Cell bio- water balance Flashcards
(120 cards)
1
Q
life depends on maintaining what three things?
A
amount of body water
proportion of water and electrolytes in the water
acid-base balance
2
Q
what is the charge and polarity of water and why?
A
neutral charge
polar= electrons are asymmetrically distributed
3
Q
what is flickering cluster?
A
at 37C, 15% of water molecules are joined to four others
4
Q
how are water molecules joined together?
A
transiently in a H-bond lattice
5
Q
what is the cohesive nature responsible for?
A
unusual properties such as high surface tension and specific heat
6
Q
what bond is stronger, hydrogen or covalent?
A
covalent
7
Q
define solution, solute and solvent
A
solution= a substance dissolved in a liquid solute= dissolved substance solvent= the liquid
8
Q
what happens to a substance when it is dissolved in water?
A
their molecules separate from each other, each becoming surrounded by water molecules
9
Q
what are hydrophilic molecules composed of, what is their likelihood to dissolve, how do they interact with water, and what are 2 examples
A
composed of ions or polar molecules that attract water through electrical charge effects
dissolve readily
water molecules surround each ion or polar molecule
NaCl and urea
10
Q
What are hydrophobic molecules composed of, what type of bonds do they have and how do they react with water?
A
contain many nonpolar bonds that are insoluble in water
hydrocarbons= C-H bonds
water molecules are not attracted to them and don’t surround them
11
Q
what is molar concentration and what does it determine?
A
the number of osmotic active particles
osmotic pressure
12
Q
what is osmotic pressure exerted by particles in a solution determined by?
A
the number of particles per unit volume or fluid, not by the mass of the particles
13
Q
what is molarity?
A
the amount of a substance per unit volume (mol/L)
14
Q
what is molality?
A
the amound of a substance per unit mass of solvent (mol/Kg H2O)
15
Q
Is molarity or molality used for living organisms and why?
A
molality.
volume is temp dependent, so molality is used to describe the concentration of solutes in solutions
16
Q
define molar?
A
the concentration of a substance in a liquid
17
Q
what is the largest single constituent of the body, what % of the body is made up of it and what are the two locations it is found?
A
water
60%
ECF or ICF
18
Q
how much fluid if ICF vs ECF?
A
2/3 ICF
1/3 ECF
19
Q
water in the interstitium (interstitial fluid) is in what 3 forms?
A
gell (proteoglycans entrap water with them)
rivulets of free fluid
free fluid vesicles
20
Q
what % of ECF is interstitial fluid, where is it found and what else is ECF made of?
A
80% IF
found in microscopic spaces between tissue cells
20% ECF= blood plasma
21
Q
what makes up 1% or ECF, where is it found?
A
transcellular water
specific places:
lymph, cerebrospinal fluid, synovial fluid (joint), eyes, endolymph & perilyph (ears), glomerular filtrate (kidneys), plearual, pericardial and peritoneal fluids (between serous membranes)
22
Q
what are 3 methods of water intake and 4 methods of water loss?
A
intake: ingested liquid, ingested food, metabolic water= by-product of respiration
loss: kidneys, sweat, lungs (vapor), GI tract (feces)
23
Q
when is an animal in fluid balance?
A
when the amount of water gained each day is equal to the amount lost to the environment
24
Q
what does the maintenance of normal fluid balance involve?
A
regulating body water content and distribution in the ECF and ICF
25
what does metabolic water volume depend on, is fluid gain due to formation of metabolic water regulated?
the level of cellular respiration which reflects the level of demand for ATP in body cells
not regulated to maintain homeostasis of body water
26
what is the main way to regulate body fluid gain?
adjusting the volume of preformed water intake, mainly by drinking more or less fluid
27
what is insensitive perspiration?
gradual movement of water across the skin and respiratory tract
28
what is sensible perspiration?
loss due to the secretory activities of the sweat glands
29
what is metabolic generation of water?
production of water within cells, primarily as a result of oxidative phosphorylation within mitochondria
30
what is the role of fluid compartments and fluid balance?
selectively permeability membranes separate body fluids into distinct compartments
31
what is the role of plasma membrane?
separate intracellular fluid from intersitial fluid of individual clels
32
what is the role of blood vessel walls?
divide intersitial fluid from blood plasma
33
what are two categories of compartments and what do they contain?
