4

Ghada Alzoubi & Mohamad Aboshaban

Jehad Samhouri

Faisal Mohammad

1 | P a g e

00:00-00:10

●Osmolarity : the number of osmoles per 1 liter of solution. (Osm/L)

● Osmolality : the number of osmoles per 1 Kg of solution. (Osm/Kg)

Notice : These two concepts are measures that are technically different, but

functionally have the same for normal use.

* There are three types of solution that may occur in your body based on

solute concentration :

1- Isotonic : which is almost equal 300 milliosmole.

2- Hypotonic : less than 300 milliosmole.

3- Hypertonic : more than 300 milliosmole.

( Note : our body fluids (ECF and ICF) have osmolarity around 300

milliosmole ).

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Example :

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● You have these two solution with the given information and there is a

semipermeable membrane between them, answer the questions :

Ans: first we calculate the number of moles for each solute.

Solute A : 100/100 = 1 mole. & Solute B : 1000/1000 = 1 mole.

since both solutes have the same number of moles and were put in 1 liter of

solvent, They have the same molarity , same osmolarity and the same number

of molecules.

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●The relation between Osmolarity and Molarity :

.per liter solution particles= index of the concentration of /LmOsm

per liter solution. moleculesmM/L = index of the concentration of

What does this mean?

Dear doctor, let’s take this example 😊

150 mM NaCl = 300 mOsm

300 mM glucose = 300 mOsm

means , which -and Cl +According to solubility rules, NaCl dissociate into Na

, that’s why ) -and Cl +(Na that for each 1 NaCl molecule there are 2 particles

we multiplied by two.

On the other side, Glucose doesn’t dissociate so for 1 Glucose molecule there

is one particle, that’s why we multiplied by 1.

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00:10-00:20

● There are two types of ions :

a- Cation (positive Charge) : related to Cathode.

b- Anion (negative charge) : related to Anode.

3 | P a g e

( Reminder : ECF → 1- plasma / 2- interstitial fluid )

From the previous picture you should know this information:

+the major cation in the ECF is : Na -1

-the major anion in the ECF is : Cl -2

+the major cation in the ICF is : K -3

, protein anions -24the major anion in the ICF is : HPO -4

Notes :

in ECF equals 140 millimoles. +Na The concentration of -a

in ICF equals 120 millimoles. +KThe concentration of -b

CF equals 110 millimoles.Ein -concentration of ClThe -c

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Very important

1-The sum of ions of these substances should be equal to 300 mOsm\L in the

ICF and ECF. In other words, the sum of ions in the ICF equals 300 mOsm\L

and the sum of ions in the ECF equals 300 mOsm\L.

2- Negative charges and positive charges in each fluid (ICF and ECF) should

be equal because of the electrical neutrality.

3- the difference between plasma and interstitial fluid is protein anions, the

plasma has more amount of protein anions than interstitial fluid ….. why ?

→ because the protein anion are big in size and they don’t pass through the

capillaries to go to interstitial fluid, the proteins are formed in the liver and

transport through the blood.

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Tonicity and its effects on RBCS

5 | P a g e

As we mentioned earlier there are three types of solution can be found in our

bodies ( Isotonic , hypotonic , hypertonic).

Now, lets examine these three cases:

solution, what will Isotonicif we put the RBCS (red blood cells) in an -1

happen to the cell? → nothing, because the net movement of water is zero.

That’s why when the doctor wants to give a patient a solution of glucose (for

example) in his blood, he gives him an Isotonic solution of glucose (300

mOsm/L) so it doesn’t affect the RBCS.

2- if we put RBCS in a hypotonic solution, what will happen to the cell? →

they will swell and burst (hemolysis) because the water will move from the

lower concentration of ions (outside the RBCS) to the higher concentration of

ions (inside the RBCS). (net movement of water is inside the cell)

3- if we put RBCS in a hypertonic solution, what will happen to the cell? →

they will shrink (crenation) for the same reason in the case 2, but this time the

lower concentration of ions is inside the cells and the higher concentration of

ions is outside the cells. (net movement of water is outside the cell)

Remember : the water movement (osmosis) is like this :

Lower concentration of ions → higher concentration of ions

Higher concentration of water → lower concentration of water

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Active transport

We define active transport as the movement of substances (ions or molecules)

against its electrochemical gradient, in other words from the lower

concentration to the higher concentration across the plasma membrane.

