Function of the Urinary System

Question 1

Function of the Urinary System

Answer 1

Removal of metabolic wastes (nitrogenous and acidic)
Removal of hormones, drugs, and other foreign material from the body
Regulation of water, electrolytes and acid-base balance
Secretion of erythropoietin
Activation of vitamin D
Regulation of blood pressure through renin-angiotensin-aldosterone system

Question 2

Kidneys

Answer 2

Superior portion protected by lower ribs
Cortex (outer layer) contains glomeruli
Medulla (inner section) contains tubules and collecting ducts. Inside the medulla is the renal pelvis and calyces through which urine flows into ureter.

Question 3

Filtration

Answer 3

A large volume of fluid including wastes, nutrients, electrolytes and other dissolve substances, passes from the blood into the tubule, cells and protein remain in the blood. When pressure is increased, more filtrate forms, more urine is produced.

Question 4

Three parts of the tubule

Answer 4

Proximal convoluted tubule, loop of Henle, and the distal convoluted tubule

Question 5

Function of tubule

Answer 5

Reabsorption of essential nutrients, water and electrolytes and secretion of certain wastes and electrolytes.

Question 6

Main action of proximal tubule

Answer 6

Most water is reabsorbed into blood along with glucose and other nutrients and some electrolytes.

Question 7

Glucosuria

Answer 7

Limit on reabsorption of glucose (transport or tubular maximum), hyperglycemia associated with diabetes mellitus.

Question 8

What is the function of hormones in the renal system?

Answer 8

Control the reabsorption of fluid and electrolytes.

Question 9

ADA

Answer 9

Antidiuretic hormone - from the posterior pituitary, controls reabsorption of water by altering the permeability of the distal convoluted tubule and collecting duct

Question 10

Aldosterone

Answer 10

Adrenal cortex, control sodium reabsorption and water by exchanging sodium ions for potassium or hydrogen ions in the distal convoluted tubule.

Question 11

Atrial natriuretic hormone

Answer 11

From the heart, also controls fluid balance by reducing sodium and fluid reabsorption in the kidneys

Question 12

How much of the cardiac output enters the rental arteries from the aorta?

Answer 12

20-25%

Question 13

Peritubular capillaries or vasa recta

Answer 13

Flow blood vessels to kidney: afferent arteriole, glomerular capillaries, efferent arteriole, then peritubular capillaries or vasa recta

Question 14

How many sets of arterioles and capillaries are included in each nephron?

Answer 14

Two arterioles: afferent and efferent

Two capillaries: glomerular and peritubular

Question 15

Summary of blood flow through kidney

Answer 15

Renal artery, interlobar artery, arcuate artery, interlobal artery, afferent arteriole, glomerular capillaries, efferent arteriole, peritubular capillaries, interlobular vein, arcuate vein, interlobar vein, renal vein.

Question 16

What is the purpose of dual arterioles (afferent and efferent?)

Answer 16

To control the pressure in the glomerular capillaries and consequently the glomerular filtration pressure. This pressure determines the glomerular filtration rate (GFR)

Question 17

What three factors control constriction in the arterioles

Answer 17

Local autoregulation - small, local reflex adjustments in the diameter of the arterioles made in response to minor changes in blood flow in the kidneys
Sympathetic nervous system - increases vasoconstriction in both arterioles when stimulated
Renin angiotensin mechanism - Renin is secreted by the juxtaglomerular cells in the kidney when blood flow in the afferent arteriole is reduced for any reason. Renin acts on the plasma protein angiotensinogen to produce angiotensin 1 and as the blood passes through the lung, angiotensin converting enzyme converts angiotensin 1 to angiotensin 2, a powerful systemic vasoconstrictor.

Question 18

What happens if blood flow to the kidney is seriously impaired? E.g. blood pressure drop

Answer 18

Both the SNS and the renin-angiotensin mechanism are activated to restore blood pressure and flow to vital areas.

