TBL5A Physiology Part 1

Question 1

Total body water makes up ___% of body mass.

Answer 1

60

Question 2

Intracellular fluid refers to fluid within the cells; whereas extracellular fluid includes ______ fluid, blood ______ and _______ fluid.

Answer 2

Extracellular fluid includes:

1) Interstitial fluid (fluid between/surrounding cells)
2) Blood plasma
3) Transcellular fluid (within epithelial-lined spaces)

Question 3

Composition of ions in the ECF and ICF are different, but _______ are the same. (always 285 mosm/L)

Answer 3

Osmolarities - Concentration of a solution expressed as total number of solutes per litre.

Question 4

________ refers to the spontaneous movement of solutes down the concentration gradient until equilibrium is reached.

Answer 4

Diffusion

Question 5

______ refers to the movement of water towards areas of (higher/lower) osmolarity.

Answer 5

Osmosis; higher

higher osmolarity –> lower water potential

Question 6

Osmolarity of 2mmol/L of glucose is ___ mosm/L.

Osmolarity of 2mmol/L of CaCl2 solution is ____ mmol/L.

Answer 6

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.

Question 7

Hypertonic solution refers to a solution which contains (more/less) NON-PENETRATING solutes compared to the cell.

Therefore, the cell will (shrink/swell).

Answer 7

more; shrink

water leaves the cell to enter the hypertonic solution.

Question 8

Hypotonic solution refers to a solution which contains (more/less) NON-PENETRATING solutes compared to the cell.

Therefore, the cell will (Shrink/swell).

Answer 8

less; swell

water enters the cell from the hypotonic solution.

Question 9

____ solution refers to a solution which contains the same number of impermeant solutes as the cell. The cell volume remains ________.

Answer 9

Isotonic; unchanged

Question 10

Normal cells (despite having higher concentration of impermeant proteins) do not burst as the ________ maintains [Na+] (higher/lower) inside than outside the cell.

Answer 10

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.

Question 11

______ cells burst (known as ______) when placed in pure water as there is no energy generated to keep the Na+/K+ ATPase pump working.

Answer 11

Red blood cells; Haemolysis

Question 12

____ transport refers to transport down the electrochemical gradient; whereas ____ transport refers to transport against the electrochemical gradient with the use of ATP.

Answer 12

Passive; Active

Question 13

Passive diffusion can be through the lipid membrane, pores/channels (ligand-gated/voltage-gated) or _______.

Answer 13

Carrier proteins

Question 14

There are two types of active transport.

Primary - through _____;
Secondary - through _______

Answer 14

1st: through carriers/pumps (use ATP to release energy)
2nd: antiporters

Question 15

______ use established gradients and the movement of a solute down its gradient to move another solute against its gradient. (Exchange of substances)

Answer 15

Antiporters

Question 16

______ is the swelling of a tissue due to excess ________ fluid.

Answer 16

Oedema is the swelling of a tissue due to excess interstitial fluid.

Question 17

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 _______

Answer 17

The imbalance of forces causes the fluid to move between the blood plasma, interstitium and lymphatics.

Question 18

Key forces which contribute to oedema:

Hydrostatic pressure prefers to pressure due to _______;
whereas colloid osmotic/_______ pressure refers to pressure due to protein concentration.

Answer 18

Hydrostatic pressure prefers to pressure due to heart pumping; whereas colloid osmotic/oncotic pressure refers to pressure due to protein concentration.

Question 19

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.

Answer 19

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.

Question 20

In leaky capillaries, _____ leak out which causes the imbalance of forces and therefore ______ fluid to leak out and accumulate in tissues, causing oedema.

Answer 20

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.

Question 21

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)

Answer 21

1) Co-transport (involves the use of symporters)

2) Counter-transport (use of antiporters)

Question 22

Ion channels are (integral/extrinsic) membrane proteins.

Answer 22

Integral - spans the membrane

Question 23

_____ ion channels are always open.

Answer 23

Leak

Question 24

Voltage-gated channels open when the cell membrane _______.

Answer 24

depolarises

dependent on membrane potential

Question 25

_________-gated channels open when cell membrane is physically distorted.

Answer 25

Mechanially

Question 26

Neurotransmitter acetylcholine is an example of a ______ which binds to a _____-gated channel at the synaptic cleft.

Answer 26

ligand

Question 27

_________ 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.

Answer 27

Diffusion potential

Question 28

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)

Answer 28

Equilibrium potential

Question 29

The equilibrium potential represents the ______ that is required to counteract the diffusion force from the concentration gradient of the ion.

Answer 29

voltage

Question 30

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.

Answer 30

Positive; diffusion forces are in (opposing to the voltage electrical force); higher concentration outside of the cell

Question 31

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.

Answer 31

negative; diffusion forces are in; lower concentration of cl- ions in the cell

Question 32

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.

Answer 32

into the cell; diffusion forces are out; higher concentration of K+ ions in the cell

Question 33

The equilibrium potential of an ion is mainly dependent on:

1) ion ________ inside and outside the cell (gradient)
2) ______ of ion

Answer 33

1) ion concentration inside and outside of the cell (Diffusion gradient)
2) Charge on ion (Electrical force)

Question 34

Resting membrane potential takes into account each ion’s ____________.

Answer 34

membrane permeability

Question 35

The cell’s negative resting membrane potential is largely due to the ______ pump.

Answer 35

Na+/K+ ATPase pump

3 Na+ ions are pumped out; 2 K+ ions pumped in.

Question 36

In the Na+/K+ ATPase,

___ Na+ ions are pumped (out/in).

___ K+ ions are pumped (out/in).

Answer 36

3 Na+ ions are pumped out; 2 K+ ions pumped in

Question 37

The Na+/K+ pump helps to create and maintain an _______ gradient in the cell.

Answer 37

electrical

Question 38

The Na+/K+ pump also helps to maintain the __+ concentration gradient across the cell.
There are more ions (inside/outside) the cell.

Answer 38

K+; there are more K+ ions inside the cell.

Question 39

The Na+/K+ pump returns the cell membrane back to resting potential after an _______ potential.

Answer 39

action potential

Question 40

__________ refers to the process of making the membrane potential less negative.

Answer 40

Depolarisation

Question 41

__________ refers to the process of returning the membrane to the resting negative potential after depolarisation.

Answer 41

Repolarisation

Question 42

__________ refers to the process in which membrane potential becomes even more negative than the resting potential.

Answer 42

Hyperpolarisation

Question 43

___________ refers to the critical level of membrane depolarisation that must occur to trigger an action potential.

Answer 43

Threshold potential

Question 44

The __________ refers to the duration in which another action potential cannot be fired after the first one.

Answer 44

refractory period

Question 45

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.

Answer 45

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)

Question 46

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.

Answer 46

K+ ions diffuse OUT of the cell

Question 47

_________ in neurons occurs when the K+ channels remain open for too long.

Answer 47

Hyperpolarisation

Question 48

In cardiac pacemaker cells, there is no true resting potential, but instead, they generate _______ and spontaneous action potentials.

Answer 48

regular and spontaneous action potentials

Question 49

The depolarisation in cardiac pacemaker cells is caused primarily by the ___ ions diffusing into the cell.

Answer 49

Ca2+