Fluid compartments Flashcards
What is the hydrophilic layer of a cell?
The outer layer that is made up of phosphate groups
What is the hydrophobic layer of a cell?
The inner layer, made up of lipids or fatty acids.
The average of the adult female body is what percentage of water?
52%
The average of the adult male body is what percentage of water?
63% water
The water in the body (about 40 litres), together with dissolved nutrients is distributed into which two major compartments?
- Intracellular fluid compartment
2.Extracellular fluid compartment
What is the intracellular fluid compartment?
Includes all water and electrolytes that the cell membranes enclose
Represents 63% of total body water
What is the extracellular fluid compartment?
-Includes all fluid outside the cells
-Within the tissue space (interstitial fluid)
-Within blood vessels (plasma)
-Within lymph vessels (lymph)
-Represents 37% of total body water
What does hydrostatic pressure do?
Drives fluid into the lymph vessels
What two types of pressure regulate fluid movement?
Hydrostatic pressure
Osmotic pressure
Fluid leaves plasma because of hydrostatic pressure and
returns to plasma because of osmotic pressure.
What does osmotic pressure do?
Regulates fluid movement in and out of cells
What is osmosis?
Flow of fluid across a semi permeable membrane from a lower solute concentration to a higher solute concentration.
What is osmotic pressure the result of?
Impermeant solutes on one side of a cell membrane
What is an electrolyte with an overall positive charge called?
Cation
What is an electrolyte with an overall negative charge called?
Anion
What are two or atoms that bond together called?
A molecule
What are organic molecules?
Carbon atoms like sugar
Why are charged atoms and compounds called electrolytes?
Because of their ability to conduct ‘electricity’ (ions)
What are inorganic molecules?
Without carbon atoms like table salt
What are the functions of electrolytes?
-Electrolytes help regulate water levels
-Water in body helps stabilise the electrolyte changes
-Contractility of cardiac and skeletal muscle function
What is blood pH levels?
7.35-7.45
What are blood sodium levels?
135-145 mmol/l
What are normal blood potassium levels?
3.5-5 mmol/l
What is sodium in the body?
Its a cation needed to regulate water to intravascular and interstitial fluid compartments.
Where sodium goes, water follows.
Its a component of circulating buffer.
What are the signs and symptoms of hypo/hypernatremia?
Anorexia/nausea
Fatigue
Headaches/seizures
Decreased BP
Thirst
Weakness
Edema
HTN
Where is most potassium found in the body?
About 98% is found inside cells of the body
What is potassium used for in the body?
-Needed for neuromuscular functions
-Needed to convert glucose into gylcogen
-K+ levels are regulated by insulin.
What does low potassium cause?
Decrease in skeletal muscle function, GI disturbances and alterations in cardiac functions.
What does high potassium levels cause?
Hyper stimulation of neuro cell transmission = cardiac arrests
What is calcium used for in the body?
-Principle cation needed for bone growth
-Assists in the functioning of heart muscle, nerves and cell membranes
-Assists in blood clotting
What its hypocalcemia and what does it cause?
.Low calcium levels
-Overstimulating of nerve cells
-Skeletal muscle cramps
-Abdo cramps
-Hypotension
-Vasoconstriction
What is hypercalcemia?
.Decreased stimulation to nerve cells
-Skeletal muscle weakness
-Lethargy
-Ataxia
-Vasodilation
-Hot flushed skin
What does bicarbonate do in the body?
It is a determining factor between acidosis and alkalosis in the body = pH
Sodium bicarbonate is the primary buffer used in all circulating body fluids
What does chloride do?
Primary regulate pH of the stomach
Regulates extra cellular fluid levels
What are the causes of dehydration?
D&V
Sweating
DKA
Elderly
Incorrect diet in infants
What is the Bronsted-Lowry theory in regard to acids and bases?
- Acids donate H+ to other substances, does
not need to be in a solution. - The substance that accepts the H+ is called the “conjugate base”
- Acid strength is defined as the tendency of that acid to donate H+.
- Strength of a base is the tendency of that
substance to accept H+ - This theory also does not account for the fact that some substances are acids despite no H+.
What is pH defined as?
pH = - log10 [h+]
-Log to base 10
-The square brackets mean concentration in mol dm-3
-The negative signs before log means the concentration of hydrogen ions is proportional to the pH of the acid.
What makes a substance more acidic?
-The more h+ ions there are the more acidic the substance and the lower the pH
How much more acidic is a pH of 6 more than a pH of 7?
10 times more acidic
A ph of 5 is 100 times mo0re acidic than a ph of 7
A ph of 4 is 1000 times more acidic than a ph of 7
This is because of the ‘log’ function.
What are the three types of acid in the body?
Fixed acids
Organic acids
Volatile acids
What are fixed acids?
They do not leave the solution, once formed they stay in until excreted by the kidneys - sulfuric acid , phosphoric acid.
Produced by the breakdown of proteins
What are organic acids?
Acids produced as by products of metabolism or act as participants in metabolism, under normal conditions these acids are metabolised by the body and do not build up significant levels.
Examles:
* Lactic acid
* Ketone bodies
* DNA
Produced by the breakdown of carbohydrates and
fats
What are volatile acids?
-Can enter and leave the body through the lungs
-They are acids that can turn into gases
Forms through the interaction of CO2 and H20
In order for acid base balance to occur what needs to happen?
The 3 types of acids need to be metabolised or excreted at the same rate that they are produced.
What are the 3 responses in acid base balance?
-First response is buffering (immediate response)
-Second response is alteration is ventilation (mins-hours)
-Third response is renal response (hours to days)
What are buffer systems?
A buffer is a solution containing substances that can minimise a
change in pH.
* When acids or bases are added or removed, the buffer system
allows for a shift in ions and components to allow for minimal
change in the total pH of the solution.
