Chapter 9 A+P

Which of the following is NOT a function of skeletal muscle? Maintain body temperature Maintain posture Metabolize food Produce movement

Maintain body temperature

Which of the following terms refers to the cytoplasm of a skeletal muscle fiber? Sarcomere Sarcoplasm Sarcosome Sarcolemma

Sarcoplasm

Which of the following organelles in skeletal muscle cells store calcium? Mitochondria Sarcoplasmic reticulum Myofibrillar filament network Intermediate filament network

Sarcoplasmic reticulum

Which of the following is the difference between skeletal muscle cells and typical cells? Skeletal muscle cells are shorter than normal cells Skeletal muscle cells are multinucleate Skeletal muscle cells have fewer mitochondria than normal cells Skeletal muscle cells are controlled by the central and peripheral nervous systems

Skeletal muscle cells are multinucleate

Which of the following describes aponeuroses? The filaments appear as striations. The tropomyosin-troponin complex The endoplasmic reticulum Broad sheets of fibers that attach to bones

Broad sheets of fibers that attach to bones

Which of the following is NOT characteristic of smooth muscle? The thin filaments of smooth muscle fibers are attached to dense bodie Smooth muscles lack sarcomeres. Smooth muscles are uninucleate. Smooth muscles form tendons and aponeuroses.

Smooth muscles form tendons and aponeuroses.

Which of the following is the advantage of having many nuclei in a skeletal muscle fiber? The ability to contract The ability to produce large amounts of the enzymes needed for contraction The ability to repair the fiber after an injury The ability to be stimuli

The ability to produce large amounts of the enzymes needed for contraction

Isotonic contractions occur when the muscle

The length of the muscle changes and a load is moved. When enough tension has developed for the needed movement, tension stays nearly constant through the remainder of the contractile period.

The nervous system communicates with skeletal muscles at which of the following sites? The transverse tubule The tail of myosin The sarcoplasmic reticulum The neuromuscular junction

The neuromuscular junction

what neurotransmitters are involved in contraction of skeletal muscle? What mineral ions are important for contraction of skeletal muscle?

acetylcholine calcium ion Na+ K

Why does muscle fatigue occur?

because of interruption of muscular blood supply or occasionally a lack of ACh in the motor neuron axons. Lactic acid accumulation is the usual cause of muscular fatigue

Define the terms sarcolemma, myofibrils, glycosomes, and myoglobin.

sarcolemma: The thin membrane covering a striated muscle fiber. myofibrils: Thread-like fibers that make up the sarcoplasm glycosomes:Granules of stored glycogen; they provide glucose during muscle cell activity. myoglobin:A pigment synthesized in the muscles to give skeletal muscles their reddish-brown color.

explain the only type of muscle that is consciously controlled.

skeletal

compare the myosin found in smooth and skeletal muscle.

smooth: There is a calcium-binding protein that activates myosin kinase, calcium ions interact with calmodulin, A different type of myosin exists in smooth muscle The calcium in smooth muscle activates an enzyme called a kinase, which transfers a phosphate group from ATP to another molecule. This changes the shape of myosin heads in order to form cross bridges skeletal: Calcium ions diffuse into sarcoplasm, binding to troponin molecules

discuss the four major characteristics of cardiac muscle.

striated cells that are connected into three-dimensional networks Cardiac muscle cells are the only type that commonly branch. only found in the heart This type of muscle is self-exciting and rhythmic

The space between the neuron and the muscle is the

synaptic cleft

A muscle is entirely covered by a(n)

epimysium

Cross-bridges are located on

myosin molecules

Skeletal muscles need all of the following factors to contract, except zinc. myosin. actin. calcium.

zinc

Describe the decomposition of ACh and the role of ACh in muscle contraction.

A nerve impulse reaches the end of an axon, and the axon terminal releases ACh into the synaptic cleft. Calcium ions activate synaptic vesicles. ACh diffuses across the cleft, attaching to ACh receptors on the muscle fiber's sarcolemma. Binding of ACh triggers electrical events that generate an action potential. The effects of ACh are quickly terminated by acetylcholinesterase, which breaks down ACh into its basic elements (acetic acid and choline)

Which of the following neurotransmitters contains the synaptic terminal of the neuromuscular junction?

ACh

Which of the following is the function of myoglobin? it produces the end plate potential It is a glycoprotein involved in the formation of DNA It breaks down glycogen It stores oxygen in muscle cells

It stores oxygen in muscle cells

explain oxygen use in relation to muscle contractions.

Oxygen is required for the breakdown of glucose in the mitochondria

Which of the following is NOT a function of skeletal muscle? The ability of the cells to respond to stimuli Providing peristalsis The ability of the muscle tissue to stretch The ability of the muscle tissue to forcibly become shorter

Providing peristalsis

In which of the following periods is a muscle unable to respond to stimuli temporarily? Latent period Fatigue period Refectory period Relaxation period

Refectory period

Which of the following is NOT a characteristic of smooth muscle? There are no sarcomeres There is a lack of troponin There are more thick filaments than thin filaments There is a calcium-binding protein that activates myosin kinase

There are more thick filaments than thin filaments

At rest, active sites on the actin are blocked by which of the following? Troponin molecules Calcium ions ATP molecules Tropomyosin molecules

Tropomyosin molecules

Discuss how troponin and tropomyosin affect skeletal muscle contraction.

Tropomyosin: To enable muscle contraction, tropomyosin must change conformation and uncover the myosin-binding site on an actin molecule, thereby allowing cross-bridge formation troponin protein molecule binds to tropomyosin, forming the troponin-tropomyosin complex Troponin is attached to the protein tropomyosin and lies within the groove between actin filaments in muscle tissue. calcium attaches to troponin, which causes it to change shape, exposing binding sites for myosin (active sites) on the actin filaments

Explain neuromuscular junctions and motor units.

neuromuscular junctions: is a synaptic connection between the terminal end of a motor nerve and a muscle (skeletal/ smooth/ cardiac). It is the site for the transmission of action potential from nerve to the muscle. Motor units: Each muscle fiber has a single motor end plate, although motor neuron axons have many branches connecting the motor neuron to various muscle fibers

Which of the following contains nerves and blood vessels that service the muscle fibers? Myofibrils Perimysium Sarcomeres Sarcolemma

perimysium

Define the terms I bands, A bands, Z discs, H zone, and M line.

the light bands (I bands) are made up of thin filaments of actin attached to round sheets known as Z lines (or Z discs). The Z lines or discs are made up of mostly alpha-actinin, a protein that anchors the thin filaments. The dark bands (A bands) are made up of thick filaments of myosin that overlap thin filaments of actin. There is a central region (H zone) of thick filaments, with a thickened area (the M line) that consists of proteins holding them in place.

A cycle of contraction and relaxation produced by a single stimulus is called a(n)

twitch