Kidneys functional unit

Fig. 15. Dynamic CT images in a person with normal kidney function (units time (seconds) after the administration of contrast medium)...

Excretion is the process by which a compound exits the body. Urinary excretion, fecal excretion, and exhaled air are the most common pathways. Compounds removed from the blood by the kidney are excreted in urine. Within the kidney, functional units called nephrons filter the blood. Some bases and weak acids are actively transported out of the blood. Ions are especially subject to the kidney s filtration. Large molecules are primarily excreted in fecal matter because of the size exclusion in the glomerulus of the kidney. In addition, large molecules may be secreted in the bile and therefore excreted in the feces. Gases with low solubility and Uquids with high volatility are efficiently excreted in exhaled air. Other less prominent excretion pathways include breast milk, sweat, and tears. Certain heavy metals such as Cr, Cd, Co, W, and U will accumulate in hair follicles and be detectable in hair. 

The Summary Drug Table Diuretics lists examples of die different types of diuretic drugp. Most diuretics act on die tubules of die kidney nephron (Pig. 46-1), the functional unit of the kidney. Each kidney contains about one million nephrons, which filter die bloodstream to remove waste products. During diis process,... 

Figure 46-1. The nephron is the functional unit of the kidney. Note the various tubules, the site of most diuretic activity. The loop of Henle is the site of action for the loop diuretics. Thiazide diuretics ad at the ascending portion of the loop of Henle and the distal tube of the nephron.

The kidneys lie outside the peritoneal cavity in the posterior abdominal wall, one on each side of the vertebral column, slightly above the waistline. In the adult human, each kidney is approximately 11 cm long, 6 cm wide, and 3 cm thick. These organs are divided into two regions the inner renal medulla and the outer renal cortex. The functional unit of the kidney is the nephron (see Figure 19.1 and Figure 19.2). Approximately 1 million nephrons are in each kidney. The nephron has two components ... 

Figure 19.1 The nephron. The functional unit of the kidney is the nephron, which has two components. The vascular component includes the afferent arteriole, which carries blood toward the glomerulus where filtration of the plasma takes place. The efferent arteriole carries the unfiltered blood away from the glomerulus. The tubular component of the nephron includes Bowman s capsule, which receives the filtrate the proximal tubule the Loop of Henle and the distal tubule. The tubule processes the filtrate, excreting waste products and reabsorbing nutrient molecules, electrolytes, and water.

Each kidney consists of approximately one million functional units called nephrons ... 

The smallest functional unit of the kidney is the nephron. In the glomerular capillary loops, ultrafiltration of plasma fluid into Bowman s capsule (BC) yields primary urine. In the proximal tubules (pT), approx. 70% of the ultrafiltrate is retrieved by isoosmotic reabsorption of NaCl and water. In the thick portion of the ascending limb of Henle s loop (HL), NaCl is absorbed unaccompanied by water. This is the prerequisite for the hairpin countercurrent mechanism that allows build-up of a very high NaQ concentration in the renal medulla In the distal tubules (dT), NaCl and water are again jointly reabsorbed. At the end of the nephron, this process involves an aldosterone-controlled exchange of Na+ against 1C or H. In the collecting tubule (C), vasopressin (antidiuretic hormone, ADH) increases the epithelial permeability for water, which is drawn into the hyperosmolar milieu of the renal medulla and thus retained in the body. As a result, a concentrated urine enters the renal pelvis. 

The functional unit of the kidney is the nephron. It is made up of the Malpighian bodies or renal corpuscles (consisting of Bowman s capsules and the glomerulus), the proximal tubule, Henle s loop, and the distal tubule, which passes into a collecting duct. The human kidney contains around one million nephrons. The nephrons form urine in the following three phases. 

NAPQI N-acetyl-p-benzoquinone imine. nephron functional unit of the kidney. 

A family of integral proteins discovered by Peter Agre, the aquaporins (AQPs), provide channels for rapid movement of water molecules across all plasma membranes (Table 11-6 lists a few examples). Ten aquaporins are known in humans, each with its specialized role. Erythrocytes, which swell or shrink rapidly in response to abrupt changes in extracellular os-molarity as blood travels through the renal medulla, have a high density of aqua-porin in their plasma membranes (2 X 105 copies of AQP-1 per cell). In the nephron (the functional unit of the kidney), the plasma membranes of proximal renal tubule cells have five different aquaporin types. 

