CELL TRANSPORT

Roselyn Aperocho – NaranjoPharmacy InstructorUSPF – College of Pharmacywww.roselynnaranjo.vze.com

The Cell Membrane

Anatomy Composition Function Thickness

Cell Coat Chondroitin sufuric AcidHyaluronic AcidCollagen, ElastinSialic Acid

Principal component of connective tissueAdsorption of compounds

Cell Membrane

ProteinTriglyceridesSteroidsPhospholipids (lecithin)

Hydrophilic LayerLipophilic Layer,bimolecular (barrier)

20-25 Å

CELL COAT

THE CELL MEMBRANE

Cell Coat

Membrane

Inside of the Cell

Protein 25 Å

Protein 25 Å

Phospholipids 25 Å

Schematic Diagram of the Cell membrane Structure having a pore

Properties of the Membranes

Permeability - Lipid soluble unionized substances dissolved in the

lipid membrane during transfer

(Factors involved: pka, pH, lipid/water partition coefficient)- - -

passive diffusion - - - ion pair

- water soluble, lipid insoluble substance of small

molecular weight transfer through water-filled pores

in the membrane- - - - convective transport

- solid substances and oil droplets may transfer the

membrane in a vessel - - - - pinocytosis

THE CELL MEMBRANE

Properties of the Membranes

Surface Tension – very low due to adsorption of protein to the

outside of the lipid layer

Electrical Properties – membrane potential due to different

distribution of ions in the extracellular and

intracellular fluid

LIPID BILAYER

Basic structural framework Consist of two back to back

layers made up of three types of lipid molecules– (75%) Phospholipids,

cholesterol, glycolipids

THE CELL MEMBRANE

2 layers of phospholipids• Phosphate head is

polar (water loving)• Fatty acid tails non-

polar (water fearing)

• Proteins embedded in membrane

Functions

a. Controls what enters and exits the cell to maintain an internal balance called homeostasis

b. Provides protection and support for the cellhave pores (holes) in it

c. Selectively permeable: Allows some molecules in and keeps other molecules out

d. The structure helps it be selective!

THE CELL MEMBRANE

Types of Cellular Transport

Passive Transport

cell doesn’t use energy1. Diffusion

2. Facilitated Diffusion

3. Osmosis

Active Transport

cell does use energy1. Protein Pumps

2. Endocytosis

3. Exocytosis

high

low

This is gonna be

hard work!!

high

low

Weeee!!!

THE CELL MEMBRANE

Passive Transport (HighLow)

cell uses no energy molecules move randomly Molecules spread out from an area of high

concentration to an area of low concentration.

Four types: 1. Diffusion 2. Facilitative Diffusion – diffusion with the help of

transport proteins 3. Osmosis – diffusion of water

THE CELL MEMBRANE

1. Diffusion: random movement of particles from an area of high concentration to an area of low concentration.

(High to Low)• Diffusion continues until all

molecules are evenly spaced (equilibrium is reached)-Note: molecules will still move around but stay spread out.

Passive Transport (HighLow)

THE CELL MEMBRANE

Passive Transport (HighLow)

2. Facilitated diffusion: diffusion of specific particles through transport proteins found in the membrane

a. Transport Proteins are specific – they “select” only certain molecules to cross the membrane

b. Transports larger or charged molecules

Facilitated diffusion (Channel Protein)

Diffusion (Lipid

Bilayer)

Carrier Protein

THE CELL MEMBRANE

Passive Transport (HighLow)

High Concentration

Low Concentration

Cell Membrane

Transport ProteinThrough a

High

Low

2. Facilitated diffusion:

Glucosemolecules

THE CELL MEMBRANE

Passive Transport (HighLow)

3.Osmosis: diffusion of water through a selectively permeable membrane

Water moves from high to low concentrations

•Water moves freely through pores.

•Solute (green) to large to move across.

THE CELL MEMBRANE

Active Transport (Low High)

cell uses energy actively moves molecules to where they are needed Movement from an area of low concentration to

an area of high concentration (Low High) Three Types:

– Protein pumps– Endocytosis– Exocytosis

THE CELL MEMBRANE

Active Transport (Low High)

1. Protein Pumps -transport proteins that require energy to do work– Example: Sodium /

Potassium Pumps are important in nerve responses.

Protein changes shape to move molecules: this requires energy!

THE CELL MEMBRANE

Active Transport (Low High)

2. Endocytosis: taking bulky material into a cell

• Uses energy• Cell membrane in-folds around food particle• “cell eating”• forms food vacuole & digests food• This is how white blood cells eat bacteria!

THE CELL MEMBRANE

Active Transport (Low High)

3. Exocytosis: Forces material out of cell in bulk• membrane surrounding the

material fuses with cell membrane

• Cell changes shape – requires energy

• EX: Hormones or wastes released from cell

THE CELL MEMBRANE

ELECTROLYTES

What are electrolytes?

Chemically, electrolytes are substances that become ions in solution and acquire the capacity to conduct electricity. Electrolytes are present in the human body, and the balance of the electrolytes in our bodies is essential for normal function of our cells and our organs.

Common electrolytes that are measured by doctors with blood testing include sodium, potassium, chloride, and bicarbonate. The functions and normal range values for these electrolytes are described on the next slide.

