Chapter 11 - Histology

muscle fiber relaxation

ATP is a necessary component for

stays same width

During contraction of a sarcomere, what happens to the A band?

disappears

During contraction of a sarcomere, what happens to the I band?

some actin and all of myosin filaments

For a relaxed sacromere, choose the answer below that would fit for being present in the A band region

only myosin filaments

For a relaxed sacromere, choose the answer below that would fit for being present in the H Zone region.

smooth muscle

Individual muscle cells of this type have only one nucleus per cell and usually display a long slender form.

I band

Intercalated disks are junctions of two cardiac muscle fibers which occur only at the

false

Large terminal cisternae are found in the sarcoplasmic reticulum of heart muscle fibers.

false

Placing heart muscle fibers in solutions lacking calcium ions can cause the gap junctions present in the intercalated disk area to fall apart

false

The actin filaments contain club-shaped extensions that contain ATPase which is utilized to break down ATP for muscle contraction

sarcoplasm

The cytoplasm of a muscle cell is called the

titin

The large elastic accessory protein in the muscle sacromere which anchors the thick myosin filament to the Z-line is

ferritin-soaked muscles show ferritin inside T-Tubule

The lumen of the T-tubule is considered to be an inner extension of the external environment because:

sarcolemma

The plasma membrane of a muscle cell is called the

false

The process of forming G-actin from F-actin requires the presence of potassium and magnesium ions and also energy from the breakdown of ATP to ADP.

false

When calcium activates ATPase on the actin molecule, the actin undergoes a conformation change

tropomodulin

Which accessory protein in the sacromere caps actin and regulates the length of the thin filaments?

reticular fibers

Which connective tissue fibers form a network which wraps itself around individual muscle fibers are arranged in bundles such as in the intestine

Myasthenia gravis

Which disease listed below is an autoimmune disease in which the body produces antibodies to the acetylcholin receptors on the muscle sarcolemma.

oxytocin

Which hormone listed below causes contraction of the smooth muscle of the uterus in terminal stages of pregnancy?

smooth muscle

Which muscle type below is categorized as involuntary and forms the musculature of most hollow organs such as the bladder and alimentary canal.

skeletal muscle

Which muscle type below is voluntary and makes up most of the flesh of our limbs and also the covering musculature of our body.

Type III (slow glycolytic fibers)

Which skeletal muscle fiber type below is not found in human skeletal muscles.

true

a motor unit is considered to be a nerve fiber and all the muscle fibers it innervates

Type I (slow oxidative fibers)

choose the fiber type which is slow twitch, fatigue-resistant and found in high number in the long muscles of the human back which help maintain posture

only actin filaments

for a relaxed sacromere, choose the answer below that would fit for being present in the I Band region

skeletal muscle

individual muscle cells of this type have many nuclei per muscle fiber (multinucleated)

smooth muscle

individual muscle cells of this type have only one nucleus per cell and usually display a long slender form

false

muscle tissue is highly vascularized and innervated but does not have much connective tissue associated with it for its functional activity.

true

smooth muscle fibers normally are arranged in bundles such that the thick portion of the fiber lies alongside the thin portion of the next fibers

sarcomere

the contractile unit of a muscle is called a

sacroplasm

the cytoplasm of a muscle cell is called the

nebulin

the elongated inelastic protein which assists in anchoring the thin filaments to the Z-line is called what?

better enable action potential to reach center of muscle fiber

the function of the T-Tubule System is to

better enable action potential to reach center of muscle fiber

the function of the T-Tubule system is to

myofibril

the individual contractile unit of a muscle cell that can be viewed with the a light microscope is called the

false

the major function of the sacroplasmic reticulum is to sequester phosphate ions for the production of ATP

Z lines

the sacromere is the area on a skeletal muscle fiber which is located between two

true

the shortening of the distance between z lines in a sacromere is another way of defining muscle fiber contraction

true

troponin and tropomyosin on the thin actin filament move away in presence of calcium to permit myosin attachment

Calcium ions are released from the sacroplasmic reticulum

when the action potential or stimulus for contraction reaches the muscle fiber, the first thing that happens is

tropomyosin

which accessory protein in the sarcomere stabilizes the thin filaments and helps regulate binding of calcium ions?

vasopressin

which hormone causes contraction of the smooth muscle surrounding walls of arterioles to increase blood pressure