Renal System Flashcards
(42 cards)
kidney functions
regulation of BP/plasma volume, ions, and plasma osmolarity
production of hormones
elimination of waste products
salvage essential compounds
function unit of kidneys
nephron
components of nephron
glomerulus
proximal tubule
loop of henle
distal tubule
collecting duct
superficial nephron
short loop of Henle, peritubular capillaries carry nutrient to tubule
juxtamedullary nephron
glomerulus larger, long loop of henle extending deep into medulla, efferent arterioles form vasa recta
reabsorption
primarily occuers in proximal tubule, but also can occur in loop of henle and distal tubule
water, glucose, electrolytes and amino acids from kidney filtrate move back into blood
secretion
primarily occurs at distal tubule and collecting duct
removes wastes and excess substances from blood that were not filtered at glomerulus
ADH
anit-diuretic hormone
increase water absorption as water moved from urine filtrate back into blood; regulates water permeability of surrounding medullary collecting tubules
action of ADH
binds to vasopressin receptors on basolateral membrane of tubular cell causing water channels to move into luminal side of membrane.
The insertion of channels allows water from tubular fluids to move into tubular cells and out into surrounding hyperosmotic interstitial fluid on basolateral side of cell.
absence of ADH
water excreted in urine
renin
converts angiotensin 1 to angiotensin 2
release signalled by mesangial cells, decrease afferent arteriolar stretch and decrease sodium chloride delivery to macula densa
angiotensin 2
vasoconstrictor = decrease in GFR, which increases systemic BP
triggers aldosterone secretion
aldosterone
increase sodium reabsorption
renin-angiotensin-aldosterone mechanism
renin converts angiotensin 1 to angiotensin 2, which acts as a vasocontrictor to afferent arterioles to increase systemic BP and triggers aldosterone secretion. Aldosterone increases sodium reabsorption, which results in extracellular volume expansion.
Therefore the mechanism increases BP, once achieved, results in a negative feedback to stop renin release
renal failure
kidneys fail to remove metabolic by-products from blood; and regulate fluid, electrolyte and pH balance of extracellular fluid
diagnostic tests for renal failure
measure GFR to determine kidney function through urine and blood tests (often creatinine)
high blood markers in renal failure
potassium, phosphate and BUN
low blood markers in renal failure
decrease pH, calcium, bicarbonate ions
acute renal injury
abrupt decline in glomerlar and tubular function, resulting in failure of kidneys to excrete N waste products and maintain fluid and electrolyte homeostasis
reversible if recognised early and treated appropriately
chronic kidney disease
irreparable damage to kidneys where 80% of nephrons are non-functioning before symptoms arise, developed slowly
pre-renal failure
marked decrease in blood flow and reversible. Manifested by sharp decrease in urine output and disproportionate elevation in BUN in relation to serum creatinine.
pre-renal causes
hypovolemia (hemorrhage, dehydration, excessive loss of GIT fluids and fluid due to burn injury)
Decreased vascular filling (anaphylactic shock, septic shock)
heart failure and cardiogenic shock
decreased renal perfusion due to sepsis, vasoactive mediators, drugs and diagnostic agents
intra-renal failure
conditions that cause damage within kidneys
major causes include renal ischemia, toxic insult to tubular structures, intratubular obstructions, acute gomerulonephritis and acute pyelonephritis
post-renal failure
obstruction of urine outflow in the ureter, bladder or urethra. Increase urine results in increased retrograde pressure through tubules and nephron causing damage.
commonly caused by prostatic hypoplasia
