Active Cell Physiology - Lecture 7

Question 1

What is diffusion

Answer 1

Movement of molecules from high to low concentration gradient

Question 2

What is osmosis

Answer 2

Movement of water across a membrane to equalise solute concentration

Question 3

Semipermeable membrane

Answer 3

Only allowing some molecules through
Don’t like large molecules or sugars or polar molecules and dislike ions
They like water

Question 4

What does the Cell membrane do

Answer 4

It divides our body fluid volumes into intracellular and extracellular spaces, and this is where osmosis needs to happen as the cell membrane is a semipermeable membrane, it is preventing movement of a lot of different types of molecules in and out of cells. This is where we move water by diffusion in a process known as osmosis.

Question 5

Isotonic

Answer 5

If the concentration of solute molecules on both sides (intracellular and extracellular ) are the same. And NO PRESSURE IS NEEDED

Question 6

Hypertonic

Answer 6

Water loss from the extracellular fluid decreases volume and makes the solution hypertonic with respect to the intracellular fluid
An osmotic water shift from ICF into the ECF will restore osmotic equilibrium but decrease the ICF volume

Question 7

Hypotonic

Answer 7

This is when the concentration of the ECF is low as there is more water, this means that there is low tonicity.
The cell will swell in hypotonic solution

Question 8

Hypotonic solution affecting the intergrity of cells

Answer 8

Water molecules would move into the blood cell and the cell would swell up

Question 9

Hypertonic solution effecting the integrity of cells

Answer 9

The cell will shrivel and die

Question 10

Chemical gradient

Answer 10

Uneven distribution of MOLECULES across the membrane

Question 11

Electrical gradient

Answer 11

Uneven distribution of CHARGES across the membrane

Question 12

What can we do if ions are imbalanced on both sides

Answer 12

We can move ions down a chemical gradient through passive ion channels this makes it easy to try equalise concentration on each side. The channels don’t need energy to work

Question 13

What does active pump do

Answer 13

Working against concentration gradient, it needs to use energy ( ATP )
Moving Na+ out of cells and K+ into cells

Question 14

How are the potassium and sodium gradient maintained

Answer 14

They are maintained by active pumps that use energy to move ions against their concentration gradient

Question 15

Resting membrane potential

Answer 15

When the cell is at rest, the intercellular space has more negative charge than the extracellular space, creating an electrical gradient
It’s typical value is around -70mV

Question 16

What is sodium potassium pump

Answer 16

Ensuring that the resting membrane potential is at a level that enables an action potential to be possible at any time. The cell membrane needs more negative intracellular for this to be accomplished

Question 17

Permeability of K+

Answer 17

The energy ( ATP to ADP ) realised drives the pump to ensure that internal Na+ is exchanged for external K+ ( 2K+ for 3Na+ ions ). This allows the intercellular charge to reach -70mV to 80mV or resting membrane potential to set an environment for action potentials to occur with proper simulation and release of neurotransmitter

Question 18

Why are ions distributed unevenly across the cell membrane at rest

Answer 18

To create chemical and electrical gradients

Question 19

What happens to the intracellular space at rest

Answer 19

It is more negatively charged.

Question 20

What is the electrical gradient called when the cell is at rest

Answer 20

Resting membrane potential

Question 21

Does positive or negative ions enter the cell during polarisation

Answer 21

Positive ions, which act as a signalling event for excitable cells, the positive ions are then removed during repolorization to return to the resting membrane potential

Question 22

What happens during depolarisation

Answer 22

Positive ions enter the cell, which acts as a signalling event for excitable cells. The positive ions are then removed during repolorization to return to the resting membrane potential

Question 23

What creates the electrical gradient known as the resting membrane potential

Answer 23

Uneven distribution of ions across the cell membrane

Question 24

What is the function of active pumps

Answer 24

Maintains the sodium and potassium gradients by using energy to move ions against their concentration gradient

Question 25

During depolarisation, what occurs in excitable cells

Answer 25

Positive ions enter the cell, creating an electrical gradient

Question 26

Higher solute concentration compared to another solution

Answer 26

Hypertonic

Question 27

What is the term for the state where a cell has lost water due to being placed in hypertonic solution

Answer 27

Plasmolysis

Question 28

What is the primary driving force for the movement of ions during depolarisation

Answer 28

Chemical gradients

Question 29

What ion is more abunedent in the extracellular space compared to the intercellular space

Answer 29

Na+

Question 30

What maintains the resting membrane potential in excitable cells

Answer 30

Movement of ions through passive channels

Question 31

What best describes resting membrane potential

Answer 31

The difference in electrical charge between the inside and the outside of the cell at rest

Question 32

Main function of ion channels in excitable cells

Answer 32

To provide a pathway for ions to move down their concentration gradient

Question 33

What channels open, allowing positive ions to enter the cell

Answer 33

Sodium channels

Question 34

What is the main function of ion channels in a cell membrane

Answer 34

Provide passive pathway for ions to move down their concentration gradient

Question 35

During repolorization, what channels open to allow positive ions to exit the cell

Answer 35

Potassium channels

Question 36

What is the primary force driving the movement of ions during depolarisation

Answer 36

Electrical gradients