Lecture 21 (Fluid & Electrolytes) Learning Objectives.docx

1.List the factors that influence the percentage of body fluid and explain the significance relative to fluid balance. - The percentage of body fluid is influenced by two main factors: age and the ratio of adipose connective tissue to skeletal muscle tissue. Infants have the highest percentage of fl...

1.List the factors that influence the percentage of body fluid and explain the significance relative to fluid balance. - The percentage of body fluid is influenced by two main factors: age and the ratio of adipose connective tissue to skeletal muscle tissue. Infants have the highest percentage of fluid, at approximately 75% fluid by weight, while elderly individuals have the lowest percentage of fluid at 45%. This trend of decreasing percentage of body fluid with increasing age is important to consider in understanding fluid balance, as individuals with a lower percentage of body fluid are more susceptible to fluid imbalance. Additionally, the ratio of adipose connective tissue to skeletal muscle tissue plays a role in determining the percentage of body fluid. Lean adult females, on average, are typically composed of 55% body fluid, whereas lean adult males are, on average, typically composed of 60% body fluid. This difference reflects the relatively lower amounts of skeletal muscle and relatively higher amounts of adipose connective tissue in a lean adult female compared to a lean adult male. Understanding these factors is crucial in assessing an individual's susceptibility to fluid imbalance and in providing appropriate patient care. 2.Describe the two major body fluid compartments and compare their chemical composition. - The two major body fluid compartments are the intracellular fluid (ICF) and the extracellular fluid (ECF). The ICF is the fluid within our cells, comprising approximately two-thirds of the total body fluid. It contains a higher concentration of potassium (K+), magnesium (Mg2+), phosphate anion (PO43-), and negatively charged proteins compared to the ECF. On the other hand, the ECF includes both interstitial fluid (IF), which surrounds and "bathes" the cells, and blood plasma within the blood vessels. It is composed of sodium (Na+), chloride (Cl-), and bicarbonate (HCO3-) ions, with a higher concentration of protein in the blood plasma compared to the interstitial fluid. The chemical composition of the two compartments reflects their distinct functions and the relative permeability of the plasma membrane and capillary wall. 3.Explain how fluid moves between the major body fluid compartments. - Fluid moves between the major body fluid compartments through the process of osmosis, which is driven by differences in solute concentration. The two major fluid compartments in the body are the intracellular fluid (ICF) and the extracellular fluid (ECF). The ICF is the fluid within our cells, while the ECF includes both interstitial fluid (IF) and blood plasma. When there is a relative difference in the concentration of solutes between these compartments, water moves by osmosis to equalize the concentration. For example, when the blood plasma becomes hypotonic to the interstitial fluid and the ICF, water moves from the blood plasma into the interstitial fluid and then into the cells. Conversely, when the blood plasma becomes hypertonic, water moves from the cells into the interstitial fluid and then into the blood plasma. This continuous movement of water helps to maintain fluid balance and ensure that the body's cells have the necessary hydration for proper functioning. 4.Define fluid balance. - Fluid balance refers to the state in which the amount of fluid intake into the body is equal to the amount of fluid output, resulting in a normal distribution of water and solutes in the major fluid compartments of the body. It is essential for maintaining optimal health and involves the coordination of various systems, including the digestive, cardiovascular, lymphatic, integumentary, respiratory, urinary, nervous, and endocrine systems. Fluid balance is regulated by monitoring blood volume, blood pressure, and blood plasma osmolarity, and it is crucial for preventing fluid imbalances such as volume depletion, volume excess, dehydration, hypotonic hydration, and fluid sequestration. The understanding of fluid balance is important for healthcare professionals in providing effective patient care and treatment for fluid-related conditions. 5.List both the sources of fluid intake and the categories of water loss - Fluid intake is the addition of water to the body and is divided into two categories: ingested water and metabolic water. Ingested water includes the water absorbed from food and drink taken into the GI tract, accounting for approximately 92% of daily fluid intake. Metabolic water includes the water produced daily from aerobic cellular respiration and dehydration synthesis, totaling approximately 200 mL of fluid per day. On the other hand, fluid output is the loss of water from the body and must equal fluid intake to maintain fluid balance. It includes fluid lost from the body as a component of expired air, through the skin by both sweat and cutaneous transpiration, and in the feces and urine. Fluid output can be categorized as either sensible or insensible water loss and as either obligatory or facultative water loss, depending on whether the loss is measurable and regulated based on the state of hydration of the body.