1. Chapter 21: Body Fluids

2. Overview

3. Key Terms acidosis cation interstitial
alkalosis dehydration intracellular
anion edema kektoacidosis
ascites effusion pH
buffer extracellular polydipsia

4. Water and Its Functions
Learning Outcomes
1. Compare intracellular and extracellular fluids.
2. List four types of extracellular fluids.
3. Name the systems that are involved in water balance.
4. Explain how thirst is regulated.

5. 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.

6. 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

7. Figure 21-1 Main fluid compartments showing relative percentage by weight of body fluid.
What are some avenues
through which water is lost?

8. Water Balance Water gain from Beverages Food Cellular respiration
Water loss from
Kidneys
Skin
Lungs
Intestinal tract

9. Sense of Thirst Control center for thirst Located in hypothalamus
Regulates total fluid volume
Excessive thirst—polydipsia

10. Figure 21-2 Daily gain and loss of water.
In what way is the most
water lost in a day? 10

11. Water and Its Functions✓
Water and Its Functions
Checkpoints
21-1 What are the two main compartments into which body fluids are grouped?
21-2 What are the four routes for water loss from the body?
21-3 Where is the control center for the sense of thirst located? 11

12. Electrolytes and Their Functions
Learning Outcomes
5. Define electrolytes and describe some of their functions.
6. Describe the role of hormones in electrolyte balance.

13. Electrolytes and Their Functions
Conduct electrical current in solution
Positive ions (cations)
Sodium
Potassium
Calcium
Negative ions (anions)
Phosphate
Chloride

14. Figure 21-3 Distribution of some major ions in intracellular and extracellular fluids.
What ions are highest in extracellular fluids?
In intracellular fluids? 14

15. Electrolyte Balance Kidneys do majority of balancing Hormones involved
Aldosterone (adrenal cortex)
Antidiuretic hormone (ADH) (pituitary)
Parathyroid hormone (parathyroid and thyroid glands)
Calcitonin hormone (thyroid)
Atrial natriuretic peptide (ANP) (from the heart)

16. Electrolytes and Their Functions✓
Electrolytes and Their Functions
Checkpoints
21-4 What is the main cation in extracellular fluid? In intracellular fluid?
21-5 What is the main anion in extracellular fluid?
21-6 What are some mechanisms for regulating electrolytes in body fluids? 16

17. Acid-Base Balance Learning Outcomes
7. Describe three methods for regulating the pH of body fluids.
8. Compare acidosis and alkalosis, including possible causes.

18. 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

19. 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

20. 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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22. ✓ Acid-Base Balance Checkpoints
21-7 What are three mechanisms for maintaining the acid–base balance of body fluids?
21-8 What are the conditions that arise from abnormally low or high pH of body fluids? 22

23. Disorders of Body Fluids
Learning Outcome
9. Describe three disorders involving body fluids.

24. Disorders of Body Fluids
Edema
Water intoxication
Effusion
Ascites
Dehydration

25. Figure 21-4 Edema of the foot.25

26. Figure 21-5 Simple test for dehydration.26

27. Disorders of Body Fluids✓
Disorders of Body Fluids
Checkpoints
21-9 What is edema?
21-10 What is ascites? 27

28. Fluid Therapy Learning Outcome
10. Specify some fluids used in therapy.

29. Fluid Therapy Fluids administered intravenously Normal (0.9%) saline
5% dextrose in 0.45% saline
5% dextrose in water
Ringer lactate solution
Serum albumin 25%
Nutritional solutions

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31. ✓ Fluid Therapy Checkpoint
21-11 When might it be necessary to administer intravenous fluids? 31

32. Case Study Learning Outcome
11. Referring to the case, describe why elderly people are particularly susceptible to dehydration. 32

33. Word Anatomy Learning Outcome
12. Show how word parts are used to build words related to bodily fluids. 33

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