```
small= interior of a single cell
large= combined interiors of the heart and blood vessels
```
34
what is homeostasis of fluid balance?
fluids are in constant motion from one compartment to another, though the volume of fluid in each compartment remains fairly stable
35
what is the role of blood for movement of body fluids?
the vehicle for transport and exchange of materials between body cells and the outside world
36
what is the movement of nutrients?
from food, enter the blood for distribution to tissues throughout the body
37
what is the movement of oxygen?
enters the lungs and then the blood
38
what is the movement of waste products generated by cellular metabolism?
diffuse from the cells into the blood stream, then excreted into urine, exhaled by lungs or follow some other route out of the body
39
what is the role of interstitial fluid in the movement of body fluids?
the go-between for exchanged between intracellular fluid and blood plasma
40
where does the echange between plasma and interstitial fluid occur?
across capillary walls
41
what are the three ways that substances enter and leave capillaries?
vesicular transport
diffusion
bulk flow
42
describe vesicular transport
substances in the plasma cross the capillary wall by endocytosis into an endothelial cell and then exocytosis into interstitial fluid
43
how frequent is vesicular transport used, and what is an example?
accounts for a tiny fraction of the exchange between plasma and interstitial fluid
exchangeable proteins
44
define diffusion
movement of molecules down their concentration gradient across the capillary wall
45
how frequent is diffusion and what are 2 exampled?
largest part of capillary exchange in most body tissue- most substances move through diffusion
exchange of )2 and CO2 between blood and lungs
independent exchange of individual solutes (glucose and AA)
46
define bulk flow
consists of both filtration and reabsorption
47
define filtration and reabsorption
```
filtration= netmovement of materials from the blood into interstitial fluid
reabsorption= net movement of material from interstitial fluid into blood
```
48
when does filtration predominate, when does reabsorption predominate, which is used more?
filtration= at the arteriolar end of capillaries
reabsorption= at the venule end of capillaries
filtration is slightly used more
49
what happens to fluid that is not reabsorbed?
```
passes into lymphatic capillaries
the fluid (lymph) moves through lymphatic vessels and drain into the circulatory system
```
50
What two forces control the movement of water from one body compartment to another?
hydrostatic pressure
| osmotic pressure
51
factors that affect the net hydrostatic or osmotic pressure will alter what?
the distribution of fluids within the ECF
52
define edema
the movement of abnormal amounts of water from the plasma into the interstitial fluids
53
what is an example of edema?
pulmonary edema can increase from an increase in the blood pressure in the pulmonary capillaries
54
what can localized edema result in? (4)
damage to capillary walls
bruising
constriction of the regional venous circulation
blockage of the lymphatic drainage
55
what will changes in the concentration of major solutes in the plasma or interstitial fluid have an effect on?
water distribution
56
what will conditions that directly affect water balance alter?
the concentration of the solutes
57
what is the most important substance that diffuses through the cell membrane?
water
58
define osmosis
movement of water through a semipermeable membrane
59
what is the amount of water in RBC compared to the volume when diffusing in/out of the plasma membrane?
amount of water is 100 times the volume
60
what is the net movement of water diffusion in both directions (in/out) and what does that mean for the volume of the cell?
zero net movement= volume of the cell remains constant
61
what is necessary to stop water movement to the more concentrated side of the membrane?
osmotic pressure of the membrane
62
homeostatic mechanisms that monitor and adjust the composition of body fluids responds to what?
