week 4: fluids & electrolytes Flashcards
1
Q
what % of water is in the ICF?
A
60%
2
Q
what is the major cation of the ICF?
A
K+
3
Q
what does the renal mechanism do if pH increases?
A
H+ absorbed by kidneys
HCO3- secreted
4
Q
what is reabsorbed in the presence of aldosterone & what is secreted?
A
Na+ reabsorbed
K+ secreted
5
Q
how can plasma pH be altered by respiratory regulation & what does in modify?
A
change in breathing rate
blood content of CO2
6
Q
what % of change in osmolarity stimulates the hypothalamic thirst centre?
A
1-2%
7
Q
what is the equation for the carbonic acid-bicarbonate buffer system if the pH drops?
A
HCO3- + H+ -> H2CO3
8
Q
how can an intake of excess base occur?
A
antacid overdose
9
Q
what % of water is in the ISF?
A
32%
10
Q
what is the pH of arterial blood?
A
7.4
11
Q
what 2 ways is H+ removed from the body?
A
urine
CO2 removed by lungs
12
Q
what % of water is in the ECF?
A
40%
13
Q
in respiratory regulation of pH what does generation of high levels of CO2 in the tissues result in?
A
higher levels of free H+ ions in the blood
14
Q
what happens with a 5-10% change in plasma volume?
A
baroreceptors detect change in BP
juxtaglomerular cells in nephrons detect the change & activate RAAS
15
Q
how are the major tasks of fluid homeostasis achieved?
A
maintaining fluid balance in the ECF
16
Q
what are 2 examples of endocrine disturbances?
A
diabetes insipidus
diabetes mellitus
17
Q
what stimulates ADH to increase water reabsorption?
A
high sodium concentration in plasma
18
Q
what does hypotonic hydration result in?
A
hyponatremia
19
Q
what primarily maintains fluid & electrolyte homeostasis?
A
kidneys
20
Q
with ADH secretion where is water reabsorbed at?
A
DT & CD
21
Q
what is lymphoedema & what is it due to?
A
accumulation of ISF
due to surgically removed/blocked lymph glands
22
Q
what can increase capillary permeability?
A
infection
23
Q
where is CO2 generated, transported by, & removed by?
A
generated in the tissues
transported in the blood
removed by the lungs
24
Q
what are respiratory regulation and renal mechanisms called?
A
physiological buffer systems
25
what are the 5 early signs of dehydration?
```
dry mucous membranes
increased thirst
dry flushed skin
decreased skin turgor
decreased urine output (oliguria)
```
26
what are 3 causes of respiratory alkalosis?
```
panic attacks (w/ hyperventilation)
early salicylate overdose
fever (particularly in infants)
```
27
when stimulated by ADH where does increased water reabsorption occur?
collecting duct of kidney
28
what is the result of increased plasma osmolarity in dehydration?
hypernatremia
29
what may lead to cerebral oedema & what 4 things may occur?
hypotonic hydration
| disorientation, convulsions, coma, death
30
what is the 2nd most common cause of acid-base imbalance?
metabolic acidosis
31
what is the most potent mechanisms of pH regulation?
renal mechanisms
32
what 2 things may increase capillary hydrostatic pressure?
L/R sided heart failure
| lymphatic obstruction
33
what is the renal mechanism able to excrete?
HCO3-
34
what % of body weight does water account for in male adults?
60%
35
how fast does the respiratory regulation of pH occur?
within minutes
36
what 2 ways to kidneys work to regulate blood pH?
remove acids produced by metabolic reactions
| conserve or renew acids when need
37
when does alkalosis occur?
pH above 7.45
38
what % of change in plasma volume stimulates the hypothalamic thirst centre?
5-10%
39
when is lactic acid production seen?
shock
| cardiac arrest
40
in order to reach the ICF, where must fluid pass through?
both the plasma & the ISF
41
what does decreased plasma volume & BP inhibit?
baroreceptors
42
how much of muscle tissue is water?
