Functions of the Kidneys and Functional Anatomy
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2020
The primary function of the kidneys is the regulation of fluid and electrolyte composition of the body. The kidneys have a high blood flow, and from this, a very large volume (180 L/day) of ultrafiltrate of plasma is produced in the renal corpuscles (glomerular capillaries and Bowman's capsule). This large glomerular filtrate is necessary for the excretion of waste products of metabolism in the urine. The filtrate passes along the nephron, where the specific processes of tubular reabsorption and secretion occur. Most of the filtered fluid is reabsorbed. The proximal tubule alone reabsorbs 60% of the water and sodium filtered into Bowman's capsule, and the normal urine volume is only 1.5 L/day. Substances can also be removed from the peritubular capillary blood into the nephron lumen by specific tubular secretory mechanisms; many drugs are handled in this way. The final volume and composition of urine are modulated to maintain normal body fluid and electrolyte balance by factors governing the processes of glomerular filtration, tubular reabsorption and tubular secretion. The kidneys have an integral role in the long-term regulation of body water and electrolyte composition, and therefore renal function is an important determinant of the long-term regulation of blood volume and arterial blood pressure.
Renal physiology
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2015
The primary function of the kidneys is the regulation of fluid and electrolyte composition of the body. The kidneys have a high blood flow, and from this a very large volume (180 L/day) of ultrafiltrate of plasma is produced in the renal corpuscles (glomerular capillaries and Bowman’s capsule). This large glomerular filtrate is necessary for the excretion of waste products of metabolism in the urine. The filtrate passes along the nephron, where the specific processes of tubular reabsorption and secretion occur. Most of the filtered fluid is reabsorbed. The proximal tubule alone reabsorbs 60% of the water and sodium filtered into Bowman’s capsule, and the normal urine volume is only 1.5 L/day. Substances can also be removed from Fluid and electrolyte balance and dietary requirements 221 the peritubular capillary blood into the nephron lumen by specific tubular secretory mechanisms; many drugs are handled in this way. The final volume and composition of urine are modulated to maintain normal body fluid and electrolyte balance by factors governing the processes of glomerular filtration, tubular reabsorption and tubular secretion. The kidneys have an integral role in the long-term regulation of body water and electrolyte composition, and therefore renal function is an important determinant of the long-term regulation of blood volume and arterial blood pressure.
Urology
Janesh K Gupta in Core Clinical Cases in Surgery and Surgical Specialties, 2014
A5: What investigations would be most helpful and why? Renal function tests are useful.Dilatation of the renal tract is often identified with an ultrasound scan. The thickness of the renal cortex often allows interpretation of the duration of the obstruction and reversible nature of obstruction. A thin renal cortex often implies long-standing disease with irreversible renal damage.CT is used to assess retroperitoneum and pelvic masses or to stage a neoplastic disease.
Effects of acute exposure to ultra-wideband pulsed electromagnetic fields on the liver and kidneys of mice
Published in Electromagnetic Biology and Medicine, 2020
Kaihong Guo, Yali Zhang, Xinlei Fang, Peiyao Fan, Sen Shang, Fan Fan, Hongyan Wu, Menghua Man, Yanzhao Xie, Xiaoyun Lu
ALT is mainly found in the liver while AST is widely present in a variety of tissues including the liver, heart and kidneys. Generally, an increase of serum ALT levels is considered the most sensitive indicator of hepatic damage. Therefore, the increases of serum ALT and AST levels suggested potential abnormalities of liver function. The renal function is usually monitored by measuring blood urea nitrogen (BUN), uric acid (UA), creatinine (CRE) and cystatin (Cys-C). BUN and UA are highly specific indicators of renal damage, but they have low sensitivity. By contrast, the serum Cys-C levels are the most sensitive predictor of a decrease in the glomerular filtration rate, and can be used as an early marker for renal dysfunction. CRE is only suitable for the evaluation of middle and late stages of renal damage. Therefore, the increase of serum UA and Cys-C levels suggested that exposure to UWB pulses resulted in mild, early kidney dysfunction. However, there were no significant changes in BUN and CRE levels between the sham and UWB pulse exposure groups, which suggested that the degree of renal injury was low. Taken together, the increase of serum AST, ALT, Cys-C and UA levels implied that the mice presented liver and kidney dysfunction after exposure to UWB pulses.
Excess costs of non-infectious comorbidities among people living with HIV – estimates from Denmark and Sweden
Published in AIDS Care, 2018
Frida Hjalte, Paul S. Calara, Anders Blaxhult, Marie Helleberg, Karoline Wallace, Peter Lindgren
We found that the one-year direct, and indirect, costs of the four major comorbidities were substantial, highlighting the importance of implementing, or further strengthening prophylactic interventions for comorbidities in the HIV-infected population. A large proportion of HIV-infected individuals are smokers, and smoking is a strong, but reversible, risk factor for cardiovascular disease and osteoporosis (Hansen et al., 2012; Rasmussen, Helleberg, et al., 2015). Hypertension is a common cause of impaired renal function and cardiovascular disease in the general population. The literature on the prevalence of, and success in, managing hypertension among HIV-infected individuals is not extensive, but it is possible that improvements in the diagnosis and management of hypertension can reduce rates of renal and cardiovascular disease in this population.
Worsening renal function, adverse clinical events and major determinants for changes of renal function in patients with atrial fibrillation: a Japanese multicenter registry substudy
Published in Current Medical Research and Opinion, 2019
Keiichiro Kuronuma, Yasuo Okumura, Katsuaki Yokoyama, Naoya Matsumoto, Eizo Tachibana, Koji Oiwa, Michiaki Matsumoto, Toshiaki Kojima, Hironori Haruta, Kazumiki Nomoto, Kazumasa Sonoda, Ken Arima, Rikitake Kogawa, Fumiyuki Takahashi, Tomobumi Kotani, Kimie Okubo, Seiji Fukushima, Satoru Itou, Kunio Kondo, Masaaki Chiku, Yasumi Ohno, Motoyuki Onikura, Atsushi Hirayama
Our study results should be interpreted in light of the study limitations. First, the study was conducted as a retrospective analysis of prospectively collected data, so we were not able to track all physical examination (body weight, for example) and laboratory values that might have factored into our study results. Second, for analysis of renal function, we could not use CrCl calculated by means of the Cockcroft–Gault formula, which requires a body weight value. We simply used the modified MDRD Study equation. Third, although we indicated that the patients with worsening renal function had a poor prognosis, it remains unclear whether it was the cause or consequence of impaired renal function. Further study is needed to clarify this point. Finally, only selected institutions within a limited geographical area in Japan participate in the SAKURA AF Registry, so we cannot say that our findings are reflective of the entire population of AF patients in Japan. We note, however, that patient selection and regional enrollment biases are limitations of all prospective observational studies.
Related Knowledge Centers
- Blood Pressure
- Clearance
- Potassium
- Sodium
- Toxin
- Signs & Symptoms
- Renal Physiology
- Fluid Balance
- Acid–Base Homeostasis
- Electrolyte