Cell phys by Karius

Question 1

2 major things used by cell to create ionic equilibrium

Answer 1

membrane selectively permeable

action of Na/K ATPase (creates conc. gradient, makes cell more -)

Question 2

Na+/K+ ATPase pump

Answer 2

pumps 3 Na+ out

brings 2 K+ in

Question 3

all ions we are concerned with haver higher conc. OUTside cell except

Answer 3

K+

Question 4

the motor unit

Answer 4

alpha motorneuron and all the muscle it innervates

Question 5

Ca++ sequestered in SR due to aciton of

Answer 5

Ca++ - Mg++ ATPase (pumps Ca++ into SR)

calsequestrin (protein that binds calcium within the SR) helps force the calcium to stay in place

Question 6

located on t-tubule and undergoes conformational change in response to AP

Answer 6

DHP receptor

Question 7

ryanodine receptor is

Answer 7

LIGAND gated

Question 8

required for the myosin-actin interaciton to be broken

Answer 8

ATP

Question 9

immediate source for ATP in muscle contraction

Answer 9

phosphorylcreatine

Question 10

in isometric contraction

Answer 10

SAME LENGTH

cross-bridge cycling changes tension but not length

Question 11

isotonic contraciton

Answer 11

SAME TENSION

muscle changes length rather than developing tension

Question 12

even if trying to lift something tooheavy for us to lit, have some shortening that occurs due to?

Answer 12

series elastic component

includes - tendons, membranes surrounding the muscle, sarcomere that are not contracting

Question 13

maximal tension is developed at sarcomere lengths of ?? why?

Answer 13

2-2.2 microns [ Lo, the resting length of the muscle]

• above it acitn and myosin unable to interact
• at sarcomere lengths less than 2.0 microns, actin filaments begin to overlap, preventing normal interaction

Question 14

as muscles get shorter, tenson..

Answer 14

decreases for same reasons as in sarcomere

Question 15

as muscles get longer, > L0

Answer 15

total tension generated by whole muscle starts to fall off, but then INCREASES (different from sarcomere)

• active tension falls off, eventually to 0
• passive tension created by stretching fibers now dominates

Question 16

preload and postload

Answer 16

preload - if the muscle “feels” the load before contraction

afterload - if it “feels” it after contraction begins

Question 17

if the resting muscle IS stretched by the load, it is a

Answer 17

PRELOAD

Question 18

if resting muscle IS NOT stretched by the load, it is an

Answer 18

AFTERLOAD

Question 19

when pushing against a wall, contraction is first.. then..

Answer 19

first isotonic (get some change in length as series elastic elements stretched)
then isometric (can't move wall so no change in length but generating force so tension changing)

Question 20

malignant hyperthermia DM

Answer 20

anesthetic agent activates Ca++ channel on SR (the ryanodine receptor) and allows calcium to leave the SR
muscle contraction occurs
- bypassing NS so no protective reflexes will cause relaxation (they work through motor neurons)

Question 21

everything wrong with Sandy R.

Answer 21

hyperkalemic periodic paralysis
inactivaiton gate protein on Na+ channels in skeletal muscle only doesn’t work properly especially when K+ levels high - after bananas or exercising or when tissue cools)

Question 22

paralysis in hyperkalemic periodic paralysis is because of

Answer 22

voltage-inactivation aka depolarization block

channels don’t “reset” because constant depolarization

Question 23

JohnnY R with his muscle twitches but no weakness/ paralysis had

Answer 23

myotonia congenita
Cl- channel mutated
should be open at rest allowing for 80% of ion flow but mutated stays CLOSED at rest; no negative ion entering, cell, cause depolarization
or maybe allowing + ions ot enter;
either case muscle cell depolarizing spontaneously