Body Fluid compartments and transport across cell membranes

Question 1

How do you calculate total body water?

Answer 1

weight in kg x .6= total body water

Question 2

what percent of BW is total body water?

Answer 2

60%

Question 3

what is the relationship between water and fat?

Answer 3

inversely related (i.e. more fat an animal has, less water)

Question 4

what are the 2 major fluid compartments?

Answer 4

intracellular fluid (ICF) and extracellular fluid (ECF)

Question 5

what makes up the extracellular fluid?

Answer 5

plasma and interstitial fluid

Question 6

what % of BW is intracellular fluid?

Answer 6

40% BW

Question 7

what % of BW is extracellular fluid?

Answer 7

20% BW

Question 8

what % of BW is interstitial fluid?

Answer 8

16%

Question 9

what % of BW is plasma?

Answer 9

4%

Question 10

what is the average blood volume?

Answer 10

6-8% of BW or 60-80 mL/kg BW

Question 11

how do you measure AMOUNTS?

Answer 11

in moles, equivalents, or osmoles

Question 12

equivalent=

Answer 12

amount of charged solute (CaCl2= 2 Eq of Ca and 2 Eq of Cl)
- moles of solute multiplied by its valence
- Ca=valence 2+
- 1 mole of Ca= 2 Eq Ca + 2 Eq Cl

Question 13

osmole=

Answer 13

of particles into which a solute dissociates in solution (NaCl= 2 osmoles in solution)
- contribute to osmotic pressure
- 2 osmol/L for osmolarity (concentration)

Question 14

how do you measure CONCENTRATIONS?

Answer 14

in mol/L or mmol/L, mEq/L, Osm/L or mOsm/L

Question 15

osmolarity=

Answer 15

osmoles/L

Question 16

pH expresses…

Answer 16

H ion concentration

Question 17

H ion concentration in body fluid are….

Answer 17

relatively low, so expresses as a logarithmic term (pH)

Question 18

what is electroneutrality?

Answer 18

each body fluid compartment must have the same concentration of cations as of anions

Question 19

what are the major ions in ECF?

Answer 19

• major cation= Na+
• major anions= Cl- and HCO3-

Question 20

what are the major ions in ICF?

Answer 20

• major cations= K+
• major anions= proteins (negatively charged) and organic phosphates

Question 21

what is specific to the ICF?

Answer 21

• low ionized Ca2+ and more acidic
• ionized Ca= free Ca -> biologically active
• total Ca= ionized and bound Ca

Question 22

what is the osmolarity in the ECF and ICF?

Answer 22

THE SAME!- electroneutrality maintained

Question 23

what is normal osmolarity?

Answer 23

290-300 mOsm/L

Question 24

selectively permeable

Answer 24

cell membranes ARE NOT freely soluble to all solutes

Question 25

what are transport mechanisms in the cell membrane?

Answer 25

- Na+/K+ ATPase pump - Ca2+/ATPase pump

Question 26

what does the Na+/K+ ATPase pump do?

Answer 26

pump Na out of cell and K into cell; creates high [Na] outside the cell - DIRECTLY USES ATP

Question 27

what does the Ca2+/ATPase pump do?

Answer 27

pumps Ca out of the cell

Question 28

why are ion concentration differences important?

Answer 28

1. allows nerve and muscle cells to have resting membrane potentials (DUE TO K+ DIFFERENCE) 2. upstroke of action potentials in nerve and muscle cells, and absorption of nutrients DUE TO NA+ DIFFERENCE 3. excitation-contraction coupling in muscle cells DEPENDS ON CA2+ DIFFERENCE

Question 29

what are cell membranes composed of?

Answer 29

lipids and proteins

Question 30

what are examples of lipids?

Answer 30

- phospholipids, cholesterol, glycolipids

Question 31

what is important about lipids?

Answer 31

- allow membrane to be permeable to lipid soluble substances - CO2, O2, fatty acids, steroid hormones receptors, antigens, ion and water channels

Question 32

what is the phospholipid component of the cell membrane?

