Chapter 32
Structure and Location of the Kidney:
•
•
Structure:
o Paired, bean-shaped organs
o Multiobular structure, composed of up to 18 lobes
o Each lobule is composed of nephrons, the functional units of the kidney
Location:
o Outside the peritoneal cavity in the back of the upper abdomen
o One on each side of the vertebral column at the level of the 12th thoracic to 3rd
lumbar vertebrae
Kidney:
•
•
•
•
Each is smaller than a person’s fist, the two organs process approximately 22% to
25% of the cardiac output or 1100 mL/ minutes
Left Kidney sits higher than the right
Waste that goes into the (from the renal vein) kidney comes from your circulation
Kidneys are not able to regenerate
o When you reach the age of 40, you lose 10% of function
Function of the nephron***
•
•
•
•
•
•
The kidney has no ability to regenerate nephrons.
o Therefore, with aging, there is a generalized decrease in functioning
nephrons.
o In fact, adults tend to lose approximately 10% of their nephrons for each
decade beginning at 40 years of age.
Blood flows into the glomerular capillaries from the afferent arteriole and flows out
of the glomerular capillaries into the efferent arteriole, which leads into the
peritubular capillaries.
The glomerulus consists of a compact tuft of capillaries encased in a thin, doublewalled capsule called Bowman capsule.
Fluid and solutes from the blood are filtered through the capillary membrane into a
fluid-filled space in Bowman capsule, called Bowman space.
The portion of the blood that is filtered into the capsule space is called the filtrate.
The mass of capillaries and its surrounding epithelial capsule are collectively
referred to as the renal corpuscle.
Capillary System Supplying the Nephron:
•
•
The glomerular capillary membrane is composed of 3 layers:
o Capillary endothelial later
o Basement membrane
o Single-celled capsular epithelial layer
The outer epithelial layer that covers the glomerulus is continuous with the epithelium
that lines the Bowman capsule.
•
The cells of the epithelial layer have unusual octopus-like structures that possess a large
number of extensions, or foot processes (i.e., podocytes), which are embedded in the
basement membrane that lies between the capillary endothelium and the outer epithelial
layer.
o These foot processes form slit pores through which the glomerular filtrate passes.
Four Segments of the Nephron Tubule:
•
•
•
•
Proximal Convoluted Tubule
o A highly coiled segment; drains into the Bowman Capsule
o Approximately 65% of all absorptive and secretory processes of the tubular
system take place in the proximal tubule. ***
o Many substances, such as glucose, are freely filtered in the glomerulus and
reabsorbed by energy-dependent cotransport carrier mechanisms.***
o Reabsorption:
▪ Na
▪ Cl
▪ HCO3
▪ K
▪ H2O
o Secretions:
▪ H+
▪ Organic acids and bases
Loop of Henle
o A thin looped structure
o The loop of Henle plays an important role in controlling the concentration of
the urine.
▪ It does this by establishing a high concentration of osmotically active
particles in the interstitium surrounding the medullary (Middle)
collecting tubules where the antidiuretic hormone (ADH) exerts its
effects.***
o The loop of Henle, taken as a whole, always reabsorbs more Na+ and Cl−
than water.
▪ This is in contrast to the proximal tubule, which reabsorbs Na+ and
water in equal proportions.***
o Reabsorption (thin descending Lopp of Henle):
▪ H2O
Distal Convoluted Tubule
o A distal coiled portion
Collecting Tubule
o Joins with several tubules to collect the filtrate
Na+ Transport as the Driving Force:
•
•
•
Na+/K+ ATPase maintains the concentration gradient
Symport
Antiport
o May result in heart or kidney failure
Question: Which of the following best describes the function of the nephron?
A.
B.
C.
D.
The detoxification of blood
The retention of important organic materials found in the filtrate
The reabsorption of water, electrolytes, and other substances from the bloodstream
The synthesis and storage of urine
Rationale: The resorption of water, electrolytes, and other substances from the bloodstream is the
main function of the nephrons.
