Renal function Flashcards
The kidney has several key functions. This includes metbaolitc waste removal from the ???, such as ? and ?.
Controlling the volume of ECF and thereby controlling ?????.
Maintaining optimal concentrations of vital solutes - such as ???
The kidney has several key functions. This includes metbaolitc waste removal from the extracellular fluid, such as urea and acids.
Controlling the volume of ECF and thereby controlling blood pressure.
Maintaining optimal concentrations of vital solutes - such as Sodium, potassium, chloride, Hydrogen, Calcium, magnesium, Phosphorus.
Total body water can thought of as being split into 3 main compartments. They are ????. What are the percentage distributions of water in each of these 3 compartments?
- Intravascular space and interstitial space (which together can be thought of as the EXTRACELLULAR SPACE
- We also have the intracellular space
Different barries exist between these water compartments. Between the interstitial space and intracellular space, the barrier is the ???. Conversley, the barrier between the intersitial space and the vascular system is the ????.
Different barries exist between these water compartments. Between the interstitial space and intracellular space, the barrier is the cell wall. Conversley, the barrier between the intersitial space and the vascular system is the endothelium .
Osmotic pressue is the pressure required to prevent movement of solvents from an area of low concentration to an area of high concentration. An alternative way of looking at it is that osmotic pressure is an indication of the forece with which pure water moves ointo that solution as a result of it’s solute concentration.
Oncotic pressure is a type of osmotic pressure which is contributed by the large molecules, the “colloid osmotic pressure”.
This is 25-30mmHg, or about 0.5% of the total osmotic pressure. Its not much, but its enough to keep the water in the vascular compartment.
Oncotic pressure is therefore effectively the pressure exerted by proteins.
Osmolarity across the cell well is maintained by the ubiquiotous ????/???? ATPase, which pumps out ?? and takes in ???. This somwhat increases the ??? on the outside.
This is balanced by the oncotic pressure generated by the highly abundant ??? inside the cell
Both of these things ensure that water levels are in balance.
Osmolarity across the cell well is maintained by the ubiquiotous Na/K ATPase, which pumps out 3 sodium and takes in 2 potassium. This somwhat increases the osmotic pressure on the outside.
This is balanced by the oncotic pressure generated by the highly abundant proteins inside the cell.
Both of these things ensure that water levels are in balance.
In the vascular system and surrounding interstitium, there are two main forces at play. Plasma proteins generally exert a higher ????/????? pressure, which tends to drive to the ???. Convsersley, pressure from the blood flowing against the walls of the vascular system is called the ??? pressure.
In the vascular system and surrounding interstitium, there are two main forces at play. Plasma proteins generally exert a higher osmotic/oncotic pressure, which tends to drive to the vascular system. Convsersley, pressure from the blood flowing against the walls of the vascular system is called the hydrostatic pressure, and drives water to the interstitum.
Hydrostatic pressure is higher at what point of capillary? There is net movement of fluid to what compartment? This fluid will go to the ???.
Oncotic pressure is higher at what point of the capillary? There will be net movememnt of fluid to what compartment?
Hydrostatic pressure is higher at the arterial end of a capillary. There is net movement of fluid to the interstitium. This fluid will go to the Lymphatics.
Oncotic pressure is higher at the venous end of the capillary. There will be net movememnt of fluid to the vascular system (although recent research suggests that the oncotic pressure at the venous end is not as much as once thought, and infact most of the fluid in the interstitum ends up in the lympahtics.
The most abundant cation in ECF is ?
The most abundant cation in ICF is ?
The most abundant anion in ECF is ?
The most abundant anion in ICF is ?
The most abundant cation in ECF is Sodium
The most abundant cation in ICF is Potassium
The most abundant anion in ECF is Chloride
The most abundant anion in ICF is Proteins.
If we inected pure water into the blood, it would be very bad. Why?
- Water has no osmolarity, whilst the redblood cells have high osmolarity, meaning water would move into the red blood cells and cause them to burst,.
What factors is ECF compositiion and volume dependent on?
At any one time, how much of the cardiac output are the kidneys receiving?
20%
Let’s look at this balloon pish that he was talking about more closely - LOL JOKE READ THE BOOK YOU FUCK
The nephron has 3 basic function.
Name and describe them
Glomerular filtration - filtering of blood into the tubule forming the primitive urine (glomerular filtrate)
Tubular Reabsorption (selective reabsorption of substances from the tubule into the blood
Tubular Secretion (secretion of substances from the blood to the tubular fluid).
water will always distribute evenly across all compartments based on the osmolarity of the compartments, in order to make osmolality the SAME across all compartments.
G
The filtration functinon of the kidney depends on this key structure; the glomerular filtration barrier. It has 3 components, what are they?
Fenestrated Endothelial cells of the glomercular capillaries
Then the glomerular basement membrane (collagen type 4 based)
Then the podocytes with their foot processes. Between each of these feet like processes are protein structrus. The podocytes also have gaps between them called slits.
