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1

Factors that affect rate of diffusion

Concentration, surface area, solubility, membrane thickness, molecular weight

2

Conditions that increase membrane thickness

Lung fibrosis, pulmonary edema, pneumonia, membranous glomerulonephritis

3

Conditions that affect surface area of the membrane

Exercise (increases SA), emphysema (decreases SA)

4

Osmoles Vs. mole Vs. mEq

150 mM of NaCl = 300 mOsm. Moles yield osmoles. 10 mOsm Ca++ = 20 mEq

5

Characteristics of protein-mediated transport

More rapid than diffusion, transport can be saturated (Tm), is chemically specific, substances compete for transporter

6

Types of protein transport

Facilitated (down a concentration gradient), active (against gradient, requires ATP)

7

Primary active transport

ATP consumed directly by the transporter. E.g. Na/K countertransport

8

Secondary active transport

Depends indirectly on ATP. E.g. Na/glucose cotransporter in the renal tubule depends on Na/K countertransporter

9

Constitutive endocytosis

Vesicles are continuously fusing with the cell membrane

10

Receptor-mediated endocytosis

The ligand binds receptor near clathrin-coated pits. More rapid and specific than constitutive endocytosis.

11

Simple diffusion curve in a graph

Linear. Slope increases if diffusion area or concentration increases. Slope decreases if membrane thickness increases

12

Facilitated diffusion curve in a graph

Reaches a plateau which represents Tm. Adding more transporters raises Tm, shifts curve up and right.

13

Amount of total body water

60% of weight in kg. 70kg = 42 L

14

Amount of intracellular fluid

2/3 of total body water or 40%. 42 L --> 28 L ICF

15

Amount of extracellular fluid

1/3 of total body water or 20%. 42 L --> 14 L ECF

16

Amount of interstitial fluid

2/3 of ECF. 14 L --> 10 L ISF

17

Amount of plasma volume

1/3 of ECF. 14 L --> 4 L plasma

18

Effective osmolarity

Represented by non-penetrating solutes such as Na. If effective osmolarity increases, cells shrink and vice versa.

19

Capillary membranes

Are freely permeable to substances dissolved in plasma except proteins. Separate ISF and plasma.

20

Isotonic fluid loss diagram

Decreased ECF, no change in ICF. Causes: hemorrhage, isotonic urine, diarrhea, vomiting

21

Loss of hypotonic fluid diagram (hypovolemia)

Decreases ECF and ICF, increases osmolarity. Causes: dehydration, sweating, diabetes insipidus.

22

Gain of hypertonic fluid diagram

Increases osmolarity and ECF, decreases ICF. Causes: salt tablets, mannitol, hypertonic saline, aldosterone

23

Gain of hypotonic fluid diagram

Decreases osmolarity, increases ECF and ICF. Causes: SIADH, drinking tap water, primary polydipsia.

24

Gain of isotonic fluid diagram

Osmolarity stays the same, ECF increases. Causes: isotonic saline infusion.

25

Loss of hypertonic fluid diagram

Osmolarity decresaes, ECF decreases, ICF increases. Causes: mineralocorticoid deficiency

26

?ECF, no change in osmolarity or ICF, isotonic urine

Loss of isotonic fluid. Causes: hemorrhage, diarrhea, vomiting

27

?ECF, ?osmolarity, ?ICF

Loss of hypertonic fluid or hyponatremic hypovolemia. Aldosterone deficiency.

28

?ECF, ?osmolarity, ?ICF, little concentrated urine

Loss of hypotonic fluid or hypernatremic hypovolemia. Cause: Dehydration

29

?ECF, ?osmolarity, ?ICF, lots of diluted urine

Loss of hypotonic fluid or hypernatremic hypovolemia. Cause: diabetes insipidus

30

?ECF, no change in ICF or osmolarity

Gain of isotonic fluid. Cause: isotonic saline infusion