*ADH also known as vasopressin
The Juxtaglomerular Complex:
•
•
The juxtaglomerular complex is thought to represent a feedback control system that
links changes in the GFR (how much you pee) with renal blood flow.***
In approximately one fifth of the juxtamedullary nephrons, the loops of Henle and special
hairpin-shaped capillaries called the vasa recta descend into the medullary portion of the
kidney.
Endocrine Function of the Kidney:
•
•
•
•
Juxtaglomerular Complex
The Renin–Angiotensin–Aldosterone Mechanism
o Plays important part in regulation of blood pressure
o Renin functions by means of angiotensin II to produce vasoconstriction of the
efferent arteriole to prevent large decreases in the GFR.
o Angiotensin II also increases sodium reabsorption indirectly by stimulating
aldosterone secretion from the adrenal gland and directly by increasing
sodium reabsorption by the proximal tubule cells.
o The renin–angiotensin–aldosterone (RAA) mechanism.***
Erythropoietin
o Regulates the differentiation of red blood cells in bone marrow
o Erythropoietin is a glycoprotein hormone that is produced by fibroblasts in
the renal interstitium and regulates the production of red blood cells in the
bone marrow.
o The synthesis of erythropoietin is stimulated by tissue hypoxia, which may be
brought about by anemia, residence at high altitudes, or impaired
oxygenation of tissues because of cardiac or pulmonary disease.
o Person with end-stage kidney disease is often anemic because of an inability
of the kidneys to produce erythropoietin.
o This anemia is usually managed by the administration of a recombinant
erythropoietin (epoetin alfa) produced through DNA technology to stimulate
erythropoiesis.***
o
Vitamin D
o Increases calcium absorption from the gastrointestinal tract
o Helps regulate calcium deposition in bone
o Activation of vitamin D occurs in the kidneys.
o Vitamin D increases calcium absorption from the gastrointestinal tract and helps
to regulate calcium deposition in the bone.
o It also has a weak stimulatory effect on renal calcium absorption.
o Although vitamin D is not synthesized and released from an endocrine gland, it is
often considered a hormone because of its pathway of molecular activation and
mechanism of action.
o Vitamin D exists in two forms—natural
Question: Which of the following hormones is produced in the kidney?
A.
B.
C.
D.
ADH
Erythropoietin
Aldosterone
Angiotensin
Rationale: Erythropoietin is formed in the kidney in response to decreased blood oxygenation.
Action of Diuretics:
•
•
•
Loop Diuretics:
o Exert their effect in the thick ascending loop of Henle
o Example:
▪ Furosemide (Lasix)
Thiazide Diuretics
o Prevent the reabsorption of NaCl in the distal convoluted Tubule
o Example:
▪ Chorhtalidone (Thalitone) used for Hypertension
The Aldosterone Antagonists (potassium-sparing diuretics)
o Reduce sodium reabsorption and increase potassium secretion in the late distal
tubule and cortical collecting tubule site regulated by aldosterone
o Used for Cronic Heart Failure
o Examples:
▪ Spironolactone and Eplerenone
Characteristics of Normal Urine:
•
•
•
•
•
A clear, amber-colored fluid **
Approximately 95% water and 5% dissolved solids
The kidneys normally produce approximately 1.5 L of urine each day.
Contains metabolic wastes and few or no plasma proteins, blood cells, or glucose molecules
If you have blood in your urine, you are also going to have protein in your urine
Renal Clearance:
•
Definition:
o The volume of plasma that is completely cleared each minute of any
substance that finds its way into the urine (1300 mL/Minute)
•
Determining Factors:
o The ability of the substance to be filtered in the glomeruli
o The capacity of the renal tubules to reabsorb or secrete the substance
Tests for Renal Function:
•
•
•
•
•
•
Urinalysis:
o Color:
▪ Yellow amber
o Appearance:
▪ Clear to clightly hazy
o PH:
▪ 4.5-8
• Average person has a pH of 5-6
Glomerular Filtration Rate
o The GFR can be measured clinically by collecting timed samples of blood and
urine.
o Creatinine is produced by muscles as a product of the metabolism of a molecule
called creatine.
