Download Body Fluids

Memmler’s
The Human Body in Health and Disease
11th edition
Chapter 21
Body Fluids
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Importance of Water
Body fluid maintenance
• Thirst mechanism maintains volume
• Kidney activity regulates volume and composition
• Hormones regulate fluid volume and electrolytes
• Buffers, respiration, and kidney function regulate pH
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Fluid Compartments
• Intracellular fluid (ICF)
– Two-thirds to three-fourths of all body fluids
• Extracellular fluid (ECF)
– Interstitial fluid
– Blood plasma
– Lymph
– Fluid in special compartments
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Main fluid
compartments
showing relative
percentage by
weight of body fluid.
Fluid percentages
vary but total about
60% of body
weight. Fluids are
constantly
exchanged among
compartments, and
each day fluids are
lost and replaced.
Zooming In: What
are some avenues
through which
water is lost?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 21-1: What are the two main
compartments into which body fluids are
grouped?
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Water Balance
• Water gain from
– Beverages
– Food
– Cellular respiration
• Water loss from
– Kidneys
– Skin
– Lungs
– Intestinal tract
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 21-2: What are three routes for
water loss from the body?
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Sense of Thirst
Control center for thirst
• Located in hypothalamus
• Regulates total fluid volume
• Excessive thirst -- polydipsia
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Checkpoint 21-3: Where is the control center
for the sense of thirst located?
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Electrolytes and Their Functions
Conduct electrical current in solution
• Positive ions (cations)
– Sodium
– Potassium
– Calcium
• Negative ions (anions)
– Phosphate
– Chloride
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Checkpoint 21-4: What is the main cation in
extracellular fluid? In intracellular fluid?
Checkpoint 21-5: What is the main anion in
extracellular fluid?
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Electrolyte Balance
• Kidneys do majority of balancing
• Hormones involved
– Aldosterone (adrenal cortex)
– Antidiuretic hormone (ADH) (pituitary)
– Parathyroid hormone (parathyroid & thyroid glands)
– Calcitonin hormone (thyroid)
– Atrial natriuretic peptide (ANP) (from the heart)
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Checkpoint 21-6: What are some
mechanisms for regulating electrolytes in body
fluids?
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Question:
When blood concentration of sodium
rises, the pituitary secretes what
hormone?
a. ANP
b. ADH
c. calcitonin
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer:
b. ADH (antidiuretic hormone)
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Acid–Base Balance
• pH scale measures hydrogen ion (H+) concentration
• Body fluids have normal pH of 7.35 to 7.45
• Three-tenths of a point shift in either direction is fatal
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Regulation of pH
• Buffer systems accept or release ions as needed
– Bicarbonate
– Phosphate
– Proteins
• Respiration provides short-term regulation
• Kidney function provides long-term regulation
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Checkpoint 21-7: What are three
mechanisms for maintaining the acid–base
balance of body fluids?
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Abnormal pH
• Acidosis
– pH less than 7.35
– Depressed nervous system
• Alkalosis
– pH greater than 7.45
– Excited nervous system
• Origins
– Respiratory—change in blood CO2
– Metabolic—change in other acids
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Checkpoint 21-8: What are the conditions
that arise from abnormally low or high pH of
body fluids?
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Disorders of Body Fluids
• Edema
• Water intoxication
• Effusion
• Ascites
• Dehydration
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Checkpoint 21-9: What is edema?
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Question:
What is effusion?
a. accumulation of excess fluid in
intercellular spaces
b. fluid leakage into a cavity
c. deficit of body fluids
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer:
b. fluid leakage into a cavity
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Fluid Therapy
Fluids administered intravenously
• Normal (.9%) saline
• 5% dextrose in .45% saline
• 5% dextrose in water
• Ringer lactate solution
• Serum albumin 25%
• Nutritional solutions
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End of Presentation
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins