exam four lecture review

movement

produce tension to move things: pulling, squeezing, etc.

posture

baseline tension exerted at all times

joint stability

constant tension holds joints together

thermogenisis

shivering

what is an example of a skeletal muscle that is not actually connected to the skeleton?

facial muscles

what do ALL muscles have in common?

dramatically shorten on command to produce force or tension

when someone mentions the muscular system, what are the actually implying?

the 650 skeletal muscles that make up the skeletal muscles (does not include the heart and smooth muscle tissue)

what is the inverse relationship between stability and mobility?

the more mobile you are the less stable you are

what’s the most mobile joint in your body?

shoulder, BUT is also easier to dislocate

what are the rotator cuff muscles?

supraspinatus, infraspinatus, subscapularis, teres minor

what is a muscle fiber also called?

a muscle cell

when you slow cook meat, what are you pulling apart?

fascicles

what is a potential also called?

a voltage

what are excitable cells?

able to produce a muscle action potential or muscle potentials

excitable

able to respond to chemical and mechanical stimuli by generating organized movement of electrical charge across membranes in a wave like manner

contractile

shortening

extensible

tolerate stretching

elastic

snap back into position after stretch

excitation-contraction coupling

muscle has to be excited to allow for contraction:

“contraction is predicated on excitation”

are skeletal muscle cells big in comparison to other muscle types?

yes

what’s a muscle fiber alsp called?

a muscle cell

what is each fascicle ?

a wrapping up of parallel muscle fibers/muscle cells

how long is a muscle fiber/muscle cell?

typically the length of the muscle BUT they are too small in diameter to see

what will the most big and strong muscles in the body have?

thick muscle fibers/cells (about 100 micrometers/1/10th of millimeter)

what is a muscle fiber defintion?

a bundle of muscle fibers (cells)

• each muscle fiber is long (>1 cm) and wide (up to 0.1 mm)

• formed by fusion of multiple myoblasts in embryo

• multiple myoblast nuclei maintained in each fiber

• sarcoplasm specializations

what are muscle stem cells?

myoblasts

how do muscles get bigger over time if the number of cells doesn’t change?

hypertrophy

protein filaments

myofilaments (actin and myosin)

what are the prefixes for muscle?

sarco- or myo-

cytoplasm in muscle

sarcoplasm

cell membrane in a muscle

sarcolemma

what did the cell membrane used to be called?

plasmolemma

SER in muscle?

sarcoplasmic reticulum

what helps muscles connect to other things in the body?

fascia

do muscles have vascularity and are innervated?

yes a LOT

epimysium

dense irregular connective tissue that surrounds muscle; links fascicles together

perimysium

outer skin of every fascicle

what is a fascicle bundling together?

muscle fibers/cells

endomysium

surrounds muscle fibers; made of reticular fiber

what are the compartmentalization of muscles?

whole muscle, muscle fascicle, muscle fibers surrounded by endomysium, myofibril, myofilaments

are myofilaments and myofibrils the same?

NO; myofilamets are protein filaments while a myofobril is a ontractile organelle

how are muscle fibers layed out in a muscle?

one by one down a line (like train cars) called sarcomeres

what is the atomic unit of contraction?

sarcomeres

what is the sliding filament hypothesis?

the idea that myosin fibers don’t move, but cling into actin filaments

what is a triad?

transverse tubule and terminal cistern

transverse tubule

folding of sarcolemma into the cell

terminal cisterns

(terminal cisterna for singular);

what is a cistern?

an object that can hold liquid

what’s the goal of exciting a muscle?

calcium release

what is the sodium concentration relationship?

higher on the outside of the cell than the inside

what’s another name for the relaxed position?

default position

i band (half i band)

all thin filament and no thick filament

a band

length of the thick filaments (has both thin and thick filaments)

h zone

all thick filament and no thin filament

how is it possible for the thick filament ot be suspended in the sarcomere?

protein connections

M line

where the thick filaments meet

what protein is connected to the z disc?

titan protein; a single string of amino acids (polypeptide) that is 27,000 amino acids long and very springy

what are titan proteins?

extensible and elastic

what size is a sarcomere when it is fully compressed?

about 2/3 of original size at cost of the H zone

what is a thick filament?

300-400 myosin proteins

dimer (dimerized structure)

two proteins involved (polypeptide dimer)

what shape are actin proteins?

spherical; spinal shaped chain of spheres

what is another name for the active site?

myosin head binding sites

what are the steps of cross bridge formation?

1. calcium indued active site exposure

2. cross bridge formation

3. power stroke

4. atp induced crossbridge release

5. recovery stroke

latent phase

0-5 msec with no apparent response

contraction phase

up to 100 msec, obvious increase in tension produced by power stroke, filament sliding

relaxation phase

up to 100 msec, crossbridges gone, filaments slide back to resting position

what does the strength of the contraction mirror?

the amount of impulses sent

action potential

change in voltage

for each “impulse” sent down the t tubule:

one bridge cycle occurs

what are the two things you need to keep contraction moving?

calcium and atp

what is the relationship between action potentials and puffs of acetocholyine?

direct

what happens when action potentials stop moving down the sarcolemma?

the calcium goes down very dramatically

complete tetanus

carrying repeated crossbridge cycling to its natural conclusion

myogram

measures tension produced in a single twitch using a force/tension

physiological contraction

rigor mortis

wen do muscles die?

your last breath

rigor mortus

rigidity of your skeletal muscles after death

motor unit

one motor neuron and all the muscle fibers it controls

what does each action potential result in?

a twitch of muscle fiber; a single cycle of filament sliding in response to sarcoplasmic calcium burst; not maximal contraction

what does binary mean?

either happens or doesn’t happen

can twitches vary in length?

yes (20-200 ish millisec)

can action potential summate?

NO, but the twitches CAN

what are two ways to prepare muscles for movement?

store ATP or make ATP at an adequate rate to support contraction

what is cool about creatine kinase?

it is reversible (can move between CP or creatine with an addition/subtraction of a phosphate)

what’s a chynase?

enzyme that transfers a phosphate (PO4-3) from one molecule to another

creatine kinase

very fast; at rest you store creatine phosphate ATP

what’s the most efficient way to make ATP?

anaerobic pathway (makes 36 ATP + water + CO₂) BUTT it’s slow (can only last abou t6-7 seconds)

where does aerobic pathway take place?

in the mitochondra

how much ATP is made in anaerobic?

2 very fast! ANDD you’re making lactic acid which is bad!

type 1 fibers

slow-twitch oxidative (SO); is making ATP through the aerobic pathway; efficient but slow

fast twitch (anaerobic) glycolytic (FG)

type IIb; uses anaerobic pathway, fast and strong with low endurance

fast twitch oxidative glycolytic (FOG)

type IIa; can do both just not as good

myoglobin

stores oxygen in muscle cells in sarcoplasm; is red!

glycogen

storage form for glucose

what are the 3 things muscles can store?

creatine phosphate, oxygen, glucose (as glycogen); which are all needed for ATP production

why is myoglobon expression higher in oxidative fibers?

more myoglobin = more O₂ availability to drive aerobic generation of ATP that fuels crossbridge cycling (type 1 and type 2a)

why is mitochondrial number higher in oxidative fibers?

more mitochondria = more O₂ dependent “power houses” to drive aerobic generation of ATP that fuels crossbridge cycling (type 2a)

where does aerobic respiration occur?

mitochondria

can mitochondria multiply in cells?

yes; by binary fission