Cellular Phsiology Flashcards
Normal adult water intake
2500ml water per day
Fluid balance primary intake and loss
Intake = digestive tract
Loss = kidneys, skin, exhalation
Hypernatremia & body stimulation
increased sodium (Excessive water loss)
thirst & release of anti-diuretic hormone
3 key processes to maintaining homeostasis
1) fluid balance
2) electrolyte balance
3) acid - base balance
what is an electrolyte
Molecule that conducts electricity when dissolved in water
Positive charged ion
Cation
Negative charged ion
Anion
What is a non-electrolyte
Compound that do not dissociate into ions in water e.g glucose, oxygen
Diffusion is …
passive movement of molecules or atoms from high concentration into low concentration, not requiring energy
Osmosis is …
water molecules moving through semipermeable membrane from high concentration into low concentration
What is osmotic pressure ?
water drawing, water is drawn towards a membrane that contains solutes not able to diffuse across
the higher the number of solutes the higher the strength of pulling pressure
Active transport is …
Movement of compounds against a concentration gradient requiring ATP
E.G sodium/potassium pump
Facilitated diffusion
Molecules passing though a plasma membrane from an area of high concentration to low concentration using the help of a transport molecule, requiring no energy
normal pH
7.35 - 7.45
acidosis is
pH less than 7.35 due to donation/release of hydrogen ions
alkalosis is ..
pH above 7.45 due to accepting hydrogen ions
A Buffer system is …
one or more compounds that act to resist change in pH
How do buffer systems work to change pH
Increased pH = release of hydrogen into blood
Decreased pH = removal of hydrogen from the blood
How do buffer systems work to correct pH
Increased = release hydrogen into the blood
Decreased = removal of hydrogen from the blood
What are the 3 buffer systems :
1) Bicarbonate buffer system
2) protein buffer system
3) phosphate buffer system
Equation for bicarbonate buffer system
CO2 + H2O = H2CO3 = (HCO3)- + H+
OR
Carbon dioxide + water = carbonic acid = Bicarbonate + Hydrogen
Where is protein buffer system located?
Intracellular fluid and plasma
Where does bicarbonate buffer system operate
Extracellular fluid
How does the protein buffer system work?
When pH decreases amino group takes up hydrogen ions
When pH increases carboxyl group releases hydrogen
When is the phosphate buffer system located ?
intracellular fluid and renal tubules
Phosphate buffer system equation
H2PO4- = H+ = HPO4-
OR
Dihydrogen Phosphate = hydrogen + hydrogen phosphate
what are the 3 types of capillaries
1) continuous
2) fenestrated
3) sinusodial
3 mechanisms of capillary transport
1) diffusion
2) active transport
3) bulk flow (starlings law)
What is starlings Law of capillaries
Rate and direction of fluid movement across the capillary membrane is determined by the balance between hydrostatic and osmotic pressure
What is hydrostatic pressure?
Pressure excreted against capillary walls
What is osmotic pressure
difference in solute to water either side of semipermeable membrane (osmotic pressure gradient)
What is blood osmotic pressure
Pressure created by concentration of colloidal proteins
What is filtration
direct flow out of capillaries into interstitial space
What is reabsorption
Direct flow into the capillaries from interstitial space
What is net filtration pressure?
Overall pressure causing filtration
What is starlings law equation?
Net filtration pressure = blood hydrostatic pressure - blood osmotic pressure
(measured in millimetre of mercury)
movement between endothelial cells
Paracellular pathways
movement through cells
Transendothelial pathway
Equation for cardiac output
CO = HR x SV
What does cardiac output measure ?
Amount of blood pumped around the body per minute (effectiveness of the heart)
What are 3 sympathetic compensatory mechanisms?
1) increasing SV
2) increasing HR
3) peripheral vasoconstriction
What is Frank Starlings Law
Hearts ability to change its force of contraction therefore stroke volume in response to changes in venous return
What is preload
Force the stretches the cardiac muscle before contraction
What is preload?
Amount of force the heart must exert to eject blood from ventricles upon contraction
What are chemoreceptors?
Sense changes in bloods chemical composition
What are baroreceptors ?
monitor BP by sending changes to pressure to stretch within blood vessels
How do baroreceptors change BP
Decreased pressure = increased HR and vasoconstriction
Increased pressure = decreased HR and vasodilation
What % of a normal person is water ?
60%
What is the water % of ICF and ECF in a normal person?
ICF = 2/3 / 66%
ECF = 1/3 / 33%
What are the 3 components of ECF and what % of them are water
1) Interstitial = 75%
2) Plasma = 21%
3) Transcellular = 4%
What is interstitial space ?
Fluid surrounding cells and tissues
What is plasma
Fluid held within blood vessels
What is transcellular
Fluid created by epithelial cell linings which is released into certain areas
