TBL5A Physiology Part 1 Flashcards
Total body water makes up ___% of body mass.
60
Intracellular fluid refers to fluid within the cells; whereas extracellular fluid includes ______ fluid, blood ______ and _______ fluid.
Extracellular fluid includes:
1) Interstitial fluid (fluid between/surrounding cells)
2) Blood plasma
3) Transcellular fluid (within epithelial-lined spaces)
Composition of ions in the ECF and ICF are different, but _______ are the same. (always 285 mosm/L)
Osmolarities - Concentration of a solution expressed as total number of solutes per litre.
________ refers to the spontaneous movement of solutes down the concentration gradient until equilibrium is reached.
Diffusion
______ refers to the movement of water towards areas of (higher/lower) osmolarity.
Osmosis; higher
higher osmolarity –> lower water potential
Osmolarity of 2mmol/L of glucose is ___ mosm/L.
Osmolarity of 2mmol/L of CaCl2 solution is ____ mmol/L.
Osmolarity of 2mmol/L of glucose is 2 mosm/L.
Osmolarity of 2mmol/L of CaCl2 solution is 6 mosm/L.
**Always take into account the dissociation of ions in water.
Hypertonic solution refers to a solution which contains (more/less) NON-PENETRATING solutes compared to the cell.
Therefore, the cell will (shrink/swell).
more; shrink
water leaves the cell to enter the hypertonic solution.
Hypotonic solution refers to a solution which contains (more/less) NON-PENETRATING solutes compared to the cell.
Therefore, the cell will (Shrink/swell).
less; swell
water enters the cell from the hypotonic solution.
____ solution refers to a solution which contains the same number of impermeant solutes as the cell. The cell volume remains ________.
Isotonic; unchanged
Normal cells (despite having higher concentration of impermeant proteins) do not burst as the ________ maintains [Na+] (higher/lower) inside than outside the cell.
Na+/K+ ATPase maintains the concentration of Na+ lower inside than outside.
It pumps Na+ out of the cell.
Intracellular osmolarity (proteins) is therefore balanced by extracellular osmolarity. –> Cell does not burst.
______ cells burst (known as ______) when placed in pure water as there is no energy generated to keep the Na+/K+ ATPase pump working.
Red blood cells; Haemolysis
____ transport refers to transport down the electrochemical gradient; whereas ____ transport refers to transport against the electrochemical gradient with the use of ATP.
Passive; Active
Passive diffusion can be through the lipid membrane, pores/channels (ligand-gated/voltage-gated) or _______.
Carrier proteins
There are two types of active transport.
Primary - through _____;
Secondary - through _______
1st: through carriers/pumps (use ATP to release energy)
2nd: antiporters
______ use established gradients and the movement of a solute down its gradient to move another solute against its gradient. (Exchange of substances)
Antiporters
______ is the swelling of a tissue due to excess ________ fluid.
Oedema is the swelling of a tissue due to excess interstitial fluid.
Oedema, which refers to the swelling of a tissue due to excess interstitial fluid, is caused by an imbalance of forces causing fluid to move between the _______, _______ and _______
The imbalance of forces causes the fluid to move between the blood plasma, interstitium and lymphatics.
Key forces which contribute to oedema:
Hydrostatic pressure prefers to pressure due to _______;
whereas colloid osmotic/_______ pressure refers to pressure due to protein concentration.
Hydrostatic pressure prefers to pressure due to heart pumping; whereas colloid osmotic/oncotic pressure refers to pressure due to protein concentration.
Hydrostatic pressure in the capillary is usually (higher/lower) than hydrostatic pressure in the interstitial fluid due to heart pumping.
However, this is balanced by the impermeable proteins in the (IF/blood plasma). This will balance the tendency for fluid to leak from the capillaries.
Hydrostatic pressure is usually higher in the capillaries –> promotes net flow of fluid into the IF
However, due to the higher osmolarity of proteins in the blood plasma, this prevents the fluid from leaking out into the IF.
In leaky capillaries, _____ leak out which causes the imbalance of forces and therefore ______ fluid to leak out and accumulate in tissues, causing oedema.
Leaky capillaries cause plasma proteins to leak out. This will cause the hydrostatic pressure in the capillaries to be significantly greater than the osmotic pressure, causing interstitial fluid to leak out.