▪ The formation and release of creatinine are relatively constant and
proportional to the amount of muscle mass present.
▪ Creatinine is freely filtered in the glomeruli, is not reabsorbed from the
tubules into the blood, and is only minimally secreted into the tubules
from the blood.
• Therefore, its blood values depend closely on the GFR.
o The comparison of creatinine levels in the blood and urine can provide a useful
measure of GFR.
o The clearance rate for creatinine is the amount that is completely cleared by the
kidneys in 1 minute.
Blood Tests
o Serum creatinine
o Blood urea nitrogen
Cystoscopy:
o the visualization of the bladder by the insertion of an instrument called a
cystoscope through the urethra into the bladder.
o Ureteroscopy involves the use of a smaller, thinner scope that may be used to
remove stones from the ureter and aid in the treatment of ureteral disorders, such
as ureteral strictures.
Ultrasonography:
o is used to visualize the structures of the kidneys and has proved useful in the
diagnosis of many urinary tract disorders, including congenital anomalies, renal
abscesses, hydronephrosis, and kidney stones.
Radiology and other image studies
QUESTION: Normal Urine should ___.
A. Be cloudy
B. Have a pH of 7.0 or greater
C. Have a specific gravity of 1.0
D. Be sterile
Rationale: There will be no bacteria present in a healthy urinary tract.
Renal Casts:
•
•
Casts are molds of the distal nephron lumen
Casts develop when the protein concentration of the urine is high (as in nephrotic
syndrome), urine osmolality is high, and urine pH in low ***
Specific Gravity:
•
•
The specific gravity of urine varies with its concentration of solutes
The urine specific gravity provides a valuable index of the hydration status and
functional ability of the kidneys
Serum Creatinine Levels:
•
In addition to its use in calculating the GFR, the serum creatinine level is used in
estimating the functional capacity of the kidneys
Measurement of PVR can be achieved quickly, accurately, and painlessly by the use of ultrasonography
(bladder scan). A PVR value of less than 50 mL is considered adequate bladder emptying, and more than
200 mL indicates inadequate bladder emptying
Chapter 33
*Whilm’s tumor is the #1 kidney tumor in a child
Fetal Anomalies:
•
•
Most common:
o Anomalies in shape and position
Less common are disorders involving:
o A decrease in renal mass
▪ Example:
• Agenesis, hypogenesis
o A change in renal structures
Organ Development:
•
•
Dysgenesis:
o Failure of an Organ to develop normally
Agenesis:
o The complete failure of an organ to develop
o Newborns with bilateral renal agenesis—
▪ a rare condition in which the kidney fails to develop at all—are stillborn or
live for only a few hours.
▪
▪
Unilateral renal agenesis occurs in about 1 of 1000 to 2000 newborn
infants.
Boys are affected more often than girls.4 Detection of unilateral agenesis
may be delayed because the healthy kidney usually undergoes
compensatory hypertrophy and performs the function of the missing
kidney.
o In renal hypoplasia, the kidneys do not develop to normal size and contain fewer renal
lobes.
o Like agenesis, hypoplasia more commonly affects only one kidney.
o When both kidneys are affected, renal failure progressively develops.
•
Hypoplasia:
o Failure of an organ to reach normal size
Potter Syndrome:
•
Characteristic facial features of newborns with renal agenesis
o
o
o
o
o
•
•
•
The eyes are widely separated and have epicanthic folds.
The ears are low set.
The nose is broad and flat.
The chin is receding.
Limb defects often are present.
Newborns with renal agenesis often have characteristic facial features, previously called
Potter syndrome, resulting from the effects of oligohydramnios.
Without the amniotic fluid to protect and cushion, the uterus may compress the
developing fetus.
The eyes are widely separated and have epicanthic folds, the ears are low set, the nose is
beaklike, the chin is receding, and limb defects are often present.
