Flow Down Gradient Flashcards by Ashley Atkins

Flow is measured by the ________________ that moves over ________.

amount of substance, over time

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What is the driving force for the flow of a substance?

energy gradient between point A and point B

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The amount of flow is directly related to the size of the ___________ between A and B

energy gradient

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The greater the gradient, the (greater/lesser) the flow.

greater

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______________ pressure causes gas or liquid to flow from point A to B.

Hydrostatic

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Physical structures (resist/encourage) flow.

resist

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True or false.
The viscosity of the fluid impacts flow.

True

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F = (P1 – P2) · (𝝅𝒓^𝟒)/𝟖𝝁𝒍
What law is this and what does it determine?

Poiseuille’s law. Rate of flow

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(PL)
F= ___________

Flow. The volume of liquid that passes through a tube per unit time. (i.e L/min)

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(PL)
P= _____________

hydrostatic pressure. The force that a substance exerts on the walls of its container

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(PL)
r=__________

radius of the tube that the fluid is moving through

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(PL)
l = _____________

length of the tube

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(PL)
𝝁 = _____________

viscosity of the fluid

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(PL) When hydrostatic pressure and radius increase, flow (increases/decreases)?

increases

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(PL) When length of tube and viscosity of fluid increase, flow (increases/decreases)?

decreases

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(PL)Which law does the body’s control of flow through vessels by: controlling pressure in large vessels and radius of small vessels relate to?

Poiseuille’s law

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(PL)What happens to the resistance if the radius decreases by half?

The resistance increases by a factor of 16 when the radius decreases by half.

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(PL)As tubes become more branched or irregularly-shaped, its harder to quantify what?

resistance

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(PL)If flow becomes turbulent, the resistance will (change as well/remain the same)?

change as well

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(PL)If a tube is flexible - like an artery - Poiseuille’s law is (more accurate/ not exact)

Not exact

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(PL)What is the most important determinant of resistance?

radius of the tube

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(FL)Movement of a solute or a gas in a gas mixture from an area of high concentration to low concentration is known as what?

diffustion

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___________ law quantifies how the rate of diffusion is affected by various parameters.

Fick’s law

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What are the parameters in Fick’s law that quantify the rate of diffusion?

Flow=flux (amount of solute moving across a barrier per unit of time

Force driving flux —> concentration gradient (C2-C1) difference in concentration on either side of the membrane

resistance: membrane surface area and thickness. Permeability of the membrane to the substance

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𝑭=𝒌 ∙ (𝑨(𝑪_(𝑨 )−𝑪_(𝑩 )) )/𝒕 What law is this?

Fick's law

(FL) F=________

Flow/flux Number of molecules of a substance diffusing from A to B over time

(FL) (CA-CB) = _______

Concentration gradient. Difference in concentration on either side of the membrane

(FL) A=___________

Surface area of the membrane

(FL) k=a constant that increases when: (2)

1.) the substance is a smaller molecule that dissolves better in the barrier 2.) the permeability of the barrier to the substance increases`

(FL) t= ____________

thickness of the membrane

(FL) Flow (increases/decreases) when concentration gradient increases.

increases

Flow (increases/decreases) when surface area increases.

increases

Flow (increases/decreases) when thickness of the membrane increases.

decreases

Flow (increases/decreases) when the substance is a smaller molecule that dissolves better in the barrier.

increases

Flow (increases/decreases) when the permeability of the barrier to the substance increases.

increases

Which systems/locations in the body are affected by Fick's Law?

Solutes through capillaries Substances through cell membranes Oxygen and CO2 from alveolus to blood

(FL) Membranes have channels or transporters in order to increase __________ of the membrane.

permeability

The need for channels/transporters depends on the __________ of the substance in the membrane.

solubility

Diffusion__________ is a common theme in disease

failure

_________ law relates to the rate of flow of charges across a membrane, which is known as _________.

Ohm's law current (I)

𝐼= 𝑉/𝑅 Equation for what law?

Ohm's law

(OL) I= _________

Current.

(OH) V=________

voltage

(OL) R= ________

resistance

(OL) _______ is the number of charges or charged particles that move across the membrane per unit of time.

