Introduction to Renal Physiology Modes of Transport Of

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Introduction to Renal Physiology Modes of Transport Of

Introduction to Renal Physiology Topics for today: • Review CO2 transport • Neural controls of ventilation • Structure of kidneys and nephron • Clearance concept • Filtration, reabsorption, and secretion • Amount of urine produced per day Modes of Transport of CO2 - ~65% as HCO3 ion (part of major blood buffer) ~27% complexed with Hb (in the form of carbamino) ~8% as simple CO2 (dissolved gas) 1 Neural controls of respiration Neural center in lower brain control rate and depth of respiration cranial and spinal nerves carry impulses from control centers to the diaphragm and intercostal muscles lung stretch receptors in lung monitor volume of lung and send feedback impulses to centers in lower brain Neural cycle of ventilation control Sequence of neural control: • phrenic nerve stimulates diaphragm vagal nerve branch • inhalation excites stretch receptors exp center insp center • feedback impulses inhibit insp. center phrenic insp exp 3.0 nerve lung stretch volume receptors (L) 2.5 phrenic tone vagal branch tone Other nerves in ventilation control Special receptors along aortic arch and carotid arteries that monitor plasma CO2 concentration 2 CO2 Effects on Ventilation Carotid and aortic body receptors continuously monitor CO 2 levels. 40 mmHg 40.5 mmHg 41 mmHg PCO2 1% increase in CO 2 causes about two-fold increase in minute volume. Design and Function of Kidneys • What essential processes are performed by kidneys? • How are kidneys designed for these processes? • How much urine do kidneys produce per day? Overview of kidney function • Kidneys receive about 20% of cardiac output • Kidneys function is to continuously ‘clear’ plasma flowing through them Kidneys anatomy is designed for processes they perform. 3 Clearance function of kidney The main function of the kidney is clearance, process by which the kidney removes (‘clears’) harmful substances from the plasma. plasma in (with harmful solutes) plasma out (less harmful solutes) C = (U x)V P urine out (with harmful solutes) Internal structure of kidney functional units of kidneys renal capsule nephrons cortex renal pyramids minor calyx major calyx renal pelvis ureter collecting duct proximal convoluted tubule The Nephron distal con. tubule (kidney functional unit) Nephron functional processes: • filtration - function of glomerulus efferent • reabsorption - function arteriole of tubules • secretion - function of afferent arteriole loop of tubules Henle renal corpuscle (Bowman’s capsule with glomerulus) vasa recta collecting interlobular artery & vein duct 4 Fine structure of renal corpuscle Design facilitates filtration, the main function of this part of nephron. Monitors input pressure; triggers release of local factors (bradykinin and endothelin) and systemic factors ( renin); these local and systemic factors affect blood pressure to modulate glomerular filtration rate. SEM view of glomeruli Urine (and filtrate) Formed per Day • Renal blood flow: ~ 24% of cardiac output (1.2 L/min) • Renal plasma flow: ~700 ml/min • Glomerular filtration rate: ~125 ml/min (or 180 L/day … ~3x body mass) • Urine formation: ~1.25 ml/min (~1.8 L/day) 5.

