The Nephron from lecture 2 Flashcards
Countercurrent Exchange is one of the most important physiological phenomena in all of nature. (Among other things) It allows ________________ of substances.
hyperconcentration
__________________ is a pair of adjacent channels or tubes containing fluids flowing in opposite directions and having an energetic gradient directed between one channel and the other. (In other words, stuff can flow between the tubes.)
1) COUNTERCURRENT EXCHANGE 2) fluids flowing in opposite directions
this is what a nephron looks like
The arrangement of tubes in ____________________ means that even as the tube starts with lower concentration and picks up solutes, even when it get to the end it can still pickup a bit, as it is encountering the highest concentration of adjacent tube.
OPPOSITE FLOW DIRECTIONS
A COUNTERCURRENT EXCHANGE SYSTEM can only work if there is an __________ in the system.
In this case, there is ___________ in only one direction. In the case of the kidney, salts are being transported to concentrate salts in the ________.
1) asymmetry
2) active transport
3) urine
Helpful to know
Proximal Convoluted Tubule:
Initiate concentration of ___________ filtrate.
About ___ of _________ removed by active transport here, and chlorine follows passively.
Remaining fluid in _________ tube is about same concentration as that of surrounding interstitial fluid.
Remaining fluid reduce to about _____ original volume
1) glomerular
2) 75% of sodium
3) nephron
4) 25%
Loop of Henle:
Acts in manner of counter current exchanger. Note that each limb of loop has fluid moving in ________________ (even though connected at one end).
Further concentrates ________.
Also means that salt concentration will be highest near bend in the loop.
1) opposite directions
2) urine
No active transport of salt out of the____________________.
Chlorine ions actively transported out of loop into the interstitial space. Oppositely charged sodium ions follow. However, water does not move out of the ________.
A concentration gradient IN THE INTERSTITIAL SPACE has been set up by the chlorine ( plus sodium) transport.
1) descending loop of Henle
2) ascending loop
Distal Convoluted Tubule:
In addition to sodium-chloride, potassium, __________, and ____________ removed from filtrate here. These are retained as needed by the body.
At this point, nephron has used materials IN the glomerular filtrate to set up a concentration gradient in the _______________________
1) ammonia
2) carbonate
3) interstitial space of the kidney
Collecting Duct:
Receives many_______________________.
Collecting duct now passes through the concentration gradient set up by many _________________.
So, as glomerular filtrate passes down collecting tubule, it moves through ___________________ concentration of salts that were set up by loops of Henle.
1) proximal convoluted tubules
2) adjacent nephrons
3) higher and higher
By process of osmosis, water wants to move from region of_________________. This pulls water from filtrate, leaving behind a more concentrated “________”.
1) higher water concentration to lower
2) urine
REMEMBER
By setting up a countercurrent system, a salt concentration gradient is set up in the interstitial space (highest concentration near curve of loop of Henle).
——–>
As fluid in collecting tubules reacts to concentration gradient, water is pulled out, concentrating filtrate as urine.
CORTEX – part that contains the convoluted tubules and _____________, and _________________.
1) proximal part of Loop of Henle
2) proximal part of collecting tubules
MEDULLA – contains _______________, and ________________. Where most of the active transport takes place.
1) distal part of Loop of Henle
2) distal part of collecting tubules
In regards to urine production, the most important hormone is _______________
ANTIDIURETIC HORMONE, or ADH.
ADH makes the collecting duct MORE ___________ to water. Thus, secretion of ADH causes the retention of water in the body, and more _____________. (ADH is usually secreted in response to environmental situations that require the retention of water.)
1) permeable
2) concentrated urine
A diuretic will decreases permiability of ____________, so you lose lots of water (copious, dilute urine). Examples of diuretics: caffiene, alcohol (beer particularly due to the hops), capsasin (the active ingredient in hot peppers), others.
collecting tubule
The blood enters the nephron thru the ______________ and exits thru the __________________
1) afferent arteriole
2) efferent arteriole
_____________ is the major way of how things gets into the nephron from the blood
Filtration
Reabsorbtion is the movement of things back into the ____________________
blood from the nephron
the movement of stuff from the blood to the nephron is called _____________
secretion
The nephron is the tiny filtering structure in your kidneys. Each of your kidneys contain more than a __________ tiny filtering nephrons that help clean your blood.
million
Function of the Nephrons
Remove excess water,wastes and other substances from __________.
Return substances like sodium, ___________ or ___________ whenever any of these substances run low in your body.
1) your blood
2) potassium or phosphorus
The glomerulus is a tiny blood vessel or capillary, which looks like a ball of yarn. Actual ____________of your blood occurs in the glomerulus. A glomerulus is enclosed in the sac.
filtering
Bowman’s capsule is a cup-like sac at the beginning of the tubular component of a nephron in the mammalian kidney that performs the first step in the filtration of blood to ____________.
form urine
Functions of Proximal convoluted tubule
It reabsorbs all of the ________, and amino acids
glucose is reabsorbed via Na-Glu cotransporter
It also reabsorbs a fraction of the bicarbonate, potassium, phosphate and calcium
It secretes ammonia, which functions as a buffer for secreted H+. It also secretes creatine, which is used to access the function of the kidney.
After filtrats leave the PCT it enters ______________. This is a u-shaped structure tube and it contains different segments which perform different functions.
1) glucose
2) the loop of Henle
Ascending Loop
In this part of the loop, _______________ is actively reabsorbed
It is impermeable to H2O
this segment makes the urine ________ concentrated
The Loop of Henle reabsorbs 10-20% sodium and chloride and 10% of the filtered water.
1) Na, K and Cl
2) less
Thin Descending Loop (TDL)
reabsorbs __________ passively
it is impermeable to _____________
it allows the urine to be concentrated, the urine in the TDL is hypertonic
1) water(H2O)
2) sodium(Na)
Distal Convoluted Tubule
this segment of the renal tubule is lined with _____________ and has no brush border
is actively reabsorbs _______________
it is relatively impermeable to water, but in the present of ______________ its permeability to water increases making urine concentrated.
it secretes ammonium ions and hydrogen ions.
forms part of the_____________
1) simple cuboidal epithelium
2) sodium and chloride
3) antidiuretic hormone (ADH)
4) juxtaglomerular apparatus
Collecting Ducts
runs through the cortex into the medulla and opens into the renal papilla. Its epithelium varies from ______________ (near the papilla). It is the final segment of the ___________
1) cuboidal to columnar epithelium
2) renal tubule.
Collecting duct has two types of cells:
(1) Principal cells
- Reabsorbs sodium and water
- secretes ____________
These functions are regulated by ADH and aldosterone. Aldosterone increases sodium _____________ and increases potassium ____________ . ADH on the other hand enhances (يعزز ) water reabsorption. Therefore one can say that when ADH is increase water in the tubule is reabsorbed casuing a low volume concentrated unrine. Decrease ADH will result in a diluted high volume urnine.
(2) Intercalated cells
- secretes ___________
- reabsorbs ___ by a H+,K+-ATPase
1) potassium
2) reabsorption
3) secretion
4) hydrogen ions
5) K
