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CVM 711- Physiology > Lecture 1: Body Fluid Compartments and Transport across cell membranes > Flashcards

Lecture 1: Body Fluid Compartments and Transport across cell membranes Flashcards

1
Q

What is total body water?

A

Total water in the body

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2
Q

The amount of water in the body is __________ related to fat.

A

Inversely

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3
Q

What are the two major fluid compartments and what percentage of body weight do they comprise?

A

Intracellular fluid (ICF)- inside cells, 40% BW
Extracellular fluid (ECF)- outside cells, 20% BW

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4
Q

There are two types of extracellular fluid. What are they and what percentage of total body weight do they comprise?

A

Plasma (inside capillaries)- ~4% total body weight
Interstitial Fluid (bathes cells & tissues)- ~16% total body weight

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5
Q

Total body water is what percentage of body weight?

A

On average 60%
range of 50-70% depending on species

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6
Q

What is the average blood volume? Important number*

A

70mL/kg BW

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7
Q

When measuring the AMOUNT of solutes in fluid compartments, you can measure amounts in _________, __________, or _________.

A

moles, equivalents or osmoles

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8
Q

what is an equivalent?

A

amount of charged solute that has participated in a chemical reaction or electrical process (ex: 2 Eq of Ca and 2 Eq of Cl)

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9
Q

what is an Osmole?

A

number of particles into which a solute dissociates in solution (NaCl= 2 osmoles in solution)

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10
Q

What is osmolarity?

A

osmoles/L

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11
Q

What is electroneutrality?

A

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

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12
Q

What are the major ions in the ECF?

A

Cation: Na+
Anions: Cl- and HCO3- (bicarb)

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13
Q

What are the major ions in the ICF?

A

Cation: K+
Anions: proteins and organic phosphates

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14
Q

What is the normal range of osmolarity?

A

290-300 mOsm/L

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15
Q

What are the two types of Ca in ICF and ECF?

A

Total Ca: bound and ionized Ca
Ionized Ca: Free Ca & active form

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16
Q

Cell membranes are selectively permeable, meaning what?

A

Cell membranes are not freely soluble to all solutes

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17
Q

What are the two transport mechanisms in the cell membrane?

A

Na+/K+ ATPase pump: pumps Na= out of the cell, K+ pumped into cells (because K+ concentration is higher in cells)
Ca2+/ATPase pump: pumps Ca2+ out of cells (pumps Ca2+ out of cells)
both mechanisms directly use ATP*

18
Q

Why are ion concentration differences important?

A

-Allows nerve and muscle cells to have resting membrane potentials (due to K+ difference)
- Upstroke of action potentials in nerve and muscle cells and absorption of nutrients due to Na+ difference
- excitation-contraction coupling in muscle cells depends on Ca2+ difference

19
Q

Cell membranes are composed of lipids and proteins. What are the three types of lipids that are in cell membranes?

A

phospholipids
cholesterol
glycolipids

20
Q

What is the function of lipids in cell membranes?

A

-allow membrane to be permeable to lipid soluble substances (CO2, O2, fatty acids, steroid hormones
low permeability to H2O soluble substances)
- transporters, enzymes, hormone receptors, antigens, ion& H2O channels

21
Q

What is the function of proteins in cell membranes?

A
  • transporters, enzymes, hormone receptors, antigens, ion& H2O channels
22
Q

What is the function of the phospholipid component in cell membranes?

A

Glycerol backbone (water-soluble) + FA tails (lipid-soluble= amphipathic*
*has both polar and non-polar components in its structure

23
Q

Cell membranes can contain peripheral proteins. Where can these proteins be found?

A

Only on one side of the membranes

24
Q

Transport across cell membranes can occur down an electrochemical gradient. What are these types of transport called?

A

Simple Diffusion
Facilitated Diffusion (needs a carrier protein to grab and move)
***No input of energy

25
Q

Transport across cell membranes can occur against an electrochemical gradient. What are these types of transport called?

A

Primary transport- direct input of energy
Secondary transport- use energy to establish the Na+ gradient, then use Na+ to move other substances

26
Q

True or False: Simple Diffusion is NOT carrier-mediated.

A

TRUE
***this is important

27
Q

When two solutions are separated by a membrane permeable to the solute, the solute will ____________ across the membrane.

A

equilibrate

28
Q

What are two additional consequences of charge on an ion that is diffusing?

A

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 to an area with positive charge)
2) A diffusion potential can be created when a charged solute diffuses down its concentration gradient

28
Q

Movement of solute depends on several factors. Name these factors.

A

1) Concentration gradient: driving force, the larger the difference in the concentration gradient, the larger the driving force
2) Partition coefficient: based on the lipid solubility of the solvent (greater the solute’s solubility in oil, the higher the partition coefficient, the more easily it can diffise)
3) Diffusion coefficient: based on the size of the solute and the viscosity of solution ( small solutes in non-viscous solution have a higher diffusion coefficient)
4) Thickness of membrane: thicker the membrane, the lower the diffusion
5) Surface area: greater surface area=higher diffusion rate

28
Q

Facilitated Diffusion: Does it use a carrier protein yes or no? Is there an input of energy yes or no?

A

Yes, uses a carrier protein
No, no input of energy

29
Q

Facilitated diffusion will proceed faster or slower at relatively low solute concentrations? Why?

A

Facilitated diffusion will proceed FASTER at low solute concentrations because there are more carrier proteins available

29
Q

There are 3 features of carrier-mediated transport. Name the 3 and describe them.

A

1) Saturation: carrier proteins have a limited number of binding sites for a solute, therefore: the 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

29
Q

Which type of transport directly uses energy and is carrier-mediated?
A) Primary active transport
B) Secondary active transport
C) Simple Diffusion
D) Facilitated Diffusion

A

A) Primary Active Transport

30
Q

Give the definition of primary active transport.

A

One or more solutes moved AGAINST a concentration gradient directly using ATP

31
Q

What is the Na+/K+ ATPase pump?

A

-Present in membranes of ALL cells
- 3 Na+ pumped to ECF and 2 K+ pumped to ICF, this creates a charge separation and potential difference
- Cardiac glycosides inhibit this protein transporter

32
Q

There are two examples of the Ca2+ ATPase pump. What are they?

A

1) Plasma-Membrane Ca2+ ATPase (PMCA): one Ca is pumped out of the cell for every ATP consumed
2) Sarcoplasmic and Endoplasmic reticulum Ca2+ATPase (SERCA): takes 2 Ca from ICF into SR or ER for every 1 ATP used

33
Q

What is the action of the H+/K+ ATPase pump?

A

Parietal cells of gastric mucosa- pumps H+ into lumen of the stomach

34
Q

What is the definition of secondary active transport?

A

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

35
Q

Co-transport (aka symport) is an example of secondary active transport. What does this mean?

A
  • all solutes are transported in the same direction
  • Na+/Glucose co-transporter (SGLT 1)
  • Na+/Amino acid co-transporter
  • Na+/K+/2Cl- co-transporter in renal tube
36
Q

Counter-Transport (aka antiport) is an example of secondary active transport.

A
  • Solutes move in opposite directions- Na+ moves INTO the cell and other solute moves OUT of the cell
  • Ca2+/Na+ exchange
  • Na+/H+ exchange

CVM 711- Physiology (19 decks)

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