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Lecture Exam 3 - Anatomy > Water Balance > Flashcards

Water Balance Flashcards

1
Q

water is ____% of total body weight

A

60%

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2
Q

total body weight percentages of water

A

65% ICF
35% ECF
-25% tissue fluid
-8% blood plasma, lymph
- 2% transcellular fluid
CSF, synovial fluid

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3
Q

how do electrolytes affect water distribution and content

A

direct water and fluids to where they are needed

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4
Q

water is gained by

A

metabolic water (aerobic metabolism/dehydration synthesis) & preformed water (ingested)

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5
Q

water is lost by

A

urine, feces, expired breath, sweat, cutaneous transpiration

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6
Q

respiratory loss increases with _____ air, dry air or heavy work

A

cold

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7
Q

perspiration loss increases with ____, humid air or heavy work

A

hot

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8
Q

insensible water loss

A

breath and cutaneous transpiration
(NOT CONSCIOUS OF IT)

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9
Q

Obligatory water loss

A

breath, cutaneous transpiration, sweat, feces, minimum urine output (400 ml/day)

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10
Q

metabolic water is

A

water created inside living organisms (from aerobic metabolism from dehydration synthesis)

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11
Q

how does dehydration affect the body ?

A

LOW blood volume and pressure ; HiGH osmolarity

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12
Q

Thirst hormones

A

-ADH (response to high osmolarity)
-angiotensin II (response to low BP)
-hypothalamic osmoreceptors (high ECF osmolarity)

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13
Q

thirst mechanisms

A

-stimulation of the thirst center in the hypothalamus
-inhibition of salivation

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14
Q

Satiation Short-term Mechanisms

A

Fast acting
-cooling and moistening of mouth
-distension of stomach and intestine

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15
Q

Satiation Long-term Mechanisms

A

Rehydration of blood -lowers blood osmolarity
stops osmoreceptor response, ↑ capillary filtration, ↑ saliva

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16
Q

how do the kidneys regulate urine volume ?

A

Only control over water output is through variations in urine volume
-By controlling Na+ reabsorption (changes volume)

-By action of ADH (changes concentration of urine)
(aquaporins synthesized in response to ADH
by cells of kidney collecting ducts, as membrane proteins to channel water back into renal medulla, Na+ is still excreted
Effects: slows ↓ in water volume and ↑ osmolarity

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17
Q

______are synthesized in response to ADH

A

aquaporins by cells of kidney collecting ducts

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18
Q

Only control over water output is through _________

A

variations in urine volume

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19
Q

aquaporins

A

mediate rapid water transport across water-permeable epithelia and play critical roles in urinary concentrating and diluting processes.

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20
Q

volume depletion (hypovolemia)

A

total body water ↓, osmolarity normal
CAUSES: hemorrhage, severe burns, chronic vomiting or diarrhea

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21
Q

dehydration

A

total body water ↓, osmolarity rises
CAUSES: lack of drinking water, diabetes, profuse sweating, diuretics

affects all fluid compartments
most serious effects: circulatory shock, neurological dysfunction, infant mortality

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22
Q

Why are infants more vulnerable to dehydration?

A

high metabolic rate demands high urine excretion, kidneys cannot concentrate urine effectively, greater ratio of body surface to mass

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23
Q

volume excess

A

both Na+ and water retained, ECF isotonic
aldosterone hyper secretion (salt retaining)

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24
Q

hypotonic hydration

A

more water than Na+ retained or ingested, ECF hypotonic - can cause cellular swelling

