physiology week 11 +12 Flashcards
How does Body fluids remain constant
Body fluids remain constant due to a balance between fluid intake and output
Name sources of daily water intake
- Ingested water(from liquids+ food)
-Synthesized water
Name sources of daily water loss
Insensible water loss:
skin
Respitatory tract
-sweat
-Feces
-Kidneys
What is the role of the kidneys
- It adjusts water and electrolyte excretion to balance intake and compensate for losses
- The regulate electrolytes like Na,cl,k
What is body fluid divided into
-ICF
-ECF
What does ECF contain
- Transcelluler fluid
-Interstitial fluid
-Blood plasma
What does Transcellular fluid contain
- Cerebrospinal fluid
and fluid in the :
-Synovial
-peritoneal
-pericadial
intraocular spacesssss
What factors does total body water depend on
- Age
-Sex - Fat percentage
What is extracellular fluid subdivided into
- interstitial fluid
- plasma
Name the cations and the amounts that ECF contains
Large amounts of Na+,
Small amounts of k+,Ca2+,Mg2+
Name the Anions and the amounts in which the ECF contains
- Large amounts of Cl- and bicarbonate ions with small amounts of phosphate and organic acids
Explain the similarity between plasma and interstitial fluid
They have a similar ionic concentration due to highly permeable capillary membranes
Explain the differences between plasma and interstitial fluid
- Plasma has a higher concentration of protons due to low permeability of capillaries to proteins
What is the Donna Effect
- It is that Plasma has slightly higher cations than interstitial fluid because plasma proteins bind cations and repel anions
How is the ICF separated from the ECF
- By a cell membrane that is permeable to water but not to most electrolytes
Name the cations that ICF contains and the amounts
- High amounts of k+ and moderate Mg2+
Name the anions that the ICF contains and the amounts
-ICF contains high amounts of phosphate and sulphate ions
- Low amounts of chloride and sodium Concentrations
How is the body fluid compartment volumes measured
- Indicator-dlution principle
Explain the method of the Indicator-Diltuion principle
- Inject a known amount of indicator into the compartment
- Allow the substanc to mix evenly throughout the compartment
- Analayze the final concentration of the indicator in the fluid sample
What does the calculation formula for indicator dilution principle :VolumeB=
ConcentrationB
VolumeA ×ConcentrationA
Require knowing for the equation to be used
Requires knowing:
-The total amount of indicator injected
- Final concentration of the indicator in the compartment
What conditions is needed for the indicator-dilution method to be accurate
- Indicator must diperse evenly throughout the compartment
-Indicator must remain restricted to the compartment being measured - Indicator should not be metabloized or excreted
What does measurement of Total body water use
- Uses substaces like radioactive water or antipyrine
What does measurement of Extracellular fluid volume use
- Substances such as radiocative sodium, radioactive chloride
What does the measurement of plasma volume use
- Using substances that remain in the vascular system, such as radioactive iodine
Explain the selective permeability of cell membranes
- Highly permeable to water
- Realtively impermeable to solutes like Na and cl
What is the effect of adding Sodium chloride to ECF
- Water moves out of cells
What is the effect of removing sodium chloride from ECF
- Water moves into cells
What does osmolality mean
osmoles per kilogram of water
What does osmolarity
osmoles per liter of solution
80% of the total osmolarity of the ECF and plasma is due to what
-Sodium and chloride ions
In ICF half the osmolarit is due to what
Potassium ions
What does small changes in extracellular solute concentrations create
High osmotic pressure across cell membranes
When does water stop moving across cell membranes
- When osmotic equillibrium is achieved
Explain what happens isotionic solutions
There is no net water movement and cells maintain their volume
Explains what happens in hypotonic solutions
- Water diffuses into cells , causing the cells to swell
What happens in hypertonic solutions
- Water diffuses out of cells , causing cells to shrink
Explain isosmotic solutions(osmolarity)
What does the Tonicity depend on in isosmotic solutions
- They have equal osmolarity to cells
- Tonicity depends on whether solutes are permeant or impermeant
Explain hyperosmotic/hypo osmotic solutions
- They have higher/lower osmolarity than ECF
Why does water move rapidly across cell membranes
- To equalize osmolarities between the ECF and ICF
What are the effects of adding isotonic saline to the ECF volume+ osmolarity
- It increases ECF volume without changing osmolarity or intracellular volume
What are the ffects of adding hypertonic saline to the ECF osmolarity
- It inceases ECF osmolarity, causing water to move out of the cells
What is the net effect of adding hypertonic to the ECF and ICF volumes
-ECF volume increases
-ICF volume decreases
What is the effect of adding hypotonic saline to the ECF osmolarity
- Decreases ECF osmolarity, causing water to move into cells
What is the net effect of adding hypotonic saline to ECF and ICF volumes
-Intracellular and extracellular vloumes increase
What is the purpose of using glucose solutions
Used to provide nutrition
Name 2 solutions that’s are used for nutritive purposes
Amino acid and homogenised fat solutions
How are nutrient solutions administered and why
-Isotonic
- Slowly
To maintain osmotic equilibrium
How is excess water excreted
By kidneys as dilute urine
What is the result of a low plasma sodium
Concentration
Hyponatremia
What is the result of high plasma sodium concentration
Hypernatremia
What are the causes of Hyponatremia
- Loss of sodium from the ECF
- Excess water in the ECF
Name some conditions that can cause hyponatermia by causing sodium loss
- Vomiting, Diarrhea,Kidnesy disease,Addisons disease
What can hyponatremia, loss of sodium lead to
- Edema
-Seizures,death
What is hyperntremia caused by
- Loss of water from the ECF
- Excess sodium in the ECF
What is the role of Central Diabetes Insipidus in causing hyperntremia
It stop the secretion of ADH, which leads tp the excretion of large amounts of dilute urine, causing sodium concentration to increase
What is the effect pf hypernatremia on cells
- Causes water to leave cell, leading to cell shrinage
What is Edema
Accumulation of fluid in the body tissues
What causes Intracellular Edema
-Hyponatremia-(Low sodium levels)
-Metabolic depression or Inadequate nutrition
-Inflammation which increases membrane permeability, allowing sodium and water to enter the cells
What causes Extracellular Edemaa
-Increased capillary pressure
-Decreased Plasma proteins
-Increased capillary permeability
-Lymphatic blockage
What causes Lymphedema
- Blocked lymphatic flow
Name the saftey factors that prevent Edema
-Low tissue compliance
-Increased Lymph flow
-Washdown of Proteins