* The body’s ability to buffer is hug
What is the respiratory response in acid bases?
Adjustment of CO2 by ventilation is a rapid response
* Changes in CO2 excretion can lead to
* Correction of acid-base disturbance (respiratory)
* Cause respiratory alkalosis/acidosis
* Compensation for metabolic acidosis/alkalosis
Because CO2 can cross membranes so quickly it changes pH
rapidly
What is the renal response regarding acid bases?
Works by changing the rate of H+ and HCO3- secretion and re-absorption in the kidneys (responding to pH changes in the plasma)
* The kidneys also rely heavily on buffers within to maintain H+ excretion.
* If the pH of the renal tubule must be maintained above pH 4 in order to allow for the excretion of H+.
* Lower pH would allow the H+ to rush back in as fast as it was pumped out.
What is acidosis?
Abnormal process or condition which lowers the pH
What is alkalosis?
Abnormal process or condition which raises the pH
What is pH is classed at acidaemia?
blood pH < 7.35
What is pH classed at alkalaemia?
blood pH >7.45
What is the conservation of charge?
The body will always try to get the charge within the body back to normal
What are some independent variables in acid bases?
CO2
Total weak acids present (albumin)
Strong ion difference
What does albumin do?
- Oncotic pressure
- Transport
- Antioxidant
What do high alumni levels do the body?
Infections
Burns
Stress to the system
Dehydration
What do low albumin levels do to the body?
Malnutrition
Poor absorption in the GIT
Renal losses
Inflammatory disorders
Is a cation positive charge or negative?
CAT ion = Positive
(pawsitive cat)
Is an anion positive charge or negative?
An IRON = negative
What are classed as strong ions?
Any anion or cations that completely dissociate in solution are considered
strong ions. For example Na and Cl are strong ions.
What are the four major problems that can occur with acid base disturbance?
- Respiratory acidosis
- Respiratory alkalosis
- Metabolic acidosis
- Metabolic alkalosis
What is respiratory acidosis?
Primary acid-base disorder in which PaCO2 increases to higher than normal levels.
This will cause increases in ventilation.
Most cases are as a result of low alveolar ventilation.
What are the causes of respiratory acidosis?
- Central respiratory depression and other CNS disorders
- Nerve or muse disorders
- Lung or muscle wall defects
- Airway disorders
- External factors
- Overproduction of Co2
- Increased intake of Co2
What are the effects of hypercapnia?
-Stimulation of ventilation
-Cerebral vasodilation
-SNS stimulation
-CNS depression at high levels
-PCO2 of >90mmg is not compatible with life
What are the symptoms of respiratory acidosis?
Rapid, shallow breaths
Low BP with vasodilation
Dyspnea
Headache
Hyperkalemia
Dysthymias (increase in K)
Drowsiness
Muscle weakness
What is respiratory alkalosis?
Primary acid-base disorder in which arterial PC02 falls to a lower level than normal.
Achieved by increased alveolar ventilation resulting in increased excretion of Co2.
What is minute ventilation?
The amount of air moved into the lungs in one minute (TV x RR)
What is the main compensation for respiratory alkalosis?
Fall in bicarbonate level
Kidney is the effector organ for this
A slow response (2-3 days)
What are the symptoms of respiratory alkalosis?
Seizures
Deep, rapid breaths
Hyperventilation
Tachycardia
Low BP
Hypokalaemia
Lethargy
Nausea/vomitting
What is metabolic acidosis?
Primary acid-base disorder in which HCO3 (bicarbonate) drops below normal level.
What does an increased anion gap indicate?
That there is the prescence of am unmeasured anion present in the blood
What is anion gap useful for in metabolic acidosis?
Gives in indication of the cause of metabolic acidosis (only used for this)
What are the cardiorespiratory effects of metabolic acidosis?
Hyperventilation
Depressed myocardial contractility
Peripheral vasodilation
Pulmonary constriction
Hyperkalaemia effects on the heart.
What is the compensation mechanism for metabolic acidosis?
Hyperventilation
The subsequent fall in Co2
How do you manage metabolic acidosis
TREAT UNDERLYING DISORDER
- Manage ABCs
- Treat cause as far as possible
- Replace fluid as needed
- Restore adequate blood pressures
TREATING REVERSIBLE CAUSES ARE VITAL
What are the symptoms of metabolic acidosis?
Low BP
Headache
Hyperkalemia
Warm, flushed skin
Nausea/ D&V
Changes in LOC
Muscle twitching
What is metabolic alkalosis?
Primary acid-base disorder in which HCO3 increases above expected level.
What is one of the major causes of metabolic alkalosis?
The depletion of chloride
What do the kidneys do in metabolic alkalosis?
They reabsorb HCO3 in an attempt to protect against the Cl depletion.
What are the effects of metabolic alkalosis?
-Decreased myocardial contractility.
-Arrhythmias
-Decreased cerebral blood flow
-Confusion
-Neuromuscular excitability
-Risk of hypoxaemia
-Hypoventilation
What is the compensatory mechanism for metabolic alkalosis?
Hypoventilation
However this is not always found.
What leads to hypoventilation in patients with metabolic alkalosis?
Pain leading to hyperventilation
Pulmonary congestion leading to hyperventilation
Hypoxia leading to hypoventilation
How is metabolic acidosis treated?
- Treat the underlying cause of the problem
- Correct the factor that maintain the disorder (chlorine depletion)
- Expand vascular volume ad increase renal perfusion which may assist in the excretion of HCO3
What are the symptoms of metabolic alkalosis?
-Restlessness
-Dysrhythmias
-Compensatory hypoventilation
-Confusion
-Nausea/ D&V
-Tremors, muscle cramps
-Hypokalemia
