Term infant means a newborn child within 28 days after birth. Nephrone is the functional and structural unit of kidney. Each nephron is made up of narrow tube that specializes in (” renal tubule ” ) secretion and reabsorption pre-filter unit ( ” renal corpuscle “). It provides a small solutes and water in tubule structure, renal corpuscle excludes solutes from blood. these renal tubules does not function in adult levels at neonatal period. Because at birth, kidney is immature. It develops with age and reaches to the adult functioning level after some time. This short analytical essay describes about the development of the renal tubules from neonates to adults for its function: that means how the renal tubules develop and adapt to their function with age.
1. Who is Infant?
From the Latin meaning of infans or ” can not tell ” and ” say “, infant is very young children of a human or animal. If you apply in person, this term is usually considered equal to the child. It may be to learn that human child walks, is used in place long walks .
Term infants will be used for infants up to the age of the moon 12 months and one month usually. However, it is possible to define the birth, it varies between 2 years and birth, or between one year. Child for several hours at only very young, several days, or up to a few weeks ago. In medical condition, ( from the Latin, neonatus, newborn ) newborns and infants, in the first 28 days after birth, it means infant, this term applies hypermature Early Childhood, infant, full -term infants .
2. Functions of the kidney
- Excretion of waste
The kidneys excrete the various products of waste by metabolism. These include, ,, nitrogenous wastes called ” urea ” from protein catabolism, such as uric acid, such as this from nucleic acid metabolism. The formation of urine, it is the function of the kidney. Accumulation of nitrogenous waste in the urine of birds and some mammals, rely on elaborate countercurrent multiplication system. This requires the nephron function of the independent functions of several .
- Re- absorption of essential nutrients
Glucose plasma levels, re- absorption in the proximal tubule is completely normal. Is reabsorbed in the proximal tubule, amino acids are sodium-dependent transporter .
- Acid-base homeostasis
Maintain the acid-base homeostasis is to maintain the pH value near the organ systems of the two kidneys, lungs, stabilized. Very important role of the two in the maintenance of acid-base balance and kidney : Re- absorption of bicarbonate from the urine, to discharge the hydrogen ions in the urine
- Regulation of blood pressure
Kidney can not be used to directly detect blood, but long term control of blood pressure is dependent on the kidney mainly. The size of, is performed via the maintenance of theextracellular water compartment depends on the plasma sodium concentration this - Hormone secretion
And kidney secret type of hormones such as erythropoietin, enzyme renin. ( Low levels of oxygen at the tissue level ) release erythropoietin in response to hypoxia in renal circulation. It is to stimulate the ( production of red blood cells ), red blood cell production in the bone marrow .
- Renal corpuscle
Configure the Bowman’s capsule and glomerulus, renal corpuscle is the commencement of the nephron. It filters the parts of the original nephron.
It is a part of the nephron, including water filtration cylindrical through glomerulus.After through the tubule of the renal tubules, and continues to collect, the duct system that is not part of the nephron is the filtrater.
- Collecting duct system
The first part is a small tube connection system of collecting duct, it provides the flow-through for each distal tubule. Collection of the duct system begins with the renal cortex and medulla to the deep. Urine so that down the collection duct system, passes the gap marrow with a high sodium concentration because the loop of henle is a countercurrent multiplier system.
- Juxtaglomerular apparatus
Angiotensin system – production of the enzyme renin involvement and juxtaglomerular apparatus is a specialized area of nephron cause of renin secretion to .
4. Functions of various segments of Renal Tubule
The type of renal tubule, and is part of the filtration nephron from the glomerulus. It is composed of the following elements:
1 .proximal convoluted tubule
2. Loop of Henle divided into three:
- thin descending limb
- thick ascending limb
3. Distal tubule
- Proximal tubule (PCT)
In the first part of the renal tubule, near corpusle kidney, which is lying on the cortex of the kidney. The filtered water from the Bowman capsule enters the proximal tubule. Has a brush border, which has been designed to cubiodal epithelium. It has eosinophilic cytoplasm due to the number of mitochondria .
