Renal & Urinary System: Pathophysio

kidney functions

-filters blood plasma

-regulates osmolarity:

-secretes renin and erythropoietin

-detoxifies free radicals and drugs

-gluconeogenesis

kidney filters: blood plasma

filters blood and returns useful substances to blood, eliminates waste

kidney filters: osmolarity

regulates body fluids, blood volume, BP, and acid/base balance

gluconeogenesis of kidney

synthesis of glucose from amino acid precursors (from non-carb substances)

approximately __________ adults with diabetes of chronic kidney disease

1 out of 3

approximately __________ adults with high BP have chronic kidney disaease

1 out of 5

kidney disease pathology

-worldwide public health problem
-increasing in the US by 8-10% per year
-best treatment: transplant
-most affected are on dialysis

mediare and financial costs of kidney disease

-cost of end stage renal disease (ESRD) was 40 billion in 2009

-cost medicare 28 billion

most common cause of kidney disease

-diabetes
-second most common is hypertension

number of individuals in the US living with ESRD (end stage renal disease) on dialysis

69%

location of kidney

-retroperitoneal
-T12-L3

renal cortex

outer layer of kidney (1cm thick), contains all the glomueruli as well as 85% of the nephron tubules and their loops of Henle

renal medulla

renal columns, pyramids, papilla

renal pelvis

large, central collecting region in the kidney

nephron

functional unit of the kidneys in the renal cortex

components of a nephron

-Bowman's capsule
(with the glomerulus_
-proximal convoluted tubule
-Loop of Henle
-distal convoluted tubule
-collecting duct

glomerular filtration rate (GFR)

the amount of filtrate formed per minute by the two kidneys combined

how much filtrate is absorbed during GFR vs urine excreted

99% of filtrate reabsorbed, leaving 1 to 2 L urine excreted

mechanisms to control GFR activity via adjusting glomerular blood pressure

-autoregulation: juxtaglomerular apparatus--> monitors salinity, changes arteries diameter
-sympathetic control: exercise shunts blood to kidneys and gives to muscles
-hormonal mechanism: renin and angiotensin

renal autoregulation of glomerular filtration rate (GFR)

-increased BP --> constricts afferent arteriole, dilate efferent
-decreased BP --> dilate afferent arteriole, constrict efferent
-stable for BP range of 80 to 170 mmHg (systolic)
-cannot compensate for extreme BP

increased vs decreased GFR (abnormalities)

-increased GFR, urine output rises -> dehydration, electrolyte depletion
-decreased GFR, wastes reabsorbed (azotemia possible)

GFR in males

125 mL/min or 180 L/day

GFR in females

105 ml/min or 150 L/day

hormones that effect the kidney

renin, angiotensin II, aldosterone

renin

an enzyme released by the kidneys when BP drops

angiotensin II

a hormone that constricts blood vessels and increases blood pressure

aldosterone

a hormone that causes the kidneys to retain sodium and excrete potassium

appearance of urine

colorless to deep amber due to urochrome- from breakdown of hemoglobin (RBC's)

odor of urine

due to bacteria degrading urea to ammonia

normal volume of urine per day

1-2 L/day

pH of urine

ranges from 4.5-8.2, usually 6.0

chemical composition of urine

-95% water and 5% solutes
-urea, NaCl, KCl, creatinine, uric acid

tubular secretion of PCT and nephron loop

waste removal and acid-base balance

tubular secretion: waste removal

-urea, uric acid, bile salts, ammonia, catecholamines, many drugs, glucose
-increase BUN (nitrogen byproduct)
-too much can cause kidney failure

tubular secretion: acid-base balance

secretion of hydrogen and bicarbonate ions regulates pH of body fluids

primary function of nephron loop

-water conservation
-generates salinity gradient, allows CD to concentrate urine
-also involved in electrolyte reabsorption

excretion

separation of wastes from body fluids and eliminating them via 4 systems (respiratory, integumentary, digestive, urinary)

respiratory excretion

CO2

integumentary excretion

water, salts, lactic acid, urea

digestive excretion

water, salts, CO2, lipids, bile pigments, cholesterol

urinary excretion

-many metabolic wastes, toxins, drugs, hormones, salts, H+, and water

-primary system for excretion

effects of diuretics

increased urine output and decreased blood volume

using diuretics can lead to...

-hypertension
-congestive heart failure

diuretics mechanism of action

increased GFR and decreased tubular reabsorption

kidney disorders

-infectious: usually from ascending bacteria from UTI
-obstructive
-tumors
-renal failure: acute, chronic or clinical management

renal pain

-slightly below the ribs to the upper part of the thighs. may be bilateral or unilateral
-can mimic low back pain

hallmark symptom of renal pain

costovertebral angle tenderness

obstructive disorders

-results in urine stasis which predisposes pt's to infection and structural damage
-includes stones, tumors, prostatic hypertrophy, and strictures of the ureters or the urethra

kidney stones in obstructive disorders

-tend to form in the urinary tract under conditions of high solute concentration, low urine volume and low urine pH
-composed of calcium crystals
-usually undetected in radiographs

kidney tumor types

benign or malignant primary tumors

kidney tumor treatment

nephrectomy (kidney removal)

renal cellcarcinoma

-resistant to hormone therapy, immunotherapy, and chemotherapy
-late stage or recurrent diagnosis --> poor prognosis

urinary bladder location

in pelvic cavity, posterior to pubic symphysis

3 layers of urinary bladder

1. parietal peritoneum, superiorly; fibrous adventitia rest

2. muscularis: detrusor muscle, 3 layers smooth muscle

3. mucosa: transitional epithelium

trigone of bladder

openings of ureters and urethra, triangular

rugae of bladder

relaxed bladder wrinkled, highly distensible

capacity of bladder

moderately full: 500ml
max: 800ml

voiding urine - micturition

at 200 ml urine in bladder, stretch receptors send signal to sacral spinal cord

low, normal, high total capacity of urine in bladder

-low: <200 ml
-normal: 300-600 ml
-high: >600 ml

micturition signals ascend to

-inhibitory synapses on sympathetic neurons
-micturition center (integrates info from amygdala, cortex)

micturition signals descending

-further inhibits sympathetic neurons
-stimulates parasympathetic neurons

micturition effect/result

-urinary bladder contraction
-relaxation of internal urethral sphincter

external urethral sphincter

corticospinal tracts to sacral spinal cord inhibit somatic neurons (relaxes)

female urethra vs male urethra

-females: 3 to 4 cm long
-males: 18 cm long

bladder disorders

-incontinence
-cystitis
-tumors

incontinence prevalence

-affects 25% of men and 65% of women (b/w 20 and 60 years old)
-health care expenditure of 26 billion anually

urge incontinence

-the loss of urine in response to a sudden, urgent need to void; the person cannot get to a toilet in time
-from detrusor overactivity

stress incontinence

-when urine leaks during exercise and certain movements that cause pressure on the bladder
-from weakening of pelvic floor muscles or intrinsic urethral sphincter deficiency

interstitial cystitis

inflammation of the bladder lining due to infection, chemical irritants, stones, or trauma

interstitial cytitis causative factors

-being female
-UTI's
-catheterization
-diabetes and any condition resulting in urinary stasis

symptoms of interstitial cystitis in older adults

lethargy, anorexia, confusion, anxiety

tumors of bladder

most originate from transitional epithelial lining

bladder tumor treatment

-benign tumors may be surgically removed
-high risk tumors are managed with intravesical immunotherapy (live tuberculin virus)
-for muscle invasive CA, cystectomy radiation