Transcript Cell Transport

CELL
TRANSPORT
Roselyn Aperocho – Naranjo
Pharmacy Instructor
USPF – College of Pharmacy
www.roselynnaranjo.vze.com
The Cell Membrane
Anatomy
Composition
Function
Cell Coat
Chondroitin
Principal
sufuric Acid
Hyaluronic Acid
Collagen, Elastin
Sialic Acid
component of
connective tissue
Adsorption of
compounds
Cell
Membrane
Protein
Hydrophilic
Triglycerides
Lipophilic
Steroids
Layer,bimolecular
(barrier)
Phospholipids
(lecithin)
Thickness
Layer
20-25 Å
THE CELL MEMBRANE
CELL COAT
Cell Coat
Protein 25 Å
Membrane
Phospholipids 25 Å
Protein 25 Å
Inside of the Cell
Schematic Diagram of the Cell membrane Structure having a pore
THE CELL MEMBRANE
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
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
THE CELL MEMBRANE
LIPID BILAYER


Basic structural framework
Consist of two back to back
layers made up of three
types of lipid molecules
– (75%) Phospholipids,
cholesterol, glycolipids
2 layers of phospholipids
• Phosphate head is
polar (water loving)
• Fatty acid tails nonpolar (water
fearing)
• Proteins embedded
in membrane
THE CELL MEMBRANE
Functions
Controls what enters and exits the cell to
maintain an internal balance called
homeostasis
b. Provides protection and support for the cell
have pores (holes) in it
c. Selectively permeable: Allows some molecules
in and keeps other molecules out
d. The structure helps it be selective!
a.
THE CELL MEMBRANE
Types of Cellular Transport

Passive Transport
cell doesn’t use energy
1.
2.
3.

Diffusion
Facilitated Diffusion
Osmosis
Weeee!!!
high
low
Active Transport
cell does use energy
1.
2.
3.
Protein Pumps
Endocytosis
Exocytosis
This is
gonna be
hard work!!
high
low
THE CELL MEMBRANE
Passive Transport (HighLow)



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
Passive Transport (HighLow)
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.
THE CELL MEMBRANE
Passive Transport (HighLow)
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 (HighLow)
Glucose
molecules
2. Facilitated diffusion:
High Concentration
High
Cell Membrane
Low Concentration
Through a 
Transport Protein
Low
THE CELL MEMBRANE
Passive Transport (HighLow)
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
•
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
Potassium
3.5 - 5.0 mEq/L
Calcium, ionized
2.24 - 2.46 meq/L
Sodium
135 - 145 mEq/L
Chloride
98 - 108 mEq/L
Ferritin
Magnesium
1.6 - 2.4 mEq/L
Folate
Phosphate
2.5 - 4.5 mg/dL
Glucose, fasting
13 - 300 (ng/ml)
3.6 - 20(ng/dl)
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
THE CELL MEMBRANE
Hypotonic Solution
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)!
THE CELL MEMBRANE
Hypertonic Solution
Hypertonic: The solution has a higher concentration of solutes and a
lower concentration of water than inside the cell. (High solute; Low
water)
shrinks
Result: Water moves from inside the cell into the solution: Cell
shrinks (Plasmolysis)!
THE CELL MEMBRANE
Isotonic Solution
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)
THE CELL MEMBRANE
What type of solution are these cells in?
A
B
Hypertonic
C
Isotonic
Hypotonic
Prepare one – half sheet of paper
Good Luck
to be continued…