75%
43
what is metabolic alkalosis due to?
excess of bases or deficit of acids --> increased blood pH
44
what is the major anion of the ICF?
HPO4^2-
45
where does loss of water occur?
lungs, skin, digestive tract & kidneys when excreting wastes
46
what 3 severe metabolic disturbances can hypotonic hydration lead to?
nausea
vomiting
muscle cramps
47
what do baroreceptors stimulate the release of?
ADH from posterior pituitary
48
what is the renal mechanisms able to conserve & generate?
HCO3-
49
what is the equation for the respiratory regulation of pH?
CO2 + H2O <--> H2CO3 <--> HCO3- + H+
50
does water intake = water output?
yes
51
what does fat metabolism produce?
fatty acids
| ketone bodies
52
what is the physiologically normal pH range?
7.35 - 7.45
53
what 3 things may decrease colloid osmotic pressure?
low plasma proteins (protein malnutrition)
liver disease
kidney disease
54
how is pH measured clinically?
using arterial blood
55
what is the absolute limit of blood pH?
6.8 - 7.8
56
what % of body weight does water account for in female adults?
50%
57
what happens when blood pH is above 7.8?
stimulation of NS --> muscle tetany, convulsions, respiratory arrest
58
what is activated if ECF volume is extremely low?
sympathetic NS
59
what 7 things result in ECF loss/dehydration?
```
haemorrhage
severe burns
severe vomiting
severe diarrhoea
profuse sweating
low water intake
endocrine disturbances
```
60
what are 4 examples of diseases that result in respiratory acidosis?
pneumonia
cystic fibrosis
emphysema
shallow breathing
61
what is hypovolaemia?
decreased circulating BV
62
what is respiratory alkalosis often caused by?
hyperventilation in association w/ stress or pain
63
why does oedema impair tissue functioning?
increased distance that oxygen, nutrients & wastes must diffuse between cells & blood
64
what is the pH of venous blood & ISF?
7.35
65
how does respiratory alkalosis occur?
hyperventilation --> excessive CO2 exhalation --> reduction in carbonic acid --> rise in pH
66
how is BV detected?
baroreceptors
67
what does aldosterone target?
kidney tubules
68
what do non-electrolytes do in solution?
stay together
69
why can constipation result in metabolic alkalosis?
excessive bicarbonate reabsorbed
70
what % of water is in cytosol?
60%
71
when does metabolic acidosis occur?
excess fixed acids in body --> decreased pH
72
can oedema result in compromised cardiovascular functioning?
yes
73
where is aldosterone synthesised & secreted from?
adrenal cortex
74
what are the 4 typical causes of metabolic alkalosis?
vomiting
intake of excess base
constipation
excessive diuresis
75
what % of water input is from cellular metabolism?
10%
76
what % of water input is from fluids?
60%
77
what do you get when you mix an acid with a base?
water & salt
78
where does fluid move from & to when oedema occurs?
from blood to ISF
79
what do changes in pH alter renal tubule reabsorption & secretion of ?
H+
80
what is the major cation of the ECF?
Na+
81
what increases when total body water decreases?
plasma osmolarity
82
what buffer system do we discuss?
carbonic acid-bicarbonate ion buffer system
83
what does ADH inhibit?
diuresis
84
when is hypovolaemic shock most likely to occur?
in haemorrhage
85
where does the conservation, generation & excretion of HCO3- occur?
renal tubule of nephron & CD
86
how fast do renal mechanisms regulate pH?
hours to days
87
what are the 2 main fluid compartments?
ICF & ECF
88
acidosis occurs when the pH is below what?
7.35
89
what 4 things occur with oedema?
swollen tissues
puffy feet
swollen ankles
puffy eyes
90
what are most free H+ ions in the body a result of?
metabolic processes (cellular respiration)
91
what % of water input is from food?
