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Renal physiology
Renal physiology
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The neural control of the kidneys is through the sympathetic nervous system, efferent renal sympathetic nerves innervation and neuroeffector junctions have been identified along the renal vasculature, the tubules, the granular cells of juxtaglomerular apparatus (Kate etal, 2004; Edward etal, 2011). The action of sympathetic system is via the release the norepinephrine at sympathetic nerve terminals into the interstitial space. A moderately high levels of nerve stimulation has more effect on efferent arteriole than afferent thereby the RBF fall more than the GFR in consistent with efferent arteriolar constriction, however at maximal nerve stimulation afferent vasoconstriction predominates and leads to drastic reductions in both RBF and GFR (DiBona and Kopp, 1997; Edward etal, 2011). Unlike many other organs the kidneys have a low resting sympathetic tone, meaning that a decrease in sympathetic nervous system cannot effectively decrease the resistance. The main aim of sympathetic nervous system is to compensate for a fall in blood pressure or to prepare the body for the fight or flight response. Studies have investigated sympathepatic activity in relation to Protein resistriction by measuring norepinephrine (NE) turnover in heart and interscapular brown adipose tissue (IBAT) and reported an increase in sympathepatic activity (Laryssa etal, 1986; Martins etal, 2011 ), but since the Resting Sympathetic Activity has a very minimal effect on renal function any influence on it by dietary protein/amino acid will have little or no effect on kidney function.
Sympathetic tone was augmented in malnourished compared with control rats (131 ± 17 vs 41 ± 11 b.p.m., respectively), whereas parasympathetic tone was reduced in malnourished com...
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...prevented the rise in both GFR and RPF. Same study also examine whether the amino acid -induced hyperfiltration was due to dopamine release from renal nerves or enhanced renal tubule dopamine synthesis, they administered amino acid to rats in which the left kidney had been chronically denervated while the right kidney remained intact. It was observed that the infusion of amino acid led to significant increments in GFR and RPF only in the intact control kidney, whereas GFR and RPF remained unaltered in the denervated kidney.
Nitric oxide (NO) is another paracrine factor that act in kidney to modulate neurotransmission activity. It is produced via the action of nitric oxide synthase (NOS) enzymes this exist in three isoforms; neuronal (nNOS, NOSI), inducible (iNOS, NOSII), and endothelial (eNOS, NOSIII) and all are expressed within the kidney (Edward etal, 2011).
The kidneys play a major role in the blood composition and volume , the excretion of metabolic wastes in the urine, the control the acid/base balance in the body and the hormone production for maintaining hemostasis. The damages to the GBM in the glomeruli alter filtration process that allows the protein and red blood cells to leak into the urine. Loss of protein like albumin in the urine results in a decrease of their level into the blood stream. Consequently, this patient’s blood reveals a decreased albumin (Alb) value of 2.9 g/dL, decreased serum total protein value of 5 .0 g/dL and in the urine presents of the protein and the RBCs. Impaired filtering capacity result in inability of kidneys to excrete excretory products like electrolytes and metabolic waste products that will then accumulate in the blood. Furthermore, inability of distal convoluted tubules to excrete sufficient quantities of potassium, sodium, magnesium (Mg), chloride (Cl), urea, creatinine (Cr), alkaline phosphatase (Alk Phos), and phosphate (PO4) results in their elevation in the blood. His laboratory values reveal an increased of sodium value of 149 meq/L, an increase of potassium value of 5.4meq/L, increased chloride value of 116 meq/L, increased blood urea nitrogen (BUN) serum of 143 mg/dL, and increased creatinine serum of 7.14 mg/dL. The other abnormal blood tests associated with a loss of kidneys’ filtration property identify in this patient are related to an increase of alkaline phosphatase value of 178 IU/L, increased magnesium value of 3.8mgdL, and increased phosphate (PO4) value of 5.9 mg/dL .
