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"Body Fluids - physiology"
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Grossology and you
Provides information in a not-so-serious manner about such topics as blood, eyeballs, brains, bruises, constipation, warts, rashes, and more.
Book
Rapid fluid removal during dialysis is associated with cardiovascular morbidity and mortality
Patients receiving hemodialysis have high rates of cardiovascular morbidity and mortality that may be related to the hemodynamic effects of rapid ultrafiltration. Here we tested whether higher dialytic ultrafiltration rates are associated with greater all-cause and cardiovascular mortality, and hospitalization for cardiovascular disease. We used data from the Hemodialysis Study, an almost-7-year randomized clinical trial of 1846 patients receiving thrice-weekly chronic dialysis. The ultrafiltration rates were divided into three categories: up to 10 ml/h/kg, 10–13 ml/h/kg, and over 13 ml/h/kg. Compared to ultrafiltration rates in the lowest group, rates in the highest were significantly associated with increased all-cause and cardiovascular-related mortality with adjusted hazard ratios of 1.59 and 1.71, respectively. Overall, ultrafiltration rates between 10–13 ml/h/kg were not associated with all-cause or cardiovascular mortality; however, they were significantly associated among participants with congestive heart failure. Cubic spline interpolation suggested that the risk of all-cause and cardiovascular mortality began to increase at ultrafiltration rates over 10 ml/h/kg regardless of the status of congestive heart failure. Hence, higher ultrafiltration rates in hemodialysis patients are associated with a greater risk of all-cause and cardiovascular death.
Journal Article
Spit and phlegm
Readers will discover the science behind the gross studying why we need saliva to eat and phlegm to protect ourselves from bacteria and illness.
Book
Effects of Beer, Non-Alcoholic Beer and Water Consumption before Exercise on Fluid and Electrolyte Homeostasis in Athletes
Fluid and electrolyte status have a significant impact on physical performance and health. Pre-exercise recommendations cite the possibility of consuming beverages with high amounts of sodium. In this sense, non-alcoholic beer can be considered an effective pre-exercise hydration beverage. This double-blind, randomized study aimed to compare the effect of beer, non-alcoholic beer and water consumption before exercise on fluid and electrolyte homeostasis. Seven male soccer players performed 45 min of treadmill running at 65% of the maximal heart rate, 45 min after ingesting 0.7 L of water (W), beer (AB) or non-alcoholic beer (NAB). Body mass, plasma Na+ and K+ concentrations and urine specific gravity (USG) were assessed before fluid consumption and after exercise. After exercise, body mass decreased (p < 0.05) in W (−1.1%), AB (−1.0%) and NAB (−1.0%). In the last minutes of exercise, plasma Na+ was reduced (p < 0.05) in W (−3.9%) and AB (−3.7%), plasma K+ was increased (p < 0.05) in AB (8.5%), and USG was reduced in W (−0.9%) and NAB (−1.0%). Collectively, these results suggest that non-alcoholic beer before exercise could help maintain electrolyte homeostasis during exercise. Alcoholic beer intake reduced plasma Na+ and increased plasma K+ during exercise, which may negatively affect health and physical performance, and finally, the consumption of water before exercise could induce decreases of Na+ in plasma during exercise.