Answer 32

- glycerol backbone (water-soluble) + FA tails (lipid-soluble)= amphipathic - helps to form a lipid bilayer

Question 33

what are the protein components of the cell membrane?

Answer 33

- integral proteins: can be transmembrane proteins (hormone or neurotransmitter receptors, pores, ion channels) - peripheral proteins: NOT bound to membrane, loosely attached

Question 34

how can transport occur DOWN an electrochemical gradient?

Answer 34

- simple or facilitated diffusion - no input of energy

Question 35

how can transport occur AGAINST an electrochemical gradient?

Answer 35

- primary transport (direct input of energy) - secondary transport (indirect input of energy)- i.e. using a Na gradient established using primary transport

Question 36

is simple diffusion carrier-mediated?

Answer 36

NO! only one that doesn't need carrier!

Question 37

what happens when 2 solutions are separated by a membrane permeable to the solute?

Answer 37

the solute will equilibrate across the membrane

Question 38

what factors does the movement of solute depend on?

Answer 38

1. concentration gradient- driving force (larger [ ] diff., greater driving force) 2. partition coefficient- based on lipid solubility of solute (greater the lipid solubility of solute, easier it can diffuse) 3. diffusion coefficient- based on size of solute and viscosity of solution (very small solutes moving through a non-viscous solution diffuse easily) 4. thickness of membrane 5. surface area- greater surface area= higher diffusion rate

Question 39

what are 2 additional consequences of CHARGE on an ion that is diffusing?

Answer 39

1. a potential difference across a membrane will alter the rate of diffusion of a charged solute - diffusion of a positively-charged ion will slow down if diffusing into an area of positive charge 2. a diffusion potential can be created when a charged solute diffuses down its concentration gradient

Question 40

what is facilitated diffusion?

Answer 40

- uses a carrier protein, NO INPUT OF ENERGY - because of limited # of carriers, it will proceed faster at relatively low solute concentrations

Question 41

what is an example of facilitated diffusion?

Answer 41

GLUT4 transporter in skeletal and adipose tissue - transports glucose into cells - D-galactose also competes for binding - this affects rate of transport - facilitated diffusion level off at saturation, while simple keeps going as long as there is conc. gradient

Question 42

what are features of carrier-mediated transport?

Answer 42

1. SATURATION - carrier proteins have limited # of binding sites for solute; therefore: RATE of transport increases at a higher rate at lower solute concentrations 2. STEREOSPECIFICITY - binding sites for solute on carrier proteins are specific 3. COMPETITION - although binding sites are specific, carriers may recognize and bind chemically-related solutes

Question 43

what is primary active transport?

Answer 43

one or more solutes MOVED AGAINST a concentration gradient directly using ATP

Question 44

what is the Na+/K+ ATPase pump?

Answer 44

- present in membranes of ALL cells - 3 Na+ pumped to ECF and 2 K+ pumped to ICF- creates a charge separation and POTENTIAL DIFFERENCE - cardiac glycosides inhibit this protein transporter

Question 45

what is the Ca2+ ATPase pump?

Answer 45

- plasma-membrane Ca2+ ATPase (PMCA) - sarcoplasmic and endoplasmic reticulum Ca2+ ATPase (SERCA)- 2 Ca from ICF into SR or ER for every ATP

Question 46

what is the H+/K+ ATPase pump?

Answer 46

parietal cells of gastric mucosa- pumps H+ into lumen of stomach

Question 47

What is secondary active transport?

Answer 47

indirectly uses energy by utilizing the Na+ gradient to transport solutes against their concentration gradient

Question 48

describe co-transport (symport)

Answer 48

- all solutes transported in same direction - Na+/glucose co-transporter (SGLT1) - Na+/amino acid co-transporter - Na+/K+/2Cl- co-transporter in renal tubule

Question 49

describe counter-transport (antiport)

Answer 49

- solutes move in opposite directions- Na+ moves INTO cell and other solute moves OUT of cell - Ca2+/Na+ exchange - Na+/H+ exchange