Week 1 Questions Flashcards
1
Q
How much of our body weight is water?
A
50-70%
2
Q
How much of our total body water is Intracellular fluid?
A
2/3 (40%)
3
Q
How much of our total body water is extracellular fluid?
A
1/3 (20%)
4
Q
What is the difference between ECF and ICF?
A
ECF: the fluid outside of the cells
ICF: the fluid inside the cells
5
Q
What is ECF composed of?
A
a. Plasma
i. Intravascular
ii. Red Blood Cells
b. Interstitial fluid
i. fluid the cells bathe in
ii. No proteins
6
Q
What separates the plasma and interstitial fluid?
A
Capillary Wall
7
Q
True False: The capillary wall is impermeable to large molecules
A
True
8
Q
Cations are ____Charged ions
A
Positively
9
Q
Anions are ____charges ions
A
Negatively
10
Q
What are the 5 substances that are higher in the ECF than ICF?
A
Na+ Ca+, ionized Cl- HCO3- PH
11
Q
What is the most important substance that is higher in the ICF?
A
K+
12
Q
True/ False: Cell membranes are dynamic, fluid structures
A
True
13
Q
True/False the membrane constituents cannot move about in the plane of the membrane
A
False- The membrane constituents are able to move about in the membrane
14
Q
About ____ of proteins encoded in an animal cell’s genome are membrane proteins
A
30%
15
Q
Are the heads of the phospholipids hydrophobic or hydophillic
A
Hydrophilic- like water
16
Q
Are the tails of the phospholipids hydrophobic or hydrophilic?
A
Hydrophobic
17
Q
The membrane fluidity refers to the ______of the lipid bilayer
A
Viscosity
18
Q
What is the importance of the cis- double bonds in the phospholipids?
A
Produces a kink
19
Q
Having saturated hydrocarbon chains within the phospholipid bilayer results in what?
A
Increased membrane thickness
20
Q
Having unsaturated hydrocarbon chains within the phospholipid bilayer results in what?
A
Reduced membrane thickness
21
Q
Why would unsaturated hydrocarbon chains with cis-double bonds allow for more diffusion than saturate hydrocarbon chains?
A
Because of the cis-double bond there is a kink, this causes more space allowing for more diffusion
22
Q
What does it mean to be amphiphilic?
A
Contains both hydrophobic and hydrophillic
23
Q
How is the lipid bilayer formed?
A
Because the phospholipids are amphiphilic it causes them to bury their hydrophobic tails in the interior and expose their hydrophilic heads to the water
24
Q
What two different shapes might the phospholipids form?
A
a. Lipid micelle
b. Lipid bilayer (more likely)
25
This property of the shape the phospholipids form provides important____capability.
Self- Healing
26
Does the process of the shape of the phospholipids require any energy?
No
27
How do they have self- healing capabilities?
a. Endocytosis
| b. Exocytosis
28
What is Endocytosis
process of capturing a substance or particle from outside the cell by engulfing it with the cell membrane
29
What is Exocytosis
Process of vesicle fusing with the plasma membrane and releasing the contents outside the cell
30
Is the formation process of phospholipid bilayer spontaneous or calculated?
a. Spontaneous
| b. energetically favorable
31
What are the four mechanisms a cell can tether membrane proteins?
a. self assemble
b. tethered to macromolecules on the outside
c. tethered to macromolecules on the inside
d. tethered to macromolecules on the surface of another cell
32
What is the importance of domains?
If proteins are not where they need to be, they cannot receive the protein
33
What are integral membrane proteins?
Proteins that are embedded into the cell membrane
34
What are transmembrane proteins?
a. span the lipid bilayer one or more times
| b. Type of integral membrane protein
35
What are peripheral membrane proteins?
a. not embedded in the membrane
| b. not covalently bound to cell membrane components
36
True/False given enough time all molecules will eventually be able to pass through the membrane
True
37
What is (passive) downhill transport?
Substances move down a conc. gradient from an area of high conc to an area of low conc.
38
Does Passive transport require energy?
No
39
What three types of transport occur by passive transport?
a. simple diffusion
b. facilitated diffusion
c. Osmosis (high--->low)
40
What is active (uphill) transport?
Substances move against a conc gradient from an area of low conc to an area of high conc
41
Does active transport require energy?
Yes
42
What two types of transport occur by active transport?
a. Primary Active transport
| b. secondary active transport
43
What are the two main classes of membrane transport proteins?
a. Channels
| b. transporters
44
What are channels?
a. Always passive-like a straw
| b. much faster (10^5 times faster)
45
What are pores?
