Ch. 12 Homework Flashcards
Skeletal muscle has ______ cells eith ______ nuclei. It functions in ______ movement of the body.
Striated, multiple, voluntary
Skeletal muscle contraction allows the body to move, remain upright, and produces heat as ATP is ______.
Broken down
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.
Attached to, tendon
Filament ______ does not change whether a sacromere is contracted or relaxed.
Length
Actin filaments slide past myosin filaments, causing the ______ to shorten.
I band
Thus, the Z line moves inward and the _____ nearly disappears.
H zone
The movement of actin in relation to myosin, which is explained by the sliding filament model, is responsible for ______.
Muscle contraction
One motor axon goes to ______.
Several muscle fibers
Within the ______, a synaptic cleft lies between each axon terminal and muscle fiber. Nerve impulses cause synaptic vesicles to discharge ______.
Neuromuscular junction, acetylcholine (ACh)
This neurotransmitter diffuses across the cleft and binds to receptops in the ______, which generate electrical signals that spread across it and down the ______.
Sacrolemma, t-tubules
This stimulates the release of calcium ions from the ______, which leads to sacromere contraction.
Sacroplasmic reticulum
The amount of ATP that normally exists in a muscle cell lasts for ______ during strenuous exercise.
A few seconds
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.
Fermentation
The speediest way for muscle cells to make ATP is by breaking down ______, which occurs in the midst of the sliding filaments.
Creatine phosphate
During fermentation, glucose is broken down into ______, which can result in cramping and fatigue.
Lactate
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.
Cellular respiration, fatty acids, myoglobin
Slow-twitch fibers have a slow and persistent contraction and tend to be involved in activities requiring mostly ______.
Endurance
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.
Myofibrils
Fast-twitch fibers derive most of their ATP from anaerobic resources such as ______.
Fermentation
The rapidly available energy and strength in fast-twitch fibers provide explosive movement an are most useful in short term activities such as ______.
Sprinting
Since fast-twitch fibers depend primarily on less efficient anaerobic energy production, they tend to fatigue quickly due to the accumulation of ______.
Lactic acid
The _______ are a group of ______ diseases that affect the muscles. These disorders vary considerably in their severity.
Muscular dystrophies, genetic
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 ______.
Fibromyalgia, infection
Myasthenia gravis is a/an ______ disease characterized by muscle weakness in the eyelids, face, neck, and extremities.
autoimmune
In people with this disease, antibodies that destroy ______ impair muscle contraction.
ACh receptors
Muscle cancer belongs to a group of cancers called soft tissue ______, which may also occur in bone, adipose, and cartilage.
Sarcomas
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.
Leiomyoma, rhabdomyosarcomas
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.
Pull
Eating is possible in part due to the contraction of ______ associated with the jaw and tongue, and the rhythmic ______ contractions of peristalsis.
Skeletal muscle, smooth muscle