Blood is delivered to the human kidney by the renal artery. Blood flows to the kidneys of the adult human at a rate of roughly 1 L/min. The adult human kidney contains approximately 1 million functional units, called nephrons, to which the blood is delivered for removal of solutes. Collected materials are excreted from the body in the urine. 

The nephron is the functional unit of the kidney. It is described in detail in Chapter 10 and illustrated in Figure 10.1. 

Figure 12.1 Schematic of a single nephron, the functional unit of the kidney. Microsolutes are filtered from blood cells in Bowman s capsules. As the filtrate passes towards the collection tubule most of the microsolutes and water are reabsorbed by a type of facilitated transport process. The fluid finally entering the collecting tubule contains the nitrogenous wastes from the body and is excreted as urine. There are about 1 million nephrons in the normal kidney [1]...

The kidney and bladder are very important in toxicology because they are the main route of elimination of hydrophilic toxicant metabolites and because damage to them in the form of impaired kidney function or bladder cancer is one of the major adverse effects of toxicants. The kidney plays a key role in maintaining body homeostasis. The basic unit of the kidney, through which the organ performs its crucial blood filtration action, is the nephron. As the main organ through which fluid is lost from the body, it is vital in the maintenance of extracellular fluid volume. It acts to maintain... 

Glomerulus A functional unit of the mammalian kidney consisting of a small bunch of capillaries projecting into a capsule (Bowman s capsule), which serves to collect the filtrate from the blood of those capillaries and direct it into the kidney tubule. 

Nephron The functional unit of the kidney that produces urine. It consists of a long tubule divided into sections in which reabsorption into the bloodstream of certain solutes filtered by the glomerulus from the blood takes place. 

The basic functional unit of the kidney is the nephron, of which there are more than a million within the cortex and medulla of each normal adult human kidney. Nephrons regulate water and soluble matter (especially electrolytes) in the body by first filtering the blood under pressure, and then reabsorbing some necessary fluid and molecules back into the blood while secreting other, unneeded molecules. Reabsorption and secretion are accomplished with both cotransport and countertransport mechanisms established in the nephrons and associated collecting ducts. 

Renal function is an indication of the physiological state of the kidney glomerular filtration rate (GFR) describes the flow rate of Altered fluid through the kidney, while creatinine clearance rate (Ccr) is the volume of blood plasma that is cleared of creatinine per unit time, and is a useful measure for approximating the GFR. Most clinical tests use the plasma concentrations of the waste substances of creatinine and urea, as well as electrolytes, to determine renal function. The nephron is the functional unit of the kidney (Figure 10.1) it consists of two parts ... 

Nephron The basic structural and functional unit of the kidney. The basic function of the nephron is to regulate water and soluble substances... 

The kidney tissue has a very intriguing structure. It is organized into several thousand structural and functional units. A single unit - a nephron (Figure 2.15b) - spans the better part of the entire distance between the organ periphery and the renal pelvis, which simply collects the final urine and feeds it into the ureters.. 

A striking example of the importance of the primary structure of polypeptides can be seen in the differences between oxytocin and vasopressin. Both of these molecules are nine-unit polypeptides that differ by only two amino acids (Fig. 22.19), yet they perform completely different functions in the human body. Oxytocin is a hormone that triggers contraction of the uterus and milk secretion. Vasopressin raises blood pressure levels and regulates kidney function. 

Chronic renal failure Is treated by dialysis, kidney transplants, and drugs, as well as by Sow-protein diets. For tlris reason, an outline of chronic renal failure occurs in this chapter. The normal giomernlar filtration rate (GFR) is 80 to 120 ml/min. In severe renal disease, the GFR can be reduced to 10 ml/min or less. This represents a 90% loss of renal function. Diabetes mellitus and hypertension thigh blood pressure) are the main causes of chronic renal failure. Sustained and chronic injury to the kidneys leads to the destruction of the nephrons, where this destruction is usually not reversible. The nephron, which is the sm a I lest unit of kidney function, isdtjtailEd in the section on dium, Potassium, Chloride, and Water. The severe loss of nephrons results in alterations of functions of many other organs of the body. The collechon of abnormalities that results is called uremia. 

In the intensive care unit muscle relaxants are used to facilitate airway management and mechanical ventilation. The duration of administration can range from a single dose to continuous infusions for up to several weeks. Patients in ICU are more hkely to have abnormalities of acid-base balance, electroljrte balance, body temperature, and liver and kidney function, predisposing them to the adverse effects of neuromuscular blocking drugs. 

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