Integral proteins that are always open
46
What are transporters?
a. can be active or passive
| i. active- use carriers
47
Which type of transport requires a protein carrier?
a. facilitated diffusion
b. Primary Active Transport
c. Secondary active transport
48
What type of transport does not require a protein carrier?
Simple diffusion
49
What is diffusion?
Random molecular movement
50
In diffusion, substances move from a____to____ conc.
High to Low (downhill)
51
What three things determine simple diffusion?
a. amount of substrate available
i. conc gradient
b. velocity of motion
i. the more energy the solute has, the faster the rate of diffusion
ii. example: the higher the temperature, the faster the molecules move
c. number and size of openings (permeability)
52
What are the two types of gradients?
a. Chemical
| b. electrical
53
What is the chemical gradient?
Conc differences across the membrane
54
What is the electrical gradients
Where the opposites attract and likes repel
55
Combined, these two gradients form the....
Electrochemical gradient
56
What is an osmole?
The number of particles into which a solute dissociates in solution
57
What is macroscopic electroneutrality?
Each fluid compartment must have the same concentration of positive valence electrons as negative electrons
58
Is the ECF or ICF more negative?
ICF
59
What are pores?
a. Integral membrane proteins
| b. Always open
60
The selectivity of a pore is based on ____and_____.
Diameter and electrical charge
61
How are channels selective?
a. Gated
| i. Respond to certain stimuli
62
What are the three types of gated channels?
a. voltage-gated
b. ligand gated
c. mechanically gated
63
What type of stimuli would open a voltage- gated channel?
Change in membrane potential
64
What type of stimuli would open a ligand- gated channel?
Ligand binding
65
True/ False: Ligand- gated channels can only respond to extracellular ligands
False: they can respond to intracellular and extracellular ligands
66
What type of stimuli would open a mechanically gated channels?
Mechanical Changes
67
Are K+ or Na_ molecules bigger in size?
K+
68
Are channels more permeable to K+ or Na+
K+
69
Why are channels more permeable to K+ than Na+?
a. Selectivity filter
i. Both molecules are polar and attract water molecules. When they get close to the filter, they are stripped of their hydration shell.
ii. K+ is more permeable because once it is stripped of its hydration shell it fits perfectly, whereas Na+ becomes too small without its shell
70
In a voltage-gated Na+ channel, before the stimulus are both the gates opened or closed?
a. Activation gate is shut
| b. Inactivation gate is open
71
In a voltage-gated Na+ channel, which gate opens first once there is a stimulus?
a. Activation Gate
72
After the stimulus, Na+ Flows____ the gated channel
Into
73
The same stimulus that caused the gate to open, would cause the inactivation gate to open or close?
Close
74
In a voltage- gated K+ channel, K+ Flows____the gated channel.
Out
75
During Resting state of a ligand- gated ACH channel, the gate is
Shut
76
What happened to allow Na + to pass through a ligand- gated ACH channel?
ACH binds to the protein channel
77
The inside of the channel is
a. Negative
i. attracted to Na+
ii. Repels Cl-
78
Does Cl- have a higher conc. on the inside or the outside of the cell?
Outside
| i. Dude to negativity of the channel
79
In a voltage gated Na+ channel, which gate opens first once there is a stimulus?
Activation Gate
80
After the stimulus, Na+ flows ____the gated channel
Into
81
The same stimulus that caused the gate to open, would cause the inactivation gate to open or close?
Close
82
In a voltage- gated K+ Channel, K+ flows ____ the gated channel.
Out
83
During resting state of a ligand- gated ACH channel, the gate is
Shut
84
What has to happen to allow Na+ to pass through a ligand- gated ACH channel?
ACH binds to the protein channel
85
The inside of the channel is
a. Negative
ii. Attracted to Na+
ii. Repels Cl-
86
Does Cl- have a higher conc on the inside or outside of the cell
Outside, due to negativity of the channel
87
The inside of the channel is ____.
Negative
i. attracted to Na+
ii. Repels Cl-
88
Which is faster between simple/ facilitated diffusion?
