Pathophysiology Exam 4 (Chapters 26+27+28+29)

Where are the kidneys located?

Posterior part of the abdomen on either side of the vertebral column. *Right kidney is slightly lower than left kidney.

Function unit of the kidney?

Each kidney is made of nearly 1 million functional units called nephrons.

Kidneys Function?

They regulate volume and the chemical make up of the blood, maintain the balance between water and salts and acids and bases

*water purification plant of the body.

Urinary system is composed of what?

Kidneys, ureters, and bladder urethra.

Nephroptosis / Renal Ptosis

Since kidneys are maintained in place by adipose tissue, in time of malnourishment if adipose tissue is lost, kidneys fall lower. This causes the ureters to kink and water to back up into the kindeys leading to necrosis and renal failure

How much fluid do the kidneys process every day?

Kidneys process about 47 gallons of blood-derived fluid daily

3 Major anatomical parts of kidney?

Renal Pelvis = Consist of urinary collecting structures called calyces.

Renal Medulla = Middle portion. Contains renal pyramids.

Renal Cortex = Outer portion. Contains glomeruli and nephron tubules.

The Nephron

Basic structural and functional unit of the kidney. More than 1 million nephrons make up each kidney. Composed of two parts: corpuscle and tubules.

Urine Formation

Major function of the kidney. Through urine formation the kidneys remove toxic waste.

Glomerular Filtration

Blood pressure produces glomerular filtrate. Filtration fraction is 20% of plasma. Filtering capacity is enhanced by thinness of membrane and large surface area of glomerular capillaries.

Glomerular Filtration Rate

High hydrostatic pressure of glomerular capillaries. Substances are filtered into Bowmans capsule at a rate of 130 ml/min. Cells and large plasma proteins are not filtered into Bowmans capsule. Glomerular filtrate is plasma without proteins.

Normally > 187,000 ml/day filtrate formed.

Net Filtration Pressure

Usually about 10 mm Hg. Net pressure is blood pressure minus pressure of fluid already in capsular space and waters urge to return to the concentrated plasma left behind since all large & medium proteins are left behind.

Normal Urine Output?

1,500 ml/day (1% of filtrate) -> 99% of filtrate is reabsorbed.

Nitrogenous Products

Urea, uric acid, ammonia.

Creatinine

Serum creatinine levels and urine creatinine excretion are a function of muscle mass in normal persons. In muscle tissue, creatine is converted to creatinine.

Creatinine is completely filtered at the glomerulus and is not reabsorbed by the tubules.

Small amounts of creatinine in the final urine is derived from tubular secretion.

Therefore, creatinine clearance can be used to estimate the GFR.

Hormonal functions of the kidneys

- Vitamin D Metabolism

- Renin

- Erythropoietin

Creatinine Clearance Test

Test for GFR.

Clearance = volume of plasma from which a measured amount of substance can be completely eliminated into the urine per unit of time. Therefore clearance rate depends on:

- Plasma concentration of the substance

- Excretory rate of that substance: which depends on GFR and renal plasma flow.

High levels of serum creatinine indicate:

Renal disfunction

Tubular Function Test

Assessment of concentration and diluting ability of the kidney. It is tested by Urinary specific gravity and Urine osmolality

- Urinalysis

Urinalysis

An analysis of the volume and physical, chemical, and microscopic properties of urine, called urinalysis, reveals much about the state of the body. Can look for cells, casts, and crystals in urine.

KUB Test

(Kidneys, ureters and bladder X-ray) identifies gross abnormalities related to size, position, and shape (may show renal calculi)

Renogram / Renal Scan Test

Shows renal vasculature.

Ultrasonography

Differentiates tissue characteristics.

CT / MRI

Used to provide detailed information about the vasculature and tissue.

Glomerularpathies

Glomerulopathies alter glomerular capillary structure and function. May result in some combination of hematuria, proteinuria, abnormal casts, decreased glomerular filtration rate (GFR), edema, and hypertension.

Glomerulonephritis

Inflammation of the glomerulus. Immune response to variety of potential triggers; may have primary or secondary etiology. Most common cause of end stage renal failures.

Treatment: Steroids, plasmapheresis, dietary and fluid management. Management of systemic and renal hypertension. If leads to end stage renal disease may require transplantation or dialysis.

Acute Glomerulonephritis

Acute inflammation of the glomeruli.

Nephrotic Syndrome

Excretion of 3.5 g or more of protein in the urine per day. Protein excretion is caused by glomerular injury.

Can cause edema, proteinuria, hypoalbuminema, hypoproteinemia, hyperlipidemia.

Characterized by increased glomerular membrane permeability

Treatment is through symptom management.

Tubular Disease

Defects in tubular function leads to decrease in secretion or reabsorption of certain molecules or impairment of urine concentration and dilution mechanisms.

Nephritic Syndrome

Characterized by immunologic response. Increase in WBC's leads to inflammation of glomerulus. Leads to loss of RBC's, WBC's, proteins.

