Urinary systemUrinary system

Medical & Surgical Medical & Surgical NursingNursing

AnatomyAnatomy

- Kidney consist of 2 district regions:• Renal parenchyma: medulla, cortex

• Renal pelvis: portion of renal artery enters & renal veins exits

- Renal artery arises from abdominal aorta, divides into small vessels (afferent) which branches to form glomerulus's (capillaries beds which responsible for glomerular function)

- Blood leaves glomerulus through efferent arterioles & flow back to veins through capillaries to inferior vena cava.

- Each kidney contains 1 million of nephrons (kidney function units)

- Nephrons consist of glomerulus, bown s capsules, proximal tubules, loop of Henel, distal tubule, collecting ducts.

• Nephron divided to 2: Cortical & Juxtamedullary

• Glomerulus is composed of 3 filtering layers: capillary endothelium, the basement membrane, and the epithelium.

• Glomerular membrane allow filtration of fluid (water), & small molecules only but large molecules (Albumin, blood cells) are not filtered (stay in blood stream).

• Urine formation is take place in nephrone.

ureter: • Urine flow kidney throughout ureterus

• Is narrow area which makes it risk for obstruction, which prevent urine leaves kidney (kidney dysfunction).

• Urine leaves renal pelvis through ureter to bladder by peristaltic waves (1-5 time/ minute) caused by contraction of smooth muscle of ureter.

Urinary bladder:• Adult bladder capacity is 300-600 ml of urine

• Bladder neck contains smooth muscle that from sphincter.

Urethral:• In male it passes throw

penis, and prostate gland.

Urinary system functionsUrinary system functions 1-Urine formation

• Formed in nephrones throughout 3 steps: glomerular filtration, tubular reabsorption, and tubular secretion.

• Substances that filtered are Na, Cl, Hco3, K, glucose, urea, creatinine, uric acids.

• Glucosuria indicate renal failure, DM.• Transient proteinuria (globulin, albumin), if less than 150mg/dl is considered

normal but if permanent proteinuria means glomerulus's is damage.

Glomerular filtration

• Blood afferent enter glomerulus then leave as filtrate (UF) throughout renal tubules.

• Only filtrate (UF) substances (water, small molecules) are filtrated and the rest stays in blood stream and flow back to IVC.

• When blood flow to kidney is decrease (hypotension, low oncotic pressure) the filtration is decrease, thus urine output is decreases.

Tubular reabsorption:

• Occur in the proximal tubules.

• Substances in the filtrate that is needed by the body is reabsorped by tubules and enter the blood streams.

Tubular secretions :

• Substances that is not needed by the body is secreted into filtrate & leaves with the urine.

2-Regualtion of electrolytes and blood pressure:• 99 % of water& Na is reabsorpred by tubules to maintain osmotic balance.

• Kidney regulate volume of the body fluid by reabsoping water and Na.

• If more Na is excreted, this leads to water excretion and dehydration.

• If low Na is excreted, this leads to low water excretion and fluid retention

(hypervolemia), thus increase BP

• When low BP & low blood flow to kidney, kidney release rennin which

convert angiotensinogen to angiotensin1, lung covert angiotensin I to

angiotension II,

- Leads to vasoconstriction, increase BP, increase renal perfusion.

- Activates Adrenal cortex to releases Aladstrone hormone increase renal

reabsorption of water and Na, thus increase BP, increase renal perfusion.

- Aldastone activate pituitary gland to release Antiduitretics hormones

( ADH) which stop diuretics, this lead to low urine output, and high Na &

water retention thus increase BP, increase renal perfusion. ADH # ACI

(Lasix).

K- Kidney excreted 90% of daily intake K- Aldastone increases K excretion- When low UO, hyperkalemia developed, which is life threatening

3- Regulation of acids excitations:• Breakdown of proteins produce amino acids which increases blood acidity. • Kidney excreted excess acids to keep pH normal

4- Vitamin D activation• Vitamin D is needed for Calcium absorption which is needed for:- Bone metabolism - Tooth metabolism - Blood clotting factor

5- Excretion of waste products • Eliminates body metabolic waste products (urea, creatinine, phosphors, uric acids,

drugs).