Journal Article
Feasibility of Bioelectrical Impedance Spectroscopy Measurement before and after Thoracentesis
Background. Bioelectrical impedance spectroscopy is applied to measure changes in tissue composition. The aim of this study was to evaluate its feasibility in measuring the fluid shift after thoracentesis in patients with pleural effusion. Methods. 45 participants (21 with pleural effusion and 24 healthy subjects) were included. Bioelectrical impedance was analyzed for “Transthoracic,” “Foot to Foot,” “Foot to Hand,” and “Hand to Hand” vectors in low and high frequency domain before and after thoracentesis. Healthy subjects were measured at a single time point. Results. The mean volume of removed pleural effusion was 1169±513 mL. The “Foot to Foot,” “Hand to Hand,” and “Foot to Hand” vector indicated a trend for increased bioelectrical impedance after thoracentesis. Values for the low frequency domain in the “Transthoracic” vector increased significantly (P<0.001). A moderate correlation was observed between the amount of removed fluid and impedance change in the low frequency domain using the “Foot to Hand” vector (r=-0.7). Conclusion. Bioelectrical impedance changes in correlation with the thoracic fluid level. It was feasible to monitor significant fluid shifts and loss after thoracentesis in the “Transthoracic” vector by means of bioelectrical impedance spectroscopy. The trial is registered with Registration Numbers IRB EK206/11 and NCT01778270.
Journal Article
Role of excess volume in the pathophysiology of hypertension in chronic kidney disease
Role of excess volume in the pathophysiology of hypertension in chronic kidney disease.
The pathophysiology of hypertension in patients with chronic kidney disease (CKD) is largely attributed to positive sodium balance. It is unclear how loop diuretics affect fluid volume compartments, especially with respect to their antihypertensive effect.
Subjects with CKD were administered a single therapeutically equivalent dose of an oral loop diuretic (furosemide or torsemide in randomized crossover design). We measured acute volume changes over 12 hours using biophysical and hormonal biomarkers and then 24-hour ambulatory blood pressure after daily diuretic therapy for 3 weeks.
Single-dose administration of loop diuretic decreased extracellular water (ECW) by 1.7L [95% confidence interval (95% CI) 1.2, 2.2, P < 0.001], total body water (TBW) by 1.2L (95% CI 0.5, 1.9, P < 0.001), and increased natural log (ln) plasma renin activity (PRA) from -1.2 ± 1.3ng/mL/hour to -0.5 ± 1.5ng/mL/hour (P < 0.001). Daily loop diuretic administration resulted in reduced ECW from 24.2 ± 6.4L to 22.3 ± 5.2L (P = 0.02) and TBW from 54.3 ± 12.7L to 51.6 ± 11.9L (P < 0.001) in 1 week. After 3 weeks of diuretic therapy, whereas ECW reduction persisted at 22.8 ± 5.1L (P = 0.05), TBW trended toward baseline level at 52.7 ± 11.8L. A concomitant increase in ln PRA from –1.0 ± 1.3ng/mL/hour to 0.4 ± 1.9ng/mL/hour (P < 0.001) and ln plasma aldosterone (PA) from 2.0 ± 0.8ng/dL to 2.3 ± 0.8ng/dL (P < 0.005) and fall in ln brain natriuretic peptide (BNP) from 4.3 ± 0.9 pg/mL to 3.7 ± 1.0 pg/mL (P < 0.01) were seen at 1 week. Despite a trend toward restoration of TBW, changes in hormonal biomarkers were maintained at 3 weeks. Over these 3 weeks, furosemide reduced 24-hour ambulatory blood pressure from 147 ± 17/78 ± 11mm Hg to 138 ± 21/74 ± 12mm Hg (P = 0.021) and torsemide reduced it from 143 ± 18/75 ± 10mm Hg to 133 ± 19/71 ± 10mm Hg (P = 0.007).
Patients with CKD have elevated extracellular fluid volume that can be corrected acutely with loop diuretics. Persistent diuretic use results in dynamic changes in ECW and other body fluid compartments that translate into chronic blood pressure reduction.
