week 3- fluid and electrolyte imbalances

Question 1

homeostasis

Answer 1

the body’s ability to maintain a stable internal environment despite external changes
ie. temp, pH, blood glucose, water balance

Question 2

body water content

Answer 2

women- 55%
men- 60%
*decreases as we age

Question 3

bodily fluid compartments

Answer 3

ICF: inside cells (2/3 of total body water, 28L)
- supports cell processes
ECF: outside cells, includes interstitial fluid (11L) and plasma (3L)
- faciliates cell communication and nutrient transport

Question 4

functions of water in the body

Answer 4

a) transport: moves nutrients, hormones and oxygen to cells
- also removes waste
b) temperature: helps regulate temp through sweating and evaporation
c) joint lubrication: cushions joints, decerasing friction
d) organ function: essential for proper functioning of organs including kidneys, liver and heart
e) cell processes: water is involved in numerous chemical reactions within cells

Question 5

weight of water

Answer 5

1L= 1kg, sudden weight change is a good indicator of fluid loss/gain

Question 6

ions

Answer 6

an atom or molecule that has gained or lost electrons, resulting in a net electrical charge

Question 7

anion

Answer 7

negatively charged ions formed when an atom gains one or more valence electrons

Question 8

cation

Answer 8

positively charged ions formed when an atom loses one or more valence electrons

Question 9

valence

Answer 9

number of chemical bonds

Question 10

electrolytes

Answer 10

• minerals that have an electric charge when they are dissolved in water or bodily fluids
• can have electrolytes in blood, urine, tissues

Question 11

role of electrolytes in body

Answer 11

• balance water content
• balance pH level
• move nutrients into your cells and waste out of cells
• supports muscle and nerve function
• keep heart rate and rhythm steady
• keep blood pressure stable
• keep bones and teeth healthy

Question 12

electrolyte composition of fluid compartments

Answer 12

ICF: primarily K and phosphate
ECF: primarily Na and Cl

Question 13

reasons for fluid imbalances

Answer 13

medications, vomitting/diarrhea, heavy sweating, heart/luver/kidney problems, decreased intake or excessive intake

Question 14

mechanisms of fluid/electrolyte movement

Answer 14

a) diffusion: movement of molecules from an area of high concentration to low concentration
b) osmosis: water moves across a semipermeable membrane from an area of high solute concentration to low solute concentration
c) facilitated diffusion: protein carrier required, no ATP used
d) active transport: requires ATP to move molecules against their concentration gradient
e) hydrostatic pressure: pressure exerted by a fluid on the walls of its container (force of blood on capillaries)
f) oncotic pressure: pressure exerted by plasma proteins

Question 15

Na/K pump

Answer 15

• moves three Na out and two K in
• this creates an electrical charge difference across the cell membrane (important for nerve cells to transmit signals and for muscle cells to contract)
• requires ATP

Question 16

hypertonic vs hypotonic solution

Answer 16

a) hypertonic: higher solute concentration outside cell, water leaves resulting in shrinkage
b) hypotonic: higher solute cincentration inside cell, water enters resulting in bursting

Question 17

fluid movement in capillaries

Answer 17

• usually a balance between hydrostatic and oncotic pressures
• at arterial end, hydrostatic pressure is greater causing fluid movement into tissues
• at venous end, oncotic pressure is greater causing fluid movement out of tissues

Question 19

first spacing

Answer 19

normal distribution of fluid in the ICF and ECF

Question 20

second spacing

Answer 20

abnormal accumulation of interstitial fluid
ie. edema

Question 21

third spacing

Answer 21

occurs when fluid accumulates in a portion of the body from which it is not easily exchanged with the ECF
ie. blister

Question 22

regulation of water balance- low plasma volume/high plasma osmolarity

Answer 22

• hypothalamus produces ADH, which is released from the posterior pituitary
• acts on kidney to incerase water reabsorption and we experience a thirst sensation
• low blood volume/BP also stimulates RAAS
• this leads to the release of aldosterone from the adrenal cortex
• aldosterone increases Na/water reabsorption

Question 23

regulation of water balance- high plasma volume/low plasma osmolarity

Answer 23

• heart releases naturietic peptides in response to high blood volume/high BP
• this leads to a decrease in sympathetic activity and RAAS activity

Question 24

RAAS

Answer 24

• low bp causes kidneys to release renin
• this activates angiotensinogen in the liver
• ACE converts angiotensin 1 into angiotensin 2
• angiotensin 2 leads to vasoconstriction, limiting the excretion of water
• also leads to release of aldosterone from AC, which increases Na retention

Question 25

insensible water loss

Answer 25

- invisible vaporization from the lungs and the skin - assists in regulating body temperature - about 900 mL/day is lost

Question 26

age-related changes- water balance

Answer 26

- structural changes in the kidney - decreased circulating renin and aldosterone - loss of subcutaneous tissue and thinning of dermis - decrease in thirst mechanism

