Lecture 7 Flashcards
What is diffusion?
The movement of molecules from an area of higher concentration to an area of lower concentration
Diffusion is a passive process that does not require energy.
What is osmosis?
The movement of water across a semi-permeable membrane to balance concentration gradients
Osmosis specifically refers to the movement of water molecules.
How does water move across a membrane to balance tonicity?
Water moves to equalize solute concentrations on both sides of a semi-permeable membrane.
Define resting membrane potential.
The electrical potential difference across a cell membrane when the cell is not actively signaling, typically around -70mV.
What occurs during depolarization?
The membrane potential becomes less negative, moving towards zero, typically due to sodium ions entering the cell.
What occurs during repolarization?
The membrane potential returns to a more negative value, typically due to potassium ions exiting the cell.
What do excitable cells use for rapid signaling events?
Excitable cells use chemical and electrical gradients.
What is the role of excitable cells in the body?
They help react to environmental stimuli.
What type of molecules cannot pass through semi-permeable membranes?
Highly charged and large molecules.
What happens when solutes cannot move across a membrane?
Water moves against gravity to balance concentrations on both sides.
What is osmotic pressure?
The pressure required to prevent the flow of water across a semi-permeable membrane due to solute concentration differences.
What is hypertonic solution?
A solution where the concentration of solutes outside the cell is higher than inside, causing water to leave the cell.
What is isotonic solution?
A solution where the concentration of solutes is equal inside and outside the cell.
What is hypotonic solution?
A solution where the concentration of solutes outside the cell is lower than inside, causing water to enter the cell.
What happens to a cell in a hypotonic solution?
The cell takes in water, which may lead to bursting.
What happens to a cell in a hypertonic solution?
The cell loses water, shriveling up and potentially dying.
What causes a chemical gradient across a membrane?
An uneven distribution of molecules creates a force that wants to balance concentrations.
What ions are mostly found outside the cell?
Sodium (Na), Potassium (K), and Calcium (Ca).
What is the role of passive ion channels?
They allow the movement of ions down their chemical and electrical gradients.
What is the sodium-potassium exchange pump?
A mechanism that uses ATP to reset the ion concentrations across the membrane.
What is the significance of the gradient in signaling?
A bigger gradient produces a faster and stronger signal.
What is passive transport?
The movement of molecules across a membrane without the use of energy.
What is the osmotic force?
The force exerted by solutes that can hold weights due to water movement.
Fill in the blank: The interior space and exterior space of a cell are separated by a _______.
semi-permeable membrane.
