Renal Physiology (Don's Class) Flashcards
Body can drop _____ % GFR before serious problems.
20%
Production of _____ begins with ______ and ______ filtration from the plasma flowing into the glomerulus via the _______ arteriole.
-urine
-water and solute
-afferent
Role of the Glomerulus is to form an _______ of _________.
ultra filtrate of plasma
It is the ______ _______ of the _______ arteriole which plays a large role in the flow through the glomerulus.
muscle tone
afferent
Basement membrane is _______ charged due to ___________ which compose it.
negatively
glycoproteins
-Negatively charged proteins are thus repelled and are unable to pass through it.
The basement membrane effectively prevents filtration of _______ _______, in part because of strong ________ electrical charges associated with the proteoglycans.
plasma proteins
negative
GFR is defined as total volume per unit time (ml/min) which leaves the ________ and enters __________ ________.
capillaries
Bowmans space
The two major determinants of filtration pressure are ________ _______ _______ and _____ ______ ______.
glomerular capillary pressure (PGC)
glomerular oncotic pressure (pgc).
GFR is around ____ml/min which is around _____ L/day
120 ml/min
180 L/day
Glomerular capillary pressure is directly related to __________ and is heavily influenced by _____ _____ at points upstream (______) and downstream(_________) from the glomerulus
-renal artery pressure
-arteriol tone
-afferent
-efferent
Renal blood flow is around ____% of cardiac output. (_______ml/min)
20%
1200
4 factors that determine GFR.
- Ultrafiltration coefficient
- Oncotic Pressure
- Capillary Pressure
- Plama Flow Rate
Capillary plasma flow rate: Higher flow =
greater filtration
How does the body get back filtered plasma?
As the plasma moves towards the end of the glomerular capillary, filtration ________ because of an increase in _______ _______ (as fluid is removed the protein concentration ________)
-slows
-oncotic pressure
-increases
This term reflects the kidney’s ability to regulate GFR over a range of conditions
Autoregulation
The ______ ______is a specialized group of epithelial cells in the ________ tubules that comes in close contact with the afferent and efferent arterioles
-macula densa
-distal
The macula densa cells contain ________ ________, which are intracellular secretory organelles directed toward the arterioles, suggesting that these cells may be secreting a substance toward the arterioles.
Golgi Apparatus
Decrease in sodium chloride concentration initiates a signal from the macula densa that has two effects:
(1) It decreases resistance to blood flow in the afferent arterioles, which raises glomerular hydrostatic pressure and helps return GFR toward normal.
(2) It increases renin release from the juxtaglomerular cells of the afferent and efferent arterioles, which are the major storage sites for renin.
Tubular __________ is quantitatively more important than tubular _________in the formation of _____, but _________plays an important role in determining the amounts of _______ and _______ ions and a few other substances that are excreted in the urine.
-reabsorption
-secretion
-urine
-secretion
-potassium
-hydrogen
Defined as the volume of plasma from which all of a given substance is removed per unit time in one pass through the kidney.
Renal Clearance
If a substance is neither secreted nor reabsorbed, then its clearance is ______to GFR (e.g., ______)
-equal
ex. insulin
If a substance is completely reabsorbed, then clearance is ______(e.g., _______ under normal cond.)
-zero
-ex. glucose
If Cx > GFR there must be net ______.
secretion
If Cx < GFR there must be net _______.
reabsorption
If Cx = GFR there is neither…..
net reabsorbtion or net secretion
Normal Renal Function and GFR
100% functioning nephrons
GFR 125 ml/min
Reduced Renal function and GFR
10-40% functioning nephrons
GFR 12-80 ml/min
Renal Failure , function and GFR
<10 % functioning nephrons
GFR <12 ml/min
3 mechanisms of Reabsorption and Secretion
- Active Transport - uses energy
- Passive Transport -2 kinds
-Simple: basically diffusion of lipid soluble
agents or gasses
-Facilitated: uses a protein channel or carrier - Secondary Active Transport- moves solute against a concentration gradient coupled to movement of another solute, uses energy indirectly.
Where does Pinocytosis occur?
Proximal Convoluted Tubule
Parts of the tubule, especially the ________ tubule, reabsorb ______ molecules such as ______ by ________.
-proximal
-large
-proteins
-pinocytosis
PCT reabsorbs ___% of glomerular filtrate and returns it to _______ capillaries.
