Exam 1 Ch6: Extracellular Environment Flashcards
1
Q
Extracellular environment
A
a. Includes all constituents of body outside cells
2
Q
cells receive nutrients from and get rid of waste over
A
plasma membranes from and to extracellular fluid
3
Q
67% of total body H20 is
A
inside cells
- intracellular compartment
4
Q
33% of total body H20 is outside cells
A
= extracellular compartment-ECF
5
Q
ECF
A
Extracellular compartment fluid
6
Q
20% of ECF
A
blood plasma contained in blood vessels
7
Q
80% of ECF
A
interstitial fluid = tissue fluid contained in gel-like matrix
8
Q
Cells of our body are surrounded by
A
extracellular matrix
9
Q
Extracellular matrix
A
a meshwork of protein fibers (collagen & elastin fibers) linked to molecules of gel-like ground substance
10
Q
interstitial fluid
A
tissue fluid resides in hydrated gel of ground substance
11
Q
interstitial fluid also contains
A
glycoproteins, proteoglycans, which form chemical bonds between carbohydrates on the surface of cells and protein fibers
12
Q
Plasma membrane
A
Separates intracellular environment from extracellular environment
13
Q
significance of plasma membrane to nutrients
A
all nutrients reaching cell and all waste leaving the cell must pass over plasma membrane
14
Q
plasma membrane allows only certain kinds of molecules to pass
A
selective permeable
15
Q
plasma membranes are impermeable to
A
proteins, nucleic acids, some ions, and/or other molecules necessary for cellular function/metabolism
16
Q
Categorization of transport into and out of cells:
A
- carrier - mediated transport
2. Non-carrier mediated transport
17
Q
carrier - mediated transport
A
involves specific protein transporters
Facilitated diffusion and Active transport
18
Q
non- carrier mediated transport
A
occurs by diffusion through membranes
19
Q
Categorization of transport into and out of cells according to energy requirements
A
- passive transport
- active transport
20
Q
passive transport
A
moves compounds down concentration gradient (from areas of ↑ concentration to areas of ↓ concentration)
21
Q
does passive transport requires energy?
A
No
22
Q
Passive transport includes
A
simple diffusion
23
Q
what are simple diffusion
A
osmosis and facilitated diffusion
24
Q
Active transport
A
moves compounds up a concentration gradient (from areas of ↓ concentration to areas of ↑ concentration)
25
active transport requires
energy & specific transporters
26
Diffusion
random motion of molecules (due to heat energy); the net movement is from region of high to low concentration
27
in diffusion what kind of compounds readily diffuse thru cell membranes
non-polar
hyrophobic
- also some small, polar, but uncharged molecules including C02 & H20
28
Diffusion of H2O is called
osmosis
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in diffusion cell membrane is impermeable to
charged and most polar compounds
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through diffusion charged moleculels must have what to move across membrane
ion channel or transporter
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rate of diffusion depends on
1. Magnitude of its concentration gradient, which creates driving force (DF)
2. Permeability of membrane to it
3. Temperature
4. Surface area of membrane
32
ions such as what require protein channels to permeate the membrane
K+ and Na+
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Osmosis
net diffusion of H20 (universal solvent) across a selectively permeable membrane
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In Osmosis H2O
H20 diffuses down its concentration gradient
| H20 is less concentrated where there are more solutes
35
In Osmosis solutes has to be Osmotically active
cannot freely move across membrane for osmosis to cccur
36
dilute solutions
more H20 (solvent), less solute
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Concentrated solutions
contain less H20 (solvent), more solute
38
H20 diffuses down its concentration gradient until
its concentration is equal on both sides of membrane, thus there is a change in volume
39
Some cells have water channels (aquaporins) to
facilitate osmosis in special membranes (ex. kidney cells)
40
osmotic pressure
measure of the tendency for a soln. to gain H2O by osmosis
41
Osmotic pressure is proportional to
solute concentration
greater solute concentration = greater osmotic pressure
42
force that would have to be exerted to stop osmosis
Indicates how strongly H20 wants to diffuse
43
Tonicity
effect of a solution (sln) on osmotic movement of H20
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Isotonic
slns have same osmotic pressure;
has an equal concentration of solute (solid);
no osmosis
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hypertonic
slns have higher osmotic pressure & are osmotically active; has a higher concentration of solute (solid)
46
hypotonic
solns have lower osmotic pressure; has a lower concentration of solute (solid)
47
Molar
pertaining to the number of moles of solute per liter of solution
48
Molal
pertaining to the number of moles of solute per kilogram of solvent
49
Osmolality
measure of the total concentration of a solution; the # of moles of solute per kilogram of solvent
50
Osmolarity
measure of the total concentration of a solution; the # of moles of solute per liter of solution
51
Mole
number of grams of a chemical that is equal to its formula weight ex: H2O mw = 18
52
Blood osmolality maintained in
narrow range around 300 mOsm
53
if dehydrated osmoreceptors in hypothalamus stimulate:
ADH antidiuretic hormone release
Which causes kidney to conserve H20 by stimulating insertion of aquaporins into kidney membranes
& thirst
54
Molecules too large & polar to diffuse are transported across membrane by
protein carriers embedded in plasma membranes
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Protein carriers exhibit
Specificity for single molecule
Competition among substrates for transport that are very similar
Saturation when all carriers are occupied
56
saturation are called
Tm (transport maximum)
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facilitated diffusion
passive transport = no energy required
down concentration gradient = from higher to lower concentration
by carrier proteins (embedded in membranes)
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examples of carrier proteins
. Glucose transporters (GLUT4 in skeletal muscle) that reside in membrane bound vesicles within the cytoplasm until stimulated by insulin to be inserted into the plasma membrane
59
Primary active transport
transport of molecules against a concentration gradient;
Requires ATP
60
Primary active transport:
| requires ATP
Molecule or ion binds to recognition site on carrier protein -> hydrolysis of ATP -> phosphorylation of carrier protein -> conformational change -> release of molecule/ion to opposite side
61
Membrane Transport Systems: Primary Active Transport: Na+/K+ Pump
uses
ATP to move 3 Na+ out & 2 K+ in against their gradients; between 200 – several million/cell!!!
