Homeostasis refers to the body's ability to maintain stable internal conditions even as external factors vary. Key aspects of homeostasis include controlling temperature, blood pressure, blood pH, and glucose levels. The hypothalamus, medulla oblongata, lungs, kidneys, and pancreas all play roles in homeostasis. Fluids and electrolytes constantly shift between intracellular and extracellular compartments to facilitate processes like oxygen transport, acid-base balance, and urine formation. Movement occurs via osmosis, diffusion, filtration, and carrier-mediated transport.

1. Fluids, Electrolytes & Acid-Base Balance
Homeostasis

2. Discussion Topics
Homeostasis
Homeostasis
Fluid &
Electrolytes
Acid Base
Balance
Arterial
blood Gas

3. What does this Mean
Homeostasis
CONTROL OF TEMPERATURE: The hypothalamus is the bodies regulatory center and is responsible
for the bodies increase and decrease in temperature.
FACT… the body is capable of maintaining a temp of between 37c-38c even when the external
temperature varies between 16c and 54c.
Homeostasis Examples
This is the name given to the process that is used by the body to maintain a “stable” internal
environment even through constant external change. Its properties help to maintain parameters within
a “NORMAL” range of values
Definition
CONTROL OF BLOOD PRESSURE: Regulator centers (called cardiac and vasomotor centers) can
increase the heartbeat and constrict the arteries. Found in the medulla oblongata of the brain.
Kidneys play a role as well by regulating blood volume
CONTROL OF pH: This is regulated by chemical buffers (the carbonate and phosphate buffer
systems). The concentration of these buffers is regulated by the lungs and/or kidneys.
CONTROL OF GLUCOSE CONCENTRATION: Most importantly through the release of insulin. This is
released when concentrated glucose stimulates the pancreas. Between meals, the blood glucose levels
remain constant. The liver is responsible for this.

5. Myocardial Infarction

6. Fluid And Electrolyte Balance
Fluid Balance
Vital part of renal function
Renal dysfunction may result in a fluid
excess or deficit
Fluids are held in 3 compartments which
have semi-permeable walls

7. The fluids
The major division is into Intracellular Fluid
(ICF: about 23 liters) and Extracellular
Fluid (ECF: about 19 liters) based on which
side of the cell membrane the fluid lies.

8. Intracellular fluid
The Intracellular Fluid is composed of at least 10 separate tiny cellular
packages.
The concept of a single united "compartment" called intracellular fluid is
clearly artificial.
Location: The distinction between ICF and ECF is clear and is easy to
understand: they are separated by the cell membranes
The use of this convention allows predictions to be made about what will
happen with various interventions and within limits these are
physiologically meaningful.

9. Extracellular fluid
The ECF is divided into several smaller compartments (eg plasma,
Interstitial fluid, fluid of bone and dense connective tissue and transcellular
fluid).
These compartments are distinguished by different locations and different
kinetic characteristics.
The ECF compositional similarity is in some ways, the opposite of that for
the ICF (ie low in potassium & magnesium and high in sodium and
chloride).

10. Extracellular Interstitial Fluid
Intravascular Fluid
Transcellular Fluid

11. Interstitial fluid
Interstitial fluid (ISF) consists of all the bits of fluid which lie in the interstices
of all body tissues.
This is also a ‘virtual’ fluid (ie it exists in many separate small bits but is spoken
about as though it was a pool of fluid of uniform composition in the one
location).
The ISF bathes all the cells in the body and is the link between the ICF and the
intravascular compartment.
Oxygen, nutrients, wastes and chemical messengers all pass through the ISF. ISF
has the compositional characteristics of ECF (as mentioned above) but in
addition it is distinguished by its usually low protein concentration (in
comparison to plasma).
Lymph is considered as a part of the ISF. The lymphatic system returns protein
and excess ISF to the circulation. Lymph is more easily obtained for analysis
than other parts of the ISF.

12. Intravascular Fluid (Plasma)
Plasma is the only major fluid compartment that exists as a real fluid
collection all in one location.
It differs from ISF in its much higher protein content and its high bulk
flow (transport function).
Blood contains suspended red and white cells so plasma has been
called the ‘interstitial fluid of the blood’.
The fluid compartment called the blood volume is interesting in that it
is a composite compartment containing ECF (plasma) and ICF (red
cell water).
The fluid of bone & dense connective tissue is significant because it
contains about 15% of the total body water. This fluid is mobilized
only very slowly and this lessens its importance when considering the
effects of acute fluid interventions.

13. Transcellular fluid
Trans-cellular fluid is a small compartment that represents all those body
fluids which are formed from the transport activities of cells.
It is contained within epithelial lined spaces. It includes cerebrospinal, pleural,
peritoneal, & synovial fluids and fluids in the GI tract
It is important because of the specialized functions involved. The electrolyte
composition of the various trans-cellular fluids are quite dissimilar
The total body water is divided into compartments and useful physiological
insight and some measure of clinical predictability can be gained from this
approach even though most of these fluid compartments do not exist as
discrete real fluid collections.

14. • Fluids and electrolytes constantly shift between
compartments to facilitate body processes such
as tissue oxygenation, acid-base balance, and
urine formation
• Fluids and solutes move across cell membranes
by four processes: osmosis, diffusion, filtration,
& carrier-mediated transport
Movement of Body Fluids

15. • The movement of water
through a semi-permeable
membrane from an area of
lesser solute concentration
to an area of greater
solute concentration in an
attempt to equalize
concentrations on both
sides of the membrane
Osmosis

16. • The movement of ions and
molecules in a solution across
a semipermeable membrane
from an area of higher
concentration to an area
of lower concentration
• The result is an even
distribution of the solute
in a solution
Diffusion

17. • The process by which
water and diffusible
substance move
together in response to
fluid pressure, moving
from an area of higher
pressure to one of
lower pressure
Filtration

18. • Moves molecules across the plasma membrane
• May be active or passive process
• Examples:
• Facilitated Diffusion – insulin binds to glucose &
transports it across the cell membrane
• Active Transport – requires energy to move materials
across cell membranes against a concentration
gradient (ie. sodium potassium pump)
Carrier-Mediated Transport

19. How Do We Lose Water?
Renal losses
Respiratory losses
Dermal Losses
GI losses
How Do We Gain Water?
GI system
Renal system
Metabolism

21. • Antidiuretic Hormone (ADH) is released by the
pituitary gland in response to changes in blood
osmolality
• Aldosterone is released by the adrenal cortex in
response to increased plasma potassium or falling
sodium levels or as part of the renin-angiotensin-
aldosterone system to counteract hypovolemia
• Natriuretic Peptides act on the peripheral vasculature,
other hormones, and the kidney to facilitate diuresis
when increased circulating blood volume is present
Hormonal Regulation of Body Fluids

23. Fluid Shifts Within the Body
May be intracellular or extracellular
ECF imbalances may be caused by an extracellular
volume deficit or excess

24. IV Fluids & Fluid Shifts
Isotonic:
• Normal Saline
• Lactated Ringer’s
Hypertonic:
• 3% saline
• D50%
• D5NS
Hypotonic:
• D5W (in the body)
• 0.45% saline

25. “Third Spacing”
Shift of fluid into a space where it is not
normally held
Example intravascular spaces to the
interstitial spaces (Ascites or Burn trauma)
May be local or systemic

26. Water Depletion
Inadequate intake
Excessive losses….includes insensible losses
Vomiting, diarrhea, excessive sweating, renal
disease, ADH deficiency (diabetes insipidus),
excessive diuretic use, diabetic ketoacidosis

27. Manifestations of fluid volume deficit
Weight loss
Thirst
↓urinary output
↑ s. osmolality, HCT and
BUN
Tachycardia
Hypotension
Flattened jugular veins
Poor skin turgor
Dry mucous
membranes
Neurological s/s
Hyperthermia
Sunken eyes
Depressed fontanelles

28. Management of fluid volume deficit
A’s and B’s
Circulation ….fluid resuscitation
Investigate and treat the cause
Monitor HR, rhythm and BP
Volume expanders
Symptomatic and supportive care
Hemodynamic monitors
Basic nursing care

29. If Left Untreated…
Shock
Renal failure
Multi-organ dysfunction syndrome (MODS)
Cardiac arrest

30. Fluid Volume Excess
Several contributing factors and causes
Causes may include:
– Disease Processes (ie. CHF, renal failure,
SIADH)
– excessive fluid intake,
– excessive Na intake,
– aggressive IV fluid administration,
– blood products

31. Clinical manifestations of fluid
volume excess
Weight gain
Muscle twitching
and cramps
Pulmonary and
peripheral edema
Hyperventilation
Confusion
Hallucinations
Coma
Seizures
Hypertension
Bounding pulse
Jugular vein
distention

32. Treatment of fluid volume excess
Airway and breathing
Circulation
Treat the cause
Diuresis
If CHF….nitrates and diuretics, bipap
Fluid restriction

33. • Electrolytes are important solutes in all body
fluids (ie. they are chemicals dissolved in body
fluid)
• When dissolved in an aqueous solution,
electrolytes separate into ions and are able to
carry an electrical current
• Positively charged lytes (Cations): Sodium,
Potassium, Calcium
• Negatively charged lytes (Anions): Chloride,
Bicarbonate, Sulphate
Electrolytes

34. • What do electrolytes do?
• They maintain osmotic concentrations in body fluids
• Necessary for enzyme reactions, nerve impulses, muscle
contraction, and metabolism
• Some minerals contribute to the regulation of hormone
production and strengthening of skeletal structures
• Electrolytes are ingested, then used for basic
physiological processes, stored for future use, or
excreted
• Electrolytes are tightly regulated in the body because
small changes can have a big impact on the body
Electrolytes

35. Potassium,
Phosphate, Sulphate
Magnesium
Sodium, Hydrogen,
Bicarbonate
Electrolytes in the ICF
(from greatest to least concentration)

36. Sodium
Chloride
Potassium
Bicarbonate
Hydrogen
Electrolytes in the ECF
(from greatest to least concentration)

37. Discussion of …
Sodium
Potassium
Calcium
Magnesium

38. Sodium (Na+)
Most abundant cation in the ECF
Primarily responsible for osmotic pressure
Exchangeable across cell membranes to maintain Na+ &
water balance & normal arterial pressure
Plays an important role in:
Maintaining body water
Movement of glucose, insulin, & amino acids across cell
membranes
Maintaining muscle strength, neural function, and urine output

39. Potassium (K+)
Primary intracellular cation (98% in ICF & 2% in
ECF)
Primarily responsible for cell membrane potential
Governs cell osmolality and volume
Secreted in sweat, gastric & pancreatic juice, bile, &
fluids of small intestine
Assists in skeletal, smooth and cardiac muscle
function
Regulation is influenced by Na+ and hormones

40. Calcium (Ca+) ~9-10.5 mg/dL
Important functions:
Smooth & skeletal muscle contraction
Bone and brain metabolism
Blood clotting
Primary ingredient in lung surfactant
Essential for membrane polarization & depolarization, action
potential generation, neurotransmission, and muscle
contraction
Calcium channels in myocardial cells allow transmembrane
calcium transport

41. Magnesium (Mg) ~1-2 mg/dL
Second most important intracellular cation
> 50% of body’s Mg is stored in bones, with the
rest in cells (particularly muscle)
1% in held in the ECF
Aids in the transport of K+ and Na+ across the
cell membrane
Competes with calcium in the gut
Imbalances ↑ mortality in combination with ACS

42. Chloride & Phosphorus (Phosphate)
Chloride is the principal anion of blood & ECF
Plays a cooperative role in maintaining acid-base balance
Takes part in the exchange of O2 & CO2 in red blood cells
Passively regulated by serum sodium levels
Phosphate is the principal anion of ICF
Essential for metabolism of carbohydrates, lipids, & proteins
Plays a role in hormonal activities & acid-base balance
Has a close relationship to calcium in maintaining homeostasis

43. • May be caused by an underlying disease or may
be the result of starvation, therapeutic drugs,
drug overdose, or other iatrogenic causes
• Almost always associated with some degree of
neuromuscular dysfunction
• Cardiac rhythm disturbances are also common
with many electrolyte abnormalities
Electrolyte Abnormalities

44. Hyponatremia ( < 135 mEq/L)
May involve depletion ….Na loss
May involve dilution ……H20 gain
Leads to a decreased osmolality of the ECS
Probably the most common electrolyte imbalance
seen in the clinical setting

45. Clinical Manifestations
Can be vague
Mainly neurological due to decreased osmolarity
& cerebral edema
Anorexia, nausea, weakness, confusion, agitation,
disorientation
When serum levels fall below 110 mEq/L:
Seizures, coma, death

46. Management Of Hyponatremia
If primary cause is fluid imbalance: IV replacement
with normal saline (0.9%)
Hypertonic saline (3%) may be cautiously
administered (via pump) for severe symptomatic
hyponatremia
If dilutional hyponatremia…diuretics
Correct other imbalances
Basic nursing care
Treat the cause

47. Hypernatremia ( > 145 mEq/L)
Occurs as a result of a water loss or a sodium gain
Hypernatremia results in a hyperosmolar state
Fluid will shift from the ICS to the ECS causing cell
dehydration
A significant risk for infants, older adults, & the
debilitated due to inability to independently replace
fluid losses