Current

___________ is the energy generated by separating charges across the cell membrane.

Voltage

_____________ is the electrical property of a component or material that impedes the flow of electric current

resistance

(OL) Current (increases/decreases) when voltage increases.

increases

(OL) Current (increases/decreases) when resistance increases.

decreases

In Ohm's law, do opposites attract, and like charges repel?

Yes

What is responsible for establishing voltage?

Electric field of the the charged particle.

(OL) The particles move (down/up) a gradient of voltage according to their charge.

down

In biology, which law is most useful when thinking about unequal distributions of charges very close on either side of a membrane?

Ohm's law

True or false. Overall positive and negative charges are balanced in all physiologic compartments.

True

The electric field (increases/declines) very rapidly as charges are separated by distance.

declines

True or false. Is all situations in physiology, there is only one force that acts on a substance at a time.

False. There are many situations in physiology where more than one force acts on the same substance

The purpose of a ___________ is to transport substances to and from tissues.

capillaries

𝐹𝑙𝑢𝑥=([("𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝐹𝑜𝑟𝑐𝑒𝑠")−("𝐷𝑖𝑓𝑓𝑢𝑠𝑖𝑜𝑛 𝐹𝑜𝑟𝑐𝑒𝑠")])/("𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑜 𝐻2𝑂 𝑓𝑙𝑢𝑥") 𝐅𝐥𝐮𝐱 = 𝐋𝐩[ (𝐏𝐜𝐚𝐩−𝐏𝐈𝐒𝐅 )−𝛔(𝛑𝐜𝐚𝐩−𝛑𝐈𝐒𝐅)] What equation is this?

Starling forces

(SF) Lp=__________

the "leakiness" of the capillary wall to water (inverse of resistance)

(SF) P= __________

Hydrostatic pressure

(SF) 𝛑 = ________

osmotic pressure

(SF) "cap"= _______

fluid within the capilllary

(SF) "ISF"=_______

fluid within the interstitial space

(SF) 𝛔=____________

how much protein leaks through the capillary wall

True or False. Starling forces are easy to measure experimentally.

False. They are difficult to measure because the value of the variables in different situations and in different locations is the subject of much debate

Flux vs. flow?

Flux= flow along a defined membrane surface area

Starling forces can describe tissue (swelling/bleeding) in a wide variety of situations.

Swelling. Inflammmation/infection. Changes in pressure within the circulation

_________particles can move across a membrane based on electrostatic forces

charged CHARGED=ELECTROSTATIC FORCES

____________ particles can move across a membrane based on their concentration gradient Energy “powering”

Dissolved DISSOLVED=CONCENTRATION GRADIENT

Which equation tells us: Diffusional forces and electrical fields are very small at large distances (Distribution of ions very close to either side of the membrane) The charge of the particle The ratio of the particle's concentration intracellular: extracellular

Nernst potential

What does the Nernst potential NOT include?

The flow of ions (current) The resistance of the membranes to flow

𝐸𝑃= ((−60𝑚𝑉))/𝑍𝑝 𝑙𝑜𝑔10 [𝑃]𝑖/[𝑃]𝑜 What equation is this?

Nernst potential

(NP) Ep= __________

The membrane voltage at which a particle (P) moves in and our of the cell at the same rate (EQUALIBRIUM)

(NP) Zp=__________

The charge and valence of P (anions are negative)

(NP) [𝑃]𝑖/[𝑃]𝑜 =____________

ratio of intracellular: extracellular concentrations a P

Nernst potential describes the ________ across a membrane that is permeable to P given the ratio of ____________

voltage of [P] inside: outside

Because living cells always have a membrane potential that is established by selective transporters and channels, it is helpful to understand what?

Nernst potential

What functions (3) do the charge and ion balance serve?

1.) cellular signaling 2.) transport of substances 3.) regulation of cell volume

A neuron relies on an inside-(negative/positve) membrane potential for the purposes of signaling

negative

The membrane potential is about______ mV in many neurons

-75

The Nernst potential for potassium is close to _____mV

-90