Study "PST2235 - Module 2: Fluid balance & Electrolyte Disorders", a flashcard deck on FORKSAI.
Define 'electrolytes' and explain their significance in maintaining fluid balance within the body.
Electrolytes are salt substances that dissociate into charged ions (cations and anions) when dissolved in water. Their significance lies in their ability to disturb vital functions if their concentrations change, and they also drive fluid movement due to the creation of concentration gradients across membranes.
How does osmosis differ from simple diffusion, and what role does a semi-permeable membrane play in osmosis?
Simple diffusion involves the movement of solid matter from an area of high concentration to low concentration until even distribution. Osmosis, however, is specifically the diffusion of water through a selectively permeable membrane from a less concentrated solution to a more concentrated solution. The semi-permeable membrane is crucial as it regulates the movement of solutes and water, allowing water to pass while restricting certain solutes, thus enabling osmotic pressure to build and drive water movement.
A patient is admitted with severe dehydration, and their cells are showing signs of shrinking. Which type of intravenous fluid would be most appropriate to administer, and why?
A hypotonic solution would be most appropriate. This type of solution has a lower solute concentration than normal cells, meaning that when infused, water will be drawn from the solution into the patient's cells, helping to rehydrate them and reverse the cellular shrinking caused by dehydration.
Describe the two main fluid compartments of the body and state the approximate percentage of total body weight each accounts for.
The two main fluid compartments are Intracellular Fluid (ICF) and Extracellular Fluid (ECF). ICF is the fluid found inside all body cells and accounts for approximately 40% of total body weight. ECF is the fluid found outside the cells, including intravascular and interstitial compartments, and accounts for about 20% of total body weight.
What is the primary goal of fluid and electrolyte balance in the human body?
The primary goal of fluid and electrolyte balance in the human body is to maintain homeostasis. This means ensuring a relatively constant internal environment where the amount of water gained equals the amount lost, and the rate of electrolyte absorption matches the rate of excretion.
Which of the following describes the movement of substances against their concentration gradient, requiring cellular energy?
C) Active transport. Active transport actively moves substances from an area of low concentration to high concentration, which requires cellular energy to overcome the concentration gradient.
Explain how fever affects fluid balance in the body.
Fever significantly increases fluid loss from the body. For every degree of increase in temperature, water loss increases by approximately 200ml per day, primarily through increased perspiration and respiration. This heightened loss can quickly lead to dehydration if not compensated for.
A patient's blood test shows an abnormally high concentration of sodium outside their cells. How would this electrolyte imbalance likely affect fluid movement between their cells and the extracellular fluid?
An abnormally high concentration of sodium (a solute) outside the cells would create a hypertonic environment in the extracellular fluid. According to the principle 'water follows salt,' water would be drawn out of the cells and into the extracellular fluid to equalize the concentration gradient. This could lead to cellular dehydration and shrinking.
What is a 'concentration gradient' and how does it drive fluid movement?
A concentration gradient is the difference in the concentration of a solute between two areas. It drives fluid movement because substances, including water, tend to move from an area of higher concentration to an area of lower concentration, or vice versa, to achieve equilibrium. This movement can occur through diffusion or osmosis.
Distinguish between 'sensible' and 'insensible' fluid losses, providing an example of each.
Sensible fluid losses are those that are noticed and measurable, such as urine and perspiration (sweat). Insensible fluid losses are those that are unnoticed and difficult to measure, such as water lost through respiration and evaporation from the skin (non-sweat).