Transport Mechanisms in Cellular Biology

Dr. Ketchum explains bicarbonate reabsorption in the proximal convoluted tubule, focusing on sodium-potassium pumps, hydrogen ion transport, and the role of carbonic anhydrase in forming and breaking down carbonic acid. The video also covers bicarbonate and chloride transport mechanisms and how carbon dioxide enters cells through cellular respiration and pressure gradients.

What is the primary role of the sodium-potassium pump in the proximal convoluted tubule?

• To secrete hydrogen ions into the plasma

• To facilitate the diffusion of bicarbonate

• To maintain low sodium and high potassium concentrations inside the cell

• To increase sodium concentration inside the cell

Which type of transport is involved in moving sodium and hydrogen ions across the apical membrane?

• Osmosis

• Sodium-hydrogen counter-transport

• Endocytosis

• Facilitated diffusion

Why can't facilitated diffusion be used for hydrogen ions moving from low to high concentration?

• Because it only works for water molecules

• Because it moves ions against their concentration gradient

• Because it is a passive transport mechanism

• Because it requires energy

What enzyme is responsible for breaking down carbonic acid into water and carbon dioxide?

• Carbonic anhydrase

• Amylase

• Protease

• Lipase

How does carbon dioxide enter the cytoplasm of the cell after being formed from carbonic acid?

• Via simple diffusion

• By osmosis

• Through active transport

• Through endocytosis

What type of transport is involved in the movement of bicarbonate and sodium across the basolateral membrane?

• Sodium bicarbonate co-transport

• Facilitated diffusion

• Active transport

• Endocytosis

Which ions are involved in the chloride bicarbonate counter-transport?

• Hydrogen and sodium

• Chloride and bicarbonate

• Calcium and magnesium

• Sodium and potassium

What is one way carbon dioxide can enter the cell besides diffusion?

• By active transport

• Through cellular respiration

• Through facilitated diffusion

• Via osmosis

Where does reabsorption occur in the capillary?

• Outside the capillary

• In the middle of the capillary

• At the venous end

• At the arterial end

What drives the movement of carbon dioxide into the cell from the capillary?

• Electrical gradient

• Pressure gradient

• Temperature gradient

• Concentration gradient