Nephron Structure and Function

Questions and Answers

What is the function of the endothelial cells in the afferent arteriole?

To line the blood vessel and allow smooth blood flow (correct)

To regulate blood pressure in the kidney

To transport oxygen and nutrients to the kidney cells

To filter waste and excess substances from the blood

What is the direction of blood flow in the afferent arteriole?

Away from the glomerulus

Towards the glomerulus (correct)

From the efferent arteriole to the afferent arteriole

Between the proximal and distal convoluted tubules

What is the location of the distal convoluted tubule in relation to the afferent and efferent arterioles?

Between the proximal convoluted tubule and the loop of Henle

Between the afferent and efferent arterioles (correct)

Inside the glomerulus

Outside the Bowman's capsule

What is the purpose of the efferent arteriole?

To carry blood away from the glomerulus Signup and view all the answers

What is the function of the cells surrounding the distal convoluted tubule?

To reabsorb essential substances from the filtrate Signup and view all the answers

What is the relationship between the afferent and efferent arterioles?

They are two different blood vessels that converge at the glomerulus Signup and view all the answers

What is the location of the Bowman's capsule in relation to the glomerulus?

Outside the glomerulus Signup and view all the answers

What is the function of the special cells in the distal convoluted tubule?

To secrete hormones that regulate electrolyte balance Signup and view all the answers

What is the main function of mesangial cells in the juxtaglomerular apparatus?

To provide structure and support to the blood vessels and nephron Signup and view all the answers

What is the term for the specialized smooth muscle cells that produce granules containing renin?

Granular cells Signup and view all the answers

Where are the macula densa cells primarily located?

In the distal convoluted tubule Signup and view all the answers

What is the purpose of the juxtaglomerular apparatus?

To release renin Signup and view all the answers

Which of the following is NOT a component of the juxtaglomerular apparatus?

Podocytes Signup and view all the answers

What is the location of the juxtaglomerular cells?

On both the afferent and efferent arteriole sides Signup and view all the answers

What is the trigger for the release of renin from the juxtaglomerular cells?

Not mentioned in the content Signup and view all the answers

What is the term for the cells that make up the inner layer of the arteriole?

Endothelial cells Signup and view all the answers

What is the function of the granules in the juxtaglomerular cells?

To store renin Signup and view all the answers

Which of the following cell types is responsible for regulating the diameter of the afferent arteriole?

Smooth muscle cells Signup and view all the answers

What is the role of the local hormone released by the macula densa cells?

To trigger the release of renin from the juxtaglomerular cells Signup and view all the answers

What is the trigger that the macula densa cells sense to release the local hormone?

Low sodium levels in the filtrate Signup and view all the answers

What is the function of renin?

To allow cells to communicate with each other at a distance Signup and view all the answers

What type of hormone is renin?

Protein hormone Signup and view all the answers

What is the location of the cells that release renin?

Juxtaglomerular cells Signup and view all the answers

What is the effect of low sodium levels in the filtrate on the macula densa cells?

They sense it as a trigger to release a local hormone Signup and view all the answers

What is the direct trigger for the release of renin by juxtaglomerular cells in response to low blood pressure?

The juxtaglomerular cells themselves Signup and view all the answers

What type of cells are the juxtaglomerular cells specialized as?

Smooth muscle cells Signup and view all the answers

What is the location of the sympathetic nerve endings that trigger the release of renin?

Tunica externa layer Signup and view all the answers

What is the function of the macula densa cells?

To sense sodium levels in the distal convoluted tubule Signup and view all the answers

What is the local messenger molecule that the macula densa cells send to the juxtaglomerular cells?

Prostaglandin Signup and view all the answers

What is the response of the juxtaglomerular cells to low blood pressure?

To increase the release of renin Signup and view all the answers

How do the macula densa cells sense low sodium levels in the distal convoluted tubule?

Through sampling of sodium levels in the distal convoluted tubule Signup and view all the answers

What is the ultimate goal of the macula densa cells in response to low sodium levels?

To increase blood pressure Signup and view all the answers

What is the significance of low sodium levels in the distal convoluted tubule?

It indicates low blood pressure in the glomerulus Signup and view all the answers

What is the relationship between the macula densa cells and the juxtaglomerular cells?

They are separate cells that communicate through a local messenger Signup and view all the answers

Study Notes

The Juxtaglomerular Apparatus

The juxtaglomerular apparatus consists of the afferent and efferent arterioles, the glomerulus, and the distal convoluted tubule.
The distal convoluted tubule has cells called the macula densa cells, which play a special role in the apparatus.

Structure of the Afferent and Efferent Arterioles

The afferent arteriole has endothelial cells lining its inner layer (tunica intima).
The endothelial cells are surrounded by smooth muscle cells in the tunica media layer.
There are also specialized smooth muscle cells called juxtaglomerular cells, which are located near the glomerulus.
The juxtaglomerular cells have granules that contain renin.

Function of the Juxtaglomerular Apparatus

The juxtaglomerular apparatus releases renin in response to certain triggers.
Renin is a protein hormone that plays a key role in blood pressure regulation.

Triggers for Renin Release

Low Blood Pressure: Low blood pressure is a direct trigger for renin release, sensed by the juxtaglomerular cells.
Sympathetic Nerve Endings: Sympathetic nerve endings in the tunica externa layer of the arterioles can stimulate renin release when they fire.
Low Sodium Levels in the Distal Convoluted Tubule: Low sodium levels in the distal convoluted tubule, sensed by the macula densa cells, trigger the release of prostaglandin, a local hormone that stimulates renin release.

The Role of the Macula Densa Cells

Macula densa cells in the distal convoluted tubule monitor sodium levels and sense low blood pressure in the glomerulus.
When sodium levels are low, the macula densa cells release prostaglandin, which stimulates renin release by the juxtaglomerular cells.

The Release of Renin

Renin is released from the juxtaglomerular cells into the bloodstream in response to the triggers mentioned above.
Renin then flows into the afferent arteriole, through the glomerulus, and out the efferent arteriole.

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Description

This quiz covers the different parts of the nephron, including the afferent arteriole, glomerulus, efferent arteriole, Bowman's capsule, proximal convoluted tubule, and loop of Henle. Understand how these components work together to filter blood and regulate bodily functions.