EXAM 4

Consider the following four phrases and select the one that does not belong with the others.

Fuels runner in a marathon

Which of the following would be caused by a contraction of smooth muscle?

Goose bumps

A toxin released by the anaerobic bacterium Clostridium botulinum causes the food-borne illness known as botulism, which inhibits the release of ACh at the neuromuscular junction. What effect does this have on a person infected with the bacterium?

It causes flaccid paralysis, and if it affects the respiratory muscles, can result in death.

Why is the contraction strength of smooth muscle relatively independent of its resting length?

It does not have sarcomeres

Why is the contraction strength of smooth muscle relatively independent of its resting length?

It does not have sarcomeres.

Atrophy at the neuromuscular junction that naturally occurs with age would have what effect on muscles?

It would decrease the number of action potentials sent to the muscle fiber.

You would look for concentric lamellae

around the central canal of an osteon.

Increase in epiphysis size is the result of bone growth at the __________.

articular cartilage

Which of the following correctly describes myoglobin's special function in muscle tissue?

Acts as a reservoir for O2

lack of mitochondria within skeletal muscle fibers would impair which ATP-yielding chemical process?

Aerobic respiration

In which type of bone tissue are osteons present?

Compact bone

Which type of bone tissue has concentric lamellae?

Compact bone

Which type of bone tissue is considered dense bone?

Compact bone

Interconnecting rods of bone are ___________.

trabeculae

Collagen and calcium hydroxyapatite are the primary constituents of __________.

bone matrix

Rigor mortis occurs after death because

cross-bridges form but can't release.

Proteoglycan molecules in the matrix of cartilage

give cartilage its resilient nature.

Betsy took a fall and broke her arm, which required that she wear a cast for a prolonged period of time. When she took the cast off, she was alarmed to see that her muscles

had undergone atrophy.

Troponin

has a calcium-binding site.

Calcium ion blocking agents would most likely affect

movement of the tropomyosin molecule.

An action potential

occurs when the local potential reaches threshold level.

Brittle bone disorder is another name for __________.

osteogenesis imperfecta

A skeletal muscle generates the greatest tension when it is

partially stretched before being stimulated.

As you are lifting a box, someone places extra weight on top of it. For your muscle to continue contracting and lifting the box, the muscle must

recruit more muscle fibers.

Which of the following individuals would have more mitochondria in her skeletal muscle?

A 22-year-old soccer player

What is tropomyosin?

A protein found along the groove of the F-actin double helix

In which of the following situations does a resting membrane potential exist?

A relaxed muscle fiber

Which of the following is true?

A threshold stimulus will cause contraction of a muscle fiber.

You are hired to work in a laboratory to measure the rate of human muscle contraction. Which of the following might decrease in quantity in muscle fibers undergoing contractions?

ATP

Which type of tissue covers the ends of long bones?

Articular cartilage

Which of the following will respond to a threshold stimulus with an all-or-none contraction?

Both a single muscle fiber and a single motor unit are correct.

Which of the following statements regarding the sliding filament model is false?

Both actin and myosin myofilaments shorten during contraction.

A lack of glycolytic enzymes within skeletal muscle fibers would impair which type of ATP-yielding process?

Both anaerobic respiration and aerobic respiration are correct.

Normal bone growth requires adequate amounts of certain substance from the diet. Which of the following list three of the dietary needs for normal bone growth?

Calcium, phosphate, and vitamin D

Which of the following is NOT an age-related change in skeletal muscle?

Decreased recovery time

Which of the following situations occurs in electrically excitable cells?

Depolarization causes voltage-gated sodium ion channels to open.

Which of the following is not an important function of calcium ions in skeletal muscle activity?

Depolarization of the sarcolemma

What is the membrane that lines the medullary cavity?

Endosteum

Substance A is found to be a competitor with acetylcholine. Which step of muscle contraction physiology would be directly affected by this substance?

Exposure of the active sites on G actin

Which of the following is NOT a function of bone?

Immunity

Which of the following is NOT a direct effect of parathyroid hormone (PTH)?

Increased Ca2+ uptake by the small intestine

A child ingested an organophosphate poison used to kill insects. Soon the child's muscles began spastic contractions. Predict what occurred at the synaptic cleft.

Increased accumulation of acetylcholine in the synapse

Select the phrase that does not belong with the others.

Increased vascularity

What is the area where marrow is located?

Medullary cavity

Which of the following structures contains the other four items listed?

Neuromuscular junction

Which of the following events occurs on the postsynaptic membrane?

Neurotransmitter combines with a receptor molecule

Which type of bone cell is a large cell that forms from fusion of several precursor cells?

Osteoclast

Which of the following is true during the resting membrane potential?

Potassium is concentrated primarily inside the cell.

What strengthens the attachment of the tendons or ligaments to bone?

Sharpey fibers

Which of the following correctly matches the bone type with an example?

