Lecture 3 - Renal concentrating mechanisms and urine formation II Flashcards
The Renin Angiotensin System is stimulated by:
- Decrease in B/P
- Decrease in Fluid Volume
- B1 Sympathetic
The Renin Angiotension System is inhibited by:
- Increase in B/P
- Increase in Fluid Volume
- Decrease in B1 Sympathetic ANP
T/F: The juxtaglomerular apparatus is the site of renin synthesis.
TRUE
What four components is the juxtaglomerular apparatus comprised of:
- Smooth muscle cells in afferent arteriole
- Smooth muscle cells in the efferent arteriole
- Extraglomerular mesangial cells
- Macula Densa cells in the distal tubule
The mongioceles are responsible for production of ____________.
prostaglandins
Renin causes _____________ to be cleaved to angiotensin I.
-angiotensinogen
Angiotension I converted to angiotensin __ in the ____ by angiotensin converting enzyme.
- II
- lung
T/F: Angiotensin is the second most potent vasoconstrictor known.
FALSE (It is the most potent)
What are the actions of angiotension II:
- Vasoconstriction
- Increase B/P
- Increase aldosterone synthesis and release
- Increase ADH
- Increase thirst
- Feedback inhibition of renin release
What hormone is produced to keep the afferent and efferent arterioles open when Angiotension is trying to close them:
Prostaglandins
T/F: Aldosterone is syntesized in the the zona glomerulosa of the adrenal cortex.
TRUE
What stimulates the synthesis and release of aldosterone:
- Increased K in the ECF
- Angiotensin II
- Dereased Na levels
Aldosterone acts on _______ tubule and ______ ducts to cause _____ secretion and also ____ in exchange for ____.
- Distal
- Collecting
- Potassium
- Hydrogen
- Sodium
Electrolytes lost by aldosterone is:
Potassium (K+)
Hydrogen (H+)
Conn’s syndrome is:
Tumor producing to much aldosterone leading to hypertension, hypernatremia, and hypokalemis.
What are the four concentrating and diluting mechanism of:
- Antidiuretc hormone (ADH)
- Atrial natriuretic peptide (ANP)
- Countercurrrent multiplier
- Role of urea
What is the maximal urine concentration of the human kidney:
1200 - 1400 mOsm/L
What is the obligatory urine volume of a 70 kg human in one day?
0.5 liters/day
Where is ADH synthesized at withing the human body:
Hypothalamus
Where is ADH stored and release:
Posterior pituitary
What cells in the hypothalamus respond to ECF osmolality:
- Osmoreeptors
T/F: An increase in osmolality will cause an decrease in the release of ADH.
FALSE
___________ in the atria and aorta will detect decreases in volume and stimulate ADH release.
-Mechanoreceptors
What stimuli will cause a increase ADH release:
- Angiotensin II
- Fright
- Nausea,
- Pain
- anesthesia
- Nicotine
- Cyclophosphamide
What inhibits the release of ADH:
- Alcohol
- Clonidine (antihypertensive drug)
- Haloperidol (dopamine blocker)
What will ADH do in the collecting ducts of the kidney:
-Increase the permeability to allow water through
T/F: ADH also increases urea permeability in the medullary collecting ducts.
TRUE
In order for ADH to work there must be a ______ force to move water out of the tubules into the interstiu. (Means you must have a __________ interstitium.
- driving
- hypertonic
T/F: the Countercurrent multiplier is crucial in the ability of the kidney to concentrate urine
TRUE
What makes the Countercurrent multiplier so effective in urine concentration:
-U shape of the loop of Henle (Gives the countercurrent its name)
-Different permeability of certain nephton segments
-
What type of energy is used for the Countercurrent:
-ATP (Na/K ATPase)
What is the anatomy the makes the medullary countercurrent mutliplier system work:
- Juxta-medullary nephrons with long loops of Henle & vasa recta peritubular capillaries reach into medulla
- Special anatomical arrangement of Juxta medullary nephrons and collecting ducts critical for countercurrent mechanism
- Anatomical relationshop allow the creation of a hyperosmotic gradient in renal medulla interstitium
T/F: Urea is a byproduct of amino acid metabolism consisting of 2 ammonia molecules.
True
Approximately ________ grams/day of urea is made in the liver.
25 - 30
What is the role of urea?
- medullary interstitium has a high concentration of urea
- This plays an important role in generating a hypertonic interstitium
T/F: The TAL is impermeable to water and urea.
TRUE
How does the medullary interstitium generate such a high urea concentration?
PHASE 1: When ADH is present water is reabsorbed into the cortex and outer medulla
PHASE 2: The The tubular contents thus become more concentrated and a high concentration of urea reaches the inner medulla
PHASE 3: The inner medulla is permeable to urea ONLY in the presence of ADH and urea diffuses into the interstitum and becomes trapped there.
T/F: The THIN ascending limb is urea permeable so some diffuses into the tubule and is recycled.
TRUE
T/F: urea contributes to 80% of osmolarity of renal medulla gradient during max urine concentration.
FALSE (Urea contributes to 40% ….)
T/F: Urea actively passes from medullar collecting duct ruing water deficits when ADH is present.
FALSE (Urea passibely diffuses from medullar..)
T/F: Urea is recirculated from medulla interstitium into loop of Henle and returned to tubular fluid.
TRUE
What is the role of the Vasa Recta:
- Remove reabsorbed fluid from the interstitium
- Minimize solute uptake from the medulla (Maintain medullary hypertonicity)
How much blood does the medullary get in the kidney?
1 - 2 %
What good is the sluggish blood flow in the medullary.
minimizes solute loss
T/F: In the descending Vasa Recta fluid leaves the Vasa Recta because of the rapid flow more fluid leaves than solute enters.
TRUE
T/F: In the ascending Vasa Recta fluid leaves the Vasa Recta because of the rapid flow more fluid leaves than solute enters.
FALSE (The ascending Vasa Recta the situation reveerses because of decreasing hydrostatic pressure and increasing osmolality of blood)