Journal Article
Essential fluid, electrolyte and pH homeostasis
This textbook provides a unique, pocket-sized, self-directed study guide to fluid, electrolyte and acid base homeostasis for undergraduate biomedical science, pharmacology, medical and allied health students. It details the chemical (mostly ionic) composition of body fluids, explains how abnormalities arise, what laboratory tests can be used to identify and analyze the cause of these disorders and shows how normality can be achieved to maintain health.
eBook
Force-free swimming of a model helical flagellum in viscoelastic fluids
We precisely measure the force-free swimming speed of a rotating helix in viscous and viscoelastic fluids. The fluids are highly viscous to replicate the low Reynolds number environment of microorganisms. The helix, a macroscopic scale model for the bacterial flagellar filament, is rigid and rotated at a constant rate while simultaneously translated along its axis. By adjusting the translation speed to make the net hydrodynamic force vanish, we measure the force-free swimming speed as a function of helix rotation rate, helix geometry, and fluid properties. We compare our measurements of the force-free swimming speed of a helix in a high-molecular weight silicone oil with predictions for the swimming speed in a Newtonian fluid, calculated using slender-body theories and a boundary-element method. The excellent agreement between theory and experiment in the Newtonian case verifies the high accuracy of our experiments. For the viscoelastic fluid, we use a polymer solution of polyisobutylene dissolved in polybutene. This solution is a Boger fluid, a viscoselastic fluid with a shear-rate-independent viscosity. The elasticity is dominated by a single relaxation time. When the relaxation time is short compared to the rotation period, the viscoelastic swimming speed is close to the viscous swimming speed. As the relaxation time increases, the viscoelastic swimming speed increases relative to the viscous speed, reaching a peak when the relaxation time is comparable to the rotation period. As the relaxation time is further increased, the viscoelastic swimming speed decreases and eventually falls below the viscous swimming speed.
Journal Article
Internal fluid pressure influences muscle contractile force
Fluid fills intracellular, extracellular, and capillary spaces within muscle. During normal physiological activity, intramuscular fluid pressures develop as muscle exerts a portion of its developed force internally. These pressures, typically ranging between 10 and 250 mmHg, are rarely considered in mechanical models of muscle but have the potential to affect performance by influencing force and work produced during contraction. Here, we test a model of muscle structure in which intramuscular pressure directly influences contractile force. Using a pneumatic cuff, we pressurize muscle midcontraction at 260 mmHg and report the effect on isometric force. Pressurization reduced isometric force at short muscle lengths (e.g., −11.87% of P₀ at 0.9 L₀), increased force at long lengths (e.g., +3.08% of P₀ at 1.25 L₀), but had no effect at intermediate muscle lengths ∼1.1–1.15 L₀. This variable response to pressurization was qualitatively mimicked by simple physical models of muscle morphology that displayed negative, positive, or neutral responses to pressurization depending on the orientation of reinforcing fibers representing extracellular matrix collagen. These findings show that pressurization can have immediate, significant effects on muscle contractile force and suggest that forces transmitted to the extracellular matrix via pressurized fluid may be important, but largely unacknowledged, determinants of muscle performance in vivo.
Journal Article
The pupal moulting fluid has evolved social functions in ants
Insect societies are tightly integrated, complex biological systems in which group-level properties arise from the interactions between individuals
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. However, these interactions have not been studied systematically and therefore remain incompletely known. Here, using a reverse engineering approach, we reveal that unlike solitary insects, ant pupae extrude a secretion derived from the moulting fluid that is rich in nutrients, hormones and neuroactive substances. This secretion elicits parental care behaviour and is rapidly removed and consumed by the adults. This behaviour is crucial for pupal survival; if the secretion is not removed, pupae develop fungal infections and die. Analogous to mammalian milk, the secretion is also an important source of early larval nutrition, and young larvae exhibit stunted growth and decreased survival without access to the fluid. We show that this derived social function of the moulting fluid generalizes across the ants. This secretion thus forms the basis of a central and hitherto overlooked interaction network in ant societies, and constitutes a rare example of how a conserved developmental process can be co-opted to provide the mechanistic basis of social interactions. These results implicate moulting fluids in having a major role in the evolution of ant eusociality.
Ant pupae secrete a fluid, derived from the moulting fluid, that elicits parental care behaviour, provides nutrients for larvae and must be removed for pupal survival.
Journal Article