Short bone - carpal bone

Name the air-filled spaces lined by mucous membranes found within flat and irregular bones.

Sinuses

Which type of muscle tissue has neuromuscular junctions?

Skeletal muscle

Whales are air-breathing aquatic mammals, and some species can remain underwater for long periods of time. Which type of skeletal muscle fibers are most likely dominant in these deep diving whales?

Slow fibers

Which type of muscle tissue causes vasoconstriction?

Smooth muscle

In which type of bone tissue are trabeculae present?

Spongy bone

Which type of bone tissue appears porous?

Spongy bone

Susan slipped on the ice and was unable to be fully mobile for several days. What disruption to homeostasis would you predict she experienced during her immobile period in terms of her muscular system?

Susan was more cold than usual because her inactivity prevented her muscles from helping to regulate her body temperature.

Which of the following descriptions best represents the appearance of the sarcomere during peak contraction?

The H zone is eliminated, and the I bands are very thin.

Which of the following events occurs during the lag phase of a muscle twitch?

The action potential is propagated from presynaptic to postsynaptic membrane.

Myastensia gravis results from the destruction of acetylcholine receptors at the neuromuscular junction, but treatment involves medications that reduce acetylcholinesterase activity. Which statement best explains the effectiveness of these medications?

The antibodies destroy some but not all of the acetylcholine receptors, so reducing acetylcholinesterase activity increases the likelihood that acetylcholine will bind to the remaining receptors.

Which of the following is true concerning isotonic eccentric contraction?

The muscle lengthens, but tension remains constant.

Consider a chemical that blocks the action of acetylcholinesterase. What effect does this have on muscles?

The muscle would have no way to relax, and spastic contractions would result.

An antibody test on smooth muscle reveals fewer dense bodies and intermediate filaments in a patient with a colon disorder. What is the purpose of these structures?

They are part of the intracellular cytoskeleton.

A volleyball player depends on the gastrocnemius muscles for plantar flexion, whereas a marathon runner depends more on the soleus muscles for the same action. What characteristic of the soleus muscles makes this so?

They make more use of aerobic respiration.

Drugs called calcium channel blockers may be used to lower blood pressure by causing arteries to vasodilate. How do you suppose these drugs work?

They prevent calcium from entering smooth muscle, thus allowing the muscle to relax.

An eccentric contraction is described as

a muscle produces tension, but the length of the muscle is increasing.

The primary mineral in bone is __________.

calcium

A passageway connecting neighboring osteocytes in an osteon is a __________.

canaliculus

If one nerve stimulus arrives at a muscle fiber so soon that the fiber does NOT relax at all from the previous twitch, the most likely result will be __________.

complete tetanus

T tubules

conduct action potentials deep into the muscle fiber.

Spongy bone tissue

contains interconnecting plates called trabeculae.

A myofibril is the

contractile thread that extends the length of the muscle fiber.

A drug that interferes with the active transport of Ca2+ from the sarcoplasm back into the sarcoplasmic reticulum would result in

contraction with no relaxation.

Smooth muscle

depolarizes when both Na+ and Ca2+ diffuse into the cell.

The elevated oxygen consumption relative to activity level after exercise has ended is called

excess post-exercise oxygen consumption.

Acetylcholine is released from the presynaptic terminal by the process of

exocytosis.

Curare blocks acetylcholine receptors at the motor end plate. This would result in

inability of the muscle fiber to respond to nervous stimulation.

As muscle activity increases, the body temperature __________.

increases

Calcitonin

is associated with decreased osteoclast activity.

Lamellar bone

is organized into thin sheets of tissue.

The refractory period

is the time during which the tissue cannot respond again.

Thin sheets of bone matrix are __________.

lamellae

The length of the resting sarcomere is

longer than the length of a contracted sarcomere.

Some marrow of long bones is termed "red" marrow. The function of red marrow is to

manufacture blood cells.

Skeletal muscle develops from cells called

myoblasts.

The sequence of events that produces growth at the epiphyseal plate is

proliferation, hypertrophy, calcification, cell death, ossification, and remodeling.

Maureen is hiking in the cold, and to maintain homeostasis her body begins to

shiver.

Some flat and irregular bones of the skull have air-filled spaces called __________.

sinuses

Hypertrophy of skeletal muscles from weight lifting is caused by an increase in the

size of muscle fibers

The sarcoplasmic reticulum

stores Ca2+

In order for muscle relaxation to occur,

the active sites on actin must be blocked.

Concentric contractions occur when

the muscle produces increasing tension as it shortens.

The plasma membrane of an excitable cell is more permeable to K+ because

there are more leak ion channels for K+ than Na+.

A muscle fiber will respond to a stimulus when that stimulus reaches the __________ level.

threshold

Channels that open or close in response to changes in the electrical charge or voltage across the plasma membrane are called

voltage-gated ion channels.