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 D
Explanation
A) The blood cells will migrate to the bone marrow:
While the bone marrow is responsible for producing red blood cells, dehydration and hypertonicity of the blood would not cause the red blood cells to migrate to the bone marrow. Migration of blood cells typically refers to white blood cells moving toward sites of infection or inflammation, not a response to dehydration.
B) The red cells will precipitate out of circulation:
Red blood cells do not precipitate out of circulation due to dehydration or hypertonic conditions. Instead, dehydration causes a shift in water balance that leads to changes in the shape and function of the red blood cells. Precipitation of cells is not a physiological response in this context.
C) They will swell and eventually rupture:
In conditions of hypertonicity, where the concentration of solutes (such as sodium) in the blood is higher than normal, red blood cells actually shrink, not swell. When blood is hypertonic, water moves out of the red blood cells into the extracellular space to balance the osmotic pressure, leading to cell shrinkage. Cells only swell in hypotonic conditions, when water moves into the cell.
D) The cells will shrink and shrivel, decreasing their oxygen-carrying ability:
When the body becomes dehydrated, the blood becomes hypertonic (more concentrated), leading to a shift of water out of the red blood cells to try to balance the osmotic gradient. As a result, the red blood cells shrink and shrivel. This shrinkage can impair their ability to carry oxygen effectively, as the cells may become more rigid and less flexible, making it difficult for them to navigate through small blood vessels and perform gas exchange in the lungs and tissues.
Correct Answer is D
Explanation
A) Decreased blood pressure:
Isoproterenol (Isuprel) is a non-selective beta-adrenergic agonist that primarily stimulates beta-1 and beta-2 receptors. It causes vasodilation through beta-2 stimulation, but its predominant effect is increasing heart rate and cardiac output via beta-1 stimulation. This tends to result in an increase in blood pressure
B) Decreased heart rate:
Isoproterenol generally leads to an increase in heart rate because of its beta-1 adrenergic activity, which stimulates the heart's pacemaker cells. It is commonly used to treat bradycardia (slow heart rate).
C) Increased body temperature:
Although isoproterenol can lead to increased heart rate and blood flow, it does not directly cause a significant increase in body temperature. Temperature changes are more commonly seen with drugs affecting metabolism or those that induce fever.
D) Increased blood pressure:
Isoproterenol stimulates beta-1 receptors in the heart, leading to increased heart rate and cardiac output, which typically results in an increase in blood pressure. However, due to its beta-2 effects, there can be some vasodilation, which may counteract this effect slightly. Despite this, the overall effect of isoproterenol is typically an increase in blood pressure, especially in a shock setting, where improving circulation is critical.
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