Deck 7: Muscle

Question 1

Identify the structure (clear area) at the tip of the arrow

A) epineurium
B) perineurium
C) endomysium
D) perimysium
E) epimysium

Answer 1

D

Question 2

Motor innervation of skeletal muscle is via myelinated α motor neurons that arborize and form synapses with the muscle fiber. Acetylcholine is released from the neuron and binds to receptors located on the

A) presynaptic membrane
B) motor end plate
C) external lamina
D) active site
E) quanta

Answer 2

B

Question 3

A medical student and her nurse boyfriend present in the emergency room of a hospital complaining about nausea, vomiting, diarrhea, stomach cramps, double vision, and drooping eyelids. Their symptoms began less than 24 hours after dinner at home and they both remembered that the can of corn that they consumed with dinner was damaged. The doctor should suspect

A) acid reflux
B) myocardial infarct
C) stroke
D) botulism
E) duodenal ulcer

Answer 3

D

Question 4

Thick filaments are held in register with one another by

A) titin
B) nebulin
C) tropomyosin
D) troponin
E) tropomodulin

Question 5

Cardiac muscle cells house granules that

A) contain renin
B) contain angiotensinogen
C) lower blood pressure
D) increase the ability of renal tubules to resorb sodium
E) increase the ability of renal tubules to resorb water

Question 6

In early May a pathologist is called to the crime scene in Baltimore, Maryland, to examine a cadaver. She notes that the body is in maximal rigor mortis and determines that the person has been dead for

A) 2 hours
B) 6 hours
C) 18 hours
D) 2 days
E) 1 week

Question 7

Which of the following is true concerning human skeletal muscle? It has

A) dyads
B) triads
C) caveolae
D) a centrally positioned nucleus
E) intercalated disks

Question 8

Annually, more than two million people in the United States have elected to be injected with botulinum toxin A in order to diminish frown lines and make their facial skin appear smoother and younger looking. The toxin paralyzes the injected facial muscles because it

A) inhibits acetylcholine binding
B) inhibits acetylcholine receptor formation
C) competes for the acetylcholine binding site
D) interferes with acetylcholine synthesis
E) interferes with the release of acetylcholine

Question 9

Cardiac muscle cells differ from skeletal muscle cells in that cardiac muscle cells

A) possess narrower T tubules
B) are multinucleated, but their nuclei are not peripherally located
C) are the same length as the ventricles of the heart
D) require calcium in the extracellular compartment, or they cannot contract
E) can sustain contraction even during complete hypoxic conditions

Question 10

A person's ability to touch her nose with her eyes closed is due to

A) muscle spindles
B) two-cell reflex arc
C) three-cell reflex arc
D) sympathetic component of the autonomic nervous system
E) parasympathetic component of the autonomic nervous system

Question 11

The extrafusal fibers of a muscle spindle receive their nerve supply from which of the following?

A) primary sensory endings
B) secondary sensory endings
C) dynamic $\gamma$ motor neuron
D) static $\gamma$ motor neuron
E) $\alpha$ motor neuron

Question 12

Each myosin II molecule of the heavy chain can be digested into smaller constituents, one of which binds ATP. Which is that constituent?

A) light meromyosin
B) S1 subfragment
C) S2 subfragment
D) papain
E) trypsin

Question 13

Smooth muscle cells lack

A) actin
B) troponin
C) tropomyosin
D) caldesmon
E) myosin

Question 14

Calcium binds to which of the following molecules?

A) TnC
B) TnI
C) TnT
D) tropomyosin
E) tropomodulin

Question 15

Which of the following occurs during skeletal muscle contraction?

A) A band elongates
B) H band disappears
C) I band becomes wider
D) Z disks disappear
E) A band becomes narrower

Question 16

Myofibrils are held in register with each other by structures known as

A) desmin
B) dystrophin
C) keratin
D) lamins
E) neurofilaments

Question 17

An entire skeletal muscle is invested by a connective tissue element known as

A) endomysium
B) basement membrane
C) external lamina
D) epimysium
E) perimysium

Question 18

A patient has the autoimmune disease myasthenia gravis. This condition is due to patient's inability to

A) release acetylcholine
B) release norepinephrine
C) make norepinephrine receptors
D) bind norepinephrine by norepinephrine receptors
E) bind acetylcholine by acetylcholine receptors

Question 19

A 49-year-old man presents to the emergency department with chest pain. The examining physician knows that conditions such as a fractured rib, pneumonia, and pericarditis can cause similar symptoms. What is the best initial diagnostic test that the doctor can perform to determine very rapidly whether or not the patient is experiencing a myocardial infarction?

A) ECG
B) EEG
C) listening to the heart with a stethoscope
D) blood test for the enzyme CK-MB
E) electron myography

Question 20

The sarcoplasmic reticulum of skeletal muscle

A) sequesters Na⁺ ions
B) possesses voltage-gated K⁺ channels
C) is depolarized by T tubules
D) is responsible for acetylcholine synthesis
E) is responsible for synthesis of actin and myosin

Question 21

The cells located within the rectangle

A) are modified smooth muscle cells
B) are modified skeletal muscle cells
C) function in contraction
D) function in impulse transmission
E) function in glucose transport

Question 22

Identify the cell whose nucleus is at the tip of the arrow

A) skeletal muscle cell
B) adipocyte
C) satellite cell
D) Schwann cell
E) endothelial cell

Question 23

Identify this tissue

A) cardiac muscle
B) dense regular elastic connective tissue
C) dense regular collagenous connective tissue
D) skeletal muscle
E) elastic cartilage

Question 24

Identify the tissue within the rectangle

A) dense regular collagenous connective tissue
B) dense regular elastic connective tissue
C) skeletal muscle
D) cardiac muscle
E) smooth muscle