Kidney/Urology-Exam 3 Flashcards
Describe the components of the nephron
- glomerulus. mechanically filters blood.
- proximal convoluted tubule. reabsorbs 75% of the water, salts, glucose, and amino acids.
- loop of henle. countercurrent exchange, which maintains the concentration gradient.
- distal convoluted tubule: regulating extracellular fluid volume and electrolyte homeostasis.
Urine is formed as a result of:
- glomerular filtration
- reabsorption of substances into the blood
- excretion of substances from the blood into the renal tubules
What are the structures of the glomerular membrane?
- fenestrated endothelial cell
- glomerular basement membrane
- Podocyte
Glomerular Membrane: fenestrated endothelial cell
Structure:
Network of capillaries in the
renal cortex that is covered by epithelium called Bowman’s capsule
Function:
Blood is filtered and fluid is
collected in Bowman’s capsule
Glomerular Membrane: glomerular basement membrane (GBM)
Structure:
is a ribbon-like extracellular matrix that lies between the endothelium and the podocyte foot processes (FPs)
Function:
glomerular filtration barrier. It provides a scaffold that supports the physiological function of the glomerular endothelium and podocytes.
Glomerular Membrane: podocyte
Structure:
have long foot processes called pedicles,
Function:
play an important role in glomerular function. Together with endothelial cells of the glomerular capillary loop and the glomerular basement membrane they form a filtration barrier.
4 ways of increasing GFR
- Increase glomerular capillary hydrostatic pressure
- Hormones
- nitric oxide, prostaglandin, bradykinin
- autacoids
Increase GFR by:
Increase glomerular capillary hydrostatic pressure
works by:
- increasing intravascular volume or MAP
- dilation of afferent arterioles=more blood flow
- constrict efferent arterioles=slower flow and greater blood volume
Increase GFR by:
Hormones and autacoids
works by:
-Local angiotensin II: constricts efferent arterioles>>increasing blood flow>>inc GFR
Increase GFR by:
nitric oxide, prostaglandin, bradykinin
works by:
dilate afferent arterioles >> increasing blood flow >> increasing GFR
Increase GFR by: autacoids
works by:
-Local angiotensin II: constricts efferent arterioles>>increasing blood flow>>inc GFR
4 ways of decreasing GFR
- Increased Bowman’s capsule by hydrostatic pressure
- Increase glomerular capillary colloid osmotic pressure
- Sympathetic nervous system
- Hormones
Decrease GFR by:
Increased Bowman’s capsule by hydrostatic pressure
works by:
obstruction of urinary tract (kidney stones)
Decrease GFR by:
Increase glomerular capillary colloid osmotic pressure
works by:
high protein intake and hyperglycemia
Decrease GFR by:
Sympathetic nervous system
works by:
- norepinephrine: increases sympathetic action>> constricts afferent arterioles >> dec blood flow >> dec GFR
- epinephrine (from adrenal medulla): constricts afferent arterioles >> dec blood flow >> dec GFR
Decrease GFR by:
Hormones
works by:
Denothelin (from vascular endothelium): constricts afferent arterioles >> dec blood flow >> dec GFR
Acute Kidney Inury
Definition: sudden decline in GFR, UOP and clearance of waste products and electrolytes
Onset: within a few hours or a few days
Common Etiologies: ischemia, hypoxia or nephrotoxicity.
Chronic Kidney Disease
Definition:
also known as chronic kidney failure, means a gradual loss of kidney function over time
Onset: 3 months
Common Etiologies: HTN, DM, high cholesterol, kidney infections, glomerulonephritis, polycystic kidney disease, blockage of urine (kidney stones or enlarged prostate), or long term use of NSAIDS
Pre-renal
Risk factors:
hypovolemia, hemorrhagic blood loss, loss of plasma volume, water and electrolyte losses, septic shock, cardiac failure, massive PE, stenosis or clamping of renal artery, increased intraabdominal pressure
Etiology:
•Lack of perfusion
•Hypotension, hypovolemia
•Renal blood flow
*cause of decrease blood flow into kid.
* kid injury is before the kidneys
Patho:
Decreased renal blood flow >> hypoperfusion >> decreased GFR >> increased proximal tubule Na and H2O reabsorption >> increased aldsosterone and ADH secretion >> increase distal tubule Na and H2O reabsorption >> oliguria
Intra-renal
Risk factors:
acute tubular necrosis, glomerulopathies, acute interstitial necrosis (tumors or toxins), vascular damage, malignant hypertension, vasculitis, coagulation defects, renal artery/vein occlusion, bilateral acute pyelonephritis
Etiology: a tubular, glomerularnephritis, or interstitial area issue. Cant filter blood properly and cells are damanaged that reabsorption and secretion is effected
- Acute tubular necrosis (nephrotoxins) caused by ischemia most common cause of intrarenal AKI; happens a lot after surgery and severe sepsis
- glomerulonephritis
- Acute insterstial nephritis ( can be d/t medications)
Patho: reanal tubular injury >> cast formation >> intratubular obstruction >> increased intratubular pressure >> tubular back leack >> decreased GFR >> oliguria
Post-renal
Risk factors:
Obstructive uropathies (usually bilateral), ureteral destruction (edema, tumors, stones, clots), bladder neck obstruction (enlarged prostate), neurogenic bladder
Etiology:
Urinary obstruction
Urine is unable to drain and system
“backs up”
Patho:
bilateral obstruction to urine flow >> increase intraluminal pressure >> release of inflammatory mediators and vasscular endothelial cell injury >> renal vasoconstriction >> cellular/interstitial edema >> decreased GFR >> oliguria
CKD stage I
Severity: mild kidney damage
GFR: 90% ore more
Progression:
Symptoms: no specific symptoms, but kidney function can slowly decline; high bp, swelling in legs, UTIs, abnormal urine test
CKD stage II
Severity: mild loss of kidney function
GFR: 60-89%
Progression:
Symptoms: no specific symptoms, but kidney function can slowly decline; high bp, swelling in legs, UTIs, abnormal urine test
CKD stage III
Severity: mild to severe loss of kidney function
GFR: 30-59%
Progression:
Symptoms: changes in urinations, swelling hands and feet, weakness/fatigue, dry/itchy skin, back pain, muscle cramping