Causes of Neonatal Renal Failure with Potter Phenotype:
•
•
•
Cystic renal dysplasia
o caused by an abnormality in the differentiation of kidney structures during
embryonic development.
o It is characterized by undifferentiated tubular structures surrounded by primitive
embryonic tissue and may contain smooth muscle and cartilage.
o Noncommunicating cysts of varying size may replace normal renal parenchyma.
Obstructive uropathy:
o usually classified according to site, degree, and duration of obstruction.Lower urinary
tract obstructions are located below the ureterovesical junction and are bilateral in
nature.
o Upper urinary tract obstructions are located above the ureterovesical junction and are
usually unilateral.
o The condition causing the obstruction can cause complete or partial occlusion of urine
outflow.
o When the obstruction is of short duration (i.e., less than a few days), it is said to be
acute and is usually caused by conditions such as renal calculi.
Autosomal recessive polycystic disease
•
Unilateral agenesis (uncommon)
Cystic Disease of the Kidney:
•
•
•
Definition:
o Fluid-filled sacs or segments of a dilated nephron
Causes:
o Tubular obstructions that increase intratubular pressure
o Changes in the basement membrane of the renal tubules that predispose to cystic
dilation
Types:
o Simple and acquired renal cysts
▪ Simple cysts are a common disorder of the kidney. The cysts may be
single or multiple, unilateral or bilateral, and they usually are less
than 1 cm in diameter, although they may grow larger.
▪ Most simple cysts do not produce signs or symptoms or compromise
renal function.****
o Medullary cystic disease:
▪ a group of renal disorders that have their onset in childhood. Common
characteristics of this ARPKD are small, shrunken kidneys and the
presence of a variable number of cysts, usually concentrated at the
corticomedullary junction.
o Polycystic kidney disease
▪ Autosomal recessive polycystic kidney disease
▪ Autosomal dominant polycystic kidney disease
Causes of Urinary Tract Obstruction:
•
•
•
•
•
•
•
Developmental defects
Calculi (stones)
Pregnancy
Benign prostatic hyperplasia
Scar tissue resulting from infection and inflammation
Tumors
Neurologic disorders such as spinal cord injury
Damaging Effects of Urinary Obstruction
•
•
•
Stasis of urine:
o Predisposes to infection and stone formation
Development of Backpressure
o Interferes with renal blood flow and destroys kidney tissue
Manifestations:
o Depend on :
▪ The site of obstruction
▪ The cause
▪ The rapidity with which the condition developed
o Common symptoms:
▪
▪
▪
Pain
Signs and symptoms of UTI
Manifestations of renal dysfunction
Kidney Stones:
•
•
•
•
•
•
•
•
•
Definition:
o Crystalline structures that form from components of the urine
Also known as renal calculi
Requirements for formation:
o A nidus (nucleus) to form
o A urinary environment that supports continuous crystallization of stone
components
The most common cause of upper urinary tract obstruction is urinary calculi***
o Most development in the kidneys
Kidney stone formation requires a supersaturated urine and an environment that
allows the stone to grow.
The risk for stone formation is increased when the urine is supersaturated with stone
components (e.g., calcium salts, uric acid, magnesium ammonium phosphate, cystine).
Factors influencing the formation of Kidney Stones:
o The concentration of stone components in the urine
o The ability of stone components to complex and form stones
o The presence of substances that inhibit stone formation
o Most kidney stones (75% to 80%) are calcium stones—calcium oxalate,
calcium phosphate, or a combination of the two materials.**
o Emerging research indicates that 13% to 44% of calcium oxalate stones are
culture positive, with Escherichia coli and Pseudomonas spp. representing
the leading organisms.
Types of kidney stones:
o Calcium stones
▪ Oxalate or phosphate
o Magnesium ammonium phosphate stones
o Uric acid stones
o Cystine stones
Treatment:
o Preventative
▪
▪
▪
o
o
o
Dietary restriction
Calcium salt supplementation
Thiazide diuretics
• Cellulose phosphate
Treatment for pain
Antibiotic infection
Removing stones
▪ Ureteroscopy removal
▪ Percutaneous removal
▪ Extracorporeal lithotripsy
o Diagnosis
▪
▪
▪
▪
Urinalysis
Radiography
Intravenous pyelography
Ultrasonography
Types of Urinary Tract Infections:
•
•
•
•
•
•
Asymptomatic Bacteriuria
Symptomatic infections
Lower UITs
o Cystitis
Upper UITs
o Pyelonephritis
UTIs are a frequent type of bacterial infection seen by health care providers.
