Cells Part II

Cells Part II

Human Anatomy and Physiology I

Oklahoma City Community College

Dennis Anderson

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Solute Concentration of Cells

0.9% NaCl300 Milliosmoles

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Concentration of Solutions

• Normal Saline or Physiological Saline– 300 millisomoles = 0.9% NaCl

• Ringers Solution– Contains NaCl and other salts that make it more

similar to blood plasma– 300 milliosmoles

Amount of solutes dissolved in water

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Hypertonic

A solution with a higher concentration than another

1% NaCl 0.2% NaCl

Hypertonic

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Hypotonic

1% NaCl 0.2% NaCl

Hypertonic

A solution with a lower concentration than another

Hypotonic

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Isotonic

A solution with the same concentration as another

0.9% NaCl 0.9% NaCl

Osmosis

Water moves across a membrane to the side with a higher concentration of

Solutes

Cell in a Hypertonic Solution

300

350 Crenate

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Cell in a Hypotonic Solution

300

250

Swell

Lyse

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Cell in Isotonic Solution

300

300

0.9%

0.9%

No net movement of water

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Isotonic Solutions

• Have the same amount of solutes as body cells– 300 Milliosmoles

– 0.9% NaCl

– 5% Glucose

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Isotonic IV Solutions

• Normal Saline or Physiological Saline– 0.9% NaCl

• D5W (Dextrose 5% in Water)

– 5% Glucose

• Lactated Ringers – Glucose, lactic acid, salt

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Tonicity

Water

Sea WaterD5 1/2 NS

Hypotonic

Hypertonic

Hypertonic

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310 mosm

300 mosm

Which Way Will Fluid Move?

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Fluid Balance

• Fluid leaving body = Fluid entering body

• Right amount of fluid in each compartment

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Electrolyte Balance

• Having the right concentration of various ions in the body– Sodium

– Potassium

– Calcium

– Magnesium

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Fluids and Electrolytes

• Electrolytes attract fluids by osmosis

• Loss of fluids results in a loss of electrolytes

• IV therapy is often needed to restore fluid balance, electrolyte balance or both

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Organs that Regulate Fluid and Electrolyte Balance

• Brain

• Adrenal glands

• Kidneys

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Hypothalamus of the BrainDecreased volume of ECF or

Increased osmolarity of ECF

Hypothalamus

Decreased saliva

Thirsty

Drink FluidIncrease ECF

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Adrenal Gland

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Hypothalamus & Kidneys

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Application Problem 1

•Richard works as a roofer. He is in the hot sun many hours a day. As a result he loses water by perspiration. How does his body maintain homeostasis?

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Answer to Problem 1

• The hypothalamus will make more ADH causing the kidneys to produce less urine.

• His hypothalamus will make him thirsty. This will cause him to drink a lot of liquids

Application Problem 2

Dawn urinates many times during the day but is able to sleep all night without the need to urinate. How do you explain this?

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Answer to Problem 2

• The kidneys produce less urine when you are asleep because the hypothalamus secretes more ADH during sleep.

Application Problem 3

Claudia has had diarrhea for the past two weeks. Her potassium level is only 25% of the normal value. Why is her potassium so low?

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Answer to Problem 3

• Claudia has lost a lot of fluid and with this fluid she has lost potassium.

• She will need to be given potassium immediately or her heart may develop arrhythmias and stop beating.

Application Problem 4

Melissa has been unable to eat anything following her surgery. Her doctor has ordered an IV of D5W. Why did he do this?

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Answer to Problem 4

• The fluid in the D5W will replace fluid she will naturally lose.

• The sugar will provide an energy source for her body.

Application Problem 5

Dr. Quack has told Sally she needs to flush the poisons out of her body. He has been giving her an IV of distilled water twice a week. What are the risks to Sally of this treatment?

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Answer to Problem 5

• Distilled water is hypotonic to blood cells.

• Many of the red blood cells will lyse creating a burden on the liver to cleanse the blood.

• Lack of blood cells could make Sally anemic.

Application Problem 6

Mike has had a severe head trauma. There is swelling on his brain. His doctor has ordered an IV of 20% glucose. Why did he do this?

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Answer to Problem 6

• 20% glucose is hypertonic.

• It will attract fluid from the brain into the blood.

Application Problem 7

Paul has a history of hypertension. His doctor has placed Paul on a low salt diet. What is the rationale for the low salt diet?

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Answer to Problem 7

• Salt will make Paul’s blood hypertonic.

• Fluid will move by osmosis into his blood.

• Increased blood volume will increase blood pressure. 310 mosm

300 mosm

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Ion

• Atom or molecule with a charge

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Solution

• A mixture of two or more substances

• Salt water–salt

–water

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Solvent

• A substance that dissolves solutes in a solution

• Water

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Solute

• Substance that dissolves in a solution

• Salt is a solute in salt water

• Sugar is a solute in sugar water

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Turgor

• Tightness of the skin or a membrane

• Poor skin turgor is a sign of dehydration

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Equilibrium

• When something is balanced with its environment

• A cell in a solution with the same concentration of solutes as the cell

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Cell in Equilibrium

0.9% NaCl

0.9% NaCl

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Dehydration

• Condition of excessive water loss

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Osmotic Pressure

• Measure of the tendency of a solution to attract water by osmosis

• Osmotic pressure increases when the difference in solute concentration between two solutions increases

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0.9% NaCl 0.9% NaCl

1% NaCl 3% NaCl

Which Solution has the Greater Osmotic Pressure?

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Milliosmole

• Unit of measurement of all the solutes in a solution

• Blood has a concentration of 300 milliosomoles

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Edema• The accumulation of excess interstitial fluid in

interstitial spaces (between cells)• Causes swelling• May be caused by increased hydrostatic

pressure in capillaries– congestive heart failure– hypertension– pregnancy

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The End