48. Hypernatremia ( > 145 mEq/L)
Pt will be thirsty and appear dehydrated
Early: anorexia, nausea, vomiting
Na >160 mEq/L:
Agitation
Irritability
Lethargy, Coma
Muscle twitching
Hyperreflexia
Intracranial hemorrhage can result from shrunken brain
tissue

49. Management Of Hypernatremia
If H20 Loss
• Drink water
• IV: Hypotonic NaCl
or D5W
If Na+ Gain
- diuretics
**Na+ must be reduced gradually to prevent too rapid
a shift of water back into the cells**

50. Hypokalemia ( < 3.5 mEq/L)
Occurs as a direct loss of potassium from the body or a
shift of potassium into the cells
Risk factors include vomiting & diarrhea, urinary
losses, diuretics, metabolic alkalosis, dialysis,
↑exogenous insulin, DKA, steroid therapy

51. Clinical Manifestations ( ↓cell excitability)
Muscle weakness
Anorexia
N/V
Parasthesia
Ascending paralysis
Diminished
respiratory effort
↓reflexes
Hypotension
Ventricular
dysrhythmias
Flattened T-waves
ST depression

52. • Less acute: p.o. replacement
• Potassium added to IV solution
• ++irritating to veins so must be in large vein or diluted
in IV solution
• Minibag concentration: do not exceed 10mEq/100ml
• Liter bag: 20-40 mEq/L
• Infusion: DO NOT exceed 10-20mEq/hour to prevent
hyperkalemia & cardiac arrest
Treatment

53. Hyperkalemia ( > 5.0 mEq/L)
Results from excess intake, poor excretion or
movement out of the cells
Risk factors include
Increased oral or IV intake
acute renal disease
metabolic acidosis
Potassium-sparing diuretics
Adrenal insufficiency
trauma, burns, diabetes
Cells are +++ irritable

54. Clinical Manifestations
Irritability
AP, diarrhea
Ascending muscle weakness
Cardiac dysrhythmias: bradycardia, sinus arrest, 1o
heart block, idioventricular rhythm, ventricular
fibrillation
Peaked T waves, wide QRS >6.5 mEq/L
Cardiac arrest

55. Management Of Hyperkalemia
Calcium chloride or calcium gluconate is the most
rapid method
Admin of glucose, insulin, & sodium bicarb (drives
potassium into the cell in exchange for sodium
Loop or osmotic diuretics to promote K+ excretion
Renal dialysis may be needed
Continuous cardiac monitoring is essential
ACLS guidelines for cardiac dysrhythmias

56. Hypocalcemia
Some Causes:
Hypoparathyroidism
Hypovitaminosis D
Malabsorption syndrome
Chronic nephritis
Cushing’s syndrome
Metastatic carcinoma of bone
Overdose of calcium channel blockers
>10 units of blood transfused

57. Clinical Findings Of Hypocalcemia
Nervous system excitability, leading to:
Anxiety, irritability
Cardiac dysrhythmias
Constipation
Lack of appetite
Skeletal muscle excitability:
Tetany, muscle twitching & cramping, parasthesias
Seizure activity
More severe: Laryngospasm, ventricular dysrhythmias,
hypotension

58. Management Of Hypocalcemia
Treat the cause
Determine magnesium level (may need to replace also)
Easily managed with IV calcium (usually 10% calcium
gluconate)
Calcium levels, blood pressure, & cardiac rhythm
should be carefully monitored during replacement

59. Causes Of Hypercalcemia
↑ ionization from bone d/t neoplasms
↑ intake
↑Vitamin D
↓urinary excretion ( thiazides)
ARF and acidosis

60. Clinical Presentation Of Hypercalcemia
Vague: headache, irritability, fatigue/lethargy,
malaise, difficulty concentrating, anorexia,
nausea, vomiting, constipation
↓muscle tone, ↓deep tendon reflexes
Dysrhythmias
Chronic hypercalcemia associated with kidney
stones, peptic ulcer, pancreatitis

61. Management Of Hypercalcemia
Treat underlying cause
Increase renal excretion with IV hydration and loop
or osmotic diuretics
Others depend on specific clinical situation:
Glucocorticoids to decrease intestinal calcium absorption
& increase urinary calcium excretion
Calcitonin or phosphate inhibits bone reabsorption

62. Hypomagnesemia
Causes:
Malabsorption syndrome
Ulcerative colitis
Cirrhosis
Alcoholism
Chronic renal disease
DKA
Diuretic therapy

