Ch. 12 Homework

Question 1

Skeletal muscle has ______ cells eith ______ nuclei. It functions in ______ movement of the body.

Answer 1

Striated, multiple, voluntary

Question 2

Skeletal muscle contraction allows the body to move, remain upright, and produces heat as ATP is ______.

Answer 2

Broken down

Question 3

Skeletal muscle is ______ the skeleton. A layer of connective tissue covers the skeletal muscle. The tissue contributes to the ______, which attaches the muscle to the bone.

Answer 3

Attached to, tendon

Question 4

Filament ______ does not change whether a sacromere is contracted or relaxed.

Answer 4

Length

Question 5

Actin filaments slide past myosin filaments, causing the ______ to shorten.

Answer 5

I band

Question 6

Thus, the Z line moves inward and the _____ nearly disappears.

Answer 6

H zone

Question 7

The movement of actin in relation to myosin, which is explained by the sliding filament model, is responsible for ______.

Answer 7

Muscle contraction

Question 8

One motor axon goes to ______.

Answer 8

Several muscle fibers

Question 9

Within the ______, a synaptic cleft lies between each axon terminal and muscle fiber. Nerve impulses cause synaptic vesicles to discharge ______.

Answer 9

Neuromuscular junction, acetylcholine (ACh)

Question 10

This neurotransmitter diffuses across the cleft and binds to receptops in the ______, which generate electrical signals that spread across it and down the ______.

Answer 10

Sacrolemma, t-tubules

Question 11

This stimulates the release of calcium ions from the ______, which leads to sacromere contraction.

Answer 11

Sacroplasmic reticulum

Question 12

The amount of ATP that normally exists in a muscle cell lasts for ______ during strenuous exercise.

Answer 12

A few seconds

Question 13

There are three ways that muscles can obtain ATP. Two methods, ______ and creatine phosphate breakdown, are anaerobic and are therefore available even when oxygen supplies are low during vigorous exercise.

Answer 13

Fermentation

Question 14

The speediest way for muscle cells to make ATP is by breaking down ______, which occurs in the midst of the sliding filaments.

Answer 14

Creatine phosphate

Question 15

During fermentation, glucose is broken down into ______, which can result in cramping and fatigue.

Answer 15

Lactate

Question 16

Most of the ATP generated by a muscle cell comes from ______, which uses either glucose or ______ to produce ATP. A muscle-specific molecule called ______ helps provide oxygen for this process.

Answer 16

Cellular respiration, fatty acids, myoglobin

Question 17

Slow-twitch fibers have a slow and persistent contraction and tend to be involved in activities requiring mostly ______.

Answer 17

Endurance

Question 18

Despite having motor units with a lower concentration of ______, slow-twitch fibers are probably useful in sustained activities such as long-distance running, biking, jogging, and swimming.

Answer 18

Myofibrils

Question 19

Fast-twitch fibers derive most of their ATP from anaerobic resources such as ______.

Answer 19

Fermentation

Question 20

The rapidly available energy and strength in fast-twitch fibers provide explosive movement an are most useful in short term activities such as ______.

Answer 20

Sprinting

Question 21

Since fast-twitch fibers depend primarily on less efficient anaerobic energy production, they tend to fatigue quickly due to the accumulation of ______.

Answer 21

Lactic acid

Question 22

The _______ are a group of ______ diseases that affect the muscles. These disorders vary considerably in their severity.

Answer 22

Muscular dystrophies, genetic

Question 23

Millions of Americans suffer from ______, a muscle and ligament disorder that causes chronic pain and fatigue. The cause of this disease is still unknown but may be due to underlying ______.

Answer 23

Fibromyalgia, infection

Question 24

Myasthenia gravis is a/an ______ disease characterized by muscle weakness in the eyelids, face, neck, and extremities.

Answer 24

autoimmune

Question 25

In people with this disease, antibodies that destroy ______ impair muscle contraction.

Answer 25

ACh receptors

Question 26

Muscle cancer belongs to a group of cancers called soft tissue ______, which may also occur in bone, adipose, and cartilage.

Answer 26

Sarcomas

Question 27

Muscle cancer can occur in smooth and skeletal muscle. For instance, a ______ occurs in the smooth muscle of the uterine wall, while ______ are a rare form of cancer that sometimes originate in skeletal muscle.

Answer 27

Leiomyoma, rhabdomyosarcomas

Question 28

The skeleton and muscles together enable movement. Skeletal muscles contract and ______ on the bones to which they are attached, allowing us to respond to changes in the environment.

Answer 28

Pull

Question 29

Eating is possible in part due to the contraction of ______ associated with the jaw and tongue, and the rhythmic ______ contractions of peristalsis.

Answer 29

Skeletal muscle, smooth muscle