Intro and body fluid Flashcards
what is physiology?
-study of normal function of the body and how the body maintains those normal functions
what is homeostasis?
- steady state
- inputs change and produce error, but outputs remain normal
- requires energy input
in general, what is feedback control?
-how we sense and react to changes to maintain homeostasis
what is negative feedback control?
- output reduces initial error
- generally good
what is positive feedback control?
- output in the same as the initial error
- rare
- ALWAYS leads to an event
in regards to feedback, when does disease and pathology occur?
- when errors exceed ability of control system to adjust
- eventually, body can no longer compensate for errors
compensation is never complete as long as…
error signal exists
what is full compensation
- the body’s best response
- normal function may or may not be restored
what is the range like for serum potassium and why is that important?
- super tight range 3.5-5mEq/L
- as little as 1mEq/L change can lead to death
- changes electrical activity of the heart
what are old people more likely for heat stroke?
-lose muscle mass as you age so you have less water
what percentage of body weight is water?
60%ish
-varies with age, race, fitness level
what is the relationship of water and body fat?
- inverse!
- more body fat means less water
what are the two compartments of body water?
- intracellular fluid
- Extracellular fluid
which water compartment is he biggest?
ICF
which compartment is it where all of the changes are actually happening?
ECF
which compartment allows for metabolic reactions?
ICF
what is intracellular fluid?
- fluid inside ALL of the cells of the body
- maintained by the cell membrane
- allows all solutes to be dissolved in the same medium
what are the two parts of extracellular fluid?
- interstitual fluid
- plasma
what are the two compartments of ECF separated by?
capillary wall
what is interstitual fluid?
-fluid around cells
what is plasma?
-fluid portion of blood
in which compartment would you expect the greatest volume change as a result of sweating?
ECF
what is ICF mostly made of? ECF?
ICF: potassium and proteins
ECF: sodium and chloride
what is osmolarity?
amount of stuff dissolved in water
the number of ions in water (mOsm) is important when considering what?
concentration gradients
the charge of dissociated ions (mEq) is important when considering?
electrochemical gradiants
what is pH?
-negative log of the amount of acid
what is found in plasma and not in interstitual fluid? why?
- proteins!!!
- proteins are too big to get through the capillaries
what are the three things that are dependent on gradients and necessary for life?
- communication uses potassium gradient (fire action potentials)
- proper absorption of nutrients uses sodium gradient
- movement of muscles uses movement of calcium
compartment content is based on what?
-membrane permeability
what does the capillary membrane filter based on?is it selective or nah?
- based on size
- not selective
is the cell membrane selective?
yes! very selective!
what can cross the cell membrane?
- small, non polar solutes
- oxygen
- carbon dioxide
- ethanol
why is water allowed across the cell membrane?
its polar, but there is so much that it gets across by mass action
what are the two ways things can get across selectively membranes?
- channels
- transport proteins
what are channels? are they specific? do they need a gradient?
- holes in the membrane for specific solutes to move along a gradient
- can be specific or not
- needs a gradient
what are transport proteins?
- bind to large solutes to more with or against gradient
- can use a gradient or not
which transport needs energy?
active transport
how does passive transport move things?
- with the gradient (from high concentration to low)
- diffusion or facilitated diffusion
how does active transport move things?
- against the gradient (from low to high)
- energy required
what is diffusion?
-movement of solutes from an area of higher to lower concentration
what two things would make diffusion go faster?
- larger gradient
- higher temperature
what is the difference between diffusion and facilitated diffusion?
-facilitated diffusion uses a transport protein
in order for a solute to diffuse through a membrane, what must the membrane have?
-it must be permeable to that solute
in active transport, the carrier proteins are usually called what?
-ATPase, porter, or exchanger
what is symport?
-active transport that moves different solutes in the same direction
what is an example of symport?
moving sodium and glucose into the cell into the small intestine and kidney
-SGLT1
what is an example of secondary active transport?
SGLT1
what is antiport?
-active transport moving different solutes in opposite directions
what is an example of antiport?
- NCX
- moving calcium out of the cell and sodium into the cell
- retina
what distinguishes the different types of active transport?
-based on where the energy is expended
what is primary active transport?
-ATP is used to directly move the solutes
what is secondary active transport?
-the gradient set up by the primary transport is used to move the solutes
what is tertiary active transport?
-cargo brought in by secondary transport is used to bring in another solute
how does digitalis increase strength of cardiac contractions?
- inhibits sodium/calcium channel
- makes a smaller gradient
- less sodium coming into cell, so less calcium is kicked out of the cell
- if the cell has more calcium, the muscle contracts more
what is the transport maximum?
-max rate of transport movement
when does saturation of transporters occur?
-when concentration of a solute is greater than the number of available transporters can handle
does the transportation rate always increase when you increase the concentration of the solute?
no!
-if youre already at the max rate, it wont matter if you add more solute because its already going as fast as it can.
what causes glucosuria in diabetes?
-glucose transporters reach max and so there is a build up of solute in urine
what kind of specificity do transport proteins have?
-stereospecificity
how do you trick transport proteins?
-hook a medication onto the thing it can bind to so the medication can be transported too
what would the transport rate do if the concentration of sodium through a channel was increased by 100%
- the rate would double!
- channels dont care or have max rates because theyre just diffusion
what are the channels in cell membranes that let water through called?
aquaporins
what generates a pressure difference?
-difference in concentration of solutes that cannot pass through a membrane
pressure difference pushes water in what direction?
-pushes water from an area of low solute concentration to an area of high solute concentration
pressure that stops movement is what?
osmotic pressure
what is osmosis?
THE DIFFUSION OF WATER EXCEPT NOT REALLY LOL JK
if something can freely move across a membrane, will it cause osmotic pressure?
nah slut
a solute is on the scale 1-0, what is 1 and what is 0?
1-not permeable (glucose)
0-fully permeable (oxygen)
what is tonicity?
-comparison of two fluids separated by a semi-permeable membrane, with respect to the bathing solution
what is hypotonic (hyposmotic)
- the INSIDE of the cell has more dissolved solutes
- water rushes in to help
what is isotonic (isomotic)
- dissolved solutes are equal
- no net water movement
what is hypertonic (hyperosmotic)
- less solute inside the cell
- water rushes out of the cell
why don’t you just shoot water into someones veins?
-you would lyse their RBC because water would rush in due to hypotonic environment
how does sweating effect the osmolarity of ECF and ICF?
ECF-volume of water goes down, so osmolarity goes up
ICF-the increased osmolarity of ECM causes the volume in ICF to go down and in turn, its osmolarity goes up.
all fluid changes originate in ECF or ICF?
- originate in ECF
- may or may not affect ICF
