Renal System Flashcards
Name 3 countercurrent systems in the body.
1) loop of Henle (nephron)
2) vasa recta (capillaries of nephron)
3) blood flow to the testes through spermatic artery and veins
What is a countercurrent system?
Inflow runs parallel to outflow for some distance; “u-shaped” tube
What is the difference in a countercurrent exchange and a countercurrent multiplier system? Which one of these does the kidney use?
Answer
What is the function of the countercurrent systems in the kidney?
Answer
What blood vessels supply the loop of Henle?
Vasa recta
The _______ regulate the volume and composition of extracellular fluid.
kidneys
The _______ is the functional unit of the kidney.
nephron
Metabolic end products are excreted by ________.
filtration; filtered into and trapped within the renal tubule
Concentration = __________
volume (in water)
Osmolality is another term for ________.
Na+ concentration
Sodium Salts are _____% of the total osmolality of the ECF.
90%
________ regulates Na+.
aldosterone
What is the normal range for osmolality?
300 mOsm/kg (range 270-310)
The kidneys maintain ECF volume by controlling _____ and ______ excretion.
salt (NaCl) and water
What are the 3 primary endocrine roles of the kidney?
1) erythropoietin–> acts on bone marrow to stimulate RBC production; chronic renal pt’s may be anemic d\t low production of erythropoietin
2) RAS—> enzyme hormone system to regulate BP, K+ excretion, and Na+ reabsorption
3) vitamin D—> starts in the skin—> liver (picks up hydroxyl group—> kidneys (picks up another hydroxyl group)—> D3 (active form)
* chronic renal pt’s may be hypocalcemic b\c vit D helps in the absorption of calcium from the intestine
Na+ concentration is another term for _______.
osmolality
Blood is delivered to the glomerulus via the _______ arteriole and exits the glomerulus via the ______ arteriole.
afferent; efferent
Kidneys get approx ______ % of cardiac output.
25% or 1.25L (based on 5L/min CO)
The kidneys rework the ECF about once every ______, thereby maintaining its composition and volume.
once every 2 hours
*dialysis machines are only capable of reworking the ECF of anephric (kidney free) pt’s once every 8-12 hours
What are the components of the renal tubule?
1) Bowman’s capsule (encapsulates the glomerulus)
2) proximal tubule
3) loop of Henle
4) distal tubule
5) collecting duct
The loop of Henle adjusts concentration of ______ and ______.
Na+ and H2O
What occurs in the descending LOH?
osmosis–> H2O reabsorbed and Na+ left behind–> becomes concentrated
What occurs in the ascending LOH?
Na+ reabsorbed and H2O stays behind
Aldosterone effects the ______ of the renal tubule, and ADH effects the _______ of the renal tubule.
aldosterone=distal tubule=Na+
ADH=collecting duct=H2O
What are the 4 primary functions of the kidney?
1) filter
2) reabsorb
3) secrete
4) excrete
Where does 2/3rds of the reabsorption of H2O, Na+, etc… take place?
proximal tubule
Where does secretion in the renal tubule take place?
proximal tubule (muscle relaxants, etc)
Where do loop diuretics work?
THICH ASCENDING LIMB (TAL) of the LOH
*inhibit the body’s ability to reabsorb Na+–> H2O follows Na+
What diuretics work on the distal tubule?
thiazide-type diuretics–> HCTZ
- inhibit Na+ chloride symporter–> retention of water in the urine, as water normally follows penetrating solutes
- The long-term anti-hypertensive action is based on the fact that thiazides decrease preload, decreasing blood pressure. On the other hand the short-term effect is due to an unknown vasodilator effect that decreases blood pressure by decreasing resistance.
What happens in the distal tubule?
“reabsorption”–> partly responsible for the regulation of potassium, sodium, calcium, and pH
- primary site for the kidneys’ hormone based regulation of calcium (Ca)
- cells of the DCT have a thiazide-sensitive Na-Cl cotransporter and are permeable to Ca, via the TRPV5 channel
- participates in calcium regulation by reabsorbing Ca2+ in response to parathyroid hormone.
- regulates pH by absorbing bicarbonate and secreting protons (H+) into the filtrate, or by absorbing protons and secreting bicarbonate into the filtrate.
What regulates Na+ absorption in the distal tubule?
Sodium absorption by the distal tubule is mediated by the hormone aldosterone.
*Aldosterone increases sodium reabsorption
What are the two types of nephrons?
1) cortical nephrons–> short LOH and glomeruli located near surface of kidney
2) juxtamedullary nephrons–> long LOH and glomeruli located deep in the cortex near cortical medullary junction
Describe the blood flow through the kidney.
afferent arterioles–> glomerular capillaries–> efferent arterioles–> peritubular capillaries–> drains into venous system
*peritubular capillaries–> rise from the efferent arteriole and engulf the renal tubule; the VASA RECTA are the peritubular capillaries of the LOOP OF HENLE of the JUXTAMEDULLARY NEPHRONS (nephrons with glomeruli adjacent to the medulla)
from the tubule to the capillary = _________
reabsorption
from the capillary to the tubule= _________
secretion
_______, _________, and __________ are found in the cortex. ______ and _______ are found in the medulla.
glomeruli, proximal tubules, and distal tubules= cortex
LOH and collecting ducts= medulla
The ______ of the outer medulla is MOST vulnerable to ischemia.
inner stripe
Name the segment of the renal tubule:
makes final adjustments on urine pH, osmolality, and ionic composition
distal tubule and collecting duct
Name the segment of the renal tubule:
reabsorbs the bulk of the filtered fluid and its dissolved constituents; coarse control mechanisms for the renal regulation of ECF and composition.
proximal tubule
Name the segment of the renal tubule:
establishes and maintains an osmotic gradient in the medulla; plays a critically important role in the regulation of water balance; handling of NaCl and water occur independently
loop of henle
The loop of henle is a __________ system.
countercurrent multiplier
A countercurrent multiplier ______ the osmotic gradient.
CREATES; LOH
A countercurrent exchange _______ the osmotic gradient.
maintains; vasa recta
The TAL of the loop of henle is impermeable to ______.
water
*has a high concentration of Na+ transporters
The deposition of Na+ in the TAL of the LOH into the medullary interstitium creates osmolality of 600 mOsm. Where does the additional 600 mOsm come from when the osmolality increases to 1200 mOsm when it reaches the tip of the medullary pyramid?
from urea
Name the end products of metabolism that are normally excreted by the kidneys.
urea, uric acid, creatinine, PO4, SO4
The reabsorption of water is under the control of ______ hormone.
ADH
The reabsorption of Na and the secretion of K+ are under the control of _________ hormone.
aldosterone
What are two BP meds that have diuretic effects?
While not classically considered potassium-sparing diuretics, ACE inhibitors (ACEi) and angiotensin receptor blockers (ARB) are anti-hypertensive drugs with diuretic effects that decrease renal excretion of potassium
Aldosterone antagonists, like ____________, help diuresis and spare _________.
spironolactone; K+
What section of the renal tubule is responsible for glucose reabsorption?
the proximal tubule–> all other sections are impermeable to glucose—> uncontrolled diabetics have glucose in the urine because they have exceeded the transport maximum for glucose in the proximal tubule
Why do untreated diabetics produce more urine?
excess glucose causes the proximal tubule to reach its transport maximum of glucose–> glucose is then trapped in the tubules causing osmotic diuresis