The Nephron

Question 1

What are the 2 parts of the Nephron?

Answer 1

The “Renal Corpuscle” where blood plasma is filtered, and a “Renal Tubule” where the filtered fluid passes through.

Question 2

What does the “Renal Corpuscle” consist of?

Answer 2

The Glomerulus and Glomerular Capsule.

Question 3

How does Fluid flow through the “Glomerulus / Glomerular Capsule”?

Answer 3

In order for this to happen the Renal Tubule consist of:

Proximal Convoluted Tubule (PCT), Loop of Helen, Distal Distal Convoluted Tubule (DCT).

Question 4

Within a Nephron how is PCT and DCT connected?

Answer 4

The Loop of Helen connects these together.

Question 5

What is the Descending limb of the loop of Helen?

Answer 5

This is the part of the Loop of Helen, where the first part of the Helen dips into the “Renal Medulla”.

Question 6

What percentage of of Nephrons are “Cortical Nephrons”?

Answer 6

80-85%

Question 7

What are the percentage of Nephrons that are “Juxtamedullary Nephrons”?

Answer 7

15-20%

Question 8

What does the “Glomerular Capsule”?

Answer 8

Consist of Visceral and Parietal layers.

Question 9

What does the Visceral layer of the “Glomerular Capsule” consist of?

Answer 9

Modified Squamous cells epithelial cells called “Podocytes”.

Question 10

What does an overview of the “Renal Physiology” consist of?

Answer 10

To produce Urine, Nephrons and the collecting ducts perform 3 basic tasks:
Glomerular Filtration, Tubular Reabsorption, and Tubular Secretion.

Question 11

When producing Urine, what is the “Glomerular Filtration” phase?

Answer 11

Water and most solutes in blood plasma move across the wall of Glomerular capillaries, where they’re filtered and move into Glomerular capsule and then into Renal Tubule.

Question 12

When producing Urine, what is the “Tubular Reabsorption” phase?

Answer 12

As filtered fluid flows through the Renal tubules and through the collection Ducts, tubule cells reabsorb about 99% of the Filtered water and many useful solutes.

Question 13

When producing Urine, what is the “Tubular Secretion” phase?

Answer 13

As filtered fluid flows through the Renal tubules and collecting ducts, the renal tubule and duct cell secret other materials, such as waste, drugs and excess ions into the fluid.

Question 14

What is Net filtration pressure?

Answer 14

Glomerular Filtration depends on 3 main pressures:

1 Pressure promotes filtration, 2 Pressures Oppose Filtration.

Question 15

What is “Glomerular Blood Hydrostatic Pressure” (GBHP)?

Answer 15

This is the BP in the Glomerular Capillaries.
Promotes filtration by forcing water and solutes in blood plasma through the filtration membrane.
GBHP is about 55 mmHg.

Question 16

What is “Capsular Hydrostatic pressure” (CHP)?

Answer 16

The Hydrostatic pressure exerted by against the filtration membrane by fluid already in capsular space nd renal tubule.
Opposes filtration and represents a “Back pressure” about 15mmHg.

Question 17

What is “Blood colloid somatic pressure” (BCOP)?

Answer 17

This is due to the presence of proteins such as albumin, globulins and fibrinogens in blood plasma.
Also opposes filtration.
30 mmHg.

Question 18

What happens if GFR is too high?

Answer 18

Needed substances may pass too quickly through the Renal Tubules that some are not reabsorbed and are lost in the Urine.

Question 19

What happens if the GFR is too low?

Answer 19

Nearly all the Filtrate may be reabsorbed and certain waste products may not be adequately secreted.

Question 20

What are the 2 mechanisms that regulate glomerular filtration?

Answer 20

They operate in 2 main ways:
Adjusting blood flow into and out of the Glomerus.
And by altering the Glomerular Capillary surface area available for filtration.

Question 21

What are the 3 mechanisms that control GFR?

Answer 21

Renal Autoregulation, Neural Regulation, Hormonal Regulation.

Question 22

What are the 2 important Outcomes of Tubular Secretion?

Answer 22

The secretion of hydrogen helps control the balance of PH in the blood.
The secretion of other substances help secrete them from the body.

Question 23

What is the 3rd function of Nephrons and collecting ducts?

Answer 23

Tubular secretion.

Question 24

What is Tubular Secretion?

Answer 24

The transfer of materials from blood and tubule cells into Glomerular Filtrate.

Question 25

Once fluid passes through the PCT, what occurs?

Answer 25

Cells located more distally fine-tune the reabsorption processes to maintain homeostatic balances of water and selected ions.

Question 26

What is involved in the Reabsorption and secretion in the PCT?

Answer 26

The largest amount of water and solute reabsorption from filtered fluid occurs in the PCT.
Most solute reabsorption is Na.

Question 27

What occurs in the Loop of Helen in respect to Reabsorption?

Answer 27

About 15% of filtered water is reabsorbed into the descending limb of the LOH.
Little or no water is absorbed in the ascending loop.

Question 28

What is involved in Absorption in the early DCT?

Answer 28

When fluid enters the early DCT about 80% of filtered water has now been reabsorbed.

Question 29

What happens in the early DCT in relation to Parathyroid hormone?

Answer 29

This is a major cite where parathyroid hormone stimulates reabsorption of Ca.

Question 30

How much ca is reabsorbed in the early DCT?

Answer 30

This depends on the bodies needs.

Question 31

What happens to fluid by the time it reaches the end of the DCT?

Answer 31

90-95% of filtered solutes and water have returned to the bloodstream.