Chapter 25: Body Fluids and Compartments (Discussion 1)

Question 1

Liquid Intake (2)

Answer 1

Ingest H2O & Foods

Synthesis from oxidation of carbs

Question 2

Liquid Output (4)

Answer 2

Insensible H2O loss (diffusion through skin/evaporation from respiratory membranes)
Sweat
Kidneys (urine)
Feces

Question 3

Body Fluid Composition

Answer 3

3/5 of the body

2/3 Intracellular Fluid (ICF) = 28 L
1/3 Extracellular Fluid (ECF) = 14L

Question 4

Extracellular Fluid Composition

Answer 4

Plasma (3L)

Interstitial Fluid (1L)

Transcellular:

a. Synovial (joints)
b. Peritoneal (abdominal cavity lining)
c. Pericardial (around heart)
d. Cerebrospinal fluid (brain and spine)
e. Intraocular

Question 5

Blood Composition

Answer 5

Plasma, cells, proteins

Blood volume - 5 L

Question 6

Hematocrit

Answer 6

% of blood composed of red blood cells (RBCs)
Men: 0.4
Women: 0.36

Question 7

Anemia

Answer 7

Decreased hematocrit

Question 8

Polycythemia

Answer 8

Increased hematocrit

Question 9

Donnan Effect

Answer 9

Large, impermeable proteins (- charge) in plasma attract cations, slightly higher cation concentration in plasma than interstitium

Question 10

ICF Ions

Answer 10

K+
Ca++
Mg++
PO4 -3
Protein (mostly - charge)

Question 11

ECF Ions

Answer 11

Na+ (originally sea water)
HCO3-
Cl-

Question 12

Osmosis

Answer 12

Diffusion of water across a semi-permeable membrane to region of higher solute concentration

Cell membranes mostly permeable to water/impermeable to ions.

Question 13

Osmotic pressure (pi)

Answer 13

Amount of pressure needed to oppose osmotic forces

Question 14

Tonicity

Answer 14

Defined w/ relationship to other side of membrane

It is the solute concentration of the ECF in relation to the solute concentration inside the cell

Question 15

Isotonic

Answer 15

Same concentration –> no change

Question 16

Hypotonic

Answer 16

Lower concentration than cell –> increase cell volume

Question 17

Hypertonic

Answer 17

Higher concentration than cell –> decrease cell volume

Question 18

What ions account for most solute in ECF

Answer 18

Na and Cl (~140 mEq/L)

Question 19

Hyponatremia

Answer 19

Decrease Na in plasma

Caused by hypo-osmotic overhydration or hypo-osmotic dehydration

Question 20

Hypo-osmotic Overhydration

Answer 20

Excess H2O

Excess ADH (causes H2O reabsorption in kidneys), or drinking a ton of water

↑ICF and ↑ECF volume

Question 21

Hypi-osmotic Dehydration

Answer 21

Loss of NaCl

Diarrhea, vomiting, excess diuretics, Addison’s disease (↓ aldosterone [aldosterone helps reabsorb NaCl])

↓ECF and ↑ICF volume

Question 22

Hypernatremia

Answer 22

Increase Na in plasma

Question 23

Hyper-osmotic Overhydration

Answer 23

Increase in NaCl

↑ aldosterone (Conn’s syndrome)

↑ECF ↓ICF

Question 24

Hyper-osmotic Dehydration

Answer 24

Decrease in H2O

Dehydration (sweating), central diabetes insipidus (No ADH), “Nephrogenic” diabetes insipidus (kidneys don’t respond to ADH)

↓ICF and ↓ECF volume

Question 25

Edema

Answer 25

Excess fluid buildup in tissues

Question 26

IC edema

Answer 26

↓nutrition or ↓metabolism in tissue --> Damaged ion pumps --> ↑ ICF [ion] --> osmosis of H2O into cell --> Inflammation --> ↑cell membrane permeability

Question 27

Filtration Rate

Answer 27

Kf x (Pcapillaries – PIF - πc+ πIF) Kf: capillary filtration coefficient Filtration = Kf x NFP

Question 28

Increase in Pcapillaries

Answer 28

Excessive H2O retention (kidneys) | Increase venous pressure (heart failure)

Question 29

Decrease in πc

Answer 29

Nephrotic syndrome (↓plasma [protein]) Liver cirrhosis: ↓plasma protein production; Portal vein compressed --> ↑Pc --> fluid build-up in abdomen (ascites)

Question 30

Increase in πIF

Answer 30

Lymphatic blockage - prevent IF flow Due to: infection, cancer, surgery

Question 31

Safety Factors Against Edema (3)

Answer 31

1. Low tissue compliance Functional at negative pressure (IF is actually more of gel w/o any free fluid) IF normally ~-3 mmHg 2. Increase lymphatic flow (can increase x10-50) Safety factor of ~7 mmHg 3. IF "protein washdown" as filtration increases Safety factor of ~7 mmHg

Question 32

Effusion

Answer 32

Edema in potential spaces

Question 33

Potential Spaces

Answer 33

Pleural Cavity Pericardial Peritoneal (abdominal effusion is called ascites) Synovial - joint and bursae (small fluid sacks in joints)