Musculoskeletal Systems

Three types of vertebrate muscle

All the vertebrate muscle use a ______ _____ ______ mechanism

_____ _____ cells are called muscle fibers and are large and _______.

Skeletal muscles form from fusion of embryonic _______

One skeletal muscle consists of many muscle fibers bundled together by _____ ____

Contractile proteins:

Each muscle fiber has several _______ (define)

How many actin filaments surround one myosin filaments

Each myofibril consists of _____ (define)

Each sarcomere is bounded by ______ which anchor actin

A band

_____ & _____ allow no overlap of actin and myosin

Titin

Bundles of _____ filaments are held in the center of the ______ by titin

When muscle contracts, ______ shorten and ______ pattern changes

The _____ _____ _____ of muscle contraction depends on structure of actin and myosin molecules

Myosin molecule has two ________ _______ coiled together, ending in a ________ head

Myosin filaments is many molecules in _______

Actin filaments is _____ _____ in a long, twisited molecules

________ twists around actin; _______ is attached at intervals

Myosin heads can bind to specific sites on ____ molecules to form _____ _____. _____ changes conformation, causes _____ filament to slide 5-10nm

Muscle cells are excitable meaning

Muscle contraction is initiated by action potentials from a _____ _____ at the _______ _____

Motor unit

One muscle may have many _____ ____. To increase strength of muscle contraction we increase rate of _____ ____ ____ or _____ _____ _____ _____ fire

Action potentials in muscle fiber also travel deep within the cell. ______ (_____ ____) descend into the sarcoplasm (____ _____ _____)

T tubules run close to the _____ _____ (define)

How many proteins span space between t tubules and sarcoplasmic reticulum & are physically _______.

The ________ receptor on the t tubule membrane is voltage sensitive. The _______ receptor in the sarcoplasmic reticulum membrane is a Ca++ channel

When an action potential reaches the dihydropyridine (DHP) it ______ ______. The ryanodine receptor then allows _____ to leave the _____ _____. ______ diffuses into the ______ and triggers interaction of _____ & ____ and sliding of filaments

At rest Ca++ concentration is higher in the ________ than in the _______

Actin filaments also include _______ & _____

Troponin has ______ ______ what does does each bind to

At rest, _________ blocks the binding on actin

When Ca++ is released, it binds to ______, which _____ _____

Troponin is bound to _____ and as ______ twists it exposes _____ ____ on actin

When Ca++ pumps remove Ca++ from the sarcoplasm, _______ stops

In skeletal muscle, the minimum unit contraction is a ____ which is measured in terms of ______ or ______ it generates. A single action potential generates a single _____.  The force generated depends on how many fibers are in the ____ ____

Tension generated by entire muscle depends on: (2)

If ______ ______ are close together in time, the ____ are summed, tension ______ and they are recognized as a ____ ____

Twitches sum because Ca++ pumps can not clear Ca++ from ______ before next _____ _____ arrives

Tetanus (w/ respect to action potential):

How long muscle fiber can sustain tetanic contraction depends on ____ ____. ____ is needed to break the _____-____ bonds and the recock the the myosin heads.

To maintain contraction, _____-_____ ____ have to keep cycling

_____-_____ _____ are oxidative or red muscle

Slow-twitch fibers contain ______ which is an ______ binding protein, and has many ______. It is well supplied w/ blood vessels

Maximum tension in slow-twitch fibers develops _____ and is _____ resistant to fatigue

Slow-twitch fibers have reserves of _____ and ____ that can produce _____ as long as ______ is available. Muscles with a high proportion of slow-twitch fibers are good for ______ work like distance jogging etc

Fast-twitch fibers are ______ or _____ _____. They have _____ mitochondria, fewer _____ ______ and little or no _____.

Fast-twitch fibers develop _____ _____ faster but _____ more quickly. They also can't replenish ATP for ______ _____.

Proportion of fast-and slow-twitch fibers in skeletal muscle is determined mostly by _____ _____. _____ can alter muscle properties to a certain extent.

The _____ _____ of the sarcomeres determines how much force can be generated. If stretched, less overlap between actin & myosin fibers means fewer ____ ____ and less ____. If fully contracted, there is no more space for _____.

Muscles have three systems for supplying ATP for contractions:

Immediate system:

Glycolytic system: 

Oxidative system:

Muscles contains _____ ______ which stores energy in a _____ bond that can be transferred to ADP

Immediate system = ____+_____. This system is exhausted within seconds

The glycolytic system enzymes are in the ______; ATP generated is then rapidly available to _____. Glycolysis alone is not very efficient because _____ _____ accumulates. Immediate and glycolytic systems provide energy for less than _____ _____

Oxidative sytems produce large amounts of ____, but takes place in the ________. ____ must diffuse from the ______ to the ____. This makes this the _____ of the 3 systems

Cardiac muscle is also ______, the cells are smaller than ______ muscle and have ____ nucleus

Cardiac muscle cells also ______ & _____ so they can withstand _____ pressures

______ & ______ cells initiate and coordinate heart muscle contraction. The heartbeat is _____ which means it is generated by the _____. ______ nervous system modifies the rate of ______ cells, but is not necessary for their function

Smooth muscle is in most ____ ____ and is under the control of the ______ _____ ____. Smooth muscle cells are arranged in _____ and have electrical contact via ____ ______. As a result _____ ______ can spread from on cell to the next in the sheet

Plasma membrane of _____ ____ cells is sensitive to stretch. Stretched cells ______ and fire ____ _____ which start contraction. This is important for ______.

Neural influences on smooth muscle comes from the _____. ______ in ______ ____ causes depolarization and action potentials, causing _____. _______ causes the same cells to ______ leading to fewer contraction.

Ca++ inlfux to sarccoplasm stimulated by ______, ______ or ______. Ca++ binds with ______ which activates _____ _____ which phosphorylates _____ ____; and can then bind and release actin