LESSON 08 - SKELETAL, NERVOUS, AND MUSCULAR SYSTEMS QUIZ

Golgi tendons cause _______________ when the muscle contraction ceases. Reciprocal inhibition orAutogentic inhibition

Autogentic inhibition Why? When muscle tension is reduced due to fatigue, the Golgi tendon organ output is also reduced. The autogenic inhibition reflex is a sudden relaxation of muscle upon development of high tension. It is a self-induced, inhibitory, negative feedback lengthening reaction that protects against muscle tear. Golgi tendon organs are receptors for the reflex.

Type I muscle fibers are used during anaerobic metabolism. T or F

FALSE Why? Type I muscle fibers are more resistant to fatigue and capable of sustaining aerobic metabolism, while type IIx muscle fibers possess a high number of glycolytic enzymes, which provide them with a considerable anaerobic capacity.

Type I muscle fibers have a small amount of mitochondria as compared to type II muscle fibers. T or F

FALSE Why? Type I muscle fibers contain relatively large amounts of mitochondria and are surrounded by more capillaries than fast-twitch fibers.

Type IIa muscle fibers can only sustain activity for less than 30 seconds. T or F

FALSE Why? Type IIa muscle fibers possess speed, fatigue resistance, and force-production capabilities somewhere between type I and type IIx muscle fibers. They can sustain an effort for longer than type IIx fibers—up to three minutes in highly trained athletes.

In order for an impulse to move from one neuron to another, myelin must be released. T or F

False In order for an impulse to move from one neuron to another, the first neuron must release a chemical transmitter substance that attaches to receptors located on the membrane of the second neuron. Myelin is a fatty substance that insulates the axon and keeps the electrical current from outside the nerve.

The four quadriceps muscles each have their own insertion point. T or F

False Although they originate from different areas, all four quadriceps muscles converge and share one tendon of insertion, the patellar tendon.

Neurons can transmit impulses because they are connected. T or F

False. For an electrical impulse to travel through the nervous system, it must be passed from one neuron to the next. Neurons remain separated from each other by a small space called a synapse.

The muscles of the rotator cuff originate on the posterior portion of the scapula. T or F

False. The four muscles of the rotator cuff (supraspinatus, infraspinatus, subscapularis, and teres minor) derive their names from the portion of the scapula from which they originate. The subscapularis originates on the anterior portion of the scapula.

The hamstring muscle group assists with knee extension. T or F

False. The quadriceps femoris is the prime mover for knee extension when acting concentrically. The hamstrings are the primary knee flexors.

Stabilization of the deltoid muscles helps prevent subluxation of the humeral head from the glenoid fossa. T or F

False.The rotator-cuff muscles surround the head of the humerus, with the primary stabilizing function of holding the humeral head in the glenoid fossa. The lack of bone supporting the shoulder joint requires that these muscles and their associated tendons work as stabilizers to prevent subluxation or dislocation of the humeral head from the glenoid fossa.

Muscle spindles respond to muscle fibers being overstretched by causing a _______________, known as the _______________.

Muscular contraction; stretch reflex Why? The muscle spindle stretches when the muscle itself experiences a stretch force, thereby exciting the muscle spindle and causing a reflexive contraction in the muscle, known as the stretch reflex.

Muscle spindles are located _______________. Parallel or perpendicular to muscle fibers

Parallel to the muscle fibers Why? Muscle spindles are located mostly in the muscle belly and lie parallel to the muscle fibers.

When the muscle spindle's reflex contraction occurs, it causes the antagonist muscle group to relax. This is known as _______________.

Reciprocal inhibition Why? The muscle spindle's reflex contraction of its associated muscle simultaneously causes the antagonist muscle group to relax. This is called reciprocal inhibition. For example, if the gastrocnemius is stretched rapidly, the muscle spindles within the muscle belly cause it to contract. At the same time, if the anterior tibialis (opposing muscle group) is contracting, the muscle spindle reflex causes it to relax.

Golgi tendon organs respond to muscle tension by causing the muscle to _______________. Contract or relax

Relax Why? One of the Golgi tendon organ's functions when it senses muscle contraction is to cause inhibition of the contraction (or relaxation). It has been theorized that this function adjusts muscle output in response to fatigue.

During _______________ stretching, the activation of the Golgi tendon organs (GTOs) cause the muscle spindles to relax and, therefore, an increase in the stretch. Static or Active

Static Why? Static stretching evokes a temporary increase in muscle tension due to muscle lengthening. After seven to 10 seconds of a low-force stretch, the increase in muscle tension activates a GTO response. Under GTO activation, muscle spindle activity within the stretched muscle is temporarily inhibited, allowing further muscle stretching.

