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NURS 5315 Advanced Patho Exam 1 questions and answers
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NURS 5315 Advanced Patho Exam 1questions and answers
Steps of the Action Potential - ANS Depolarization
Repolarization
Hyperpolarization
Depolarization - ANS movement of the intracellular charge towards zero (more positive
charge)
Voltage gated Na channels open and allow Na to enter the cell -> voltage inside the cell moves
towards zero
Repolarization - ANS Once the intracellular charge reaches zero, the negative polarity of the
inside of the cell is restored back to its baseline of -70 to -85 mV
-Na channels close, K channels open
Hyperpolarization - ANS when the cell's resting membrane potential is greater than -85mV. Is
less excitable, because there is a greater distance between the resting membrane potential and
the threshold potential.
In order for the action potential to be sucessful - ANS t has to depolarize by 15-20 mV
(threshold potential) to reach -55 to -65 mV.
An alteration in action potential may result from - ANS neurologic diseases, muscle disease
or electrolyte imbalances.
What is the main protein responsible for maintaining the correct balance of extracellular Na and
intracellular K, which is needed for cellular excitation and membrane conductivity. - ANS
Na+-K+ ATPase
Resting membrane potential - ANS when the cell is in a nonexcited state and is at -70 to -85
mV.
Refractory Period - ANS is a period of time during most of the action potential which the cell
membrane resists stimulation and it cannot depolarize
Absolute refractory period - ANS occurs when the membrane will not respond to ANY
stimulus no matter how strong.
,Relative Refractory Period - ANS occurs when the membrane is repolarizing and will only
respond to a very strong stimulus.
Hyperpolarized - ANS when the cell's resting membrane potential is greater than -85mV.
Is less excitable, because there is a greater distance between the resting membrane potential
and the threshold potential.
Hypopolarized - ANS when the cell's resting membrane potential is closer to zero, for
instance it is -65mV.
Is more excitable because the resting membrane potential is closer to the threshold potential,
there is less distance between them.
Action potential altered by hypokalemia - ANS (serum outside of cell is low)
-Hyperpolarized (cell becomes more negative, ex: -100)
-Affects the resting membrane potential of cells
-The cell is less likely to depolarize and transmit impulses
Can cause a decrease in neuromuscular excitability and leads to weakness, smooth muscle
atony, paresthesias, and cardiac dysrhythmias
Action potential altered by hyperkalemia - ANS Hypopolarized
-Also has an effect on the resting membrane potential
-If the ECF potassium increases without any change in the ICF potassium levels, the resting
membrane potential of the cell becomes more positive.
-The cells are more excitable and conduct impulses more easily and more quickly because the
resting membrane potential is closer to the threshold potential. Therefore, the person will have
peak T waves on EKG.
-As potassium rises, the resting membrane potential will continue to become more positive and
it will eventually become equal to the threshold potential. As this happens the EKG will show a
widening QRS complex. If the resting membrane potential equals the threshold potential, an
action potential will not be generated and cardiac standstill will occur. Paralysis and
paresthesias may also occur.
Action potential altered by hypocalcemia - ANS -Causes an increase in the cell permeability
to Na causing a progressive depolarization
-Causes the RMP and the TP to be closer to one another & making it easier to initiate an action
potential - the cells are more excitable.
-Results in tetany, hyperreflexia, circumoral paresthesias, seizures, dysrhythmias
Action potential altered by hypercalcemia - ANS -Causes a decrease in cell permeability to
Na
-Causes the RMP and the TP to increase in distance - the cells are less excitable and requires
more of a stimulus to initiate an action potential.
-Leads to weakness, hyporeflexia, fatigue, lethargy, confusion, encephalopathy, a shortened QT
segment and depressed widened T waves on EKG.
, Atrophy - ANS decrease or shrinkage in the size of the cell
-Imbalance between protein synthesis and degradation, , reduction of the intracellular contents,
also includes a self-eating process called autophagy.
-Example: aging brain cells, malnutrition, uterus decreasing in size after childbirth
Hypertrophy - ANS increase in the size of cells, which ultimately increases the size of the
organ
-Etiology: triggers include repetitive stretching, chronic pressure, volume overload
-Pathophysiology: hormonal stimulation or increased functional demand, which increases the
cellular protein in the plasma membrane, endoplasmic reticulum, myofilaments, and
mitochondria
Hyperplasia - ANS -increase in number of cells, not the size of the cell, which results from an
increased rate of cell division, it can only happen in cells that are capable of mitosis *
-Etiology: results from the production of growth factors which stimulate cells to produce new
cellular contents and divide
Dysplasia - ANS -abnormal changes in the size, shape, and organization of mature cells due
to persistent, severe cell injury or irritation
-Disordered cell growth and is mainly found in epithelial tissue of the uterine cervix, the
endometrium, GI and respiratory tract mucosa,
-Ex: pap smears often show dysplastic cells of the cervix, uterine cells
Referred to as atypical hyperplasia - ANS dysplasia - abnormal changes in size, shape, and
organization of mature cells due to persistent, severe cell injury or irritation
Metaplasia - ANS -reversible change in which one adult cell is replaced by another adult cell
-Etiology: found in tissue damage, repair, and regeneration
-Results from the exposure of the cells to chronic stressors, injury, or irritation. If the influences
that cause the cellular changes remain present, they can induce a malignant change in the cells
-Ex: most common is the change from columnar cells to squamous cells - this occurs in chronic
smokers or gastroesophageal reflux (GERD)
Physiologic Example of Hyperplasia - ANS -Occurs when there is an increase in tissue mass
after damage or partial resection, allowing the organ to regenerate
Ex - removal of part of the liver and the cells regenerating, uterine and mammary gland
enlargement occur during pregnancy to meet the demands of the increased work load, callus on
foot
Ex: (Hormonal) Breast and uterine enlargement during pregnancy.
Pathological Example of Hyperplasia - ANS -Is an abnormal proliferation of normal cells
usually caused by increased hormonal stimulation
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