WEEK 1: Control of water and electrolytes Flashcards
What is the internal pool?
Internal pool – the quantity of any particular substance in the ECF.
State 2 aspects that affect the internal pool.
If quantity is to remain stable within the body
Input must be balanced with output.
- Ingestion: Metabolic Production
- Excretion: Metabolic consumption
State 2 ways of input into the internal pool.
- Input form external environment (inhalation, absorption through body surface, artificial injection and ingestion
- Body metabolic production
State 2 ways of output from the internal pool.
- Excretion to external environment (Kidney, lungs, digestive tract and body surface.)
- Body metabolic consumption
Describe the following:
Positive balance:
Negative balance:
Stable balance:
Positive balance: input > output
Negative balance: output > input
Stable balance: input = output
Between input and out, which is poorly controlled?
Input
-Input of substances into plasma is poorly controlled or not controlled
-Eating habits are variable
Output
-Compensatory adjustments usually occur on output side by urinary excretion
Water (synonymous with ‘fluid’)
*Most abundant substance in body
*Amount varies in different kinds of tissues
*Content remains fairly constant within an individual
In human physiology, what is the reference point of weight is an apparently healthy man?
In human physiology, the reference point is a 70kg apparently healthy man.
What is the % TBW for males?
What is the TBW for females? Why?
Describe the trend of TBW with age. Does it increase or decreases? Why?
60% of the total body weight is water (about 40L)
About 50% in females (35L), They generally have high body fat.
% water declines with age.
Classification of body fluids REVISION TABLE ON NOTES!!!
State the minor ECF components.
(i) Lymph
(ii) Transcellular fluid
-Cerebrospinal fluid
-Intraocular fluid
-Synovial fluid
-Pericardial, intrapleural, and peritoneal fluids
-Digestive juices
Ionic Composition of the Major Body-Fluid Compartments (Revision) CHECK THE NOTES
State the barriers separating the body fluid compartments.
Describe the distribution of ions between the ICF and ECF.
What is Interstitial fluid?
(i) Plasma membrane: ICF and ECF
ICF (more K+, Proteins, Phosphates)
ECF (more Na+, Cl- & HCO3-)
(ii) Capillary walls: Plasma and ISF
NB! ISF is essentially plasma minus proteins
What is extracellular fluid?
ECF - an intermediary between cells and external environment.
State Two factors are regulated to maintain fluid balance in the body.
Two factors are regulated to maintain fluid balance in the body.
ECF volume
(ii) ECF osmolarity
What is the difference between osmolarity and osmolality?
Osmolarity= mOsmol/L
Osmolality= mOsmol/ kg
ECF volume must be closely regulated to help maintain blood pressure.
What is very important in long-term regulation of ECF volume?
How does ECF volume maintain blood pressure?
Maintaining salt balance is very important in long-term regulation of ECF volume.
NB- Osmo… has to do with water! Plasma volume very influential in BP regulation. BP regulation influenced by salt control.