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Ghada Alzoubi & Mohamad Aboshaban

Jehad Samhouri

Faisal Mohammad

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❖ Osmolarity • the number of osmoles per )1 liter or Kg ( of solution

• depends on the no.of molecules

to determine which substance has more no.of molecules we consider the

molecular weight (mole: gram molecular weight)

✓ gram molecular weight (mole) of any substance has the same no.of

molecules which is Avogadro’s number

✓ Ex: Mw of K=39 Mw of Na=23 we dissolve each one in 1 liter of

solution so the concentration is 1 molar and the no.of molecules is the

same. But if we dissolve 1 gram of K and 1 gram of Na in 1 liter of solution,

Na has more molecules because (1/23)*NA > (1/39)*NA so we care about

no.of molecules not about the grams

• Types of solution that may occur in your body based on solute concentration

A. Isotonic: which is almost equal 300 milliosmoles

B. Hypotonic: less than 300 milliosmoles

C. Hypertonic: more than 300 milliosmoles

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

Ex:

• You have these two solutions with the given information and there is a semi

permeable 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

mOsm/L = index of the concentration of particles per liter solution

mM/L = index of the concentration of molecules per liter solution

This means 150 mM NaCl = 300 mOsm 300 mM glucose = 300 mOsm

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

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

• There are two types of ions:

A. cation (positive Charge): related to Cathode

B. Anion (negative charge): related to Anode

Reminder: ECF is plasma and interstitial fluid

From the previous figure you should know these information

✓ the major cation in the ECF is: Na+ and the major anion in the ECF is: Cl-

✓ the major cation in the ICF is: K+ and the major anion in the ICF is: HPO42- , protein

anions

Notes

✓ The concentration of Na+ in ECF equals 140 millimoles

✓ The concentration of K+ in ICF equals 120 millimoles

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✓ The concentration of Cl- in ICF equals 110 millimoles

Important information

• 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

• Negative charges and positive charges in each fluid (ICF and ECF)

should be equal because of the electrical neutrality

• 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 anions 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

❖ Tonicity and its effects on RBCS

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

(Isotonic, hypotonic, hypertonic)

❖ There are three cases

1) if we put the RBCS (red blood cells) in an Isotonic solution, what will happen to

the cell? Nothing will happen to the cell

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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 to higher concentration of ions Higher concentration of water to lower concentration of water

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.

😊 Types of active transport :

Primary

Secondary

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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 -

in the cell is bigger than outside the cell.+ concentration of Na* the

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

outside the cell is bigger than inside the cell. +*the concentration of K

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

against their gradient.

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

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

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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2- Secondary Active Transport

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

)+molecule (Na

– indirect use of energy

Examples :

gradient (which is formed by the +) : uses the downhill Nacotransportglucose -+(Na -a

This picture pump) to transport the glucose against an uphill glucose gradient. ''K -+ Na''

glucose cotransport.-+represents only the Na

) +K -+ (Na used energy on the didn’t use the energy directly. First, we Notice that we

gradient then transported glucose. +pump to make Na

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

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

. 2+Caenters in exchange for +), Nacounter transportexchanger ( 2+Ca-+we use Na

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

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

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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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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 plasma into: materials move ndocytosisE, Firstmembrane. 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.

Endocytosis

Exocytosis

Transcytosis

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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”.

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c- Receptor-mediate endocytosis

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

. substances specific

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their releasingvesicles fuse with the plasma membrane, – Exocytosis ,Secondcontents into the extracellular fluid.

Third, Transcytosis – a combination of endocytosis and exocytosis.

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

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Dear Doctor, the last slide will be discussed in the next chapter by 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 😊

The end