Cell Physiology

Question 1

Soft cells

Answer 1

Have a cuboidal shape, mostly H2O, sac of ions

Makes epithelial cells that line the GI tarct and airway

Question 2

Concentration gradient

Answer 2

Water requires a concentration gradient

Solute goes from an area of high conc. to an area of low conc. with the concentration gradient

The equalised concentration is attainted through a process of diffusion

Question 3

Ionic conc. Gradient

Answer 3

Ions in body go from area of high conc. to area of low through diffusion down conc. gradient

Question 4

How do ions diffuse?

Answer 4

Through semi-permeable membrane, it is similar to a cellular membrane.

It has Osmotic pressure that provides structure and shape

Question 5

Why can’t big molecules pass through?

Answer 5

Becasue semi permeable mem can’t pass through large molecules

Question 6

What does Osmosis and osmotic potential do?

Answer 6

Give the cells shape and tonicity (determines the appearance of the cell)

Question 7

Buildup of male and female cells

Answer 7

FEMALE
*50% H20
*27% ICF (Intercellular fluid)
*18% ECF (Interstital fluid)
Solids (organic +inorganic) 50%
Plasma 4.5
Other fluids «1%

MALE
*60% H20
*33% ICF (Intercellular fluid)
*21.5% ECF (Interstital fluid)
Solids (organic +inorganic) 40%
Plasma 4.5
Other fluids «1%

Question 8

Journey of H20

Answer 8

*Water absorbed by the GI tract - 2200 mL

*Water los by breathing and vapour - 1150
*feces - 150
*sweat glands
*Urine - 1200

Solutes and ions are also found in ICF and RCF

Question 9

Isotonic

Answer 9

*When there a balance between the ions of H20 and solute
*The ICF and ECF have letters. The volume of ICF would be larger has the insides needs to host more H20 in case of emergency.

Question 10

Hypertonic (change in ECF induced)

Answer 10

When the ECF loses water content resulting in a higher solute to water ration, causing the ECF to become hypertonic in relation to ICF. As conc. of solute is large per volume, the osmotic conc./ osmolarity has increased.

Question 11

Hypertonic (response of the cell)

Answer 11

In response, water molecules from the cell go down the conc. gradient from an area of high conc. of H2O (low in solute) to low conc. of water in order to restore osmotic equilibrium. In the process the cell loses volume resulting in it to shrivel. If the extra reserve of H2O starts to deplete, it shrivels even more eg changes in total blood volume cause cells are loosing water

Question 12

Hypotonic solution

Answer 12

Concentration of H2O is too much in the ECF, so water moves down the conc. gradient to maintain the osmotic equilibrium, to enter the cells, causing the cells to swell. Eg is brain swelling when theres too much h2o and kidneys cannot flush H2O very in a short period of time, too much h2o results in hyponatriemia.

Question 13

How is ion concentration in the bodily fluids maintained?

Answer 13

Ion absorbtion, ion reserves and ion excretion

Question 14

Ion absorption

Answer 14

From intestines

Question 15

Ion reserves

Answer 15

1º from skeletal system

Question 16

Ion secretion

Answer 16

Through 1º i.e the kidneys and 2º i.e sweat glands etc

Question 17

What are excitable cells?

Answer 17

Those that have a membrane potential and rely on a balance of Na+, K+, Ca2+ and Cl- ions. eg are neurons and muscle cells

Epithelial cells have a membrane potential but they are not excitable

Question 18

How can ions move across into the cell to maintain ionic equilibrium?

Answer 18

*The phospho bilayer is an insulator and doesn’t allow ions to just flow through.

So to maintain the ionic balance, ions must travel through ion channels or through active transport

Question 19

Resting membrane potential

Answer 19

Na+ inside the cell is less compared to the outside while K+ is more tha the outside. K+ is a lot bigger than Na+, meaning that more Na+ fits in the cell than K+.

There is a small charge when cell is at rest because of the difference in ions. This is resting mem potential at around -70mV inside the cell

Question 20

Passive channels

Answer 20

Na goes from out to in

K goes from in to out

Through the channels, regulated by sodium-potas exchange pump to maintain the chemical gradient at a charge of -70mV

Question 21

sodium-potas exchange pump

Answer 21

Is ATP operated, takes out 3 Na in exchange for two K+ into the inside, ATP –> ADP

Active system, overall energy expenditure in system

Question 22

Na+ electrochem gradient

Answer 22

positive Na chem grad + a positive Na electrical gradient = very large inwards Na electrochemical gradient

Question 23

K+ electrochem gradient

Answer 23

outward K+ chem grad and inwards K+ electro grad = a smaller outwards K+ electrochem grad

Question 24

Difference between chem and elec gradients

Answer 24

Chemical gradient: Forms due to the difference in concentrations on opposite sides of a membrane. Electrical gradients: Forms due to difference in charge on opposite sides of a membrane.