Facilitated
89
The more conc you have, the ___rate of diffusion
Faster; not with facilitated diffusion
90
What limits max rate of facilitated diffusion? (why does it plateau)
a. Saturation
i. Limited number of carrier proteins
ii. This is why at first facilitated diffusion is faster than simple diffusion
b. Speed of conformational change
i. The rate of transport can never be greater than the speed of conformational change
91
46. What are the five factors that affect net diffusion?
a. Concentration gradient
b. Partition coefficient (K)
i. How soluble the molecule is
c. Diffusion coefficient
i. Size of the molecule and viscosity of the medium
d. Thickness of the membrane
i. The thicker the membrane, the slower the rate of diffusion
e. Surface area
i. The more surface area, the faster the diffusion
92
47. What is another name of net diffusion?
a. Flux, flow
93
48. What two factors determine the diffusion coefficient
a. Size of the molecule
| b. Viscosity
94
49. The thicker the membrane, the ___ rate of diffusion?
a. Slower
95
50. The less surface area, the ___ rate of diffusion.
a. Sloweri. Example-- if you spill water in one spot vs all over the table, the water that was spilled over the entire table will dry faster than the water in one spot
96
51. What are two factors that affect diffusion of electrolytes?
a. Potential difference
| b. Diffusion potential
97
52. What is the difference between potential difference and diffusion potential?
a. Potential difference is the difference in electrical potential between the inside and outside of the cell
b. Diffusion potential is the potential difference generated across a membrane when a charged solute diffuses down its concentration gradient
i. Caused by diffusion of ion
ii. Can only occur it the membrane is permeable to the electrolyte
98
53. What is another name for the Nernst equation?
a. Equilibrium potential
99
54. If the cells in the ECF are more negative than the cells in the ICF, when will the negatively charged molecules stop entering the cell?
a. Based on the Nernst potential, they will stop when they are equal in magnitude but opposite in direction to the concentration force
100
55. Does primary active transport require ATP?
a. Yes
101
56. In active transport, substances move from a ___ to ___ area of concentration
a. Low---> high
102
57. What is an example of primary active transport?
a. Na+-K+ ATPase pump
103
58. In primary active transport is energy driven directly or indirectly?
a. Directly
104
59. This pump is responsible for maintaining high concentration of ___ outside the cell and a high concentration of ___ inside the cell.
a. Na+ outside
| b. K+ inside
105
60. Uses ATP to move ___ Na+ out of the cell, and __ K+ into the cell.
a. 3 Na+
| b. 2 K+
106
61. What is the importance of this pump?
a. Contributes to the negative resting membrane potential-- electrogenic (10%)
b. Important for controlling cell volume
c. In some nerve cells, 60-70% of energy requirements is devoted to this pump
d. Maintaining osmotic pressure
107
62. What would happen if this pump stopped working?
a. Too much Na+ inside the cell
i. Increase osmotic pressure
ii. Cells would swell
iii. Burst
b. Stop nerve conduction
108
63. What is cardiac glycosides?
a. Class of drugs that inhibit the Na+-K+ ATPase pump
| b. Examples: oubain and digitalis
109
64. In secondary active transport is energy driven directly or indirectly?
a. Indirectly
110
65. Uses the __ from the Na+-K+ ATPase pump to bring in other molecules into the cell.
a. Na+
111
66. Does glucose have a high concentration inside or outside of the cell?
a. Inside
112
67. How does glucose enter into the cell?
a. Using the Na+ electrochemical gradient
| b. Rides in the Na+
113
68. What are the two types of secondary active transport?
a. Symport
| b. Antiport
114
69. What is symport?
a. When the transported and cotransporter molecule go in the same direction
115
70. What is an example of symport?
a. SGLT1
116
71. Where are most of SGLT1 found?
a. Intestinal epithelial cells
117
72. What is antiport?
a. When the transporter and cotransporter molecule go in opposite directions
i. One is going into the cell and the other is going out of the cell
118
73. What is an example of antiport?
a. Na+- Ca+ exchanger
i. This also depends on the Na+-K+ ATPase pump
ii. Na+ goes into the cell, while Ca+ or H+ goes out
iii. Na+ that comes in gets kicked out via Na+-K+ ATPase pump
119
1. What is osmosis?
a. The flow of water across a semipermeable membrane due to a difference in solute concentration
120
2. True/ False: Osmosis is merely diffusion of water
a. False: it is NOT. Osmosis occurs because of a pressure difference
121
3. What is osmotic pressure?
a. The driving force for osmotic water flow
| b. The difference in solute concentration creates and osmotic pressure difference across the membrane
122
4. What determines osmotic pressure?
a. Molar concentration
| i. The number of particles per unit volume (regardless of its mass)
123
5. Particles roughly exert the same amount of pressure against the membrane regardless of its ____.
a. Mass
124
6. Water will always follow the side with ___ particles.
a. More
125
7. What is osmolarity?
a. The concentration of osmotically active particles expressed as osmoles/milliosmoles per liter- in solution
126
8. Quiz Questions: Assuming complete dissociation of all solutes, which of the following solution would be hyperosmotic to 1 mM NaCl?