Question 27

hypernatremia

Answer 27

- above 145 mEq/L - caused by water loss (diabetes insipidus) or excess sodium intake (hypertonic solutions) - can lead to brain shrinkage and neurological dysfunction, leading to seizures and coma - treated with decreasing Na intake, increasing water intake and an isotonic IV solution

Question 28

symptoms of hypernatremia

Answer 28

F: fatigue R: restless I: increased reflexes E: extreme thirst D: decreased urine output

Question 29

hyponatremia

Answer 29

- below 135 mEq/L - caused by excess water intake, fluid retention (heart failure, kidney disease or liver disease) or sodium loss (diuretics, vomitting/diarrhea, addison's disease, sweating) - treated with increased Na intake, decreased fluid intake and an isotonic solution

Question 30

symptoms of hyponatremia

Answer 30

S: seizures A: abdominal cramping L: lethargy T: decreased tendon reflexes L: loss of urine/appetite O: orthostatic hypotension S: shallow respirations S: muscle spasm

Question 31

tonicity

Answer 31

refers to the ability of a solution to cause water to move across a cell membrane, due to the presence of impermeant solutes

Question 32

assessment of skin turgor

Answer 32

if you pinch the skin and it remains tented for 20-30s, the patient is likely extremely dehydrated

Question 33

causes of hypervolemia

Answer 33

heart failure, cushing's syndrome, chronic liver disease, renal failure, corticosteroids

Question 34

causes of hypovolemia

Answer 34

GI losses (diarrhea, vomitting), GI tract suction, excessive sweating, hemorrhage

Question 35

hypokalemia

Answer 35

- below 3.5 mEq/L - most commly caused by abnormal losses in the kidney or GI - severe hypokalemia can cause weakness or paralysis of respiratory muscles, leading to shallow respirations and respiratory arrest - treated with KCl supplements and increasing dietary intake

Question 36

hyperkalemia

Answer 36

- above 5 mEq/L - most commonly caused by renal failure - symptoms include cramping leg pain, followed by weakness or paralysis of skeletal muscles - high risk of dysrhythmias - treated with IV calcium gluconate

Question 37

hypercalcemia

Answer 37

- caused by hyperparathyroidism or malignancy - symptoms include decreased memory, confusion, disorientation, fatigue, muscle weakness, constipation, cardiac dysrhythmias, and renal calculi - treated with a loop diuretic and isotonic saline

Question 38

hypocalcemia

Answer 38

- caused by decrease in PTH production - characterized by increased nerve excitability and sustained muscle contraction

Question 39

tests for hypocalcemia

Answer 39

a) chvostek's sign: contraction of facial muscles in response to a light tap over the facial nerve in front of the ear b) trousseau’s sign: a carpal spasm induced by inflating a blood pressure cuff above the systolic pressure for a few minutes

Question 40

phosphate

Answer 40

- essential to function of muscle, RBCs and NS - hyperphospatemia: caused by acute or chronic renal failure - hypophosphatemia: caused by malnourishment or malabsorption

Question 41

magnesium

Answer 41

- hypomagnesemia: neuromuscular and CNS hyperirritability - caused by prolonged starvation or chronic alcoholism - hypermagnesemia: depresses neuromuscular and CNS functions - caused by increased Mg intake coupled with renal failure

Question 42

hypoproteinemia

Answer 42

- caused by inadequate intake - leads to edema, slow healing, anorexia, fatigue, anemia and muscle loss - treated with high-carb, high-protein diet

Question 43

buffer system

Answer 43

carbonic acid-bicarbonate, phosphate and protein

Question 44

lung buffer system

Answer 44

help maintain a normal pH by excreting CO2 and water, which are byproducts of cellular metabolism

Question 45

renal buffer system

Answer 45

three renal mechanisms of acid elimination are secretion of small amounts of free hydrogen into the renal tubule, combination of H+ with ammonia (NH3) to form ammonium (NH4−), and excretion of weak acids

Question 46

acid base imbalances

Answer 46

classified as respiratory (affect carbonic acid concentrations) or metabolic (affect the base bicarbonate)

Question 47

respiratory acidosis

Answer 47

carbonic acid excess, occurs whenever there is hypoventilation | we'd see high levels of PCO2 in blood

Question 48

respiratory alkalosis

Answer 48

carbonic acid deficit, occurs whenever there is hyperventilation | we'd see low levels of PCO2 in blood

Question 49

metabolic acidosis

Answer 49

base bicarbonate deficit, occurs when an acid other than carbonic acid accumulates in the body or when bicarbonate is lost from body fluids

Question 50

metabolic alkalosis

Answer 50

base bicarbonate excess, occurs when a loss of acid (prolonged vomiting or gastric suction) or a gain in bicarbonate occurs

Question 51

arterial blood gas values

Answer 51

pH: 7.35–7.45 PCO2: 35–45 mm Hg bicarbonate (HCO3−) level: 21–28 mmol/L PO2: 80–100 mm Hg base excess: 0 ± 2.0 mmol/L