UTIs include several distinct entities, including asymptomatic bacteriuria,
symptomatic infections, lower UTIs such as cystitis, and upper UTIs such as
pyelonephritis.***
Causes of UTI:
•
Most uncomplicated UTIs caused by Escherichia coli
•
Other uropathic pathogens include
o Staphylococcus saprophyticus in uncomplicated UTIs
o Both non–E. coli gram-negative rods (Proteus mirabilis, Klebsiella pneumoniae,
Enterobacter, Pseudomonas, and Serratia)
o Gram-positive cocci (Staphylococcus aureus, group B streptococcus) in complicated UTIs
Most caused by bacteria that enter through the urethra
•
Causes of UTIs associated with Stasis or Urine Flow:
•
•
•
Anatomic obstructions
o Urinary tract stones
o Prostatic hyperplasia
o Pregnancy
o Malformations of the ureterovesical junction
Increased pressure resulting in reflux
Functional obstructions:
o Neurological bladder
o Infrequent voiding
o Detrusor (bladder) muscle instability
o Constipation
Question: is the following statement True or False?
Static urine flow will predispose your patients to development of a UTI
True: Rationale: Static urine flow will predispose your patient to development of a UTI.
Glomerulonephritis:
•
•
Immune mechanisms
o Glomerular antibodies
o Circulating antigen-antibody complexes
Characteristics
o Hematuria with red cell casts
o
o
o
o
•
A diminished glomerular filtration rate (GFR)
Azotemia
▪ (presence of nitrogenous wastes in the blood)
Oliguria
Hypertension
o Acute postinfectious glomerulonephritis usually occurs after infection with
certain strains of group A beta-hemolytic streptococci**
Causes:
o Diseases that provoke a proliferative inflammatory response of the endothelial,
mesangial, or epithelial cells of the glomeruli
o
The inflammatory process:
▪ Damages the capillary wall
▪ Permits red blood cells to escape into the urine
▪ Produces hemodynamic changes that decrease the GFR
Cellular Changes in Glomerular Disease:
•
•
•
•
•
•
•
•
Proliferative:
o Endothelial
o Mesangial
o Leukocyte
o Crescent formation
Basement membrane thickening
Sclerosis
Fibrosis
Diffuse glomerular changes
Focal glomerular changes
Segmental glomerular changes
Mesangial changes
Urinary Changes in Glomerulonephritis:
•
•
•
•
•
•
•
Proteinuria (protein)
Hematuria (blood)
Pyuria (pus)
Oliguria (low urine output)
Edema (swelling)
Hypertension (high blood pressure)
Azotemia (Elevated levels of urea and nitrogen in the blood)
Question: Glomerulonephritis will result from which of the following?
A.
B.
C.
D.
E.
Basement membrane thickening
Sclerosis
Fibrosis
Hypercellularity
All of the above
Rationale: Each of these changes can lead to glomerulonephritis.
