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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
Q

serious effects of fluid access

A

pulmonary and cerebral edema

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26
Q

fluid sequestration is ______ fluid in a particular location

A

excess

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27
Q

examples of fluid sequestration (3)

A

edema, hematomas (hemorrhage in tissues blood lost to circulation), pleural effusions(fluid accumulate in some lung infections)

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28
Q

what makes cold weather a threat to water balance?

A

constriction of blood vessels to the skin

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29
Q

major cations of the body

A

H+, K+,Ca2+, Na+

30
Q

major anions of the body

A

Cl-, HCO3-, PO4 3-

31
Q

functions of sodium

A
  1. membrane potential
    2.90-95% of ECF
    3.Na+ - K+ pump (exchanges ICF Na+ for ECF K+)
  2. Sodium bicarbonate (pH buffer)
32
Q

what is the major pH buffer in the body?

A

NaHCO3 (sodium bicarbonate) has

33
Q

is sodium deficiency common or rare?

A

rare

34
Q

sodium homeostasis mechanisms

A

-ADH
-Aldosterone
-ANF
estrogen -retains water in preg.
progesterson- diuretic effect

35
Q

Hypernatremia

A

high plasma sodium >145 mEq/L

CAUSES : water retension, hypertension and edema

36
Q

Hyponatremia

A

plasma sodium < 130 mEq/L

CAUSES: the result of excess body water, quickly corrected by excretion of excess water

37
Q

Potassium functions

A

Most abundant cation of ICF
Determines intracellular osmolarity
Membrane potentials (with sodium)
Na+-K+ pump

38
Q

potassium homeostasis

A

-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
Q

What is the most dangerous imbalance of electrolytes?

A

Potassium

40
Q

Hyperkalemia

A

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
Q

Hypokalemia

A

sweating, chronic vomiting or diarrhea, laxatives
nerve and muscle cells less excitable
muscle weakness, loss of muscle tone, ↓ reflexes,
arrhythmias

42
Q

Functions of chloride (4)

A

-ECF osmolarity
-Stomach acid
-Chloride shift (CO2 loading and unloading in RBC)
-pH

43
Q

Homeostasis of Chloride

A

Na+ homeostasis strongly influences since chloride is attracted to it

44
Q

Hyperchloremia

A

result of dietary excess or IV saline

45
Q

Hypochloremia

A

result of hyponatremia

46
Q

The primary effect of chloride imbalances are ______

A

pH imbalance

47
Q

Calcium functions

A

Skeletal mineralization
Muscle contraction
Second messenger
Exocytosis
Blood clotting

48
Q

Calcium homeostasis

A

-PTH
-Calcitriol (vitamin D)
-Calcitonin (in children)

49
Q

In order to prevent phosphate calcium crystals….

A

cells maintain low ca in the icf the potassium is high in the icf

50
Q

Hypercalcemia

A

alkalosis, hyperparathyroidism, hypothyroidism
↓ membrane Na+ permeability, inhibits depolarization
concentrations > 12 mEq/L causes muscular weakness, depressed reflexes, cardiac arrhythmias

51
Q

Hypocalcemia

A

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
Q

Phosphate functions

A

-Concentrated in ICF
-Components of nucleic acids, phospholipids, ATP, GTP, cAMP
-Activates metabolic pathways by phosphorylating enzymes
-Buffers pH

53
Q

Phosphates Homeostasis

A

-Renal control
if plasma concentration drops, renal tubules reabsorb all filtered phosphate
-Parathyroid hormone
↑ excretion of phosphate

54
Q

is phosphate imbalance critical?

A

No the body can tolerate broad concentrations of phosphate

55
Q

Normal pH range of ECF

A

7.35-7.45

56
Q

What do buffers do?

A

They resist changes in pH

57
Q

Physiological buffer

A

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
Q

Chemical buffer systems

A

restore normal pH in fractions of a second
bicarbonate, phosphate and protein systems

59
Q

Bicarbonate buffer system

A

-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
Q

Phosphate buffer system

A

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
Q

ICF average pH is ______

A

6.7

62
Q

Protein buffer system

A

-More concentrated than bicarbonate or phosphate systems especially in the ICF
-Acidic side groups can release H+
-Amino side groups can bind H+

63
Q

The most concentrated system is _____, especially in the ICF

A

Protein buffer system

64
Q

Respiratory control of pH

A

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
Q

The most POWERFUL buffer system is ?

A

Urinary/RENAL CONTROL
(but slow response)
Renal tubules secrete H+ into tubular fluid, then excreted in urine

66
Q

How low can urine pH get before H+ secretion stops in tubular fluid?

A

4.5

67
Q

Acidosis casues and effects

A

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
Q

Alkalosis causes and effects

A

H+ diffuses out of cells and K+ diffuses in, membranes depolarized, nerves overstimulate muscles causing spasms, tetany, convulsions, respiratory paralysis

69
Q

Metabolic alkalosis

A

overuse of bicarbonates (antacids), loss of acid (chronic vomiting)

70
Q

Metabolic Acidosis

A

↑ production of organic acids (lactic acid, ketones), alcoholism, diabetes, acidic drugs (aspirin), loss of base (chronic diarrhea, laxative overuse)

71
Q

respiratory is faster than renal composition but not as strong

A

Lecture Exam 3 - Anatomy (2 decks)

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