Nephron Function and Transport Mechanisms

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Questions and Answers

Which part of the nephron is responsible for filtration?

Glomerulus (correct)

Renal tubule

Medullary pyramid

Bowman's capsule

What is the primary function of the nephron?

Absorb nutrients from food

Transport oxygen throughout the body

Regulate blood flow to the heart

Filter blood and produce urine (correct)

What structure surrounds the glomerulus?

Renal tubule

Calyx

Bowman's capsule (correct)

Ureter

What is primarily reabsorbed in the Proximal Convoluted Tubule (PCT)?

Essential nutrients and 70-80% of electrolytes and water Signup and view all the answers

Which part of the nephron follows after the glomerulus in the filtration process?

Renal tubule Signup and view all the answers

How many nephrons does each kidney contain approximately?

1 million Signup and view all the answers

In the nephron, which segment is primarily responsible for the reabsorption of water and electrolytes through passive mechanisms?

Descending Limb of Loop of Henle Signup and view all the answers

Which process is NOT primarily involved in the function of the Distal Convoluted Tubule (DCT)?

Active transport of glucose Signup and view all the answers

What is the primary role of Henle's Loop in the nephron?

Creating a high osmolarity in medullary interstitial fluid Signup and view all the answers

What is the term for the combined structure of the glomerulus and Bowman's capsule?

Malpighian body Signup and view all the answers

Which part of the nephron is NOT located in the medullary region of the kidney?

Distal convoluted tubule Signup and view all the answers

Which ions are secreted by the tubular cells during the process of tubular secretion?

H+ and K+ Signup and view all the answers

The function of the collecting duct primarily involves what process?

Concentration of urine through water reabsorption Signup and view all the answers

What structure forms the afferent arteriole leading to the glomerulus?

Renal artery Signup and view all the answers

What is the significant difference in permeability between the ascending and descending limbs of Loop of Henle?

Ascending limb is permeable to electrolytes; descending limb is impermeable to water. Signup and view all the answers

Which of the following substances is actively reabsorbed in the nephron?

Glucose Signup and view all the answers

What is the function of the proximal convoluted tubule (PCT) in the nephron?

It reabsorbs water and solutes from the filtrate. Signup and view all the answers

What is the average weight range of an adult human kidney?

120-170 g Signup and view all the answers

What distinguishes cortical nephrons from juxta medullary nephrons?

Cortical nephrons have shorter loops of Henle. Signup and view all the answers

What is the role of the efferent arteriole in kidney function?

It transports filtered blood away from the glomerulus. Signup and view all the answers

What describes the structure of the loop of Henle?

It includes a descending and an ascending limb. Signup and view all the answers

The peritubular capillaries surrounding the renal tubule are primarily formed from which vessel?

Efferent arteriole Signup and view all the answers

Which structure is primarily responsible for urine concentration within the nephron?

Loop of Henle Signup and view all the answers

Where do the distal convoluted tubules (DCTs) of multiple nephrons converge?

Collecting duct Signup and view all the answers

Study Notes

Mechanisms of Reabsorption and Secretion

Tubular epithelial cells in the nephron utilize active transport for reabsorbing glucose, amino acids, and Na+ from the filtrate.
Passive transport is used to absorb nitrogenous wastes.
Water reabsorption occurs passively in initial nephron segments.
Tubular secretion includes H+, K+, and ammonia, important for maintaining ionic and acid-base balance in body fluids.

Proximal Convoluted Tubule (PCT)

Lined by simple cuboidal brush border epithelium, increasing surface area for reabsorption.
Reabsorbs nearly all essential nutrients and 70-80% of electrolytes and water.
Maintains pH and ionic balance by selectively secreting hydrogen ions and ammonia and absorbing HCO3–.

Loop of Henle

Ascending limb has minimal reabsorption but maintains high osmolarity of medullary interstitial fluid.
Descending limb is water-permeable but nearly impermeable to electrolytes, concentrating the filtrate.
Ascending limb is impermeable to water, actively or passively transporting electrolytes, leading to dilution of concentrated filtrate.

Distal Convoluted Tubule (DCT)

Allows conditional reabsorption of Na+ and water.
Capable of reabsorbing HCO3– and selectively secreting hydrogen ions and potassium ions to maintain blood’s pH and sodium-potassium balance.

Collecting Duct

Extends from the kidney's cortex into the medulla.
Capable of significant water reabsorption to produce concentrated urine.

Kidney Structure

Average dimensions: 10-12 cm (length), 5-7 cm (width), 2-3 cm (thickness), and weighs 120-170 g.
Hilum: Notch where ureter, blood vessels, and nerves enter the kidney.
Renal pelvis: Broad funnel-shaped space located inner to the hilum with projections known as calyces.
Surrounded by a tough outer capsule and divided into two zones: outer cortex and inner medulla.
Medulla contains conical structures called medullary pyramids.

Nephron Structure

Each kidney contains approximately one million nephrons, the functional units.
Nephrons consist of glomerulus (a tuft of capillaries) and renal tubule, which begins with Bowman’s capsule.
The glomerulus and Bowman’s capsule together form the renal corpuscle or Malpighian body.
The renal tubule includes the proximal convoluted tubule (PCT), Henle’s loop, and distal convoluted tubule (DCT).

Nephron Types

Cortical nephrons: Have short loops of Henle that extend minimally into the medulla.
Juxta medullary nephrons: Possess long loops of Henle extending deep into the medulla.

Peritubular Capillaries

Efferent arterioles from glomeruli form a capillary network around the renal tubule, known as peritubular capillaries.
A vessel from this network runs parallel to Henle’s loop, forming a U-shaped structure called the vasa recta.

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Description

Explore the various transport mechanisms utilized by tubular epithelial cells in different nephron segments. This quiz covers active and passive reabsorption processes, including the handling of glucose, amino acids, and nitrogenous wastes. Test your understanding of urine formation and tubular secretion.