Anatomy Lecture exam 3

What is the sacroplasmic reticulum?

- Similar to smooth endoplasmic reticulum, - surrounds bundles of contractile proteins - Terminal cisternae and calcium; Triads

terminal cisternae

-Blind sacs of sarcoplasmic reticulum -Serve as reservoirs for calcium ions -Combine in twos with central T-tubule to form triads

what is fast oxidative fibers

-Intermediate or type illa -Least numerous of types -Intermediate size -Fast ATpase -Produce fast, powerful contraction primarily aerobic respiration, but delivery of oxygen lower -Contain myoglobin, but less than slow oxidative

myofibrils

-Long cylindrical structures -Extend the length of muscle fiber -Compose 80% of the volume of muscle fiber -Each fiber with hundreds to thousands

Put the steps of cross-bridge cycling in the order they occur, starting with formation of cross-bridges between myosin and actin.

1. Cross-bridge formation (myosin binds to actin) 2. Myosin head pulls and slides actin filament, myosin releases ADP and Pi 3. Myosin head binds ATP and releases from actin. 4. Myosin head resets as it breaks down ATP into ADP and Pi.

Most parts of the sarcomere shorten during contraction, but what part of the sarcomere stays the same size during contraction?

A band

What is the I band of the sarcomere?

Actin filaments, Z discs, and connectin - but no overlap with thick filaments.

Of the three systems that make energy for muscle cells, which one uses oxygen and makes the most ATP?

Aerobic cellular respiration

What is the sarcoplasm?

- Cytoplasm of muscle fibers (cells comprising muscle) - Contains typical cellular structures (Golgi apparatus, ribosomes, vesicles) - Has specialized cellular structure

What is the 'neuro' part of the neuromuscular junction?

It's the axon terminal of a motor neuron that contacts the muscle cell.

What does the sarcoplasmic reticulum do in muscle cells?

Stores calcium and releases it when the action potential travels into the T tubule.

The muscle fibers arranged in the orbicularis oculi have a circular arrangement -- what does this mean?

They are arranged in a ring around an opening.

What do you know to be true for "slow oxidative fibers"?

They use aerobic respiration to make ATP, are a darker red color because they have myoglobin, and usually have slower contractions than fast fibers.

The occipitofrontalis muscle has its origin on the occipital bone and inserts into the skin of the eyebrows and nose. What would you expect its action to be?

To wrinkle the forehead, as it moves the scalp and eyebrows.

What is a synergist?

a muscle that assists the agonist in performing its action

What is an antagonist?

a muscle working in opposition to agonist

The muscle whose action is opposite that to the action of the agonist is the _____.

antagonist

Where is the rectus abdominus located?

anterior-most part of the abdominal wall, under the rectus sheath.

The erector spinae muscles (spinalis, longissimus, and iliocostalis)

are the superficial trunk muscles that maintain posture and keep the spine erect.

what is a belly of a muscle?

between origin and insertion

Which one of the following muscles is most likely to be involved in a frown?

depressor anguli oris

The following muscles are all used in breathing. Which one is the prime mover?

diaphragm

As part of the posterior compartment muscles of the thigh, the hamstrings

extend the hip

what is the origin?

fixed, less mobile end(s) of the muscle

Generally speaking, the anterior arm muscles (ie, biceps brachii)

flex the elbow

Which set of muscles moves the tongue?

genioglossus, palatoglossus, styloglossus

The _____ is the more mobile end of the muscle.

insertion

what is an action of a muscle?

movement that occurs when muscle contracts

Due to its size and locations of its origin and insertion, the trapezius muscle has multiple actions. One of those actions is

moves/stabilizes the scapula

What is an agonist?

muscle that contracts to produce a movement

What protein will you find in thick filaments?

myosin

Muscles in the posterior compartment of the leg, like the gastrocnemius muscle,

plantar flex (push down) the foot.

sarcolemma

plasma membrane of a muscle fiber

What is a prime mover?

plays major role in accomplishing movement

The masseter is the prime mover of the muscles involved in chewing (mastication). It

pulls the jaw up and forward.

Why is skeletal muscle rich in blood vessels and innervation?

skeletal muscles need to bring in a lot of oxygen and nutrients and quickly remove wastes to function properly. Nerves allow us to control contraction consciously.

what is fixators?

stabilize the point of origin of the prime mover

What is the H zone of a sarcomere?

that consists of the thick myosin filaments and its embedded M lines.

The sternocleidomastoid has its origins on the manubrium and clavicle and inserts onto the mastoid process. When both contract equally,

the neck flexes.

what is the z disc of a sarcomere?

the zig zag portion that marks the end of each sarcomere and allows for the attachment of actin filaments and titin.

what is the A band of the sacromere?

which is a section that contains the entire length of a thick myosin filament, along with overlapping portions of the thin actin filaments. This section makes up the dark part of the striation pattern.