6-Erythroprotein production:- When low Oxygen deliver to kidney (anemia, hypoxemia), kidney produce

erythropoietin, which activates bone marrow to produce RBC. - In kidney failure we give blood transfusion, or synthesis erythropoietin.

Renal clearance:• The ability of the kidney to clear solutes from the plasma• 24 hours urine collection• Creatinin clearance : waste products of muscle metabolism when kidney decrease , the

creatinin in the blood is increases.• Glumerular Filtration Rate (GFR) is 100- 120 ml/minute.

Urine storage :• Bladder is reservoir for urine.• When filling occur, the receptors in the bladder is stretch which activates

sympathetic nervous system to void (bladder emptying).• In male the pressure in the bladder is increase with age due to increase prostate

size (benign prostate hyperplasia BPH) which slow and prolonged flow of the urine.

• In spinal problem occur, this decrease voiding control (incontinence) & residual urine increase .

• Chronic urine retention is more in male.

• Dysuria, hematuria, nocturia, oliguria, polyuria, urgency, hesitancy, anuria.

Urinary incontinence:

• Unplanned loss of urine (involuntary) that is sufficient to be considered a problem.

• Urinary continence relies on intact urinary, neurologic, musculoskeletal system.

• Effect all ages but more common in elderly.

• Types are

- Urge incontinence: strong urge to void that cant be suppressed.

- Overflow incontinence: over distention of the bladder (emptying problem)

- Stress incontinence: due to high intra abdominal pressure (coughing)

• Rx:

- underlying causes

- Drug to inhibit bladder contraction & increases bladder neck resistance(atropin).

Urinary retention:• Inability to empty the bladder completely during attempts to void (residual

urine).

• Common in post anesthesia & OR.

• Pathophysiology :

- May result from diabetes, prostate enlargement, urethral pathology (infection, calculi, tumor), and neurological problem.

- Some medications may inhibits bladder contraction, or increase bladder neck resistance (atropine).

• Assessment :

- Patient may feel incomplete bladder emptying.

- Post voiding scan can be used, if residual urine is more than 100 ml, cauterization is needed to prevent infection.

Complications : infection, pyelonephritis, sepsis, calculi.

Urinary Tract Infection (UTI)• Caused by pathogenic micro-organism

• clinical manifestation includes :

- Pain, burning urination

- Frequency, urgency, nocturia, nausea, vomiting.

- Urine culture is used to identify the specific organism.

- CT scan used to detect placement of the infection.

• Rx: antibiotics.

Renal failureRenal failure • Result when kidneys can't remove the body metabolic wastes or perform

its regular function.

• Can be acute or chronic.Acute renal failure:

• Sudden & complete loss of kidney function, low GFR over period of hours to days.

• Manifested by oliguria (less than 400 ml / day of urine), anuria (less than 50 ml/ day of urine).

• High blood urea nitrogen (BUN), high creatinin.

• Categorized to- Pre renal: low blood flow (hemorrhage, low CO, heart failure), which

decreases GFR.- Intra renal: damage to glomerulus's or tubules (burn, infection), which

decrease kidney function.- Post renal : distal obstruction in the kidney which decrease kidney function• Rx:- Kidney has the ability to recover , so the primary goal is to treat underlying

cause to allow recovering.- Monitor & treat K level.- Cauterization for urine retention.- Ensure adequate nutrition ( due to nauseas & vomiting).

Chronic renal failure :• Called end stage renal failure (ESRF). • Irreversible damage to the kidney.• Pathophysiology :- As result of low kidney function, protein accumulates in the blood .- BUN effect every system in the blood.- Fluid retention caused HTN.• Manifestation : HTN, sever itching (pruitus), neurological problem (low

LOC)

• Assessment: GFR, 24 hours urine collection, BUN, Na & water retention, acidosis, anemia, electrolyte imbalance.

• Rx:

- Antihypertention drugs, synthesis erythropoietin, dialysis

- Nutrions: low protein intake, fluid intake, electrolyte balance, increases caloric intake.

Conclusion

Any question