→It requires energy (up to 90% of cell energy expanded for active transport).

→It’s associated with enzymes.

→It’s saturable, which means its rate is limited by Vmax or Tmax.

6 | P a g e

😊 Types of active transport :

1- Primary Active Transport

• Molecules are “pumped” against a concentration gradient at the expense of

energy (ATP)

– direct use of energy

Examples :

(it uses ATP directly) →ATPaseor ) pump+K -+Na(-a

)against its gradientICF to ECF (from the +Na3It pumps -

the cell. sideinthan higherthe cell is outside +concentration of Na* the

from the ECF to ICF (against its gradient) +It pumps 2K-

the cell. outsidethan higherthe cell is sidein +the concentration of K *

Primary

Secondary

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😊 That’s why the active transport needs Energy (ATP), because it pumps

substances against their gradient.

why? ….. ) pump is called electrogenic pump+K -+NaSometimes the ( 😊

outside the cell, which +inside the cell and 3Na+ Because it pumps 2K →

makes an electrical potential across the cell membrane.

against its gradient.2+pump) in muscles, which pumps Ca-2+(Ca -b

pump) in stomach. -+(H -c

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00:20-00:30

2- Secondary Active Transport

• Transport is driven by the energy stored in the concentration gradient of

)+another molecule (Na

– indirect use of energy

Examples :

gradient (which is +the downhill Na) : uses cotransportglucose -+(Na -a

) pump) to transport the glucose against an uphill +K -+Naformed by the (

.glucose cotransport-+NaThis picture represents only the glucose gradient.

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Notice that we didn’t use the energy directly. First, we used energy on

gradient then transported glucose. +to make Na ) pump+K -+ (Nathe

inside is 2+in the muscle cells the concentration of Ca exchanger : 2+Ca-+Na -b

to outside the cell? 2+lower than outside, then how can we transport the Ca

enters in exchange for +), Nacounter transportexchanger ( 2+Ca-+we use Na →

. 2+Ca

.+using the gradient of Na transported against its gradient 2+*Ca

😊+.is exported for the import of 3 Na 2+Additional information: a single Ca

Look at this table carefully: (VERY IMPORTANT)

COUNTERTRANSPORT COTRANSPORT

Antiporter Symporter ANOTHER

NAME

The 2 involves substances

transport in different

directions (one substance

enters the cell and the other

exits)

Both 2 involved

substances transport in

the same direction (both

enters the cell)

DIRECTION OF

TRANSPORT

2+Ca-+Na* +H-+*Na

glucose -+Na*

amino acids-+*Na

EXAMPLE

Secondary active transport Secondary active

transport

TYPE OF

ACTIVE

TRANSPORT

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00:30-00:40 Transport in vesicles

*Vesicle - a small spherical sac formed by budding off from a membrane.

-They are considered a type of active transport because it needs energy, and

they’re not much related to the gradient-

Transporting via vesicles comes in three parts:

😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊

a cell in a vesicle formed from the intomaterials move : ndocytosisE ,Firstplasma membrane. It contains three types:

a- Phagocytosis (engulfing of solids material)

a cell engulfs a particle by extending pseudopodia around it and packaging it

within a membranous sac called a food vacuole. The particle will be digested

after the food vacuole fuses with a lysosome.

b- Pinocytosis-Bulk phase (engulfing of liquids material)

a cell continually “gulps” droplets of ECF into tiny vesicles, formed by

infoldings of the plasma membrane, the parts of the plasma membrane that

form vesicles are lined on their cytoplasmic side by a later of coat protein, so

they said to be “coated”.

Endocytosis

Exocytosis

Transcytosis

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c- Receptor-mediate endocytosis

It’s a specialized type of pinocytosis that enables the cell to acquire bulk

. substances specificquantities of

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releasingvesicles fuse with the plasma membrane, – Exocytosis ,Secondtheir contents into the extracellular fluid.

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Third, Transcytosis – a combination of endocytosis and exocytosis.

The following picture is not important, ignore it if u want :

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Dear Doctor, the last slide will be discussed in the next chapter in details, so

there is no need to mention it now. 😊

Notes:

This sheet covers what the doctor said, there are some details hidden in the

book you may refer to if u want. 😊

______________________________________________________________

Learning never exhausts the mind.

Leonardo Da Vinci ~ 1452 – 1519

The end