63. Symptoms of Hypomagnesemia
Dysrhythmias: torsades de pointes, ventricular tachycardia,
ventricular fibrillation

64. Management Of Hypomagnesemia
ABCD’s
Treat the cause
IV or IM replacment
Critical care nursing interventions

65. Hypermagnesemia
Causes:
Poor renal excretion (usually caused by renal
failure)
Excessive intake (either by overdose or routine
dosing with impaired renal excretion)

66. Symptoms of Hypermagnesemia
Decreased CNS activity
GI upset
Altered LOA
Hypotension
Bradycardia
Paralysis
Atroventricular (AV) block

67. Treatment of Hypermagnesemia
Calcium chloride
Saline diuresis
Lasix
Hemodialysis for severe cases
Monitor magnesium levels, vital signs, &
deep tendon reflexes during treatment

68. Acid-Base Balance
https://www.youtube.com/watch?v=A_URRb5mk5Q

69. Arterial Blood Gas
Acid-base
Disorders.
Acid- Base
Balance
Synopsis

70. ABG Analysis
• This test enables the evaluation of gas exchange in the lungs
by measuring the partial pressure of gases dissolved in the
blood!!!
ABG 101
• Values obtained through ABG analysis tells us how well a patient
is oxygenating and also if he/she is developing acidosis or
alkalosis.
• It reflects how much oxygen is available to peripheral tissues.

71. ABG Values and What They Indicate
pH measurement = indication of the bloods acidity or alkalinity.
PaCO2 = adequacy of ventilation of the lungs.
PaO2 (partial pressure of arterial oxygen) = body’s ability to pick up
oxygen from the lungs.
Bicarbonate (HCO3) level = reflects the activity of the kidneys in
retaining or excreting bicarbonate.
SaO2 = refers to the ratio of actual hemoglobin oxygen content to
potential maximum oxygen carrying capacity of the
hemoglobin.

72. Normal ABG Values – blood acid base balance
pH: 7.35 to
7.45
PaCO2: 35
to 45 mm hg
PaO2: 80 to
100 mm hg
HCO3: 22 to
26 mEq/L
SaO2: 95%
to 100%
** Please note that the respiratory and metabolic systems work together
to keep the body’s acid-base balance within normal limits!!!!

73. Acid-base Disorders
ABG Findings Possible Causes Signs and Symptoms
Respiratory Acidosis
(excess carbon dioxide retention)
• pH<7.35
• Bicarbonate (HCO3) >26mEq/L
• Partial pressure of arterial
carbon dioxide (Paco2) >45
mmHg
• Asphyxia
• Central Nervous system
depression from drugs,
injury or disease.
• Hypoventilation from
pulmonary, cardiac,
musculoskeletal or
neuromuscular disease.
• Diaphoresis, headache,
tachycardia, confusion,
restlessness, apprehension,
flushed face.
Respiratory Alkalosis
(excess carbon dioxide excretion)
pH >7.45
HCO3 <22 mEq/L
PaCO2 <35 mm hg
• Gram-negative Bacteremia
• Hyperventilation
• Respiratory stimulation by
drugs, disease, hypoxia or
increased room
temperature.
• Rapid / deep respirations
• Parasthesia;light-headedness,
• Possibly anxiety.

74. ABG Findings Possible Causes Signs and Symptoms
Metabolic Acidosis
(bicarbonate loss, acid retention)
pH <7.35
HCO3 <22 mEq/L
Paco2 <35mm Hg
• Bicarbonate depletion from
diarrhea
• Excessive acid production
from hepatic disease,
endocrine disorders, shock or
drug intoxication.
• Inadequate acid excretion r/t
renal disease.
• Rapid deep breathing
• Fruity breath, fatigue,
headache, lethargy,
drowsiness, nausea, vomiting,
abdominal pain
• Coma (if severe)
Metabolic Alkalosis
(bicarbonate retention, acid loss)
pH >7.45
HCO3 >26 mEq/L
Paco2 >45 mm Hg
• Excessive alkali ingestion
• Loss of hydrochloric acid from
prolonged vomiting or gastric
suctioning.
• Loss of potassium from
increased renal excretion
(diuretics) or steroids.
• Slow, shallow breathing,
hypertonic muscles.
• Restlessness, twitching,
confusion, irritability, tetany
• Seizures, Coma (if severe)

75. Next Week…..
ABG (cont’d)
• Appropriate interventions for Acid-
base disorders.
• Practice tips/knowledge for obtaining
arterial blood gases.