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25
serious effects of fluid access
pulmonary and cerebral edema
26
fluid sequestration is ______ fluid in a particular location
excess
27
examples of fluid sequestration (3)
edema, hematomas (hemorrhage in tissues blood lost to circulation), pleural effusions(fluid accumulate in some lung infections)
28
what makes cold weather a threat to water balance?
constriction of blood vessels to the skin
29
major cations of the body
H+, K+,Ca2+, Na+
30
major anions of the body
Cl-, HCO3-, PO4 3-
31
functions of sodium
1. membrane potential 2.90-95% of ECF 3.Na+ - K+ pump (exchanges ICF Na+ for ECF K+) 4. Sodium bicarbonate (pH buffer)
32
what is the major pH buffer in the body?
NaHCO3 (sodium bicarbonate) has
33
is sodium deficiency common or rare?
rare
34
sodium homeostasis mechanisms
-ADH -Aldosterone -ANF estrogen -retains water in preg. progesterson- diuretic effect
35
Hypernatremia
high plasma sodium >145 mEq/L CAUSES : water retension, hypertension and edema
36
Hyponatremia
plasma sodium < 130 mEq/L CAUSES: the result of excess body water, quickly corrected by excretion of excess water
37
Potassium functions
Most abundant cation of ICF Determines intracellular osmolarity Membrane potentials (with sodium) Na+-K+ pump
38
potassium homeostasis
-90% of K+ in glomerular filtrate is reabsorbed by the PCT -DCT and cortical portion of collecting duct secrete K+ in response to blood levels -Aldosterone stimulates renal secretion of K+
39
What is the most dangerous imbalance of electrolytes?
Potassium
40
Hyperkalemia
if concentration rises quickly, (crush injury) the sudden increase in extracellular K+ makes nerve and muscle cells abnormally excitable slow onset, inactivates voltage-gated Na+ channels, nerve and muscle cells become less excitable
41
Hypokalemia
sweating, chronic vomiting or diarrhea, laxatives nerve and muscle cells less excitable muscle weakness, loss of muscle tone, ↓ reflexes, arrhythmias
42
Functions of chloride (4)
-ECF osmolarity -Stomach acid -Chloride shift (CO2 loading and unloading in RBC) -pH
43
Homeostasis of Chloride
Na+ homeostasis strongly influences since chloride is attracted to it
44
Hyperchloremia
result of dietary excess or IV saline
45
Hypochloremia
result of hyponatremia
46
The primary effect of chloride imbalances are ______
pH imbalance
47
Calcium functions
Skeletal mineralization Muscle contraction Second messenger Exocytosis Blood clotting
48
Calcium homeostasis
-PTH -Calcitriol (vitamin D) -Calcitonin (in children)
49
In order to prevent phosphate calcium crystals....
cells maintain low ca in the icf the potassium is high in the icf
50
Hypercalcemia
alkalosis, hyperparathyroidism, hypothyroidism ↓ membrane Na+ permeability, inhibits depolarization concentrations > 12 mEq/L causes muscular weakness, depressed reflexes, cardiac arrhythmias
51
Hypocalcemia
vitamin D ↓, diarrhea, pregnancy, acidosis, lactation, hypoparathyroidism, hyperthyroidism ↑ membrane Na+ permeability, causing nervous and muscular systems to be abnormally excitable very low levels result in tetanus, laryngospasm, death
52
Phosphate functions
-Concentrated in ICF -Components of nucleic acids, phospholipids, ATP, GTP, cAMP -Activates metabolic pathways by phosphorylating enzymes -Buffers pH
53
Phosphates Homeostasis
-Renal control if plasma concentration drops, renal tubules reabsorb all filtered phosphate -Parathyroid hormone ↑ excretion of phosphate
54
is phosphate imbalance critical?
No the body can tolerate broad concentrations of phosphate
55
Normal pH range of ECF
7.35-7.45
56
What do buffers do?
They resist changes in pH
57
Physiological buffer
system that controls output of acids, bases or CO2 1. urinary system buffers greatest quantity, takes several hours 2. respiratory system buffers within minutes
58
Chemical buffer systems
restore normal pH in fractions of a second bicarbonate, phosphate and protein systems
59
Bicarbonate buffer system
-reversible reaction in ECF lowers pH by releasing H+ raises pH by binding h+ Urinary and Respiratory system use this to lower pH, kidneys excrete HCO3- to raise pH, kidneys and lungs excrete CO2
60
Phosphate buffer system
Important in the ICF and renal tubules where phosphates are more concentrated and function closer to their optimum pH of 6.8 constant production of metabolic acids creates pH values from 4.5 to 7.4 in the ICF, avg.. 7.0
61
ICF average pH is ______
6.7
62
Protein buffer system
-More concentrated than bicarbonate or phosphate systems especially in the ICF -Acidic side groups can release H+ -Amino side groups can bind H+
63
The most concentrated system is _____, especially in the ICF
Protein buffer system
64
Respiratory control of pH
Neutralizes 2 to 3 times as much acid as chemical buffers can inc. CO2 and dec. pH stimulate pulmonary ventilation, while an ↑ pH inhibits pulmonary ventilation
65
The most POWERFUL buffer system is ?
Urinary/RENAL CONTROL (but slow response) Renal tubules secrete H+ into tubular fluid, then excreted in urine
66
How low can urine pH get before H+ secretion stops in tubular fluid?
4.5
67
Acidosis casues and effects
H+ diffuses into cells and drives out K+, elevating K+ concentration in ECF H+ buffered by protein in ICF, causing membrane hyperpolarization, nerve and muscle cells are harder to stimulate, CNS depression from confusion to death
68
Alkalosis causes and effects
H+ diffuses out of cells and K+ diffuses in, membranes depolarized, nerves overstimulate muscles causing spasms, tetany, convulsions, respiratory paralysis
69
Metabolic alkalosis
overuse of bicarbonates (antacids), loss of acid (chronic vomiting)
70
Metabolic Acidosis
↑ production of organic acids (lactic acid, ketones), alcoholism, diabetes, acidic drugs (aspirin), loss of base (chronic diarrhea, laxative overuse)
71
respiratory is faster than renal composition but not as strong

Lecture Exam 3 - Anatomy (2 decks)

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