The gaseous free radical nitric oxide is an abundant intracellular messenger molecule that plays a central role in maintenance of health, and is heavily involved in signal transduction in various cells of the body [1]. This molecule acts as a mediator in the regulation of cardiac function as well as having an important role in regulating contractility of the heart and maintenance of vascular tone in the cardiovascular system. As one of the most significant individuals in our discovery of nitric oxide, Dr. Robert Furchgott pioneered our understanding of this molecule through his experiments on the vasorelaxant properties of acetylcholine and the subsequent proposal of the presence of the endothelium derived relaxing factor, which was later identified to be nitric oxide [7]. Given the observation that cardiovascular disorders are the number one cause of death in many nations around the world, research into the vasorelaxant properties seems particularly relevant in order to help combat rising rates of vascular hypertension and high blood pressure. In this paper, the properties of nitric oxide are discussed largely with respect to the cardiovascular system. This paper focuses on the synthesis and characteristics of nitric oxide, the mechanisms of action by which nitric oxide works and the regulation of nitric oxide in the body, and finally a short summary of Robert Furchgott’s contributions to the discovery of nitric oxide and its properties.
Renin angiotensin system activation: Because of decreased blood flow to the kidneys the compensatory mechanisms activate to hold on to sodium and water. When the Blood flow is decreased Angiotensin II is released causing vasoconstriction
Hurtado R, Bub G, Herzlinger D: The pelvis–kidney junction contains HCN3, a hyperpolarization-activated cation channel that triggers ureter peristalsis. Kidney International 2010;77:500–508.
Together extra-renal factors (insulin, epinephrine, aldosterone) and renal factors maintain a normal potassium plasma concentration in the body. The extra-renal mechanisms are responsible for moving potassium into the intracellular compartment. The renal mechanisms are responsible for chronic maintenance of body potassium content. When these mechanisms are functioning correctly, large intake of potassium has a minor and insignificant effect on the potassium concentration in the plasma. [5&6]
When a receptor is activated and the stimulus is taken to the hypothalamus and then relayed out to the “limbic system and neocortical areas…impulses stimulate the neuroendocrine and autonomic nervous system,” which can cause an array of issues if not careful and if the stress signal is prolonged. (3)
... uptake during submaximal exercise but did increase heart rate and the rate-pressure product at rest and during both exercise and recovery’.
Sympathetic pathways change nerve activity during times of stress, exercise, low blood glucose levels, excitement or fear, due to the flight or fight response. These changes can have an effect on homeostasis by increasing heart rate, increasing blood flow, dilating pupils, sweating, releasing glycogen, increasing oxygen intake and diverting blood flow away from the gastrointestinal tract.
Norepinephrine is the neurotransmitter released by sympathetic nerves (e.g., those innervating the heart and blood vessels) and, within the brain, those of the locus coe...
In the human body, there are a number of systems that have their own importance and provide different functions to help keep us alive. One of these systems is the urinary system, also known as the renal system. As blood courses through the body, waste products are transferred into the bloodstream that needs to be extracted. The urinary system is designed to help the body remain free of excess water and waste that we no longer need. This particular system is made up of two kidneys, two ureters, a urinary bladder and a urethra that produces, stores, and then excretes urine out of the body. When it comes to the urinary system,
The second aspect of this presentation was the 5-HT Receptor Antagonist. These antagonists are capable of decreasing the effect of NPY levels within the body. One antagonist, in particular, was shown to have a great effect on NPY effect, known as DOI. It was found that DOI blocks NYP responses inside the brain. One specific part of DOI was signaled out as being responsible for the blockage of NPY, known as 2A. Even though the DOI is able to decrease the sense of hunger, it is not used in humans because it causes very bad after effects, especially great nausea.
Another benefit is that low carb diets do not have any effect on the kidneys. It was found that being on a...
The purpose of this paper is to take an in depth look at a renal diet which is designed for people suffering from certain kidney conditions. A renal diet can be described as a nutritional regime which is: “low in sodium, phosphorous and protein... [It] also promotes the importance of consuming high-quality protein and usually limits fluids. Some patients may also need to limit potassium and even calcium” (Nephcure). Throughout the course of this paper various aspects are addressed. these include: the role of the kidneys, the importance of professional guidance, the reasons why people follow a renal diet, monitoring sodium intake, monitoring potassium intake, monitoring phosphorus intake, protein consumption, and fluid control.
Kidney Function Introduction and definition of terms: The kidneys are the main organs in the urinary system. They filter waste products out of blood from the renal artery. These are then excreted. Useful solutes are reabsorbed into the blood. They also have a major homeostatic role in the body, and help to control the water content (osmoregulation) and pH of the blood.
Postlethwait, John H., and Janet L. Hopson. "Body Function and Nutrition." Modern Biology. Orlando: Holt, Rinehart and Winston, 2006. Print.