Anatomy & Physiology Cht 8 HWK Muscular System

Which of the following best describes the role of calcium in muscle contraction?

It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin.

The chemicals then bind to receptors located on the ____________ , a specialized area of the sarcolemma.

motor end plate

At this junction, the ____________ releases a type of chemical called a ____________ .

motor neuron, neurotransmitter

An electrical impulse traveling along the sarcolemma and into transverse tubules causes calcium ions to diffuse from the ________ into the ________.

sarcoplasmic reticulum; sarcoplasm

The site where the neuron communicates with the muscle fiber is called the ____________ .

synapse

These chemicals diffuse across a small gap between the neuron and muscle fiber called the ____________ .

synaptic cleft

Muscle fatigue is due in part to decreased ATP levels in muscle cells.

True

The amount of oxygen needed to repay the oxygen debt includes the amount of oxygen that muscle cells need to resynthesize ATP.

True

The steps of muscle relaxation in the proper sequence

1. Nerve impulses no longer arrive at neuromuscular junction. 2. Acetylcholine is no longer released. 3. Acetylcholinesterase decomposes ACh, and the muscle fiber is no longer stimulated. 4. Calcium ions are actively transported from sarcoplasm into the sarcoplasmic reticulum. 5. Troponin and tropomyosin shift, blocking further interaction between myosin and actin. 6. Muscle fiber relaxes.

Chronological order the events that occur at a neuromuscular junction.

1.Nerve impulse arrives at distal end of motor neuron axon. 2. Some vesicles release acetylcholine. 3. Acetylcholine diffuses across synaptic cleft. 4. Acetylcholine binds to receptors on motor end plate. 5. Membrane permeability to sodium is increased (opening of sodium channels) 6. Sodium enters muscle cell. 7. Triggers an electrical impulse along sarcolemma.

Fast-twitch fibers

Fatigable Glycolytic Used in forceful exercise

Slow- twitch fibers

Fatigue resistant Oxidative Many mitochondria Extensive capillary networks Used in low intensity exercise

Visceral smooth muscle

Fibers can stimulate each other Responds as a single unit Exhibits rhythmicity Found in the urinary bladder Found in the walls of the digestive tract

Multiunit smooth muscle

Fibers function as separate units Found in the iris of the eye Found in walls of blood vessels

Order from largest to smallest the components of a skeletal muscle

Muscle Fascicle Muscle fiber Myofibril Myofilaments

The binding of the chemicals to the muscle cell causes a electrical impulse to travel across the sarcolemma and down the ____________ tubules.

Transverse

The chemical used at the junction with a skeletal muscle is ____________ .

acetycholine

The neurotransmitter that is released at neuromuscular junctions and that stimulates skeletal muscle to contract is ______.

acetylcholine

In order for muscle contraction to occur, cross-bridges form between:

actin and myosin.

The structures found within a skeletal muscle

page 190 figure 8.1

Know the features of a neuromuscular junction

page 193 figure 8.5

Know the components of a myofibril

page 193 figure 8.6

The figure depicting the steps in cellular respiration

page 197 figure 8.10

Know the phases of a muscle twitch

page 199 figure 8.11

Know the indicated muscles of the body

page 206 figure 8.17

Know the indicated muscles

page 210 figure 8.20

The muscles seen in the lateral view of the thigh

page 215 figure 8.27