Tubulointerstitial Disorder:
•
Damage to the proximal, loop, or distal portion of the nephron
o Acute tubular necrosis
o Renal tubular acidosis
o Pyelonephritis
o The effects of drugs and toxins
▪ Gentamycin
Proximal and Distal Tubular Acidosis:
•
Renal tubular acidosis:
o Proximal tubular disorders that affect bicarbonate reabsorption
o Distal tubular defects that affect the secretion of fixed metabolic acids
Major Groups of Renal Neoplasms:
•
•
Embryonic kidney tumors occurring during childhood
o Wilms tumor
▪ Onset at 3 to 5 years
▪ In one or both kidneys
▪ WT1 mutation on chromosome 11
Adult kidney cancers
o Renal cell carcinoma
Chapter 34
Renal Failure:
•
•
Definition:
o A condition in which the kidneys fail to remove metabolic end products from the
blood and regulate the fluid, electrolyte, and pH balance of the extracellular fluids**
Underlying Causes:
o Renal disease
o Systemic disease
o Urologic defects of nonrenal origin
Prevention and Early Diagnosis of Acute Renal Failure:
•
Assessment measures to identify persons at risk for development of acute renal failure
o Those with preexisting renal insufficiency and diabetes
o Elderly persons (due to the effects of aging on renal reserve)
Types of Renal Failure:
•
•
Acute Renal Failure
o Abrupt in onset
o Often is reversible if recognized early and treated appropriately
Chronic Renal Failure:
o The end result of irreparable damage to the kidneys
o It develops slowly, usually over the course of a number of years
o Hypertension and diabetic kidney disease are the two main causes of CKD in the
United States.**
o A GFR of less than 15 mL/min/1.73 m, usually accompanied by most of the signs and
symptoms of uremia, or
o A need to start renal replacement therapy (dialysis or transplantation)”
Prerenal Cases if Acute Renal Failure:
•
•
•
•
Hypovolemia
Decreased vascular filling
Heart failure and cardiogenic shock
Decreased renal perfusion due to vasoactive mediators, drugs, diagnostic agents
Postrenal Causes of Acute Renal Failure
•
•
Bilateral ureteral obstruction
Bladder outlet obstruction
Question: Congestive Heart Failure would be a(n) ___ cause of renal failure
A. Prerenal
B. Intrarenal
C. Postrenal
Rationale: Prerenal causes of acute kidney injury include profound depletion of vascular volume,
impaired perfusion due to heart failure and cardiogenic shock, and decreased vascular filling because of
increased vascular capacity.
Intrinsic or Intrarenal Causes of Acute Renal Failure:
•
Acute tubular necrosis
o Prolonged renal ischemia
o Exposure to nephrotoxic drugs, metals, organic solvents
o Intratubular obstruction resulting from hemoglobinuria, myoglobinuria, myeloma light
chains, or uric acid casts
o Acute renal disease
Common causes of Chronic Renal Disease:
•
•
•
•
•
•
•
•
•
Hypertension
Diabetes mellitus
Polycystic kidney disease
Obstructions of the urinary tract
Glomerulonephritis
Cancers
Autoimmune disorders
Diseases of the heart or lungs
Chronic use of pain medication
Stages of the Progression of Chronic Renal Failure:
•
•
•
•
•
Albuminuria serves as a key marker of kidney damage.Urine normally contains small amounts
of protein***.
Mild reduction of GFR to 60 to 89 mL/min/1.73 m2
Moderate reduction of GFR to 30 to 59 mL/min/1.73 m2
Severe reduction in GFR to 15 to 29 mL/min/1.73 m2
Kidney failure with a GFR < 15 mL/min/1.73 m2, with a need for renal replacement therapy
Question: a GFR of ___ best describes renal failure.
A.
B.
C.
D.
60 to 89 mL/min/1.73 m2
30 to 59 mL/min/1.73 m2
15 to 29 mL/min/1.73 m2
<15 mL/min/1.73 m2
Rationale: Less than 15 mL/min/1.73 m2 is the result of significantly decreased renal filtration and is the
cut-off point of renal failure.
Clinical Manifestations of Chronic Renal Failure:
•
•
Accumulation of nitrogenous wastes
Alterations in water, electrolyte, and acid–base balance
•
•
•
•
•
•
•
•
•
•
•
•
•
Mineral and skeletal disorders
Anemia and coagulation disorders
The accumulation of nitrogenous wastes in the blood, or azotemia, is an early sign of kidney
failure, usually occurring before other symptoms become evident.
Urea is one of the first nitrogenous wastes to accumulate in the blood, and the BUN level
becomes increasingly elevated as CKD progresses.***
Uremia, which literally means “urine in the blood,” is the term used to describe the clinical
manifestations of kidney failure.
