Question :
Why is it possible for potassium to diffuse easily into and out of cells?
Student Answer:
... [Show More]
Potassium has a greater concentration in the ICF. Sodium has a greater concentration in the ECF.
The resting plasma membrane is more permeable to
potassium.
An excess of anions is inside the cell.
Instructor Explanation:
Because the resting plasma membrane is more permeable to K+ than to Na+, K+ can easily diffuse from its area of higher concentration in the ICF to its area of lower concentration in the ECF. Because Na+ and K+ are both cations, the net result is an excess of anions inside the cell, resulting in the resting membrane potential. The remaining options do not correctly identify the process that most easily diffuses K+.
-565503819 MultipleChoice 27 False
0 -565503819 MultipleChoice 27
0 -565503818 MultipleChoice 56
Question 3
.
Question :
A major determinant of the resting membrane potential necessary for the transmission of nerve impulses is the ratio between:
Student Answer:
Intracellular and extracellular Na+ Intracellular and extracellular K+ Intracellular Na+ and extracellular K+
Intracellular K+ and extracellular Na+
Instructor Explanation:
The ratio of K+ in the ICF to K+ in the ECF is the major determinant of the resting membrane potential, which is necessary for the transmission and conduction of nerve impulses, for the maintenance of normal cardiac rhythms, and for the skeletal and smooth muscle contraction. This is not true of the other options.
-565503817 MultipleChoice 87 False
0 -565503817 MultipleChoice 87
0 -565503816 MultipleChoice 92
Question 5
.
Question :
What is a consequence of plasma membrane damage to the mitochondria?
Student Answer:
Enzymatic digestion halts DNA synthesis. Influx of calcium ions halts ATP production.
Edema from an influx in sodium causes a reduction in ATP
production.
Potassium shifts out of the mitochondria, which destroys the
Instructor Explanation:
infrastructure.
The most serious consequence of plasma membrane damage is, as in hypoxic injury, to the mitochondria. An influx of calcium ions from the extracellular compartment activates multiple enzyme systems, resulting in cytoskeleton disruption, membrane damage, activation of inflammation, and eventually DNA degradation. Calcium ion accumulation in the mitochondria causes the mitochondria to swell, which is an occurrence that is associated with irreversible cellular injury. The injured mitochondria can no longer generate ATP, but they do continue to accumulate calcium ions. The remaining options do not accurately describe the consequence of plasma membrane damage to the mitochondria.
-565503815 MultipleChoice 42 False
0 -565503815 MultipleChoice 42
Question 6
.
Question :
Current research supports the belief that after heart muscle injury, the damage:
Student Answer:
Remains indefinitely because cardiac cells do not reproduce Is repaired by newly matured cardiomyocytes
Gradually decreases in size as mitotic cell division occurs Is replaced by hypertrophy of remaining cells
Instructor
Explanation:
The recent discovery that cardiac stem cells exist in the heart and
differentiate into various cardiac cell lineages has profoundly changed the
understanding of myocardial biology; it is now believed that bone marrow–
derived cardiac stem cells or progenitor cells that have the ability to mature
into cardiomyocytes may populate the heart after injury. The other options
do not accurately describe the process that is believed to occur to address
cardiac muscle damage. [Show Less]