Ibhs 524 Exam 2 Lecture 2

Front 1

Functions of skeletal muscle

Back 1

support soft tissues, guard entrance/exit, store nutrient reserves (proteins)

Front 2

What does the endomysium contain?

Back 2

capillary network, nerve fibers, myosatellite cells

Front 3

aponeurosis

Back 3

sheet that attaches to bone

Front 4

myosatellite cells

Back 4

myoblasts that don't fuse with developing muscle fibers and remain; used for repair

Front 5

myofibrils

Back 5

bundles of protein filaments (myofilaments) at end of 'lemma, have thick/thin/titin (sarcomeres), surrounded by mitochondria

Front 6

sarcomeres

Back 6

A band (length of thick filaments), I band (has thin but NOT thick)

Front 7

A band

Back 7

H band, (connection pt of thick), H band (light region on either side of M line - thick only), ZOO

Front 8

I band

Back 8

Z line (striated appearance, titin)

Front 9

tropomysium

Back 9

DS protein that covers 7 AS on G actin, each bound to 1 troponin

Front 10

what are myosin tails pointed toward?

Back 10

M line

Front 11

synaptic terminal

Back 11

axon branches and ends there, contains ACh

Front 12

motor end plate

Back 12

sarcolemmal surface that contains ACh receptors

Front 13

neural stimulation of muscle fibers

Back 13

1. AP at terminal 2. release ACh from surface 3. ACh binds to plate, Na IN 4. AP in 'lemma/AChE 5. return to initial state

Front 14

exctation contraction coupling

Back 14

at triads, AP down T tubules, trigger Ca+2 release from TC of SR

Front 15

exposure of active site

Back 15

1. AP triggers release of Ca+2 from SR 2. Ca2+ binds trop C 3. troponin removes tropomysium 4. crossbridge formation

Front 16

contraction cycle

Back 16

1. Ca2+ rel as exposed 2. head attaches to actin, crossbridge 3. stored E released, head pivots to M line = powerstroke 4. crossbridge detachment 5. myosin activation

Front 17

amount of tension produced by muscle fiber depends on formation of crossbridges AND?

Back 17

fiber's resting length, frequency of stimulation

Front 18

what does decreased resting length result in?

Back 18

thin filaments extending across center of sarcomere (decreased tension)

Front 19

incomplete tetanus

Back 19

increased stimulation frequency, 4x tension of wave summation

Front 20

complete tetanus

Back 20

increased stimulation frequency, continuous contraction

Front 21

tension produced by whole skeletal muscle depends on what?

Back 21

tension produced by single muscle fibers (motor unit), total number of fascicle stimulated (recruitment)

Front 22

what typically occurs to the motor units during sustained contraction?

Back 22

motor units are activated on a rotating basis - asynchronous motor unit summation

Front 23

resting tension

Back 23

feature of muscle tone where some motor units are active but not enough to produce movement

Front 24

isotonic

Back 24

tension rises length of skeletal muscle changes (concentric and eccentric)

Front 25

concentric contraction

Back 25

isotonic - muscle tension exceeds resistance, muscle shortens, bicep contracting

Front 26

eccentric contraction

Back 26

isotonic - muscle tension doesn't exceed resistance, muscle elongates, bicep relaxing

Front 27

isometric contraction

Back 27

tension rises, skeletal muscle length doesn't change

Front 28

tetanus the disease

Back 28

deep puncture, less O2, clostridium tetani, block NT that normally inhibit motors neurons, 40-60 mortality, DTaP kids then booster (body makes antibodies) or get "anti toxin"

Front 29

muscular dystrophy

Back 29

no cures, progressive muscle weakness, myotonic dystrophy (alteration in gene that codes for myosin kinase)

Front 30

DMD

Back 30

type of muscular dystrophy: mutation in gene that codes for dystrophin - this protein attaches to thin filaments to anchoring proteins on sarcolemma

Front 31

malignant hyperthermia

Back 31

defect in receptor that allows calcium to be released from SR and initiate muscle contraction, inherited

Front 32

symptoms of malignant hyperthermia

Back 32

>105, muscle rigidity, dark brown urine (rhabdomyolysis), increased HR, acidosis

Front 33

malignant hyperthermia triggered by and what are treatment options

Back 33

general anesthetics, pts given dantrolene (muscle relaxant that dissociated excitation contraction coupling.

Front 34

non depolarizing neuromuscular blocking drugs

Back 34

antagonist at ACh receptor, prevents ACh from binding, reversed by cholinesterase inhibitors (tubocurarine, cisatracurium)

Front 35

depolarizing neuromuscular blocking drugs

Back 35

depolarizing agonist at ACh receptor, phase I binds to receptor and causes depolarization. Phase II acts as if channel is in prolonged state (desensitized), reversed by cholinesterase inhibitors in phase II (succinylcholine)

Front 36

spasmolytics neuromuscular blocking drugs

Back 36

act to decrease muscle spasms and increased muscle tone - diazepam etc.