Study guide Chapter 9

Distinguish between a muscle's origin and its insertion

The origin of a muscle is the end of the muscle attached to an immovable part. The insertion is the end of a muscle attached to a moveable part. When a muscle contracts, the insertion is pulled toward the origin

The chemical that is necessary for the transmission of an impulse from a nerve to a muscle fiber is _________

acetylcholine

The characteristic striated appearance of skeletal muscle is due to the arrangement of alternating protein filaments composed of _________ and _____________

actin, myosin

Identify the major events that occur during skeletal muscle contraction

1. An action potential in a motor neuron causes acetylcholine to release in the synaptic cleft. 2. Acetylcholine binds with receptors on the cell membrane on the muscle fiber, opening Na+ (Calcium) channels. 3. Calcium is released from the terminal cisternae into the muscle fiber. 4. Calcium binds to troponin 5. Troponin shifts tropomyosin, which was blocking the active site on the actin. 6. Myosin heads attach to actin by breaking down ATP to ADP and a phosphate via Myosin-ATPase 7. The Myosin head forms a 'cross-bridge' on the active site of the actin filament. 8. The cross bridge pulls actin, which slides over the myosin - known as the 'Power Stroke.' 9. The release of ADP completes the cross-bridge movement and ATP attaches to myosin, breaking the actin-myosin crossbridge. 10. Every time ATP is split into ADP + P, the myosin head 'cocks' into place to form another cross bridge with actin.

List three outcomes of muscle actions

1. Movement 2. Muscle actions provide muscle tone. 3. Propel body fluids and food 4. Generate heartbeat 5. Distribute heat

Describe the neural control of skeletal muscle contraction

A neurotransmitter is a chemical stored in the synaptic vesicles, which, when stimulated by a nerve impulse, is released into the gap at the motor end plate and stimulates the fiber to contract

Describe the difference between a tendon and an aponeurosis

A tendon is a projection of connective tissue beyond the ends of the muscle that attaches to bone. An aponeurosis is a broad fibrous sheet of connective tissue that connects muscles to adjacent muscles.

Distinguish between a twitch and a sustained contraction

A twitch is the contractile response of a single muscle fiber to a muscle impulse. During a sustained contraction, many action potentials are triggered in a motor neuron, resulting in a contraction of increasing strength

Muscle tone refers to ___________________ A- a state of sustained, partial contraction of muscle that is necessary to maintain posture B- a feeling of well-being following exercise C- the ability of a muscle to maintain contraction against an outside force D- the condition athletes attain after intensive training

A- a state of sustained, partial contraction of muscle that is necessary to maintain posture

A person feels out of breath after vigorous exercise because of oxygen debt. Which of the following statements helps explain this phenomenon? A- anaerobic respiration increases during strenuous activity B- Lactic acid is metabolized more efficiently when the body is at rest C- conversion of lactic acid to glycogen occurs in the liver and requires energy D- priority in energy use is given to ATP synthesis

A- anaerobic respiration increases during strenuous activity C- conversion of lactic acid to glycogen occurs in the liver and requires energy D- priority in energy use is given to ATP synthesis

Peristalsis is due to which of the following characteristics of smooth muscle? A- capacity of smooth muscle fibers to excite each other B- automaticity C- rhythmicity D- sympathetic innervation

A- capacity of smooth muscle fibers to excite each other C- rhythmicity

The kind of energy that muscles use to contract ________ A- chemical B- electrical C- heat

A- chemical

The period of time between a stimulus to a muscle and muscle response is called the ____________ A- latent period B- contraction C- refractory period

A- latent period

When the cross bridge of the myosin molecule forms linkages with actin filaments, the result is ______ A- shortening of the muscle fiber B- membrane polarization C- release of acetylcholine

A- shortening of muscle fiber

The energy used in muscle contraction is supplied by the decomposition of __________

ATP

Layers of connective tissue extending into the muscle to form partitions between muscle bundles are continuous with attachments of muscle to periosteum called ________ A- ligaments B- tendons C- aponeuroses D- elastin

B- tendons

The union between a nerve fiber and a muscle fiber is the _________ A- motor neuron B- motor end plate C- neuromuscular junction D- neurotransmitter

C- neuromuscular junction

The strength of a muscle contraction in response to different levels of stimulation is determined by the ______________ A- level of stimulation delivered to individual B- number of fibers that respond in each motor unit C- number of motor units stimulated D- characteristics of each muscle group

C- number of motor units stimulated

Describe how oxygen is supplied to skeletal muscles

Oxygen is carried from the lungs by hemoglobin in the blood. When the hemoglobin reaches the muscle, the oxygen is transferred to the myoglobin in the muscle fiber. Myoglobin is similar to hemoglobin in its oxygen capacity, and reduces the muscle's need for continuous blood supply during contraction

Define peristalsis and explain its function

Peristalsis consists of alternating contractions and relaxations of the longitudinal and circular muscle fibers. It functions to force the contents of a tube along its length

Distinguish between concentric and eccentric contractions, and explain how each is used in body movements

Concentric = Shortening occurs If a person lifts an object, the muscles remain taut, their attached ends pull closer together, and the object is moved. The muscle contracts with force greater than resistance and shortens. Eccentric = lengthening occurs The muscle contracts with less force than resistance and lengthens. Laying a book down on a table is an example

Explain how limb movements function as levers

Limb movements function as levers in that they contain all four basic components: a rigid bar, a pivot, an object that is moved against resistance, and a force that supplies energy

The ion necessary to link myosin and actin is _______

calcium

Atrophy refers to a(n) (increase, decrease) in the size and strength of a muscle.

decrease

A neurotransmitter ____________

diffuses across a synaptic cleft from a neuron to muscle cell

The attachment of a muscle to a relatively fixed part is called the _______________; the attachment to a relatively movable part is called the ______________

origin, insertion

Smooth muscle contracts (more slowly, more rapidly) than skeletal muscle following stimulation.

more slowly

A motor neuron and the muscle fibers it controls are called a __________

motor unit

Two types of smooth muscle are _____________ muscle and __________ muscle.

multiunit, visceral

Impulses travel relatively (rapidly, slowly) through cardiac muscle.

rapidly

List the tissues found in skeletal muscle.

skeletal muscle tissue blood nervous tissue connective tissue

After prolonged muscle use, muscle fatigue occurs due to an accumulation of ________________

lactic acid

The minimal strength stimulus needed to elicit contraction of a single muscle fiber is called a ______________

threshold stimulus