ELECTROLYTES

NATRIUM/ SODIUM

Sodium is the major positive ion (cation) in fluid outside of cells. The chemical notation for sodium is Na+. When combined with chloride, the resulting substance is table salt. Excess sodium (such as that obtained from dietary sources) is

excreted in the urine. It regulates the total amount of water in the body and the transmission

of sodium into and out of individual cells also plays a role in critical body functions.

Many processes in the body, especially in the brain, nervous system, and muscles, require electrical signals for communication. The movement of sodium is critical in generation of these electrical signals.

Too much or too little sodium therefore can cause cells to malfunction, and extremes in the blood sodium levels (too much or too little) can be fatal.

ELECTROLYTES

NATRIUM/ SODIUM

Increased sodium (hypernatremia) in the blood occurs whenever there is excess sodium in relation to water. There are numerous causes of hypernatremia; these may include kidney disease, too little water intake, and loss of water due to diarrhea and/or vomiting.

A decreased concentration of sodium (hyponatremia) occurs whenever there is a relative increase in the amount of body water relative to sodium. This happens with some diseases of the liver and kidney, in patients with congestive heart failure, in burn victims, and in numerous other conditions.

A Normal blood sodium level is 135 - 145 milliEquivalents/liter (mEq/L), or in international units, 135 - 145 millimoles/liter (mmol/L).

ELECTROLYTES

POTASSIUM

Potassium is the major positive ion (cation) found inside of cells. The chemical notation for potassium is K+. The proper level of potassium is essential for normal cell function. Among the many functions of potassium in the body are regulation of the heartbeat and the function of the muscles. A seriously abnormal increase in potassium (hyperkalemia) or decrease in potassium (hypokalemia) can profoundly affect the nervous system and increases the chance of irregular heartbeats (arrhythmias), which, when extreme, can be fatal.

ELECTROLYTES

POTASSIUM

Increased potassium is known as hyperkalemia. Potassium is normally excreted by the kidneys, so disorders that decrease the function of the kidneys can result in hyperkalemia. Certain medications may also predispose an individual to hyperkalemia.

Hypokalemia, or decreased potassium, can arise due to kidney diseases; excessive loss due to heavy sweating, vomiting, or diarrhea, eating disorders, certain medications, or other causes.

The normal blood potassium level is 3.5 - 5.0 milliEquivalents/liter (mEq/L), or in international units, 3.5 - 5.0 millimoles/liter (mmol/L).

ELECTROLYTES

CHLORIDE

Chloride is the major anion (negatively charged ion) found in the fluid outside of cells and in the blood. An anion is the negatively charged part of certain substances such as table salt (sodium chloride or NaCl) when dissolved in liquid. Sea water has almost the same concentration of chloride ion as human body fluids. Chloride also plays a role in helping the body maintain a normal balance of fluids.

ELECTROLYTES

CHLORIDE

The balance of chloride ion (Cl-) is closely regulated by the body. Significant increases or decreases in chloride can have deleterious or even fatal consequences:

Increased chloride (hyperchloremia): Elevations in chloride may be seen in diarrhea, certain kidney diseases, and sometimes in overactivity of the parathyroid glands. 

Decreased chloride (hypochloremia): Chloride is normally lost in the urine, sweat, and stomach secretions. Excessive loss can occur from heavy sweating, vomiting, and adrenal gland and kidney disease.

The normal serum range for chloride is 98 - 108 mmol/L.

ELECTROLYTES

BICARBONATE

The bicarbonate ion acts as a buffer to maintain the normal levels of acidity (pH) in blood and other fluids in the body. Bicarbonate levels are measured to monitor the acidity of the blood and body fluids. The acidity is affected by foods or medications that we ingest and the function of the kidneys and lungs. The chemical notation for bicarbonate on most lab reports is HCO3- or represented as the concentration of carbon dioxide (CO2).

The normal serum range for bicarbonate is 22-30 mmol/L.

ELECTROLYTES

BICARBONATE

The bicarbonate test is usually performed along with tests for other blood electrolytes. Disruptions in the normal bicarbonate level may be due to diseases that interfere with respiratory function, kidney diseases, metabolic conditions, or other causes.

ELECTROLYTES Normal Value

Calcium 8.8 - 10.3 mg/dL

Calcium, ionized 2.24 - 2.46 meq/L

Chloride 98 - 108 mEq/L

Magnesium 1.6 - 2.4 mEq/L

Phosphate 2.5 - 4.5 mg/dL

Potassium 3.5 - 5.0 mEq/L

Sodium 135 - 145 mEq/L

Ferritin13 - 300  (ng/ml)

Folate 3.6 - 20(ng/dl)

Glucose, fasting 60 - 110(mg/dl)

Glucose (2 hours postprandial)  (mg/dl) Up to 140

Hemoglobin A1c 6-8

Iron  (mcg/dl) 65 - 150

Lactic acid  (meq/L) 0.7 - 2.1

LDH (lactic dehydrogenase)  56 - 194 IU/L

Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water)

Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

Hypotonic Solution

THE CELL MEMBRANE

Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water)

Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

shrinks

Hypertonic Solution

THE CELL MEMBRANE

Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell.

Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

Isotonic Solution

THE CELL MEMBRANE

What type of solution are these cells in?

A CB

Hypertonic Isotonic Hypotonic

THE CELL MEMBRANE

Good Luck

Prepare one – half sheet of paper

to be continued…