- Work of PCT
- PCT is, H2O If you re- absorb 2/ 3 ( percent 65-80 and Na) or, filtered glucose, and this is, to re- absorb all amino acids
- Na glucose – is re- absorbed by the co-transport of Glu
- The section, I resorb potassium bicarbonate, calcium phosphate
- Thin descending loop (TDL)
- I reabsorb water (H 2 O) passively
- it is impermeable to sodium (Na)
- I will allow a hypertonic urine in the TDL, urine is concentrated
Thick ascending loop and, in this part of the loop, CL and K is reabsorbed actively
- This does not transmit H2O
- In this section, urine is a low concentration
- Distal tubule
- This part of the tubules are lined with a simple cubic epithelium with Musuri-ko edge
- The re- absorption of sodium chloride actively ,
- This secrete hydrogen ion and ammonium ion .
- be part of the juxtaglomerular apparatus
- Collecting duct
Is on the CD, and is performed through the cortex to the medulla and leads to renal papilla. The epithelium is different in cubic columnar epithelium with ( almost nipple ). This is the last part of the renal tubule. It has two types of cells .
5. The Renal Function in Neonates
Compared with adults, renal function, and is changed newborns. Complete structure in terms of the number of nephrons of 36 weeks, but the baby of the kidney is functionally immature still. Renal function is subject to rapid maturation in postbirth during the first week of both of preterm infants with time. Because I control the balance of water and electrolytes at that time, a small amount, because of the extremely low birth weight infants, and there was especially. Overhydration, dehydration, and the biggest risk for children, contains the electrolyte imbalance .
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It is possible to maintain a normal state, the homeostasis of the kidney after birth. However, infants early, most can be less, which is to maintain the water balance of the normal electrolyte, or bicarbonate. To maintain homeostasis, the control of renal blood flow and glomerular filtration plays an important role in determining the ability of the kidney. The biggest factor that determines the renal function is probably maturity. Renal formation, up to 34 weeks of pregnancy is not complete. In particular, under the glomerular filtration, and absorption and filtration of the kidney, which has a significant effect on the hormone-sensitive nephron control .
6. Renal Function of the Elderly
Including glomerulosclerosis a decrease in size of the kidney, increased vascular changes and arterioles, the type of anatomical defect in the aging kidney, have been identified. Also physical changes, including a decrease in renal blood flow, decreased glomerular filtration rate, tubular framework of the kidney, the shape of the endocrine renal function, are described. From one point of treatment by a physician or disease, clinical outcome of these changes is the ability of the kidney -shaped age to cope with stress. Vigilance and special care is needed when you take care of the elderly .
7. Renal Function in Relation to the age
In comparison, the growth and food intake of adults in maintaining the biochemical stable environment, when it is more important for infants than kidneys. Infants, kidney’s are developing with the normal function of the ` s properly. However, it is very adaptable to emergency THN in adults. It is not present in urine excrection rhythm birth of a normal adult. These have been developed within a few years. GFR is a baby less than adults. However, the proportion of adult products and to compare, this low GFR is enough to excrete a small amount .
8. Structural changes of Kidney with age
The number of structural change takes place in the kidney of aging. Kidney of aging is characterized in that the number of news kidney, vascular sclerosis, hyaline artery disease, hardening of glomerular increases, tissue fibrosis and renal tubules is lost. Pathogenesis of structural changes associated with aging are not fully understood. Both the hemodynamic factors and genetic background, are associated with the development of physical changes associated with age. Structural changes in the aging kidney, is a non-specific, diabetes and be seen in many situations, including high blood pressure, such as a, and, can, is a diagnosis of exclusion is arterionephrosclerosis aging Decline associated with aging, host of the structure and function of the kidney. Might disrupt the assessment of the impact of aging on renal function, appreciation and selection of the population, the problem, methodological, which led to the re-evaluation of recent. Well as a decrease in renal function protected areas, the common denominator of these changes, is the subject of kidney of either excess or defect of constraints and the ability to respond appropriately. These changes, to achieve clinical significance when the residual renal function was challenged by the superposition of acute disease, under the conditions of day-to-day, but there is likely to have a major clinical results. Finally, often amplify these drawbacks whereby, elderly patients should be emphasized may be a change in the aging and addition, can co-morbidities, such as heart disease or high blood pressure, suffer .