Few symptoms of uremia appear until at least two thirds of the kidney’s nephrons have been
destroyed.
Uremia differs from azotemia, which merely indicates the accumulation of nitrogenous wastes
in the blood and can occur without symptoms.
Approximately 90% of potassium excretion is through the kidneys
Hypertension and alterations in cardiovascular function
Gastrointestinal disorders
Neurologic complications
Disorders of skin integrity
Immunologic disorders
Hemodialysis:
•
A hemodialysis system, or artificial kidney, consists of three parts: a blood delivery system, a
dialyzer, and a dialysis fluid delivery system. ***
Disorders of Water, Electrolyte, and Acid-Base Balance:
•
•
•
Sodium and water balance
o The kidneys function in the regulation of extracellular fluid volume.
Potassium balance
o Approximately 90% of potassium excretion is through the kidneys.
Acid–base balance
o The kidneys normally regulate blood pH by eliminating hydrogen ions produced in
metabolic processes and regenerating bicarbonate.
Question: Which of the following alterations may affect drug efficacy in a patient with CKD?
A.
B.
C.
D.
Loss of K+
Alteration in pH
Loss of albumin
Increased Ca2+
Rationale: Loss of albumin will result in altered drug metabolism via increased intermediates and faster
action.
Treatment of Renal Failure:
•
Medical Management
o Dialysis
•
▪ Hemodialysis
▪ Peritoneal dialysis
o Transplantation
Dietary Management
▪ The major component in the treatment of CKD is nutritional management. **
o Protein:
▪ Restriction of dietary proteins may decrease the progress of renal impairment in
people with advanced renal disease.
▪ Proteins are broken down to form nitrogenous wastes, and reducing the
amount of protein in the diet lowers the BUN and reduces symptoms.
o Carbohydrates, fat, calories
o Potassium
o Sodium and fluid intake
CKD in Elderly:
•
•
Normal decrease in the GFR with age
o Increased detrimental effects of nephrotoxic drugs
Greater incidence of cerebrovascular, cardiovascular, and skeletal system effects
Chapter 35
Structure of the bladder:
•
•
Parts:
o Fundus (body)
o Neck (posterior urethra)
Urine:
o Passes from the kidneys to the bladder through the ureters
▪ Ureters:
• Enter the bladder bilaterally at a location toward its base and close to
the urethra
▪ Trigone:
• The triangular area bounded by the ureters and the urethra
*Detrusor Muscle is a network of smooth muscle fibers and helps with the process of micteration
(peeing)
Bladder:
•
•
A muscle that is important to the bladder function is the external sphincter
o A circular muscle composed of striated muscle fibers that surrounds the urethra distal to
the base of the bladder
Muscles in the bladder neck are sometime referred to as internal urethral sphincter
o It’s a continuation of the detrusor muscle
Three main levels of Neurologic Control of Bladder Function:
•
•
•
•
Spinal cord reflex centers***
o The centers for reflex control of bladder functions are located in the sacral (S1-S4) and
thoracolumbar (T11-L2) segments of the spinal cord.
o The parasympathetic lower motor neurons (LMNs) for the detrusor muscle of the
bladder are located in the sacral segments of the spinal cord; their axons travel to the
bladder by way of the pelvic nerve.
o LMNs for the external sphincter are also located in the sacral segments of the spinal
cord.
o These LMNs receive their control from the motor cortex through the corticospinal
tract and send impulses to the external sphincter through the pudendal nerve.
Innervation:
o Pelvic nerve innervates detrusor.
o Pudendal nerve
o Hypogastric
Micturition center in the pons
Cortical and subcortical centers
Question: is the following statement True or False?
The micturition reflex involves both sympathetic and parasympathetic input.
True: the reflex is both conscious and unconscious
Storage and Emptying of Urine:
•
Micturition or the act of bladder emptying involves both sensory and motor functions
associated with bladder emptying ***
AND Drugs:
•
•
Nicotinic (N) receptors are found in the synapses between the preganglionic and
postganglionic neurons of the sympathetic and the parasympathetic system, as well as in the
neuromuscular end plates of the striated muscle fibers of the external sphincter and pelvic
muscles.