a. 1 mM glucose
b. * 1 mM CaCl2
i. Have more active particles
c. 1 mM sucrose
d. 1 mM KCl
127
9. What is the difference between osmolarity and osmolality?
a. osmolaRity-- is the concentration of osmotically active particles per kg/solution
b. OsmolaLity-- is the concentration of osmotically active particles per kg/water
128
10. What is the normal level for plasma osmolality?
a. 280-294 mOsm/kg of water
129
11. The osmolality can increase with ____ or ___.
a. Water deficit
| b. Sodium excess
130
12. Plasma osmolality is the same as ____.
a. Intracellular osmolality (ICF)
131
13. What is tonicity?
a. Related to the effect of the solution on the volume of a cell
132
14. What would happen if you put a cell into an isotonic solution?
a. No change
| b. Osmolarity of the solution = ICF
133
15. What would happen if you put a cell into a hypertonic solution?
a. Cell would shrink
| i. Because the solution has a higher osmolarity, the water will want to follow where there are more particles
134
16. What would happen if you put a cell into a hypotonic solution?
a. Cell would swell
i. Because the solution has a lower osmolarity than the cell, the water will follow the particles into the cell causing it to swell
135
17. What is does it mean for a red blood cell to become crenated?
a. Cell is shriveled up
| b. Occurs when you place a cell in a hypertonic solution
136
18. What does it mean for a cell to become lysed?
a. Cell burst-- cell death
| b. Occurs when you place a cell in a very hypotonic solution
137
19. Why is common to see lysed cells in heart attacks?
a. The heart cell does not receive blood
b. With no blood means no energy
c. Cannot maintain Na+-K+ ATPase pump
d. Increase in Na+ in the cells
e. Water follows Na+ into the cell causing increase in osmolarity
f. Cell burst
138
20. What would happen if you added an isotonic NaCl solution to the ECF?
a. No change to the ICF
b. Increase in ECF
i. Seen when we want to increase things such as cardiac output
139
21. What would happen if you added a hypertonic NaCl solution to the ECF?
a. Osmosis of water to the ICF
b. Increase of osmolarity in ICF and ECF
c. Decrease volume of ICF
d. Increase volume of ECF
140
22. What would happen if you added a hypotonic NaCl solution to the ECF?
a. Decrease osmolarity
b. Increase volume of ICF
c. Increase volume of ECF
i. Adding fluid to the ECF
141
23. ___ accounts for almost 90% of the ECF, therefore it is an indicator of plasma osmolarity.
a. Na+
142
24. What is the normal range for Na+ levels?
a. 135-145 mEq/L
143
25. What is hyponatremia?
a. [Na+] < 135
b. Loss of NaCl
c. The most common electrolyte disorder in clinical practice
144
26. What causes hyponatremia?
a. Dehydration
b. Diarrhea
c. Vomiting
d. Overuse of diuretics (inhibits kidneys from retaining Na+)
e. SIADH (increased water retention-->dilutes Na+ and causes hypo-osmolarity)
145
27. Why is hyponatremia dangerous?
a. Causes brain cell edema
146
28. What are they symptoms of hyponatremia?
a. Headache
b. Nausea
c. Lethargy
d. Disorientation
e. Seizures
f. Coma
g. Herniation
h. Alter nerve and muscle action potentials and may cause twitching, depressed reflexes and weakness
147
29. How can hyponatremia be treated?
i. It can't cross the BBB (blood brain barrier) so when it is administered intravenously it creates an osmotic gradient across the BBB and pulls water out of the brain tissue
ii. Has to be done slowly
148
30. What is the function of glial cells?
a. Reduce intracellular osmolytes to minimize cell swelling
| b. Synthesize myelin which is essential for proper nerve conduction
149
31. What is osmotic demyelinization syndrome?
a. The glial cells shrink and die
i. If disturbed water balance is corrected too quickly, the glial cells dies
ii. Usually affects the pons
150
32. True/False: if this happens, there are medications to reverse the effects.
a. False-- effects are often irreversible
151
33. Who is at greater risk for hyponatremia?
a. Elderly
| i. Contributes to cognitive deficits, falls, fractures, and long-term hospitalizations
152
34. What is hypernatremia?
a. [Na+] > 145
b. Severe symptoms occur is > 160
c. Loss of water from ECF or excess Na+
d. Less common than hyponatremia
153
35. What are symptoms are hypernatremia?
a. Dehydration
b. Thirst, weight gain, bounding pulse, and increased blood pressure
c. Twitching, hyperreflexia, convulsions, cerebral hemorrhage
154
36. How do we treat hypernatremia?
a. SLOWLY giving hypo-osmotic solutions