There are two types of secondary active transport:
1) __________ (Transport two molecules that cross in the same direction)
2) __________ (Transport two molecules that cross in opposite directions)
1) Co-transport (involves the use of symporters)
2) Counter-transport (use of antiporters)
Ion channels are (integral/extrinsic) membrane proteins.
Integral - spans the membrane
_____ ion channels are always open.
Leak
Voltage-gated channels open when the cell membrane _______.
depolarises
dependent on membrane potential
_________-gated channels open when cell membrane is physically distorted.
Mechanially
Neurotransmitter acetylcholine is an example of a ______ which binds to a _____-gated channel at the synaptic cleft.
ligand
_________ potential is the potential difference generated across the cell membrane because of the difference in the intracellular and extracellular concentration of an ion.
It only exists for permeant ions.
Diffusion potential
There is no more net movement of an ion across the membrane at ________ potential. This indicates that the diffusion force and the electrical force are in balance (i.e. they counteract each other)
Equilibrium potential
The equilibrium potential represents the ______ that is required to counteract the diffusion force from the concentration gradient of the ion.
voltage
A (positive/negative) equilibrium potential of a positive ion will indicate a positive voltage is required to push the ions OUT.
This indicates that diffusion forces are (in/out) and there is a higher concentration of the ion in the (outside/inside) of the cell.
Positive; diffusion forces are in (opposing to the voltage electrical force); higher concentration outside of the cell
A negative equilibrium potential of a negative ion (e.g. Cl-) will indicate that a (negative/positive) voltage in the cell is required to push the Cl- ions OUT.
This indicates that diffusion forces are (in/out) and there is a (higher/lower) concentration of Cl- ions in the cell.
negative; diffusion forces are in; lower concentration of cl- ions in the cell
A negative equilibrium potential of a positive ion (e.g. K+) indicates that a negative voltage is required to push the ion (into/out) of the cell.
This indicates that diffusion forces are (in/out) and there is a (higher/lower) concentration of K+ ions in the cell.
into the cell; diffusion forces are out; higher concentration of K+ ions in the cell
The equilibrium potential of an ion is mainly dependent on:
1) ion ________ inside and outside the cell (gradient)
2) ______ of ion
1) ion concentration inside and outside of the cell (Diffusion gradient)
2) Charge on ion (Electrical force)
Resting membrane potential takes into account each ion’s ____________.
membrane permeability
The cell’s negative resting membrane potential is largely due to the ______ pump.
Na+/K+ ATPase pump
3 Na+ ions are pumped out; 2 K+ ions pumped in.
In the Na+/K+ ATPase,
___ Na+ ions are pumped (out/in).
___ K+ ions are pumped (out/in).
3 Na+ ions are pumped out; 2 K+ ions pumped in
The Na+/K+ pump helps to create and maintain an _______ gradient in the cell.
electrical
The Na+/K+ pump also helps to maintain the __+ concentration gradient across the cell.
There are more ions (inside/outside) the cell.
K+; there are more K+ ions inside the cell.
The Na+/K+ pump returns the cell membrane back to resting potential after an _______ potential.
action potential
__________ refers to the process of making the membrane potential less negative.
Depolarisation
__________ refers to the process of returning the membrane to the resting negative potential after depolarisation.
Repolarisation
__________ refers to the process in which membrane potential becomes even more negative than the resting potential.
Hyperpolarisation
___________ refers to the critical level of membrane depolarisation that must occur to trigger an action potential.
Threshold potential
The __________ refers to the duration in which another action potential cannot be fired after the first one.
refractory period
Depolarisation in neurons is caused by the opening of the ___ channels, causing ___ to diffuse into the cell, decreasing the negative membrane potential in the cell.
Na+ ions
recall: acetylcholine (neurotransmitter) will diffuse through the synaptic cleft and bind to the acetylcholine receptors, which will cause Na+ channels on the cell membrane to open. (this causes an action potential)
In neurons, repolarisation is caused by the opening of the ___ channels, which cause the ___ ions to diffuse (in/out) of the cell, returning the membrane potential back to its negative resting membrane potential.
K+ ions diffuse OUT of the cell
_________ in neurons occurs when the K+ channels remain open for too long.
Hyperpolarisation
In cardiac pacemaker cells, there is no true resting potential, but instead, they generate _______ and spontaneous action potentials.
regular and spontaneous action potentials
The depolarisation in cardiac pacemaker cells is caused primarily by the ___ ions diffusing into the cell.
Ca2+