Muscarinic (M) receptors are found in the postganglionic parasympathetic endings of the
detrusor muscle
Urine Tests and Studies:
•
•
•
Laboratory and Radiographic Studies
o Urine tests and x-rays
Urodynamic Studies
Uroflowmetry
o Cystometry
o Urethral pressure profile
o Sphincter electromyography
o Ultrasound bladder scan
Question: Increased PVR volumes is the result of ___?
A.
B.
C.
D.
Hematuria
Detrusor muscle weakness
Infection
Drug treatment
B. Rationale: Detrusor muscle weakness results in decreased void pressure and therefore greater
volume left in the bladder.
Alteration in Bladder Function:
•
•
Types:
o
o
Causes
o
o
Urinary obstruction with retention or stasis of urine
Urinary incontinence with involuntary loss of urine
Structural changes in the bladder, urethra, or surrounding organs
Impairment of neurologic control of bladder function
Signs of Outflow Obstruction and Urine Retention:
•
•
•
•
•
•
•
Bladder distention
Hesitancy
Straining when initiating urination
Small and weak stream
Frequency
Feeling of incomplete bladder emptying
Overflow incontinence
Common causes of Neurogenic Bladder:
•
•
•
•
•
•
•
Stroke and advanced age
Parkinson disease
Spinal cord injury
Injury to the sacral cord or spinal roots
Radical pelvic surgery
Diabetic neuropathies
Multiple sclerosis
Neurogenic Bladder Disorders:
•
•
Spastic Bladder Dysfunction
o Failure to store urine
o Neurologic lesions above level of the sacral cord allow neurons in the micturition center
to function reflexively without control from the CNS centers.
Flaccid Bladder Dysfunction
o Bladder emptying is impaired.
o Neurologic disorders affect motor neurons in the sacral cord or peripheral nerves that
control detrusor muscle contraction and bladder emptying.
Treatments for Neurogenic Bladder Disorders:
•
•
•
•
Catheterization
Bladder retraining
Pharmacologic manipulation
Surgical procedures
Question: Which of the following is not a cause of neurogenic bladder?
A.
B.
C.
D.
Parkinson disease
Spinal cord injury
Alzheimer disease
Injury to the sacral cord or spinal roots
E. Radical pelvic surgery
Rationale: Alzheimer disease is primarily a cognitive condition, not motor related.
Types of Incontinence:
•
•
•
•
Stress Incontinence
o Involuntary loss of urine during coughing, laughing, sneezing, or lifting
o Increases intra-abdominal pressure
Urge Incontinence
o Involuntary loss of urine associated with a strong desire to void (urgency)
Overflow Incontinence
o Involuntary loss of urine occurs when intravascular pressure exceeds the maximal
urethral pressure because of bladder distention in the absence of detrusor activity
Mixed Incontinence
o Combination of stress and urge incontinence
Diappers:
•
There are many neurologic conditions that predispose to urinary incontinence. The transient
and often treatable causes of urinary incontinence in older adults may best be remembered
with the acronym DIAPPERS:
o D stands for dementia/dementias
o I for infection (urinary or vaginal)
o A for atrophic vaginitis
o P for pharmaceutical agents
o P for psychological causes
o E for endocrine conditions (diabetes)
o R for restricted mobility
o S for stool impaction
Bladder Cancer:
•
•
Signs:
o Increased frequency
o Urgency
o Dysuria
o Hematuria
Cancerous Lesion Types:
o Superficial
o Invasive
Diagnosis Measures for Cancer of the Bladder:
•
•
Cytologic studies
Excretory urography
•
•
•
•
•
Cystoscopy
Biopsy
Ultrasonography
CT scans
MRI
Treatment Methods for Bladder Cancer:
•
•
•
Treatment methods depend on
o The cytologic grade of the tumor
o The lesion’s degree of invasiveness
Methods include
o Surgical removal of the tumor
o Radiation therapy
o Chemotherapy