Kidney consists of millions of small units called nephron. The nephron is mainly divided into two parts: 1) Glomerulus ) tubules.
Glomerulus is a network of capillaries covered by epithelial cells and encased in Bowman’s capsule. It performs filtration of the plasma. From the capillary lumen to the urinary space the filtering membrane is consist of:
1. Fenestrated endothelial cells.
2. Glomerular basement membrane.
3. Visceral epithelial cells (podocytes).
Tubular portion of nephron is divided into 2 parts. (i) Bowman’s capsule and space, (ii) Tubules. The function of tubules is to reabsorb the water and electrolytes and to secrete the subtances which are secreted from the plasma into the tubular fluid. In this way the basic function of tubules is the conversion of filtered fluid into urine.
1. Excretory : Excretion of waste products and drugs.
2. Regulatory: Control of body fluid volume and composition (regulates acid base balance).
3. Endocrine: Production of erythropoietin, renin and prostaglandins.
4. Metabolic: Activation of Vit D
Anuria: Complete suppression of urinary secretion by the kidney.
Polyuria: Passage of large volume of urine in a given period.
Oligouria: Diminished amount of urine secretion.
Pyuria: Presence of pus in urine.
Dysuria: Painful Or difficult urination.
Hematuria: Presence of blood in urine.
Renal Failure: The Condition in which renal function is not adequate to maintain the internal environment is respect of volume and composition is called renal failure. It is manifested by uremia.
Azotemia: Retention of nitrogenous waste products either through their failure to be deliverd to the kidney such as in CHF, shock, hemorrhage or failure of the kidney to excrete them is called azotemia. Azotemia is a biochemical abnormality that refers to increased blood urea and serum creatinine due to decreased glomerular filtration rate.
Uremia: when azotemia becomes symptomatic, it is called uremia.
It is a clinical syndrome characterized by failure of renal excretory function and metabolic and endocrine alterations resulting from renal damage.
When azotemia bocomes symptomatic, It is called uremia.
. uremia is a pathological term while renal failure is a clinical term.
uremia may be classified in 3 Groups.
1. Pre-renal: uremia resulting from hypoprfusion of the kidneys in conditions such as shock, congestive cardiac failure hemorrhage etc.
2. Renal: uremia resulting form renal diseases such as glmerulonephrits, pyelonephritis tubular necrosis and transplant regection.
3. Post Renal: uremia resulting form obctruction in the urinary tract caused by calculi, fibrosis, tumor or damage by trauma.
salt water retention prodecting edems
water retention produces fluid overlaod which laods to congestive heart failure
failure of renal regulation of acid base balance leads to progessive heart metabolic acidosis which is manifested by shortness of breath.
Most important derangement are hyperclamia and hypocalcemai which may leads to cardaic arrhythmiass and reduced mycrodail contractility generalized muscle weakness neuromuscular excitability.
uremia hyperphosphatemia enhanced calcium entry into the bones resuting hypocalcemia compensatory increase in paratheyroid hormone level. both hypocalcemia and hyperparathyroidsm lead to skeletal abnormalities called renal osteodystrophy.
.congestive heart failure due to salt and water retention.
.hypertentiondue to hypervolimia.
.normochromic normocytic anemia due to decreased production of erythropoetin by diseased kidney.
.Nausea,vomiting and anorexia.
.peculiar sallow coloration of the skin due to accumulation of urainary pigments in the skin especially urochome.
Myopathy ,urenic encephalopathy and peripheral neuropathy. They are caused by hypertensive crices , cerebral and
genralized edems dehydration occuring in uremia.