Exam 3 Flashcards
Tubular reabsorption
movement of fluid and water from tubular lumen (urine) to peritubular capillary plasma (blood)
Tubular secretion
movement from capillary (blood) to tubular lumen (urine)
Excretion
elimination of a substance in the final urine
PCT
Reabsorbs MOST ions and some molecules that have been filtered from blood into urine:
– Puts back into the blood Na+, Cl‐, K+, glucose, – Requires active transport
Loop of Henle
Function: create a concentration gradient to reabsorb water and concentrate the urine
Descending limb
- Thin
- No active transport – osmosis only here
- Water will move out of the urine (reabsorbed) • Urine becomes very concentrated (hypertonic)
Thick ascending limb
- Actively transports ions out of the urine (reabsorbed)
* Urine will become less concentrated (hypotonic) • Passes urine into the DCT
Distal convoluted tubule (DCT)
• More reabsorption of substances by active transport
Primary Kidney Function
The primary function of the kidney is to maintain a stable internal environment for optimal cell and tissue metabolism.
What hormones do the kidneys secrete
secretes the hormones renin for regulation of blood pressure, erythrocyte production
erythropoietin,
1,25‐dihydroxy‐vitamin D3 calcium metabolism
Where are the kidneys located
posterior region of the abdominal cavity behind the peritoneum
Cortex
outer layer of the kidney
contains all of the glomeruli, most of the proximal tubules, and some segments of the distal tubule.
Medulla
Forms the inner part of the kidney and consists of region called the pyramids
Renal columns
are an extension of the cortex and lie between the pyramids and extend to the renal pelvis
Minor calyces
receive urine from the collecting ducts through the renal papilla
Major calyces
join to form the renal pelvis which connects with the proximal end of the ureter
Nephron
Functional unit of kidney
A tubular structure with subunits that include the renal corpuscle (includes glomerulus, Bowman capsule and mesangial cells), proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct, all of which contribute to the formation of urine.
Glomerulus
Synthesizes nitric oxide (vasodilator) and endothelin‐1 vasoconstrictor) to regulate blood flow and control GFR.
Afferent arteriole
Brings blood in
Juxtaglomerular cells
produce renin, JGA is formed by the afferent arteriole and a portion of the DCT and regulates renal blood flow and glomerular filtration
Macula densa
Na and Cl sensing cells
Podocytes
adhere to basement membrane of glomerular capillaries. Gaps between them allow filtration.
Efferent arteriole
exits the glomerulus.
GFR
The filtration of the plasma per unit of time, directly related to the perfusion pressure in the glomerular capillaries
How are resistance and pressure
They are affected in same direction
Neural regulation BP decreases
aortic baroreceptors sense it, increase sympathetic
output (epinephrine), which results in vasoconstriction and decreases GFR
Decreased GFR diminishes
excretion of Na and H2O, resulting in increase in blood volume…increasing BP
Angiotensin II
Produced sustemically and within kidneys; constricts afferent and efferent arterioles decreases RBF and GFR
Function of PCT
reabsorption of most ions; active transport
Loop of Henle
Thin
Descending-highly permeable to water, not ion, no active transport
Loop of Henle
Thick
ascending-actively transports ions into interstitium and passes urine into the DCT
Distal convoluted tubule (DCT):
reabsorption and secretion of ions, creates dilute
fluid. Secretes H+ contributing to acid‐base balance.
Collecting duct:
Principal cells (reabsorb Na+ and H20, secrete K+); intercalated cells (secrete H+ and reabsorb K+)
Concentration/dilution of urine occurs mainly
in the loop, DCT and collecting duct.
Diuretics
enhance urine flow
they interfere with renal Na reabsorption and decrease
extracellular fluid volume
Glucose
normally entirely reabsorbed should be negative
Nitrates:
should be negative, positive with some bacteria
Ketones
By products of fat breakdown. Positive in starvation and diabetic ketoacidosis
Albumin
Normally doesn’t make it past glomerulus. Positive in glomerular failure
Hemoglobin
Normally not free, positive in RBC breakdown
Myoglobin
Normally not free, positive in muscle breakdown
Leukocyte esterase
Enzyme in white blood cells normally not present in urine, should be negative
Urine Sediment
Urine sediment is a microscopic analysis; it can cover everything from crystals, casts, RBCs, WBCs, and urothelial cells including urothelial cells with cancer or la cart
Blood Urea Nitrogen
- Reflect urine concentrating ability and glomerular filtration
- Rises in states of dehydration as well as in acute and chronic renal failure because passage of fluid through the renal tubules is slowed
As BUN levels increase
GFR drops
Normal BUN level in adults
10-20mg/dL
Normal plasma creatinine
.7-1.2 mg/dL
This is most useful in monitoring over time; it takes 7‐10 days for creatinine to stabilize when GFR declines. Less useful in acute renal failure.