Question 19

The renin-angiotensin-aldosterone

Answer 19

When blood flow decreases for any reason, angiotensin causes systemic vasoconstriction and stimulates production of aldosterone which increased reabsorption of sodium and water to increase blood volume

Question 20

Location of bladder

Answer 20

Retroperitoneally

Question 21

What can obstruct urine flow in men?

Answer 21

Prostate gland, hypertrophied in older men.

Question 22

What facilitates kidney infection?

Answer 22

The mucosa lining the urinary tract is continuous through the urethra, bladder, and ureter to the pelvis of the kidney

Question 23

Micturition

Answer 23

Urination, occurs when a reflex is stimulated by increased pressure as the bladder distends.

Question 24

Enuresis

Answer 24

Involuntary urination by a child after age 4-5 - associated with developmental delay, sleep pattern, or psychosocial aspects rather than a physical defect

Question 25

Stress incontinence

Answer 25

Increased intra-abdominal pressure forces urine through the sphincter - coughing, lifting, laughing women after urogenital diaphragm weakend by multiple pregnancies and age.

Question 26

Overflow incontinence

Answer 26

Incompetent bladder sphincter - elderly, weakened detrusor muscle may prevent complete emptying leading to frequent emptying and incontinence.

Question 27

Neurogenic bladder

Answer 27

Spastic or flaccid due to interference with CNS

Question 28

Retention

Answer 28

Inability to empty the bladder, may be accompanied by overflow incontinence - a spinal cord injury at the sacral level can block the micturition reflex Retention can occur after anesthesia

Question 29

Catheter

Answer 29

Tube inserted in the urethra that drains urine from the bladder to a collecting bag - irritating to the tissue, can be a means of introducing bacteria however prevent kidney damage due to backup of urine

Question 30

Urine pH range

Answer 30

4.5-8.0

Question 31

Urinalysis - cloudy

Answer 31

Indicates presence of large amount of protein, blood cells, or bacteria and pus

Question 32

Urinalysis - dark colour

Answer 32

May be hematuria, excessive bilirubin, or highly concentrated

Question 33

Urinalysis - Unusual odor

Answer 33

Infections or certain dietary components or medications

Question 34

Abnormal constituents of urine

Answer 34

Blood - hematuria -infection, inflammation, tumors in urinary tract, increased glomerular permeability or hemorrhage in the tract Protein - Leakage of albumin or mixed plasma proteins into the filtrate, inflammation, increased glomerular permeability Bacteria (bacteriuria) and pus (puyuria) infection in urinary tract Urinary casts - microscopic sized molds of tubules - inflammation of kidney tubules. Glucose and ketones - when diabetes is not well controlled.

Question 35

Specific gravity

Answer 35

Ability of tubules to concentrate the urine, very low (dilute urine) usually related to renal failure (assuming normal hydration)

Question 36

Blood tests for urinary tract disorders

Answer 36

Elevated serum urea and serum creatinine - failure to excrete nitrogen wastes due to decreased GFR Metabolic acidosis - decreased serum pH and decreased serum bicarbonate - decreased GFR and failure of tubules to control acid-base balance Anemia - decreased erythropoietin secretion Electrolytes Antibody levels Renin levels - indicate a cause of hypertension.

Question 37

Conditions that prescribed diuretics

Answer 37

Renal disease, hypertension, edema, congestive heart failure, liver disease, pulmonary edema Most common diuretic - inhibits sodium chloride resorption in the tubules Side effect - loss of electrolytes

Question 38

Dialysis

Answer 38

Provides an artificial kidney (an individual can function normally with half of one kidney) Used to treat someone with acute renal failure until problem reversed or transplant

Question 39

Hemodialysis

Answer 39

Special equipment and training - patient's blood moves from implanted shunt or catheter in an artery through a tube to a machine where it exchanges wastes, fluid and electrolytes. Semipermeable membrane separates patient's blood from the dialysis fluid and the constituents move between the two compartments Wastes move from blood to dialysate while bicarbonate ion moves into blood Blood cells and protein remain in the blood Movement occurs by ultrafiltration, diffusion (by a concentration gradient) and osmosis. Heparin administered. 3 times a week 3-4 hours

