Sodium potassium pump

What ion primarily controls water movement in the body?

Sodium (Na⁺)

Why does sodium control water movement?

Water follows sodium via osmosis

What type of transport does the Na⁺/K⁺ pump use?

Primary active transport (uses ATP)

How many Na⁺ ions are pumped out of the cell?

3

How many K⁺ ions are pumped into the cell?

2

What is the net charge effect of the Na⁺/K⁺ pump?

Net negative inside the cell

What is the main purpose of the Na⁺/K⁺ (sodium) pump?

Maintain electrochemical gradients

What is the functional unit of the kidney?

nephron

What occurs in the glomerulus?

filtration of blood

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

Bulk reabsorption of water, ions, glucose, and amino acids

Which part of the nephron establishes the medullary osmotic gradient?

Loop of Henle

What is the main function of the distal convoluted tubule (DCT)?

Fine-tuning of ion balance

What hormone primarily acts on the collecting duct?

ADH (antidiuretic hormone)

Which limb of the Loop of Henle is permeable to water?

Descending limb

Which limb actively transports Na⁺, K⁺, and Cl⁻?

Ascending limb - impermeable to water

What happens to filtrate in the descending limb?

becomes more concentrated

What happens to filtrate in the ascending limb?

becomes more dilute

Why does the ascending limb dilute filtrate?

It pumps out ions but does not allow water to follow

What is the medullary osmotic gradient?

Increasing solute concentration in the kidney medulla

What creates the medullary gradient?

Active transport of Na⁺ in the ascending limb

Why is the medullary gradient important?

Allows water reabsorption in the collecting duct

What would happen without the medullary gradient?

Inability to concentrate urine

Why is the Na⁺/K⁺ pump highly active in the Loop of Henle?

To create the ion gradient necessary for water reabsorption

What happens if the Na⁺/K⁺ pump is inhibited in kidney cells?

Loss of ion gradients and decreased water reabsorption

What process depends on the Na⁺ gradient created by the pump?

Secondary active transport

Is water actively transported in the nephron?

No, it moves passively by osmosis

Which part of the nephron reabsorbs the most water overall?

Proximal convoluted tubule

Which part is responsible for urine concentration?

Loop of Henle (gradient) + collecting duct (water reabsorption)

What happens if the ascending limb becomes permeable to water?

The medullary gradient would collapse

What is the key relationship between sodium and water?

Sodium moves first, water follows

What is the main function of the ascending limb of the Loop of Henle?

Establish osmotic gradient by pumping out Na⁺

What is required to concentrate urine?

Medullary gradient + ADH

What is the main function of the descending limb?

Allow water to leave, concentrating filtrate