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Kidney, Renal Tubule – Dilation
Kidney, Renal Tubule – Dilation Figure Legend: Figure 1 Kidney, Renal tubule - Dilation in a male B6C3F1 mouse from a chronic study. Dilated tubules are noted as tracts running through the cortex and outer medulla. Figure 2 Kidney, Renal tubule - Dilation in a male F344/N rat from a chronic study. Tubule dilation is present throughout the outer stripe of the outer medulla, extending into the cortex. Figure 3 Kidney, Renal tubule - Dilation in a male B6C3F1 mouse from a chronic study. Slight tubule dilation is associated with degeneration and necrosis. Figure 4 Kidney, Renal tubule - Dilation in a male F344/N rat from a chronic study. Tubule dilation is associated with chronic progressive nephropathy. Comment: Renal tubule dilation may occur anywhere along the nephron or collecting duct system. It may occur in focal areas or as tracts running along the entire length of kidney sections (Figure 1). 1 Kidney, Renal Tubule – Dilation Renal tubule dilation may occur from xenobiotic administration, secondary mechanisms, or an unknown pathogenesis (see Kidney – Nephropathy, Obstructive (Figure 2). Dilation may result from direct toxic injury to the tubule epithelium interfering with absorption and secretion (Figure 3). It may also occur secondary to renal ischemia or from prolonged diuresis related to drug administration. Secondary mechanisms of tubule dilation may result from lower urinary tract obstruction, the deposition of tubule crystals, interstitial inflammation and/or fibrosis, and chronic progressive nephropathy (Figure 4). A few dilated tubules may be regarded as normal histologic variation. Recommendation: Renal tubule dilation should be diagnosed and given a severity grade. The location of tubule dilation should be included in the diagnosis as a site modifier.
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Female Urethra
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Excretory Products and Their Elimination
290 BIOLOGY CHAPTER 19 EXCRETORY PRODUCTS AND THEIR ELIMINATION 19.1 Human Animals accumulate ammonia, urea, uric acid, carbon dioxide, water Excretory and ions like Na+, K+, Cl–, phosphate, sulphate, etc., either by metabolic System activities or by other means like excess ingestion. These substances have to be removed totally or partially. In this chapter, you will learn the 19.2 Urine Formation mechanisms of elimination of these substances with special emphasis on 19.3 Function of the common nitrogenous wastes. Ammonia, urea and uric acid are the major Tubules forms of nitrogenous wastes excreted by the animals. Ammonia is the most toxic form and requires large amount of water for its elimination, 19.4 Mechanism of whereas uric acid, being the least toxic, can be removed with a minimum Concentration of loss of water. the Filtrate The process of excreting ammonia is Ammonotelism. Many bony fishes, 19.5 Regulation of aquatic amphibians and aquatic insects are ammonotelic in nature. Kidney Function Ammonia, as it is readily soluble, is generally excreted by diffusion across 19.6 Micturition body surfaces or through gill surfaces (in fish) as ammonium ions. Kidneys do not play any significant role in its removal. Terrestrial adaptation 19.7 Role of other necessitated the production of lesser toxic nitrogenous wastes like urea Organs in and uric acid for conservation of water. Mammals, many terrestrial Excretion amphibians and marine fishes mainly excrete urea and are called ureotelic 19.8 Disorders of the animals. Ammonia produced by metabolism is converted into urea in the Excretory liver of these animals and released into the blood which is filtered and System excreted out by the kidneys.
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Claudins in the Renal Collecting Duct
International Journal of Molecular Sciences Review Claudins in the Renal Collecting Duct Janna Leiz 1,2 and Kai M. Schmidt-Ott 1,2,3,* 1 Department of Nephrology and Intensive Care Medicine, Charité-Universitätsmedizin Berlin, 12203 Berlin, Germany; [email protected] 2 Molecular and Translational Kidney Research, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany 3 Berlin Institute of Health (BIH), 10178 Berlin, Germany * Correspondence: [email protected]; Tel.: +49-(0)30-450614671 Received: 22 October 2019; Accepted: 20 December 2019; Published: 28 December 2019 Abstract: The renal collecting duct fine-tunes urinary composition, and thereby, coordinates key physiological processes, such as volume/blood pressure regulation, electrolyte-free water reabsorption, and acid-base homeostasis. The collecting duct epithelium is comprised of a tight epithelial barrier resulting in a strict separation of intraluminal urine and the interstitium. Tight junctions are key players in enforcing this barrier and in regulating paracellular transport of solutes across the epithelium. The features of tight junctions across different epithelia are strongly determined by their molecular composition. Claudins are particularly important structural components of tight junctions because they confer barrier and transport properties. In the collecting duct, a specific set of claudins (Cldn-3, Cldn-4, Cldn-7, Cldn-8) is expressed, and each of these claudins has been implicated in mediating aspects of the specific properties of its tight junction. The functional disruption of individual claudins or of the overall barrier function results in defects of blood pressure and water homeostasis. In this concise review, we provide an overview of the current knowledge on the role of the collecting duct epithelial barrier and of claudins in collecting duct function and pathophysiology.
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Urogenital Kit Identification Guide
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