Endurance athletes, such as those who participate in cross-country running, generally possess a large percentage of type I muscle fibers. T or F

TRUE Why? Fiber composition of skeletal muscles is thought to play an important role in sport and exercise performance. It is commonly believed that successful endurance athletes generally possess a large percentage of type I, or slow-twitch, muscle fibers, while power athletes possess a relatively large percentages of type II, or fast-twitch, muscle fibers.

Type I muscle fibers are considered slow-twitch.

TRUE Why? Slow-twitch fibers are also called type I muscle fibers.

Type I muscle fibers are fatigue-resistant. T or F

TRUE Why? The high concentration of myoglobin, the large number of capillaries, and the high mitochondrial content make type I fibers resistant to fatigue and capable of sustaining aerobic metabolism.

Type IIx muscle fibers are considered fast-twitch. T or F

TRUE Why? There are two subtypes of fast-twitch fibers: type IIx and IIa.

Type IIa muscle fibers are fast-twitch fibers. T or F

TRUE Why? Type IIa are a second subtype of fast-twitch muscle fibers.

Type IIx muscle fibers are the largest and fastest muscle fibers in the body. T or F

TRUE Why? Type IIx fibers are the largest and fastest, and are capable of producing the most force of all the skeletal muscle fibers, but are notably less efficient than type I muscle fibers.

Type IIx muscle fibers are known as fast-glycolytic fibers. T or F

TRUE Why? Type IIx muscle fibers are sometimes called fast-glycolytic fibers.

Type IIx muscle fibers have a small amount of mitochondria. T or F

TRUE Why? Type IIx muscle fibers contain a relatively small amount of mitochondria, while type I muscle fibers contain relatively large amounts of mitochondria.

Type IIx muscle fibers are less resistant to fatigue than type I fibers. T or F

TRUE Why? Type IIx muscle fibers fatigue more easily than type I muscle fibers. In fact, these fibers cannot sustain their effort for more than a few seconds.

Type IIx muscle fibers have limited capacity for aerobic metabolism. T or F

TRUE Why? Type IIx muscle fibers have a limited capacity for aerobic metabolism and fatigue more easily than type I muscle fibers. In fact, these fibers cannot sustain their effort for more than a few seconds.

Type IIa muscle fibers can be trained to become more oxidative or glycolytic. T or F

TRUE Why? With endurance training, type IIa muscle fibers can increase their oxidative capacity to levels similar to those observed in type I muscle fibers.

Neurotransmitters are released to carry impulses from one neuron to another. T or F

True, To carry an impulse across the synapse from one neuron to the other, the first neuron must release a chemical transmitter substance that attaches to receptors located on the membrane of the second neuron.

Flexion and external rotation at the knee are performed by the biceps femoris. T or F

True. The hamstrings are referred to as a biarticular group of muscles, producing knee flexion as well as hip extension when acting concentrically. Additionally, the lateral hamstring, the biceps femoris, is an external rotator of the knee.

The sartorius functions at both the hip and knee joints. T or F

True. The sartorius is the longest muscle in the body, originating from the anterior superior iliac spine (ASIS) and inserting onto the medial tibia, just below the knee. This multijoint muscle flexes, abducts, and externally rotates the hip while flexing and internally rotating the knee.

When the rhomboids stabilize the scapula, the teres major can internally rotate the humerus. T or F

True. The teres major arises from the lower medial portion of the scapula and primarily acts to internally rotate the humerus.

The posterior fibers of the deltoid extend and laterally rotate the humerus. T or F

True. Whereas the anterior fibers flex and internally rotate the humerus, the posterior fibers extend and laterally rotate the humerus.

There is only one axon in a neuron, but there can be hundreds of dendrites. T or F

True.Neurons may have hundreds of the branching dendrites, depending on the neuron type, but each neuron has only one axon.

Dendrites conduct electrical impulses toward the cell body. T or F

True.The neuron is composed of a cell body and one or more fibrous extensions called axons and dendrites. Dendrites conduct electrical impulses toward the cell body, while axons transmit electrical signals away from the cell body.

Golgi tendon organs are sensory receptors located in the _______________.

between the muscle belly and its tendon Why? The Golgi tendon organ is connected to approximately 15 to 20 muscle fibers and is located between the muscle belly and its tendon.