65%
-peritubular
_______ _______ reabsorbs another 25% of filtrate
Nephron Loop
DCT reabsorbs ___ , _____and ____ under hormonal control, especially, ______ and _____.
-Sodium, chloride and water
-Aldosterone and ANP
DCT completes the process of determining the chemical composition of _______.
urine
The Nephron and its Regions:
Proximal Tubule
Loop of Henle
Distal Convoluted Tubule
Collecting Ducts
_____% of filtrate is reabsorbed in the PCT
70%
PCT ____ Reabsorption
Active Reabsorption
-nutrients (glucose and amino acids)
-Ions (K+, Na+, Cl-)
-Small plasma proteins
-some urea and uric acid
Where does carbonic anhydrase work?
PCT!
The ____ tubule functions as the main re-absorptive area of the nephron
PCT
ALL REABSORBTION IN THE PROXIMAL TUBULE IS ___________.
ISO-OSMOTIC
Only region of the nephron where carbonic anhydrase is present on the luminal membrane
PCT
Reabsorption in the PCT: 2/3 of filtered ____ and _____ reabsorbed (mostly thru active transport of Na at the_______ membrane
-Na and Water
-basolateral
Preferential site of HCO3- reabsorption (using carbonic anhydrase)
PCT
Vitamin and K reabsorption also take place here
PCT
PCT (secretion): Site of ________ secretion which is important in acid base function.
Ammonia
The 3 functional distinct segments of the Loop of Henle:
- The Descending THIN segment
- The Ascending THIN segment
- The THICK Ascending segment (most important)
What is the most important segment in the Loop of Henle?
THICK ASCENDING
-Highly permeable to water and moderately permeable to most solutes
-The function of this segment is to allow simple diffusion of substances through its walls
-Twenty percent of filtered water is reabsorbed in this segment
The Descending Thin Segment
-Virtually impermeable to diffusion of water
-Some re-absorptive capacity for ions such as calcium, bicarbonate, and magnesium
The Ascending Thin Segment
Diluting segment portion of the nephron:
-Thick Ascending Limb (TAL)
MOST IMPORTANT
The key feature of the TAL is that it is ______ ___ ______ while solute is pumped out of the tubular fluid.
impermeable to water
The luminal membrane has 1___, 1____, 2_____ transporter pump.
Na+, K+, Cl
This is the target site of Lasix and the only nephron segment where Cl is actively transported).
Thick Ascending Limb
Unique apical Na+ transport Na-K-2Cl symport
Thick Ascending Limb
Na-K-2Cl symporter is a target of a very common ________.
-loop diuretic (furosemide = lasix)
The intraluminal charge is positive in the TAL, this drives reabsorbtion of _____ and ______
Mg++ and Ca++
Distal Tubule & Cortical Collecting Tubule is…..
Virtually impermeable to water
The first portion of the distal tubule forms part of the juxtaglomerular complex to provide feedback control of GFR and blood flow in the same nephron
Macula Densa
Control the degree of dilution or concentration of urine. Absence of ADH – tubular cells virtually impermeable to water
Later Distal Tubule
Reabsorption of sodium and secretion of potassium – the rate which is controlled by _______.
Aldosterone
2 types of cells that regulate Hydrogen and Potassium
Principal Cells and Intercalated Cells
_________:which reabsorbed sodium and water from the lumen and secrete potassium into the lumen
Principal Cells
_______:reabsorb bicarbonate and potassium ions and secrete hydrogen into the lumen (important for acid-base regregulation by the kidneys)
Intercalated cells
Final site for processing the urine
Reabsorbs less than 10 percent of the filtered water and sodium
Medullary Collecting Duct
___________is capable of secreting ________ ions against a large concentration gradient which is important for regulating ___-____ _____.
-Collecting Duct
-hydrogen
-acid – base balance
Permeability to water is controlled by the level of ADH
Medullary Collecting Duct (location)
2 Mechanisms of Autoregulation
-Constriction and Dilation of pre capillary sphincters in the afferent and efferent arterioles
-Increased Na delivery to macula dense will decrease GFR via adenosine induced vasoconstriction of the afferent arteriole
-Increased Na delivery to _______ _______ will decrease GFR via ________ induced ________ of the afferent arteriole
-macula densa
-adenosine
-vasoconstriction
