David's body temperature rises far above normal during his surgery. Which of the following structures plays a role in regulating body temperature?
skin and skeletal muscle
The major cause of malignant hyperthermia is uncontrolled release of calcium into the sarcoplasm of muscle cells. What intracellular organelle functions to store and release calcium?
Skeletal muscle contraction is calcium dependent. The protein ________ binds calcium and is part of the _________ myofilament.
During David's hyperthermic crisis, Dr. Hodges reports that he has an elevated level of exhaled carbon dioxide. Which ATP-generating metabolic pathway produces carbon dioxide as a by-product?
Malignant hyperthermia causes a high demand for ATP within the muscle cells. If there is not enough ATP, muscles cannot relax. Which of the following events allows skeletal muscles to relax?
binding of ATP to myosin head
The drug Dantrolene treats malignant hyperthermia by blocking calcium release into the sarcoplasm and terminating skeletal muscle contractions. Which of the following statements best describes why skeletal muscle relaxes in the absence of calcium?
The active site on actin is blocked by tropomyosin.
During malignant hyperthermia, there is an increased amount of calcium released into the sarcoplasm of skeletal muscle cells. In a previous question you named the organelle which stores and releases calcium. Place in correct order the following events that must occur in the muscle cell before calcium is released from this organelle.
1. ACh molecules land on receptors on the motor end plate
2. an action potential reaches the synaptic terminal
3. calcium ions are released into the sarcoplasm
4. an action potential is generated and travels across the sarcolemma surface
5. acetylcholine is released into the synaptic cleft
6. the action potential travels down t tubules
2, 5, 1, 4, 6, 3
David's tight jaw muscles during surgery would mean that which of the following muscles is likely to be contracting without relaxing?
masseter, temporalis, and medial pterygoid
Jaw muscles tend to contract slowly over long periods of time. As such, which of the following are correct?
These muscle fibers are likely to be red in color. The jaw muscles have extensive capillary networks. The contraction speed of these muscle fibers is slow.
David's tight jaw muscles are not the same thing as having what people refer to as "lock jaw." Tetanus (lock jaw) is caused by the bacterium Clostridium tetani. Which ONE of the following choices is the most likely source of this organism?
deep puncture wound
During which phase of a muscle twitch are active sites on thin filaments exposed, and cross-bridge interactions occur?
Which of the following occurs during the relaxation phase of a muscle twitch?
Calcium levels are falling.
The rapid rise and fall in force produced by a muscle fiber after a single action potential is
When a muscle is stimulated repeatedly at a high rate, the amount of tension gradually increases to a steady maximum tension, and a higher stimulation frequency eliminates the relaxation phase. This is called
If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called
The increase in muscle tension that is produced by increasing the number of active motor units is called
In which of the following would the motor units have the fewest muscle fibers?
muscles that control the eyes
Which of these would lead to increased oxygen consumption?
increased conversion of lactic acid to glucose, increased aerobic respiration by muscle cells, increased heat production, increased muscle activity
Which of the following is/are characteristic(s) of Type II-A skeletal muscle fibers?
They are known as fast-twitch oxidative fibers.
Large-diameter, densely packed myofibrils, large glycogen reserves, and few mitochondria are characteristics of
Which of the following statements is (are) true regarding human muscles?
Slow fibers are abundant in the back muscles. Eye muscles are composed entirely of fast fibers. Most have both slow and fast fibers. Slow fibers are abundant in the calf muscles.
Tetanus is most likely to result from which condition?
a deep puncture wound, such as that from a nail
Which of the following hormones directly stimulates growth of muscle tissue, leading to increased muscle mass?
After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as
The muscle weakness of myasthenia gravis results from
loss of acetylcholine receptors in the end-plate membrane.
Which of the following acts as an ATPase during the contraction cycle of muscle?
the head portion of the myosin molecule
What causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum within a muscle cell?
arrival of an action potentia
The most important factor in decreasing the intracellular concentration of calcium ion after contraction is
active transport of calcium into the sarcoplasmic reticulum.
In response to action potentials arriving along the transverse tubules, the sarcoplasmic reticulum releases
Which of the following become connected by myosin cross-bridges during muscle contraction?
thin filaments and thick filaments
When calcium ion binds to troponin,
tropomyosin moves into the groove between the helical actin strands.
The end of a neuron that contains acetylcholine-filled vesicles is called the __________.
What causes the vesicles inside a neuron to fuse with the plasma membrane?
an action potential in the neuron
Curare is a poison that prevents acetylcholine from binding to acetylcholine receptors. Which of the following is the most likely cause of death from curare exposure?
paralysis of skeletal muscles
The role of acetylcholinesterase in the neuromuscular junction is to __________.
remove acetylcholine from the synaptic cleft
Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle fiber
Interactions between actin and myosin filaments of the sarcomere are responsible for
Mature skeletal muscle fibers:
individually contain hundreds of nuclei just internal to the plasma membrane.