Glomerular filtration barrier acts like sieve. Study the size of particles that are allowed through
??? arterioles, upon entering the ???, split in a lace-like nerwirk of capillaries. Unlike the afferent arterioles, which are enclosed by ????, the capillary lace loops are only thin endothelium with no surrounding structure.
They then extend back out of the glomerulus, where they form ???? arterioles.The efferent arterroles folllow the tubules of the nephron closley, before forming a capillary loop called the ????.
Afferent arteries, upon entering the glomerulus, split in a lace-like nerwirk of capillaries. Unlike the afferent arterioles, which are enclosed by smooth muscle, the capillary lace loops are only thin endothelium with no surrounding structure.
They then extend back out of the glomerulus, where they form efferent arterioles. The efferent arterioles follow the tubules of the nephron closley, before forming a capullary loop called the vasa recta. These vasa recta drain back into the renal circulation via the renal vein.
Since small charged particles flow freely across the glomerulus, the concentration of small particles within the first part of the tubules mirrors that of serum. Thus, if 180 L is delivered to the tubules daily, with a concentration of sodium that is the same as serum (say 140 meq/L), approximately 25,000 meq of sodium reaches the tubule daily. There are also about 18,000 mmol of chloride, 4,500 mmol of bicarbonate, 900 mmol of glucose, and 720 mmol of potas-sium. Reclaiming all this solute is indeed a challenge!
There is no hydrostatic gradient to drive solute reclamation, i.e., movement of molecules from tubule to the renal interstitium, this is all happening in capillaries which is very low pressure.
An Absolute cruical transporter is the Na/K ATPase - the workhorse of the tubule. Na/K ATPase exchanges three positive sodium ions for two positive potassium ions. The movement of three Na+ ions out of the cell in exchange for two K+ ions leads to a negative voltage inside of the cell relative to the outside and causes the cell to have a potassium concentration in the range of 150 meq/L and a sodium concentration in the range of 10 30 meq/L. By contrast, the extracellular fluid has a potassium concentration of 4 meq/L and a sodium concentration of 140 meq/L. Meaning we also have a clear concentration gradinet.
The placement of transporters within the apical membrane allows na+ to flow from the tubule into the cell, down its electrochemical gradient. the movement of many anions is coupled to the movement of sodium - one example of this is Chloride, although in reality it can be any anion.
Because sodium is moving, this will create an osmotic gradient, and water will move as well from the lumen into the well.
In Summary, the ATPase has a critical role in the absorption of sodium, anions (mainly chloride) and water, and basically underpins absorption of essentiall everything in the nephron.
Another important pump found more around the collecting duct has a key role in regulating acid and potassium secretion, again under the control of the sodium/potassium ATPase.
- As before, we have our grand master Sodium/potassium pump generating an negative ??? gradient
- This is balanced out by the???? (epithelial sodium channel), leaving a negative electric gradient
- To correct this, we get movement of ????? and/or ?????? ions (obviously which one depends on whats happening in the body, what hormones are at play)
Another important pump found more around the collecting duct has a key role in regulating acid and potassium secretion, again under the control of the sodium/potassium ATPase.
- As before, we have our grand master Sodium/potassium pump generating an negative electrochemical gradient
- This is balanced out by the ENaC (epithelial sodium channel), leaving a negative electric gradient
- To correct this, we get movement of Potassium and/or Hydrogen ions (obviously which one depends on whats happening in the body, what hormones are at play)
Yet another key channel is one that can be found in the thick ascending loop of henle. This is called the ????? channel. The filtrate travelling up the ascending limb has a very high concentration of ?? and ??. with relatively less ???. The Na/K ATPase creates the electrial gradient inside the cell, permiting movement of Sodium, 2 Chlorides and a potassium in the cell via the ?? channel. By moving two cations along with two anions, this cotrans-porter moves particles in an electrostatically neutral manner. ??? subsequently exits via the apical side back into the tubule down a concentration gradient (effectively recycling it), while the ?? exits by the basolateral side. slight backleak of potassium ions into the lumen, creates a positive charge of about +8 millivolts in the tubular lumen. This positive charge forces cations such as ??? and ??? to diffuse from the tubular lumen through the paracellular space and into the interstitial fluid.
Yet another key channel is one that can be found in the thick ascending loop of henle. This is called the NK2CL channel. The filtrate travelling up the ascending limb has a very high concentration of sodium and chloride. with relatively less potassium. The Na/K ATPase creates the electrial gradient inside the cell, permiting movement of Sodium, 2 Chlorides and a potassium in the cell via the NK2Cl channel. By moving two cations along with two anions, this cotrans-porter moves particles in an electrostatically neutral manner. Potassium subsequently exits via the apical side back into the tubule down a concentration gradient (effectively recycling it), while the chloride exits by the basolateral side. The slight backleak of potassium ions into the lumen, creates a positive charge of about +8 millivolts in the tubular lumen. This positive charge forces cations such as calcium and magnesium to diffuse from the tubular lumen through the paracellular space and into the interstitial fluid.
