Nephron Parts and Reabsorption

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Questions and Answers

What is being reabsorbed in the proximal convoluted tubule?

Water and ions

Glucose, amino acids, and sodium (correct)

Potassium and chlorine

Salts and calcium

What is unique about the proximal tubule?

It is the longest part of the nephron

It is the narrowest part of the nephron

It has a thick basement membrane

It has a brush border (correct)

What is the direction of the glomerular filtrate flow in the nephron?

Through the nephron in a circular motion

From the border of the tubule to the lumen

In the opposite direction of blood flow

From the lumen to the border of the tubule (correct)

What is the main function of the nephron?

To filter waste from the blood Signup and view all the answers

What is the term for the process of pumping ions against their concentration gradients?

Active transport Signup and view all the answers

What is the purpose of the ascending part of the loop of Henle?

To reabsorb salts, such as sodium, potassium, and chlorine Signup and view all the answers

What is the term for the inner space of the nephron?

Lumen Signup and view all the answers

What makes up the border of the tubule?

A bunch of cells Signup and view all the answers

What is the purpose of the sodium-potassium pumps on the basolateral side of the cells?

To pump sodium out of the cell and potassium into the cell Signup and view all the answers

What is the term for the side of the cells facing the lumen?

Apical side Signup and view all the answers

What is the function of the peritubular capillaries?

To surround the tubules and facilitate transportation of substances Signup and view all the answers

What is the result of the sodium-potassium pump process?

Sodium is pumped out of the cell and potassium is pumped in Signup and view all the answers

What type of transport is occurring in the sodium-potassium pump process?

Active transport Signup and view all the answers

What is the term for the membrane that separates the basal and apical sides of the cell?

Basolateral membrane Signup and view all the answers

What is the purpose of ATP in the sodium-potassium pump process?

To change the conformation of the protein Signup and view all the answers

What is the shape of the tubules in the nephron?

Cylindrical Signup and view all the answers

What is the term for the process of transporting substances out of the lumen and into the peritubular capillaries?

Reabsorption Signup and view all the answers

What is the meaning of the prefix 'peri' in the term 'peritubular capillaries'?

Around Signup and view all the answers

What is the primary function of the sodium-potassium ATPase?

To break ATP and pump sodium out and potassium in Signup and view all the answers

What is the term for a protein that transfers two types of molecules in the same direction?

Symporter Signup and view all the answers

What is the purpose of the sodium-potassium pump in the context of glucose transport?

To pump sodium out and potassium in, establishing a concentration gradient Signup and view all the answers

What happens to the glucose concentration in the cell as a result of the symporter?

It increases as glucose is transported into the cell with sodium Signup and view all the answers

What is the purpose of the symporter in the loop of Henle?

To reabsorb salts into the bloodstream Signup and view all the answers

Why do symporters use the energy from the sodium concentration gradient?

Because the energy from the sodium concentration gradient is more efficient Signup and view all the answers

What is the result of the symporter's action in the loop of Henle?

Salts are reabsorbed into the bloodstream Signup and view all the answers

What is the role of the protein in the symporter process?

To bind to sodium and glucose, then change its shape to release them into the cell Signup and view all the answers

Why does the symporter require a high sodium concentration in the lumen?

Because a high sodium concentration gradient is required for the symporter to work Signup and view all the answers

What happens to the glucose concentration in the cell after it is transported by the symporter?

It eventually decreases as glucose diffuses out of the cell into the bloodstream Signup and view all the answers

What is the name of the symporter found in the ascending loop of Henle?

Sodium-potassium-chlorine cotransporter Signup and view all the answers

What is the purpose of the sodium-potassium pump in the distal convoluted tubule?

To transport sodium out of the cell Signup and view all the answers

What type of transport is used in the distal convoluted tubule to transport calcium out of the lumen?

Secondary active transport Signup and view all the answers

What is the direction of movement of sodium ions in the antiporter in the distal convoluted tubule?

Down its concentration gradient Signup and view all the answers

What is the role of the peritubular capillary in the distal convoluted tubule?

To collect ions and water from the cells Signup and view all the answers

What is the term for the type of transport used in the nephron to transport ions out of the lumen?

Secondary active transport Signup and view all the answers

What is the function of the apical membrane in the distal convoluted tubule?

To allow calcium to flow down its concentration gradient Signup and view all the answers

What is the purpose of the revolving door-like mechanism in the antiporter?

To exchange sodium for calcium Signup and view all the answers

What is required for the antiporter to function in the distal convoluted tubule?

Active transport of sodium out of the cell Signup and view all the answers

What is the result of the sodium-potassium-chlorine cotransporter in the ascending loop of Henle?

The medulla becomes saltier Signup and view all the answers

Study Notes

Nephron Function

The nephron has different parts that reabsorb various molecules, including glucose, amino acids, sodium, potassium, chlorine, and calcium.
These molecules are selectively transported out of the lumen (inside of the tubule) or reabsorbed out of the filtrate.

Proximal Convoluted Tubule

The proximal convoluted tubule has a brush border with microvilli that increase the surface area for reabsorption.
Sodium-potassium pumps are located on the basolateral membrane (side of the cell facing away from the lumen).
These pumps use ATP to transport sodium out of the cell and potassium into the cell.
Sodium bond to the pump, and then ATP binds, causing a conformational change that releases sodium outside and allows potassium to bind.
The pump then returns to its original shape, releasing potassium and preparing for another cycle.
This process is an example of active transport, as it uses energy to transport molecules against their concentration gradient.

Glucose Transport

A symporter (or cotransporter) is a protein that helps transport glucose into the cell along with sodium.
The sodium-potassium pump creates a low sodium concentration inside the cell.
Sodium then moves down its concentration gradient into the cell, bringing glucose with it.
The symporter changes shape, releasing sodium and glucose inside the cell.
Glucose then diffuses out of the cell and into the peritubular capillaries.

Loop of Henle

The ascending part of the loop of Henle has a similar mechanism to the proximal convoluted tubule.
Sodium-potassium pumps are present, creating a low sodium concentration inside the cell.
Symporters help transport chloride and potassium ions into the cell along with sodium.
The sodium-potassium-chloride cotransporter is a specific example of this in the ascending loop of Henle.
Chloride ions then diffuse out of the cell and into the peritubular capillaries.

Distal Convoluted Tubule

Calcium is transported out of the lumen in the distal convoluted tubule.
An antiporter is used, which transports calcium out of the cell in exchange for sodium.
Sodium moving down its concentration gradient into the cell drives the transport of calcium out of the cell.
This process is also an example of secondary active transport.

General Mechanisms

Secondary active transport is the use of a concentration gradient created by active transport to drive the transport of another molecule.
Active transport uses energy (in the form of ATP) to transport molecules against their concentration gradient.
Symporters and antiporters are proteins that facilitate the transport of molecules into or out of cells.

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Description

This quiz covers the different parts of the nephron and the molecules reabsorbed by the body in each part, including the proximal convoluted tubule, ascending part of the loop of Henle, and distal convoluted tubule.