30%
92
what 3 ways is pH regulated?
chemical buffer systems
respiratory regulation
renal mechanisms
93
what are 3 things oedema is caused by?
increased capillary hydrostatic pressure
increased capillary permeability
decreased colloid osmotic pressure
94
how are changes in osmolarity detected?
by osmoreceptors in hypothalamus
95
what is hypernatremia?
high Na+ in the ECF
96
does the fluid shift that occurs with oedema cause a severe increase or decrease in circulating BV?
decrease
97
what does respiratory acidosis lead to?
carbonic acid excess
| decrease in pH
98
how much of adipose tissue is water?
10%
99
what is oedema?
abnormal accumulation of fluid in the ISF
100
what is the ultimate pH balance of the blood achieved by?
kidneys
101
what is the equation for the carbonic acid-bicarbonate buffer system if the pH rises?
H2Co3 -> HCO3- + H+
102
Does hypernatremia occur in haemorrhage?
no, whole blood is lost (fluids & solutes lost equally)
103
what are 6 examples of causes of metabolic acidosis?
```
renal disease
excessive ingestion of acids
lactic acid production
excessive loss of bicarbonate ions
ketosis
starvation
```
104
what are the 2 major tasks of fluid homeostasis?
1. maintaining ICF water balance
| 2. maintaining plasma water balance
105
what occurs with hypoventilation?
retention of CO2
| respiratory acidosis
106
how does excessive ingestion of acids occur?
alcohol
107
what does the renal mechanism do if pH drops?
excess H+ secreted by kidneys
| HCO3- reabsorbed & generated (alkaline reserve)
108
what 3 locations is water in the body
plasma, ISF, cytosol
109
where are 2 baroreceptors located?
carotid sinus
| aortic arch
110
what are 2 things pH is important for?
protein function
| biochemical reactions
111
do electrolytes dissociate in solution?
yes
112
what are 4 examples of acute causes of respiratory acidosis?
status asthmaticus
CNS depression
pulmonary oedema
pneumothorax
113
what is the ideal blood pH?
7.4
114
what is the average water intake/output per day in mls?
2500 ml
115
what does anaerobic respiration of glucose produce?
lactic acid
116
what is oliguria?
decreased urine output
117
what is the major anion of the ECF
Cl-
118
what 2 things stimulate aldosterone secretion?
angiotensin II
| elevated K+ in ECF
119
what % of water is in plasma?
8%
120
what is a buffer?
a substance or solution that minimises changes in pH by binding or releasing free H+ ions
121
why is the carbonic acid-bicarbonate buffer system extremely important in the ECF?
for its ability to buffer the blood
122
what 2 things does hypotonic hydration occur with?
renal insufficiency
| rapid excess water ingestion
123
what is the most rapid way pH is regulated?
chemical buffer systems
124
what are 2 important bases in the body?
bicarbonate (HCO3-)
| ammonia (NH3)
125
where is ADH made, stored & released from?
made by hypothalamus
| stored & released from posterior pituitary
126
what do chemical buffer systems do?
temporarily tie up H+ ions
127
what are 2 important acids in the body?
```
acetic acid (HC2H3O2)
carbonic acid (H2CO3)
```
128
what happens when blood pH is below 6.8?
NS shock
coma
death
129
how are H+ (and HCO3-) removed or retained?
by the respiratory & renal regulatory mechanisms
130
what is the pH of the ICF
7.0
131
what is hypotonic hydration/water intoxication/over-hydration?
water intake > water output
132
what % of body weight does water account for in infants?
75%
133
what is the most common pH problem?
respiratory acidosis
134
when does excessive loss of bicarbonate ions occur?
persistent diarrhoea
135
what 4 things might occur with prolonged dehydration?
hypovolaemia
confusion
disorientation
hypovolaemic shock
136
what 3 feedback mechanisms inhibit thirst?
moistening of mucosa
stretch receptors (stomach, intestine)
decrease in osmolarity
137
large amounts of acidic substances enter the body by ingestion (true/false)
false
138
what has greater osmotic power; electrolytes or non-electrolytes?
electrolytes
