LECTURE 10- Active cellular physiology

Question 1

Shape of a cell is defined by…

Answer 1

how cell manages water, ions and solutes in the body.

Question 2

Concentration gradient can depend on…

Answer 2

water and its solute. eg sugar in solution moving from high conc. of solute to a low conc. as solute dissolves. (diffusion)

Question 3

Osmosis

Answer 3

Water moves through a semi-permeable membrane from an area of high conc. to an area of low conc. (passive transport)/

Question 4

Which form of transport is used for the movement of a solute between membranes?

Answer 4

Osmosis. Membrane is permeable to water. However holes are too small for solute to move through. Water molecules move from high conc side of water to low conc side of water. Water attempts to dilute solute.

Question 5

What happens when water moves across a membrane?

Answer 5

The volume of water on the side that the water molecules move to will increase, and decrease on opposite side.

Question 6

What is osmotic pressure (tonicity)?

Answer 6

Applying pressure to an area of water that will counteract its change in volume and will make volume on either side of the membrane equal.

Question 7

Purpose of osmotic pressure?

Answer 7

Maintains plump, strong but soft cells in lining of organs.

Question 8

Water can be taken in/ and lost by…

Answer 8

drinking water. Lost through skin, sweat, lungs , faeces etc. Moves through ICF and ECF.

Question 9

Where are solutes and ions found ?

Answer 9

In ICF and ECF.

Question 10

What does isotonic mean? (iso= same)

Answer 10

Solutes within ICF and ECF are at same concentrations for a given volume. It is balanced

Question 11

What does hypertonic mean? (hyper= more than)

Answer 11

When water is lost in ECF, but concentration of this solute remains the same just in a smaller volume.

Question 12

How do we reach equilibrium in an hypertonic situation?

Answer 12

Water from ICF moves across to the ECF to compensate loss of water in ECF, and restore osmotic equilibrium. Consequence= total volume within cell decreases= so cell shrinks.

Question 13

What does hypotonic mean? (hypo=

Answer 13

If volume of water increase, this water will flow from area of low conc of solutes and increase volume of water in this space.

Question 14

Shape of cell in isotonic solution..

Answer 14

Maintains its shape.

Question 15

Shape of cell in hypertonic solution…

Answer 15

Cell shrinks as water is lost.

Question 16

Shape of cell in hypotonic solution…

Answer 16

Cell expands as water moves into cell.

Question 17

Ions are absorbed through which organs?

Answer 17

Epithelial lining of small intestine and colon (large intestine.

Question 18

Skeleton, body fluids, sweat glands and kidneys contain…

Answer 18

ions. ( ICF and ECF). Ion levels must be balanced

Question 19

What are excitable tissues?

Answer 19

In neurons and muscles- excitable membrane potential.

Question 20

Do epithelial cells have an excitable membrane?

Answer 20

No. They only have a membrane potential.

Question 21

Which ions do the cellular membrane potential rely on?

Answer 21

Na+ and K+. Important for health of excitable cells.

Question 22

Cations and anions of cell are found…

Answer 22

inside and outside of cell. Inside cell, across plasma membrane there is a slight negative over positive side.

Question 23

What acts as an insulator in the plasma membrane?

Answer 23

The lipid bilayer. Channels are formed in this to allow ions to pass between cells. Prevents free flow.

Question 24

Which ions are used like a small battery in cell?

Answer 24

Charge difference between two sides of membrane. High Na+ and low K+ on ECF outside ( think of sweat). Na+ low on ICF inside and K+ high.

Question 25

What is the resting membrane potential?

Answer 25

Distribution of ionic concentration that generate resting membrane potential. Have to be maintained for ‘battery’ to maintain.

Question 26

Ion channel or pore…

Answer 26

Channel for ions to pass between ICF and ECF. Ions DO NOT PASS THROUGH PLASMA MEMBRANE. Can only move when channels are open. They move to where their low conc would be.