GFR declines what happens to creat
creat increases proportionally
Creatinine Clearance
- Estimates GFR
- Requires 24‐hour volume or urine and 1 blood draw for plasmacreatinine
GFR formula
Urine Creat x Urine Volume)/Plasma Creat
Renal and urinary function can be affected by a variety of disorders including
Infection (most common)
Obstruction by stones, tumors, or inflammatory edema
Dysfunction from kidney disorders or systemic disease
Urinary tract obstruction
- Interference with flow of urine at any site along the urinary tract
- Obstruction impedes flow, leads to dilation of structures prior to the obstruction, increases risk of infection and impairs renal function
- Anatomic changes in the urinary system related to an obstruction are called obstructive uropathy
Upper Urinary Tract Obstruction
Compression of calyx, ureteropelvic junction, ureterovesical junction (within kidney, ureter, before bladder)
Stones
Causes increased pressure, dilation of ureter, renal pelvises, calyces and renal parenchyma prior to obstruction
Causes of upper urinary tract obstruction
Stones *, compression from abnormal vessel, tumor, abdominal inflammation and scarring
upper urinary tract obstruction effect on GFR
Increased pressure transmits back to glomerulus, decreasing glomerular blood flow and ultimately, GFR
Hydronephrosis
Lots of obstruction leads to hydronephrosis. The renal pelvis expands which increases the intra‐renal pressure. Renal pyramids infarct, and nephrons are destroyed. The cortex atrophies, and the remaining kidney scars (tubulointerstitial fibrosis) and becomes dysfunctional.
calculi
Made of crystals, proteins or other substances; classified by the primary substance from which they are formed
Can be in the kidney or urinary tract (ureters, urethra, bladder)
calculi clinical presentation:
renal colic‐ severe, off‐and‐on flank pain, urinary urgency, frequency, blood in urine
Calcium oxalate and calcium phosphate calculi
calcium and oxalate precipitate to form stone in the renal pelvis. Cutting dietary calcium is NOT recommended since dietary calcium binds dietary oxalate in the gut – the gut can handle some “stones”
Lower Urinary Tract Obstruction 4
Disorders of the bladder‐ primarily of urine storage or emptying
• Incontinence
• Neurogenic bladder
• Urethral obstruction: stricture, prostate enlargement, tumor
• Pregnancy‐related
UTI
Inflammation of urinary epithelium usually caused by gut bacteria
Can occur anywhere along the urinary tract
treated with antibiotics
UTI symptoms
frequency, dysuria, urgency, and low back and/or suprapubic pain or asymptomatic
Urine culture of specific microorganisms
with counts of 10,000/ml
or more
Complicated UTI presents with
fever, develop when there is an abnormality in the urinary tract and/or a condition that compromises ability to defend against infection (spinal cord injury, HIV, DM)
Cystitis:
bladder inflammation
Pyelonephritis:
inflammation of upper urinary tract
Recurrent UTI :
3+ UTIs in 12 mos or 2+ in 6 mos
uti risk factors
Premature newborns, pre‐pubertal children, pregnant and sexually active females, females treated with antibiotics (disrupt vaginal flora), spermicide users, estrogen‐deficient post‐menopausal women, individuals with indwelling catheters, people with diabetes mellitus, neurogenic bladder, urinary obstruction.
protective urinary mechanisms for UTI
Washed out of the urethra during urination
• Low pH and high osmolality of urea
• Secretions from the uroepithelium: Bactericidaleffect
• Women: Mucus‐secreting glands
• Men:Length of the male urethra
Glomerulopathies
• Disorders that directly affect the
significant cause of chronic kidney disease and end‐stage renal failure worldwide.
Acute Glomerulonephritis
Inflammation of the glomerulus
primary glomerular injury:
immunologic responses, ischemia, free
radicals, drugs, toxins, vascular disorders, infection
Secondary glomerular injury:
result of systemic diseases, including diabetes mellitus, systemic lupus erythematosus,
Patho of glomerulonephritis
Formation of immune complexes (antigen/antibody) in the circulation with
subsequent deposition in glomerulus
Antibodies produced against the organism that cross‐react with the glomerular endothelial cells
Glomerulonephritis effects
Decreased glomerular filtration rate (GFR)
– Decreased glomerular perfusion (glomerular blood flow) as a result of inflammation – Glomerular sclerosis (scarring)
– Thickening of the glomerular basement membrane, but increased permeability to proteins and red blood cells
Nephrotic
massive loss of protein
frothy urine
anasarca
urine contains massive amounts of proteins/microscopice amount or no blood
nephritic syndrome
Usually also extra‐renal syndromes (lupus, history of strep, goodpastures also affects lung)
Urine contains massive amounts of blood and varying degrees of protein, which is not usually severe