changes in the ECF
63
What is the role of receptors? (3)
monitor the composition of the plasma and the interstitial fluid
detect significant changes in the composition or volume
trigger neural and endocrine responses
64
what are physiological adjustments regulated by?
hormones
65
what does hormone-mediated responses affect?
the balance between dietary absorption and urinary excretion of water
66
define electrolytes
compounds that dissociate into ions when in solution and are able to conduct electricity
67
what are 4 functions of electrolytes in the body?
cell metabolism and contribute to body structures
facilitate osmotic movement of water between body compartments
maintain the H concentration (acid-base balance) for normal cellular function
production and maintenance of membrane potentials and action potentials
68
What are 4 major cations and anions and are they found more extracellular or intracellular
cations:
Extra= Na, Ca; Intra= K, Mg
anions:
Extra= Cl, HCO3; Intra= phosphate, protein
69
what is the function of calcium? (7)
```
bone and teeth building
blood coagulation
neural transmission
muscle contraction
plasma membrane and cell-cell junctions
activation of enzymes
messenger molecule
```
70
what is the function of chloride? (2)
formation of HCl in stomach
| transmission of nerve impulses
71
what is the function of magnesium? (2)
enzyme activation
| neuromuscular transmission
72
what is the function of potassium? (3)
regulation of water and electrolyte content of ICF
transmission nerve impulses
acid-base balance
73
what is the function of sodium? (5)
```
regulaiton of fluid volume within ECF
increase plasma membrane permeability
control body water distribution
acid-base balance
nerve impulse transmission
```
74
whata re the 3 principal ions of ECF and ICF?
ECF: sodium, chloride, bicarbonate
ICF: potassium, magnesium, phosphate
75
alterations in water balance are considered changes in what?
changes in either ECF or ICF
76
how does transcellular fluid affect fluid balance of the body?
it has little to no effect
77
what is fluid shifts?
water movement between ECF and ICF
78
what speed does fluid shifts occur?
rapidly
| reaches equilibrium within minutes to hours
79
Fluid shifts occur in the response of what?
changes in the osmolality of the ECF
80
what happens if the osmolality of the ECF increases and what causes the increase?
it will become hypertonic compared to ICF, water will move from the cells into the ECF
inc occurs if the subject losses water but retains electrolytes
81
what happens if the osmolality of the ECF decreases and what causes the cecrease?
it will become hypotonic compared to ICF and water will move from ECF into the cells, volume of ICF will increase
dec if the subject gains water without a corresponding gain of electrolytes
82
what does tonicity refer to?
effective osmotic pressure
| whether the movement of water will cause a cell to change in size
83
define isotonic
a solution which causes a cell to neither shrink nor swell
84
define hypotonic
a solution which causes a cell to swell
85
what happens with higher hypotonic stress?
higher point of membrane stress will cause the plasma membrane to rupture= cytolysis
86
define hypertonic and what are two other names?
a solution which causes a cell to shrink
| crenation, plasmolysis
87
how does the cell protect against volume fluctuations?
plasma membrane contains mechanosensors that stimulate ion flow accompanied by water, K and Cl outflow in cell volume expansion
Na, K, Cl inflow in cell shrinkage
88
what is net water loss called and what how does it affect ECF osmolality?
hypovolemia
| increases ECF osmolality
89
what is insensible water losses and what are 2 examples?
