Active Cellular Physiology

Question 1

What is an isotonic solution?

Answer 1

Isotonic means the intracellular fluid is in balance or equal to the extracellular fluid

Question 2

What does hypertonic mean?

Answer 2

Water loss from ECF decreases volume and makes the solution hypertonic in regards to ICF
Higher concentration of solutes for a given volume

Question 3

How does a cell restore equilibrium when it is hypertonic?

Answer 3

To restore equilibrium water moves from low concentration to high concentration but decreased ICF volume causing cell to shrink/shrivel

Question 4

What does hypotonic mean?

Answer 4

Hypotonic is when water moves from low concentration of solutes to high concentration of water

Question 5

How does a cell restore equilibrium when its hypotonic?

Answer 5

To restore equilibrium water will flow from low concentration to high concentration increasing water volume in ICF causing cell to swell

Question 6

What is ion absorption?

Answer 6

Ion absorption occurs in the epitheal lining of the small intestine and colon

Question 7

What is ion excretion?

Answer 7

Ion excretion occurs at the sweat and kidney glands to regulate concentration of ions in body fluids

Question 8

Why is having a balance of sodium, potassium and chloride ions important for maintains ion equilibrium?

Answer 8

Distribution of ions creates the membrane potential which has a charge difference between the two sides, 70mV is the resting membrane potential due to distribution of ions

Question 9

What is depolarisation ?

Answer 9

Where sodium channels open and sodium is transported into the cell

Question 10

What is hyperpolarisation?

Answer 10

Where the potassium channels open and more potassium ions leave the cell

Question 11

What is the electrochemical gradient for sodium and potassium?

Answer 11

Inside cell is negative, outside is positive
- Sodium is on outside (ECF) so wants to come in (moves into ICF)
- Potassium is in the cell (ICF) so moves outside into ECF due to its potassium gradient but not as readily as Na moves

Question 12

What are excitable tissues?

Answer 12

Neurons and muscle: excitable membrane potential
Epithelial cells also have a membrane potential but not excitable

Question 13

Concentration of K+ and Na+ present in cells

Answer 13

ECF: High Na+ , low Ka+
ICF: Low Na+ , high Ka+
Creates a charge difference = Resting membrane potential -70mV
Potassium gradient is slightly outwards, sodium gradient is inwards