62
Steep Na+ gradient
drives coupled transport;
adjusting the pump activity helps regulate resting (basal) metabolic rate;
Na+ and K+ concentrations are used by muscle and nerve cells to conduct electrical impulses;
osmoregulation
63
Secondary Active Transport (Coupled Transport)
Uses energy from “downhill” transport of Na+ to drive “uphill” movement of another molecule
64
ATP required to maintain Na+ gradient via
Na+/K+ ATP-ase, BUT IS NOT USED DIRECTLY!v
65
Cotransport (symport)
secondary transport in same direction as Na+ (ex. glucose)
66
Countertransport (antiport)
moves molecule in opposite direction of Na+ (ex. Ca2+)
67
epipthelial membranes
cover all body surfaces and line the cavities of all hollow organs
- Molecules/ions must pass through these epithelial membranes
68
absorption
transport of digestion products across intestinal epithelium into blood
69
reabsorption
transports molecules out of urinary filtrate back into blood
70
transcellular transport
moves material through the cytoplasm of epithelial cells
71
paracellular transport
moves material through tiny spaces between epithelial cells
72
Bulk transport
Is way cells move large molecules/particles across plasma membrane
73
Bulk transport occurs by
endocytosis (into cells) & exocytosis (out of cells) via the fusion of membrane bound vesicles
74
Recall: H2O distribution
Intracellular
| exgtracellular
75
intracellular H2O distribution
(~ 67%) = 2/3 of body H2O is inside cells (~27 – 30 L H2O)
76
extracellular H2O distribution
(~ 33%) = 1/3 total body H2O is outside of cells (~14 – 16.5 L H2O)
( Interstitial and Blood)
77
Interstitial (tissue fluid)
(80% ECF) = 11 – 13 L H2O
78
blood
(20% ECF) = 3 – 3.5 L H2O
79
Nutrients and waste must be exchanged via
fluid in capillaries (blood) and the fluid in tissues (extracellular fluid)
80
Distribution of ECF between blood & interstitial compartments is in state of
dynamic equilibrium
81
dynamic equilibrium
continuously circulating, formed from, and returned to the vascular system
There are forces at work controlling this movement
82
Fluid movement into/out of capillaries depends on
Net filtration pressure
83
Net filtration pressure
hydrostatic pressure in capillaries (17-37 mm Hg) – hydrostatic pressure in ECF (1 mm Hg)
84
Hydrostatic pressure is exerted by
fluid
85
hydrostatic pressure
~ 37 mm Hg at arteriolar end of systemic capillaries and ~17 mm Hg at the venular and of capillaries
86
Oncotic pressure
Colloid osmotic pressure in capillaries (25 mm Hg) - Colloid osmotic pressure in tissue fluid (0 mm Hg)
87
Colloid Osmotic pressure
osmotic pressure exerted by proteins in fluid
88
Overall Fluid Movement into and out of Capillaries
| The 2 factors
net filtration
| oncotic pressure
89
net filtration is determined by
hydrostatic pressure (HP)
90
Oncotic pressure is determined by
determined by colloid osmotic pressure (COP)
91
****At the arteriole end of capillary bed, HP is highest inside….What happens?
Close to the arterial end of the capillary, it is approximately 10 mm Hg, because the CHP of 35 mm Hg minus the BCOP of 25 mm Hg equals 10 mm Hg. Recall that the hydrostatic and osmotic pressures of the interstitial fluid are essentially negligible. Thus, the NFP of 10 mm Hg drives a net movement of fluid out of the capillary at the arterial end
92
At the venule end of the capillary bed, COP is the highest inside, what happens?
At approximately the middle of the capillary, the CHP is about the same as the BCOP of 25 mm Hg, so the NFP drops to zero. At this point, there is no net change of volume: Fluid moves out of the capillary at the same rate as it moves into the capillary. Near the venous end of the capillary, the CHP has dwindled to about 18 mm Hg due to loss of fluid. Because the BCOP remains steady at 25 mm Hg, water is drawn into the capillary, that is, reabsorption occurs. Another way of expressing this is to say that at the venous end of the capillary, there is an NFP of −7 mm Hg.
93
85% of fluid filtered from capillaries is returned directly to
capillaries
94
5% of fluid filtered from capillaries is returned to
circulation via lymphatic system
95
Edema
excessive accumulation of tissue fluid
96
What maintains proper ECF levels
Normally filtration, osmotic reuptake, & lymphatic drainage
97
edema can result from
- High arterial blood pressure
- Venous obstruction
- leakage of plasma proteins into ECF
- Myxedema
- Decreased plasma protein levels
- Obstrucgtion of lyphatic drainage
98
high arterial blood pressure
↑ capillary pressure excessive filtration
99
Venous obstruction produces
congestive ↑ in capillary pressure
100
leakage of plasma proteins into ECF causes
↓ in osmotic flow into capillaries
101
Myxedema
excess production of glycoproteins (mucin) in extracellular matrix from hypothyroidism
102
Decreased plasma protein levels results from
liver or kidney disease
103
obstruction of lymphatic drainage caused by
elephantiasis (filariasis = parasitic nematode)