```
some water losses can't be regulated or measured= non sensed
exhaled air (evaporation)
skin (diffusion, independent of sweating- cornified layer of the skin prevents it)
```
90
what is sensible water loss and what are 3 examples?
volume that can be measured
urine production
sweat
feces
91
define dehydration
reduced (less than normal) fluid volume
92
what is the most common form of dehydration?
hypertonic
93
define hypertonic dehydration
water loss exceeds electrolyte loss= increased osmolalilty of ECF, leads to increased osmolality in ECF
94
define isontonic dehydration
water loss equals electrolyte loss (haemorrhage, sweat) = decreased volume of ECF, which leads to hypovolemia
95
define hypotonic dehydration
loss of electrolytes exceeds loss of water (diarrhea, kidney disease) not common= osmolalilty of ECF is decreased
96
define overhydration
fluid volume greater than normal (hypervolemia)
97
define hypotonic overhydration and what is a cause?
gain of water, electrolytes unchanged = decreased ECF osmolalilty which leads to decreased ICF osmolality
caused by water intoxication= over consumption, drowning
98
define isotonic overhydration and what is a cause
gain of isotonic fluid= increased ECF which leads to hypercolemia but no change in osmolality
caused by error in fluid administration, elevated Na reabsorption in renal tubes
99
define hypertonic overhydration and what is a cause?
gain of electrolytes exceeds gain of water
| cause: rare to see, rapid administration of hypertonic solutions (hypertonic saline)
100
what are 4 main causes of water loss?
vomiting
diarrhea
hemorrhage
hyperventilation
101
what happens inf fluid loss is grater than solute loss?
water moves from the ICF to the ECF= increased osmolality in the ECF (salt is more concentrated in the ECF)
102
what happens when the osmolality of the ECF is affected?
water will be redistributed between the extra and intracellular compartments
103
what three hormones regulate fluid loss?
```
antidiruetic hormone (ADH)
aldosterone
atrial natriuretic peptide (ANP)
```
104
what monitors the osmotic concentration of ECF?
osmoreceptors in the hypothalamus
105
What releases ADH and where is it released?
axons of osmoreceptor neurons in the anterior hypothalamus
| released in the posterior pituitary gland
106
what does the rate of ADH release based on?
osmolarity : the higher the osmolarity, the greater amount of ADH released
107
what are the two effects of ADH?
stimulates water conservation at the kidneys, reducing urinary water loss and concentrating the urine
stimulates the thirst center to promote drinking of fluid
108
what secreted aldosterone?
adrenal cortex
109
what is the role of aldosterone
determines the rate of sodium absorption in kidneys
110
increase in plasma aldosterone concentration causes what?
the more efficiently the kidneys will conserve sodium, which stimulates water retention
111
what is aldosterone release a response to?
activation of the renin-angiotensins system
112
what are the three methods to activate the renin-angiotensin system
fall in plasma volume or blood pressure= inc secretion= dec urination and inc in fluid retention, which leads to an inc blood volume
a rise in ECF osmolarity= reduces release, dec renal Na reabsorption and inc urinary excretion of Na
ECF k levels: inc K stimulates secretion= kidneys eliminate excess K
113
what is atrial natriuretic peptide (ANP) released by and in response to what?
cardiac muscle cells
| in response to abnormal stretching of the atrial walls caused by elevated blood pressure or an inc in blood volume
114
ANP reduces blood volume and blood pressure by what 4 methods?
inc water losses at the kidneys
reducing thirst
blocking the release of ADH
stimulating peripheral vasodilation
115
actions of angotensin 2 are opposed by what?
actions of ANP
116
how are compartment volumes measured and how is it calculated?
by determining the volume of distribution of a tracer substance
volume = amount of tracer / concentration of tracer
117
what are 6 requirements of a tracer?
nontoxic
rapidly and evenly distribute throughout the compartment and not enter any other compartment
not be metabolized
not be excreted during the equilibration period
be easy to measure
not interfere with body fluid distribution
118
what are two types of tracers used and what are examples of each?
ionics (82Br, 35SO4, chloride isotopes)
| crystalloids (insulin, mannitol)
119
describe ionic tracers, what is a problem with them and what is their result?
small and distribute throughout the ECF
some entry into cells
ECF will be over-estimated
120
describe crystalloids, what is a problem with them and what is their result?
larger and less diffusable through ECF
don't enter cells but lack full ECF distribution results
a low estimate of ECF
