Test Two - Muscles

a twitch

A contractile response of a single muscle fiber to a single muscle impulse is called: -complete tetanic contraction -summation -the latent period -a twitch

Motor neuron; neurotransmitter

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

series of twitches

Classify the myograms based on frequency of stimulation: -Each stimulus is seperate

Summation

Classify the myograms based on frequency of stimulation: -Faster stimulus frequency: force increases because calcium ions are available in the cell

tetanus

Classify the myograms based on frequency of stimulation: -rapid stimulus frequency: maximum force is reached with no relaxation between stimuli

In order to produce movement, muscles must be attached to two different points called an origin and an INSERTION When a muscle contracts, the ORIGIN is the part of the muscle that is attached to the non-moving bone. The part of the muscle that is attached to the bone that will move is called the INSERTION Muscles of the limbs tend to have their insertions located in more DISTAL positions along the limbs while their origins are located more PROXIMAL Origins and insertions can attach directly to bone or via dense regular connective tissue sheets referred to as APONEUROSES or via rope-like cords called TENDONS

Complete each sentence describing muscle attachments. Labels can be used more than once.

Muscle fiber contractions called MUSCLE TWITCHES result from a single stimulus to a muscle fiber. Each contraction generates the same force. These contractions aren't physiologically useful. Two mechanisms can be used to cause contractions of greater force. One involves increasing the FREQUENCY of stimulation. The result is called SUMMATION in which each successive contraction is a bit stronger. If the frequency of stimulation is fast enough, a SUSTAINED contraction results. This is called TETANUS, during which no relaxation occurs between stimuli. Another way of increasing force of contraction is by the process of RECRUITMENT during which an increasing number of MOTOR UNITS are stimulated to contract.

Complete the sentences describing processes that result in stronger contractions.

As strenuous activity begins, muscle cells first use the *ATP* molecules present in their cytoplasm as their source of energy. The supply of this molecule, however, is limited. It must be produced by other means in order for exercise to continue. In order to produce more ATP, the muscle cells next start to use CREATINE PHOSPHATE, also present in the cytoplasm, to form new ATP. This is done by moving a phosphate and its energy from this molecule to ADP, forming new ATP. As exercise continues, the cells now begin to use GLUCOSE as a fuel to produce ATP. Initially, the anaerobic pathway called GLYCOLYSIS uses this fuel to produce 2 ATP and 2 molecules of pyruvic acid If little or no oxygen is available, pyruvic acid is converted to LACTIC ACID. If, however, oxygen is available, the pyruvic acid molecules enter the aerobic respiration pathways. As long as oxygen is available, the oxidation of each glucose molecule using aerobicmetabolism will produce *36* ATP molecules.

Complete the sentences describing the energy sources for the skeletal muscle contraction.

1) After a muscle fiber is stimulated by a motor neuron, an electrical impulse travels along the sarcolemma and deep into the fiber via TRANSVERSE TUBULES 2)As the electrical impulse reaches the SARCOPLASMIC RETICULUM, permeability of the cisternae to calcium increases. 3)CALCIUM IONS diffuse from the sarcoplasmic reticulum into the sarcoplasm. These ions bind to TROPONIN molecules. 4)Interaction between troponin and TROPOMYOSIN results in exposure of binding sites on actin. Then, MYOSIN HEADS bind to these sites. 5)Thin (actin) filaments are pulled toward the center of the SARCOMERE by myosin cross-bridges. The muscle fiber SHORTENS and contracts.

Complete the sentences describing the steps that occur during excitation-contraction coupling. Then put the steps in order.

During an action such as flexion of the elbow, the muscle that causes the action is called the AGONIST. The muscle(s) that works against a particular action is called the ANTAGONIST. Often there are additional muscles that assist the agonist. These muscles are called SYNERGISTS. In our example of elbow flexion, the agonist would be the BICEPS BRACHII and the antagonist would be the TRICEPS BRACHII

Complete the sentences describing the various roles of muscles during particular actions.

contraction of muscles while at rest

Define muscle tone. -Contractions that occur without stimulation of the muscle by a motor neuron. -Single muscle contraction resulting from a single stimulation. -Maximum force generated by a particular muscle. -Contraction of muscles while at rest.

MUSCLE TWITCH: -Complete relaxation between stimulations -same force for each contraction

Drag and drop each label to the myogram of the correct muscle response. Bottom Box:

TETANUS -Sustained contraction -high frequency of stimulation

Drag and drop each label to the myogram of the correct muscle response. Middle Box:

SUMMATION -Progressively stronger contractions

Drag and drop each label to the myogram of the correct muscle response. Top Box:

Left Boxes: (Top to Bottom) -Motor neuron Axon -Mitochondrion -Synaptic Vesicle -Acetylcholine molecule Right Boxes: (Top to Bottom) -Synaptic cleft -motor end plate

Label the features of a neuromuscular junction. -Mitochondrion -Motor end plate -Synaptic Cleft -Synaptic vesicle -Acetylcholine molecule -Motor neuronaxon

from Left to right: -Force of contraction -time of stimulation -latent period -period contraction -time -period of relaxation

Label the phases of a muscle twitch

eccentric contractions

Muscle contractions that generate less force than the resistance and result in lengthening of the muscle are called: -concentric contractions -eccentric contractions -isometric contractions

True

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

transverse

The binding of the chemicals to the muscle cell causes an electrical impulse to travel along the sarcolemma and down the ________ tubules

acetycholine

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

motor end plate

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

Picture One: -Concentric Contraction -Movement Picture Two: -Eccentric Contraction -movement Picture Three -Isometric Contraction -no movement

The images illustrate three different types of contractions. Using the labels, indicate the name of each contraction type. Then, indicate whether or not movement occurs with each contraction type.

From left to right: -force -overly shortened -optimal length -overly stretched Bottom: -muscle fiber length

The labels illustrate different arrangements of filaments within a sarcomere. Place each label in the correct location on the graph showing the length-tension relationship for skeletal muscle.

-Recovery from vigorous activity -liver cells -glucose -muscle cells -ATP -blood

The oxygen debt is the amount of oxygen required by muscle and other tissues during __________. This oxygen is used by the ___________ to convert lactic acid into ___________; by the ________ to resynthesize __________ and creatine phosphate; and by the _________ to restore previous levels of oxygenation.

synapse

The site where the neuron communicates with the muscle fiber is called a

synaptic cleft

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

Fast-twitch fibers

Which fiber type is most prone to muscle fatigue? -fast-twitch fibers -slow-twitch fibers