What substance move freely in and out of a cell by diffusion?
Proteins
Enzymes
Hormones
Electrolytes
The Correct Answer is C
A) Proteins:
Proteins are generally too large to diffuse freely across the cell membrane. They require specific transport mechanisms, such as endocytosis or transport proteins, to move in and out of cells. The hydrophilic nature of most proteins further complicates their passage across the lipid bilayer.
B) Enzymes:
Like proteins, enzymes are large molecules that do not freely diffuse across cell membranes. Enzymes, being proteins, also need specialized transport mechanisms or need to be secreted or endocytosed to enter or exit cells.
C) Hormones:
Many hormones, particularly lipid-soluble ones like steroid hormones, can diffuse freely across the cell membrane. These hormones pass through the lipid bilayer due to their hydrophobic nature and bind to intracellular receptors, initiating cellular responses. However, water-soluble hormones (e.g., insulin) typically do not diffuse freely but interact with receptors on the cell surface.
D) Electrolytes:
Electrolytes (such as sodium, potassium, calcium, and chloride ions) are charged particles that cannot pass freely through the lipid bilayer due to the hydrophobic interior of the cell membrane. They require specific ion channels or transporters to move in and out of the cell. Diffusion of electrolytes is facilitated through these channels, but it is not a simple diffusion process as seen with small, uncharged molecules.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A) Risk for dehydration related to diarrhea:
Diarrhea is not a common issue directly associated with Parkinson’s disease or its typical treatments, such as dopaminergic medications. While some medications or conditions can cause gastrointestinal disturbances, dehydration due to diarrhea is not a primary concern in Parkinson’s disease.
B) Diarrhea related to dopaminergic effects:
Dopaminergic medications, such as levodopa, may cause gastrointestinal side effects, but diarrhea is not a primary or common side effect. Typically, dopaminergic effects can lead to constipation, not diarrhea.
C) Risk for injury related to CVS effects and incidence of orthostatic hypotension:
Parkinson's disease can cause autonomic dysfunction, which often leads to orthostatic hypotension increasing the risk of falls and injury. This is a valid and appropriate nursing diagnosis because patients with Parkinson’s disease often experience balance issues and dizziness due to this condition, making them more vulnerable to falls and injury.
D) Constipation related to dopaminergic effects:
While constipation is a common side effect of dopaminergic medications used to treat Parkinson's disease, the more appropriate diagnosis for a patient who has Parkinson’s disease would be one that addresses the immediate risks or complications related to mobility or autonomic dysfunction.
Correct Answer is B
Explanation
A) Pupil constriction: Pupil constriction (miosis) is primarily mediated by the parasympathetic nervous system through muscarinic receptors, not nicotinic receptors. Nicotinic receptors, when stimulated, affect skeletal muscle contraction, not the size of the pupils.
B) Muscle contraction: Nicotinic receptors are located on skeletal muscle cells and are responsible for mediating muscle contraction when activated. When a drug stimulates nicotinic receptors, the expected outcome is muscle contraction, as these receptors play a critical role in neuromuscular transmission.
C) Increase GI motility: While nicotinic receptors are involved in muscle contraction, they are not the primary mediators of gastrointestinal motility. Muscarinic receptors, which are part of the parasympathetic nervous system, primarily control GI motility. Stimulating muscarinic receptors would lead to increased motility, but not nicotinic receptors.
D) Decrease in heart rate: A decrease in heart rate is typically associated with the stimulation of muscarinic receptors, particularly those that influence the parasympathetic nervous system (vagal tone). Nicotinic receptor activation does not directly influence heart rate; in fact, their stimulation is more related to skeletal muscle contraction.
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