9. Functional changes of Kidney with Growth
Renal function, started the development of a program ,It continues to evolve in the first year of life Full adult rate. Under this process, the responsible kidney Changes and to provide renal function during childhood, in particular the Characteristics. Human kidney to begin the development in five Started production of urine between the pregnancy and the 10th week 12 weeks of gestation. It was completed in around the 36 week from 35 to newborn long-term kidney formation, but are born with a nephron all of its What is not a case of one of the initial born before, Renal formation is complete. Entire process of fetal kidney The progress to be regulated by many genes have recently been shown For example, as cytokines and growth factors such gene products and, Intrauterine environment itself in a special process known as, Epigenetics. Kidney regulates homeostasis to the basic operation of the two, Glomerular and tubular. It is the work of all neonatal although neonatalkidneys flaws and is equipped with, Of them to develop a physiological process, is severely limited The response to stress. Infants having a glomerular filtration rate (GFR) Was increased stepwise to achieve, the low and 20 ml/min/1.73 m², at birth Adult levels at 18 months. Completely new nephron has not been played in childhood, but is available in sizes from increasing, I mature in the workplace. Tubular function and glomeruli, but may mature level Between 12-18 months, kidney child maintaining a low capacity for dealing with residual Susceptible to trauma of childhood .Started developing early, renal function, twisted creature Evolution in the first few years of his life full, to adults Level. Under this process, is responsible for changes giving kidney Kidney Function in the reputation of his childhood and childhood somewhat. But From, the main challenge for developing kidney events of the migration I adjust the uterus to life outside the womb, the homeostasis of the continuous for Organisms childhood and growing during childhood are also sought .
10. Developmental changes of Renal Tubules for it`s Function
If you have corrected the size of the body, starting in stages it, remains relatively constant 4 of life up to 10 years old, shows the age of 1 year and kidney capacity fully functional, standard of renal function a decline in the use of age-related indicators, the glomerular filtration rate such. Be predicted without knowledge of the exact mechanisms involved Avoid reabsorption and tubular secretion of positive and negative ions in order to provide an opportunity for drug interactions is difficult. Data to support the development changes in the net tubular secretion of several items. For digoxin, clearance of digoxin observed in children during puberty, most of the creatinine clearance is reduced at a rate under consideration in adults, this decrease, and more mature than the age of the annual, and more there is a good correlation. Renal excretion of metabolites and active drug and a very important medicine provides important clinical information definition of the mechanism of renal tubular net .
In preterm infants, secretion tubular reabsorption and organic acids certain amino acids, and potassium hydrogen ion is a relatively immature at birth in particular, was increased as a function of postnatal age. As part of the animal and continuous, immature state, on the other hand, the ability of phosphate reabsorption is enhanced when you adapt to their environment. In the case of glucose, under 34 weeks, transport system is relatively mature at the time of the infants so during pregnancy. One, as well as the treatment of pharmacological preterm infants tubular transport amino acids development, potassium, phosphorus, and nutrition, in the evaluation of long-term, you need to consider organic acid, these changes. Adult levels is different from ability and dilution capacity of the urine should be considered. To dilute the ability to be in the ability to take into account the fact that normal adult level three months and level of adult 14th. The ability to excrete water load reached adulthood at the end of January. Inability to concentrate urine at the level of the adult is due to it is impossible to correspond to the ADH The inherited microtubules and a small amount of ureThis article has reviewed the maturation of major renal tubular transport systems. The tubular reabsorption of certain amino acids and the secretion of organic acids, hydrogen ions, and potassium increases as a function of postnatal age, being relatively immature at birth, especially in the preterm infant. In contrast, the ability for phosphate reabsorption is enhanced during the immature state as the developing animal attempts to adapt to its environment. In the case of glucose, the transport system is relatively mature in the term infant and less so in the infant of less than 34 weeks’ gestation. One should consider these developmental changes in the renal tubular transport of amino acids, potassium, phosphate, and organic acids in the nutritional assessment and pharmacologic treatment of preterm as well as term infants.
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