Question 40

Peritoneal Dialysis

Answer 40

May be done at night while patient sleeps or while ambulatory The peritoneal membrane which is large in surface area, thin and highly vascular serves as the semipermeable membrane A catheter with entry and exit points is implanted in the peritoneal cavity Dialyzing fluid is instilled through the catheter into the cavity and remains there allowing exchange of wastes and electrolytes to occur by diffusion and osmosis, then the dialysate is drained from cavity. Requires more time than hemodyalisis. Can cause infection resulting in peritonitis.

Question 41

Urinary Tract Infections

Answer 41

Urine generally provides an excellent medium for growth of microorganisms. Common causative organism - Escherichia coli - resident flora of the intestine 85% - not washed out when bladder empties Other various associated organisms

Question 42

Why are women more vulnerable to UTIs then men?

Answer 42

Shortness of urethra, proximity to anus, frequent irritation from sexual activity, baths, feminine hygiene products

Question 43

Causes of UTI in men

Answer 43

Prostatic hypertrophy and retention of urine (any infection of prostate or testes likely to spread to urinary structures)

Question 44

Predisposing factors for UTIs

Answer 44

Incontinence with incomplete emptying of bladder Retention of urine in bladder Obstruction to urine flow - not flushing out organisms, pregnancy, scare tissue, kidney stones Immunosuppression and diabetes mellitus Catheterization

Question 45

Cystitis and Urethritis

Answer 45

Cystitis - bladder wall - capacity usually reduced Urethritis - urethral wall - inflamed, red, swollen and can be ulcerated Lower abdominal pain Dysuria (painful urination), frequency, urgency, nocturia Systemic signs - fever, malaise, nausea, leukocytosis Cloudy urine, unusual odor Urinalysis - bacteriuria, pyuria, hematuria

Question 46

Pyelonephritis

Answer 46

One or both kidneys Infection extends from ureter into the kidney, involves renal pelvis and medullary tissue (tubules and interstitial tissue) Purulent exudate fills the kidney pelvis and calyces, and the medulla is inflamed Abscesses and necrosis can be seen in the medulla and may extend through the cortex to the surface of the capsule. If severe - exudate can compress renal artery and vein and obstruct urine flow to ureter. Recurrent infection can lead to fibrous scare tissue over calyx, leading to loss of tubule function and hydronephrosis.

Question 47

Signs and symptoms of pyelonephritis

Answer 47

When bladder infection spreads to kidneys Signs of cystitis like dysuria Pain - dull aching in lower back or flank area - inflammation stretching renal capsule Systemic signs Urinalysis similar to cystitis except urinary casts consisting of leukocytes or renal epithelial cells are present.

Question 48

Glomerulonephritis (Acute Poststreptococcal Glomerulonephritis

Answer 48

Many forms APSGN - follows strep infection with certain strains. These infections usually originate as upper respiratory infections, middle ear infections or "strep throat" Develops 10 days to 2 weeks after antecedent infection. Antistreptococcal antibodies lodge in glomerular capillaries, causes inflammatory response in the glomeruli Increased permeability and proliferation, results in leakage of some protein and large numbers of erythrocytes into filtrate. Congestion and cell proliferation interfere with filtration in the kidney causing decreased GFR and retention of fluid and wastes. Renal failure, elevated blood pressure and edema

Question 49

Signs and symptoms of glomerulonephritis

Answer 49

Urine dark and cloudy - protein and red blood cells Facial and periorbital edema as colloid osmotic pressure of blood drops and sodium and water retained Blood pressure elevated due to increased renin secretion and decreased GFR Flank or back pain develops as kidney tissue swells and stretches General signs of inflammation - malaise, fatigue, headache, anorexia and nausea Urine output decreases as GFR declines.