- Hematuria

- Pyuria

- Proteinuria

- Oliguria

- High BP

Renal Failure Results In?

Retention of salt and water (high bp), urea (uremia or uremic poisoning), and metabolic acids (acidosis).

Dialysis Treatment

Passes blood through membrane channels bathed in a plasma-like solution to remove wastes.

Acute Renal Failure

An abrupt reduction in renal function producing an accumulation of waste materials in the blood. Potentially reversible, occurs over hours to weeks.

May be due to aging, associated with comorbidities, or due to insults to the kidney.

Renal Function is monitored by?

Serum creatinine and creatinine clearance.

Pre-Renal Acute Renal Failure

Due to conditions that impair renal blood flow such as hypovolemia, hypotension, cardiac failure, and renal artery obstruction.

Characterized by low GFR, oliguria, high urine specific gravity and osmolality, and low urine sodium.

Post-Renal Acute Renal Failure

Due to obstruction within the urinary collecting system distal to the kidneys. Elevated BP in Bowmans capsule; impedes GFR. Clinical findings are based on duration of the obstruction.

Intra-Renal Acute Renal Failure

Due to primary disfunction of the nephrons. Most often due to problems within renal tubules resulting in acute tubular necrosis; may also occur with glomerular, vascular, or interstitial etiologies.

BUN

Blood Urea Nitrogen

Measures the amount of urea nitrogen, a waste product of protein metabolism, is in the blood. Typically cleared from blood by kidneys, therefore measuring how much urea nitrogen remains in the blood can be a test for renal clearance.

Azotemia

Elevated BUN.

May be caused by: impaired renal function, congestive heart failure, dehydration, shock, hemorrhage, acute MI, stress, and excessive protein intake

Acute Tubular Necrosis

Occurs in 3 stages.

Oliguric Stage: Characterized by oliguria, progressive uremia, decreased GFR, hypervolemia. May last 1-2 week May require dialysis.

Diuretic Stage: Urine volume increases, but tubular function remained impaired and azotemia continues. May last 2-10 days.

Recovery Stage: Characterized by gradual normalization of serum creatinine and BUN. May last up to a year.

Chronic Renal Failure

Chronic renal failure is the irreversible and progressive loss of renal function that affects nearly all organ systems. Most common causes are diabetes an high bp.

Defined as decreased kidney function or kidney damage of 3 months duration with GFR < 60 ml/minute/1.73m^2

Is the final outcome of chronic kidney disease and leads to end stage renal failure.

Renal Osteodystrophy

Elevated parathyroid hormones causes altered bone and mineral metabolism. Kidneys are unable to reabsorb calcium.

Lower Urinary Tract

Role is to transport urine formed by the kidneys and allow removal from the body.

Urine Movement

Due to the effect of gravity and facilitated by peristaltic movements of the ureters.

Bladder Innervation

Supplied by the sympathetic nerves that exit the spinal chord at L1 and L2 and allow relaxation and filling. Stimulation from parasympathetic nerves S1-S4 results in bladder contraction and relaxation of the internal sphincter.

Void Disfunction

May be secondary to

- Disorders of the lower urinary tract

- Pathologies affecting the central, autonomic, and peripheral nervous systems.

- A wide variety of factors affecting control of micturition, including medication and access to toileting facilities

Urge Incontinence

May be idiopathic, due to bladder infection, radiation therapy, tumors or stones, or CNS damage.

Stress Incontinence

Due to weakening of the pelvic muscles or intrinsic urethral sphincter deficiency.

Mixed Incontinence

Due to a combination of urge and stress incontinence.

Neurogenic Bladder

Broad classification of voiding dysfunction in which the specific cause is a pathology that produces a disruption in nervous communication governing micturition .

Urinary Tract Infection

Characterized by presence of bacteria in urine.

> 100,00 colonies/ml.

3 Types

Urethritis = Infection in urethra

Cyctitis = Infection in bladder

Pyelonephritis = Inflammation in kidneys

Urethritis

Inflammation of the urethra. Caused by infection from the bladder, STD-related, or external factors. STD's confined to the urethra; infection of other etiologies may ascend to the bladder before symptoms present. Treatment depends of cause.

Cystitis

Inflammation of lining of the bladder. From infection, chemical irritant, stones, trauma. Most causes have infectious etiology and result from infection originating in urethra.

Urinary Tract Obstruction

Interferes with flow of urine. Obstruction can occur at any point in urinary tract.

Renal Calculi (Nephrolithiasis)

Also known as kidney stones. Are crystal aggregates of organic and inorganic materials located within the urinary tract. Can form after either recurrent UTI's by urease producing organisms, or when urine is super saturated by calcium, uric acid, cystine, or xanthine.

Lower Urinary Tract Urolithiasis

Most often caused by stones traveling to the ureters, bladder, or urethra from the kidneys. Bladder urolithiasis due to stones traveling from ureters, but may form in bladder because of urinary stasis