Which thin filament structure is distinguished by its constituents of three globular subunits, one of which has a receptor that binds two calcium ions?
Determine the correct structural hierarchy of skeletal muscles, from microscopic to gross levels.
myofibril - fiber - fascicle - muscle
How is the H band distinguished from the other prominent structural features of the sarcomere?
It is a lighter region that contains thick filaments, but no thin filaments.
Which statement about the microscopic anatomy of skeletal muscle fibers is true?
Each fiber has many nuclei. Muscle fibers are continuous from tendon to tendon. Cross striations result from the lateral alignment of thick and thin filaments. Tubular extensions of the sarcolemma penetrate the fiber transversely.
Which statement is correct regarding thick filament structure?
It consists of a core of titin, forming a strand that continues across the I band to the Z line on that side
The thin filaments of striated muscle are made of which protein(s)?
actin, tropomyosin, nebulin, troponin
The skeletal muscle complex known as the triad consists of
a transverse tubule and two terminal cisternae.
The advantage of having many nuclei in a skeletal muscle fiber is
the ability to produce large amounts of the muscle proteins needed for muscle contraction.
Which of the following is a recognized function of skeletal muscle?
maintain posture, guard body entrances and exits, maintain body temperature, produce movement
The bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone is called a(n
One of Mrs. Morgan's fractures is described as being located on the proximal diaphysis. Which of these phrases best describes the anatomical location of this fracture?
shaft of the bone closest to the shoulder joint
Mrs. Morgan's fracture is described as having "bone tissue sticking out of the skin." This could make her susceptible to which of the following complications?
Mrs. Morgan's fracture has not developed a soft callus. Which type of cartilage is her body having trouble forming?
One way bones are classified is by their shape. How would you classify the bones fractured by Mrs. Morgan?
humerus - long; occipital - flat; vertebrae - irregular
With such a fall, Mrs. Morgan could have also dislocated her shoulder joint. Which of the following terms specifically refers to a shoulder dislocation?
luxation of the humerus
Mrs. Morgan also had a tooth knocked out of its socket. (Yes it was a bad day!) Which of the following terms best describes the articulation of a tooth in its bony socket?
synarthrosis and gomphosis
Which of these is one of the four major types of synarthrotic joints?
synchondrosis, gomphosis, suture, synostosis
Which bony structure(s) is/are continuous with the capsule of the joint, adding strength and helping to stabilize the joint?
The joint between the trapezium and metacarpal bone of the thumb is an example of a(n) ________ joint.
The joint that permits the greatest range of mobility of any joint in the body is the ________ joint.
While on a school skiing trip in Colorado, Heidi falls and breaks her tibia and fibula in a Pott fracture. What would you expect as a prominent part of her clinical assessment several hours after the fall?
Which type of fracture occurs in vertebrae that are subjected to extreme stresses?
After a fracture of the diaphysis has healed, the thickened region that results is called the
Which of the following describes spiral fractures?
fractures that are produced by twisting stresses that spread along the length of the bone
Which condition, due to excessive cartilage formation at the epiphyseal cartilages, results in individuals who are very tall, with long, slender limbs?
What characteristic may cause life-threatening issues in individuals with Marfan syndrome?
genetic mutation that affects the structure of connective tissue throughout the body
osteoblasts begin producing bone faster than chondrocytes are producing new epiphyseal cartilage.
The following are important steps in the process of endochondral ossification.
1. Enlarged chondrocytes die.
2. Osteoblasts replace calcified cartilage with spongy bone.
3. Chondrocytes enlarge and the surrounding matrix begins to calcify.
4. Blood vessels penetrate the cartilage.
5. Perichondrial cells become osteoblasts and produce a thin shell of bone.
3, 1, 5, 4, 2.
To form perforating fibers, osteoblasts from the periosteum cement collagen fibers from tendons, ligaments, and joint capsules into which structures?
When cartilage is produced at the epiphyseal side of the metaphysis at the same rate as bone is deposited on the opposite side, bones
In appositional bone growth, how are layers of compact bone added to the bone's outer surface?
Bone is deposited by superficial osteoblasts.
The following are major steps in the process of intramembranous ossification.
1. Clusters of osteoblasts form osteoid that becomes mineralized.
2. Osteoblasts differentiate within mesenchymal connective tissue.
3. Spicules of bone radiate out from the ossification centers.
4. Mesenchymal cells aggregate.
4, 2, 1, 3.
Which of the following is formed by intramembranous ossification?
both the roof of the skull and the clavicle