The Nephron from lecture 2

Question 1

Countercurrent Exchange is one of the most important physiological phenomena in all of nature. (Among other things) It allows ________________ of substances.

Answer 1

hyperconcentration

Question 2

__________________ 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.)

Answer 2

1) COUNTERCURRENT EXCHANGE 2) fluids flowing in opposite directions

Question 3

this is what a nephron looks like

Answer 3

Question 4

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.

Answer 4

OPPOSITE FLOW DIRECTIONS

Question 5

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 ________.

Answer 5

1) asymmetry
2) active transport
3) urine

Question 6

Helpful to know

Answer 6

Question 7

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

Answer 7

1) glomerular
2) 75% of sodium
3) nephron
4) 25%

Question 8

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.

Answer 8

1) opposite directions
2) urine

Question 9

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.

Answer 9

1) descending loop of Henle
2) ascending loop

Question 10

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 _______________________

Answer 10

1) ammonia
2) carbonate
3) interstitial space of the kidney

Question 11

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.

Answer 11

1) proximal convoluted tubules
2) adjacent nephrons
3) higher and higher

Question 12

By process of osmosis, water wants to move from region of_________________. This pulls water from filtrate, leaving behind a more concentrated “________”.

Answer 12

1) higher water concentration to lower
2) urine

Question 13

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).

——–>

Answer 13

As fluid in collecting tubules reacts to concentration gradient, water is pulled out, concentrating filtrate as urine.

Question 14

CORTEX – part that contains the convoluted tubules and _____________, and _________________.

Answer 14

1) proximal part of Loop of Henle
2) proximal part of collecting tubules

Question 15

MEDULLA – contains _______________, and ________________. Where most of the active transport takes place.

Answer 15

1) distal part of Loop of Henle
2) distal part of collecting tubules

Question 16

In regards to urine production, the most important hormone is _______________

Answer 16

ANTIDIURETIC HORMONE, or ADH.

Question 17

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.)

Answer 17

1) permeable
2) concentrated urine

Question 18

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.

Answer 18

collecting tubule

Question 19

The blood enters the nephron thru the ______________ and exits thru the __________________

Answer 19

1) afferent arteriole
2) efferent arteriole

Question 20

_____________ is the major way of how things gets into the nephron from the blood

Answer 20

Filtration

Question 21

Reabsorbtion is the movement of things back into the ____________________

Answer 21

blood from the nephron

Question 22

the movement of stuff from the blood to the nephron is called _____________

Answer 22

secretion

Question 23

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.

Answer 23

million

Question 24

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.

Answer 24

1) your blood
2) potassium or phosphorus

Question 25

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.

Answer 25

filtering

Question 26

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 ____________.

Answer 26

form urine

Question 27

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.

Answer 27

1) glucose
2) the loop of Henle

Question 28

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.

Answer 28

1) Na, K and Cl
2) less

Question 29

Thin Descending Loop (TDL)

reabsorbs __________ passively

it is impermeable to _____________

it allows the urine to be concentrated, the urine in the TDL is hypertonic

Answer 29

1) water(H2O)
2) sodium(Na)

Question 30

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_____________

Answer 30

1) simple cuboidal epithelium
2) sodium and chloride
3) antidiuretic hormone (ADH)
4) juxtaglomerular apparatus

Question 31

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 ___________

Answer 31

1) cuboidal to columnar epithelium
2) renal tubule.

Question 32

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

Answer 32

1) potassium
2) reabsorption
3) secretion
4) hydrogen ions
5) K