Chapter 10

For the muscle to contract and relax, what must be present (choose all that apply)?

- ATP - calcium ions - ACh

Myofibrils contain what type of proteins? Select all that apply.

- contractile proteins. - regulatory proteins. - structural proteins.

During muscle contractions , thin filaments are pulled towards the

M line

The zone of overlap increases during the

contraction period

Which type of muscle tissue is capable of undergoing the stress-relaxation response when stretched?

single-unit smooth muscle fibers

Why will an individual who lifts weights build larger muscles?

skeletal muscles increase number of myofibrils but not number of cells

A brief contraction of all muscle fibers in a motor unit in response to a single action potential moving down the somatic motor neuron is known as

twitch contraction.

What energizes the myosin head?

ATP hydrolysis reaction

When an athlete performs a pull up (raising their chin to a bar while their body hangs), the process of pulling the body up so the chin can touch the bar is

Concentric

What is the result of acetylcholine attaching to the ligand gates of the motor end plate?

the sarcolemma increases permeability to sodium

For crossbridges to occur, what events must happen? Select all that apply.

- ATPase breaks down ATP. - calcium ions be present in the sarcoplasm - myosin binding sites be exposed.

What proteins are found in thin filaments of skeletal muscle fibers? Select all that apply

- tropomyosin - myosin - actin - nebulin

Which regions of the sarcomere contain thick filaments? Select all that apply.

- zone of overlap - A band - H zone

In skeletal muscles, the combined amounts of creatine phosphate and ATP provide enough energy for the muscle to contract maximally for approximately

15 seconds

Which age group would be most susceptible to an increase in slow oxidative muscle fibers?

30+ years

Which region of a sarcomere contain thin filaments?

Both I band and A band

When an athlete performs a pull up (raising their chin to a bar while their body hangs), the process of lowering the body down is

Eccentric

When athletes is preparing to perform a pull up, they hang from the bar. At this point, they are performing what type of contractions?

Isometric

Myasthenia Gravis is an autoimmune disorder that targets the ACh receptors at the NMJ and ultimately reduces the number of available receptors. Predict what happens if you treat the patient with a drug that inhibits the activity of acetylcholinesterase?

The drug will increase contraction.

Which statement explains the sarcomere appearance change during a muscle contraction?

The light A bands remain at a constant length.

Writer's cramp can occur in Anatomy and Physiology lecture class. What factor would most likely contribute to the muscles not being able to relax?

a deficit of ATP keeping myosin from detaching

The opening of ligand gates on the sarcolemma is directly caused by

all choices are correct - acetylcholine attachment. - calcium influx into the motor neuron . - sodium influx into the muscle fiber. - acetylcholinesterase activity

After prolonged strenuous exercise has stopped, heavy breathing will often continue for several minutes in order to provide the oxygen needed to

all of these choices are correct - convert the lactic acid produced during exercise back into glycogen. - resynthesize creatine phosphate. - replace oxygen displaced from muscle myoglobin

Which ATP production would be sufficient to run in place for one minute?

anaerobic cellular respiration

Which correctly lists the sequence of structures that action potentials must move through to excite skeletal muscle contraction?

axon of neuron, sarcolemma, T tubules

Smooth muscle tone is maintained by the prolonged presence of [_____] in the muscle cell's cytosol?

calcium ions

At the neuromuscular junction, _______must enter the synaptic end bulb to stimulate the release of ____________, which binds to ligand gates so ________can enter the muscle fiber.

calcium ions; ACh, sodium ions

Contraction of myofibrils within a muscle fiber begins when

calcium is released from the sarcoplasmic reticulum

Which type of muscle tissue contracts when excited by their own autorhythmic muscle fibers?

cardiac muscle

The relaxation phase of a muscle contraction is often prolonged in a fatigued muscle, raising the likelihood of fused summation of action potentials causing painful disturbances to a skeletal muscle. What disturbance is being described?

cramp

Which protein is used to reinforce the sarcolemma and help transmit the tension generated by the sarcomeres to the tendons?

dystrophin

The outermost layer of connective tissue surrounding a skeletal muscle is the

epimysium

Which property of muscle gives it the ability to stretch without damage?

extensibility

World class shot-putters will have a higher percentage of ______in their arm muscles.

fast glycolytic fibers

Leg muscles are predominantly composed of which type of muscle fiber?

fast oxidative-glycolytic

Which of the regions of a sarcomere contain titin?

from M line to Z disc

After the fusion of myoblasts, the muscle fiber loses its ability to

go through mitosis

Strength training would result in

hypertrophy of fast oxidative-glycolytic fibers

Motor unit recruitment occurs when there is _______ in the number of active motor units within a skeletal muscle.

increase

Which microscopic structure is found only in the cardiac muscle tissue?

intercalated discs

Which term describes a somatic motor neuron and all the skeletal muscle fibers it stimulates?

motor unit

Which function do all three muscles perform?

moving and storing material throughout the body

Which disorder occurs when little to no proteins are produced to support the sarcolemma?

muscular dystrophy

Muscle damage can be indicated by...

myoglobin found in blood.

Which functions as a motor protein in all three types of muscle tissue?

myosin

Cross bridges are formed during muscle contraction when _____ binds to _____.

myosin; actin

In a neuromuscular junction, the effect of acetylcholine (ACh) binding to receptors on the motor end plate lasts only briefly due to

rapid destruction of ACh in the synaptic cleft by acetylcholinesterase.

Place the muscle tissue type in order from least to most ability to regenerate.

skeletal, cardiac, smooth

Which characteristics describe both skeletal and cardiac muscle?

striations

Skeletal muscle contraction is triggered to begin when calcium is released from

terminal cisterns of sarcoplasmic reticulum

Mitochondrial activity in skeletal muscle cells are usually efficient, but can have limited ATP production if

there is limited O2 availability

Why would cardiac muscles have longer refractory periods than skeletal muscles. Choose the best answer?

to preserve the normal rhythm of the heart and prevent fatigue