Homework 6

Cardiac muscle fibers are joined by special gap junctions call into collated desk; the disc allow heart actively to be costly coordinated

True

The effect of the neurotransmitter on the muscle cell membrane is to temporarily modify its permeability of ions such as Nat and K'

True

The formation of cross bridges requires both calcium ions and ATP

True

The neurotransmitter used by the nervous system to activate skeletal muscle cells is acetylcholine.

True

The sacralplasmic reticulum wraps like a sleeve around the myofibril and stores and releases calcium

True

The striations seen in skeletal muscle are actually alternating dark A and light I bands

True

When a muscle fiber contracts, the I bands nearly disappear, the H zones disappear, and the A bands move closer together but do not change in length.

True

In a neuromuscular junction, synaptic vesicles in the motor neuron contain which neurotransmitter?

acetylcholine ( ACh )

What initiates action potential on a muscle cell?

acetylcholine binding to receptors on the sarcolemma within the neuromuscular junction

What enzyme breaks down acetylcholine into acetic acid and choline to prevent continued contraction of the muscle fiber?

acetylcholinesterase

A myosin head binds which molecule to form a cross bridge?

actin

Which of these increases as muscles age?

amount of connective tissue in a muscle

What causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum within a muscle cel?

arrival of an action potential

What causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum within a muscle cell?

arrival of an action potential

What causes the myosin head to disconnect from actin?

binding of ATP

What mineral is released within muscle cells to trigger contraction?

calcium

Striated involuntary muscle tissue is classified as ________ muscle.

cardiac

What type of muscle tissue is both striated And involuntary?

cardiac muscle

Muscle tissue has the abity to shorten when adequately stimulated, a characteristic known as

contractility

The heads of the myosin myofilaments are calledwhen they link the thick and thin filaments together during skeletal muscle contraction.

cross bridges

What is the function of creatine phosphate?

directly regenerates ATP from ADP within a muscle cell

Which layer of connective tissue surrounds each skeletal muscle fiber?

endomysium

What means of membrane transport is used to release the neurotransmitter into the synaptic cleft?

exocytosis

A smooth, sustained contraction, with no evidence of relaxation, is called

fused, or complete, tetanus

What term describes the ability of a muscle to vary its degree of shortening to generate the strength needed to lift a 5 lb weight, a 7 lb weight, and finaly a 10 lb weight?

graded responses

A motor neuron and all of the skeletal muscle fibers it stimulates are termed a

motor unit

Which of the following is an example of an isometric contraction?

pushing against an immovable wall

What is key to offsetting the effects of aging on the muscular system?

regular exercise

What can older individuals do to increase muscle strength?

regularly use hand weights and practice leg lifts

What causes the power stroke?

release of ADP and Pi

What type of exercise causes increase in muscle size?

resistance exercise

How is acetylcholine (ACh) removed from the synaptic cleft?

simple diffusion away from the synaptic cleft and acetylcholinesterase (AChE; an enzyme)

The gap between the axon terminal of a motor neuron and the sarcolemma of a skeletal muscle cell is called the

synaptic cleft

What term refers to a muscle that aids another muscle by producing the same the movement or reducing undesirable movements?

synergist

Which one of the following is composed mostly of the protein myosin?

thick filaments

The binding of calcium to which molecule causes the myosin binding sites to be exposed?

troponin

When an action potential arrives at the axon terminal of motor neuron, which ion channels open?

voltage-gated calcium channels

The binding of the neurotransmitter to receptors on the motor end plate causes which of the following to occur?

Binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate junctional folds of the sarcolemma) and sodium enters the cell.

Striated involuntary muscle tissues found in the heart is

Cardiac Muscle

The perimysium wraps a fascicle of muscle cells and is represented by

Label C

What happens to a muscle when the nerve supplying that muscle is cut?

Muscle paralysis and atrophy occur

The action potential on the muscle cell leads to contraction due to the release of calcium ions. Where are calcium ions stored in the muscle cell?

O O terminal cisterns (cisternae) sarcoplasmic reticulum

Which connected tissue bundles muscle fibers into fascicles

Perimysium

What type of muscle tissue contracts must quickly upon stimulation

Skeletal

The type of muscle tissue pictured in the figure is

Smooth Muscle