Lecture 4 Flashcards
What is the plasma volume of a 70kG man?
0.6 x 70 = 42L (equation is 0.6 x weight in Kg)
What is 2/3 of the plasma?
It is intracellular
What is 1/3 of the plasma?
It is extracellular
What does the intravascular component contain?
It contains blood which consists of cells and plasma
What do the doctors do if you have been vomiting and had diarrhoea for a few days?
Isotonic solution is the best type to rehydrate you
What is a hypotonic IV solution able to treat?
Diabetic ketoacidosis or cellular dehydration
What is a hypertonic IV solution able to treat?
Someone in critical care, to increase intravascular fluid volume - Brain injuries to reduce intracranial pressure
How would you make an isotonic IV?
Add glucose to water to make it isotonic
What is dextrose?
It is chemically identical to blood sugar and glucose.
is dextrose a good IV fluid for someone that has an diarrhoea?
Yes as the water will diffuse across all compartments, only 80ml stays in the blood vessels so its a very good replacement fluid
What is the best fluid for someone that has diarrhoea?
Saline - it only ends up in the interstitial and in the blood vessels.
How much saline will end up in the vascular space and in the interstium?
250ml in the vascular space and 750mls in the interstitum
What is the circulating volume?
Plasma volume and how much pressure there to be able to be pumped around the body
Why would there be a decrease in circulating volume?
If the blood pressure failing or if the blood vessels are empty
What does the kidney do if it wants to expand and increase blood pressure?
It will reabsorb Na+/Cl- which will = an increase in plasma volume - the kidney prefers to absorb Na+
What do the kidneys release in response to a drop in blood pressure?
It will release renin
What is the reabsorption rate for the PCT?
50-60%
What can work for kidney expansion?
Salty water
What happens if the kidney decide to absorb salt?
There will be a much bigger expansion of the intracellular compartments whereas if it was to absorb water the water would be distributed around the body.
What is the equation for BP?
CO x peripheral resistance
What are the three steps of volume regulation?
Monitoring, signalling and action at targets
What is renin produced by?
By the kidneys when your blood pressure decreases
What does renin allow the conversion of?
It allows the conversion of angiotensin which tells the body to absorb salt, vessels to constrict and tells the adrenal glands to make aldosterone
What does aldosterone do?
It helps control the balance of water and salt in the kidneys by keeping Na+ and releasing K+.
