has been stimulated by the neuron

Question 51

what happens when no more stimulus is present?

Answer 51

relaxation of muscle tissue | Ca2+ are rapidly moved back into the SR by active transport (ATP needed)

Question 52

rigor mortis

Answer 52

stiffness that covers body several hours after death. loss of intracellular containment of the Ca2+ and lack of ATP causes constant increasing contractions (rigor) in the hours after death. after 24 hours the muscle cell proteins will deteriorate and begin to relax