L14 Flashcards
(26 cards)
What characteristics of the capillary make perfect for two way exchanged?
- Steep conc gradient
- Short distance diffusion pathway
- Slow blood flow
- large surface area
What are the three type of capillaries?
- Continuous =
- Fenestrated = Contains pores allow allow exchange of WATER and solutes
- Sinusoidal = Large clefts and incomplete basement membrane, allows exchange of WATER and LARGE SOLUTES
Forces in the capillary that affect blood flow?(4)
- Capillary hydrostatic pressure
- Interstitial hydrostatic pressure
- Blood colloid osmotic pressure
- interstitial fluid COLLOID osmotic pressure
What is Capillary hydrostatic pressure in terms of what it does it to the fluid in capillaries?
- blood pressure exerting on pushing fluid out
What is interstitial hydrostatic pressure?
Pressure exerted by interstitial fluid pushing blood in the capillaries
What is blood colloid osmotic pressure?
plasma pressure that draws blood into capillary
What is interstitial colloid osmotic pressure?
osmotic pressure that pulls fluid out of the capillary
How can you measure NET FILTRATION PRESSURE?
Net hydrostatic pressure - Net osmotic pressure
How can net HYDROSTATIC pressure be calculated?
Capillary hydrostatic pressure - interstitial fluid hydrosstatic pressure
What movement of the fluid does net HYDROSTATIC pressure favour?
Movement of the fluid out of the capillary into interstitial fluid= FILTRAATION is favoured
What movement of the fluid does the net OSMOTIC pressure favour?
Favours reabsorption of fluid into capillary
Where will fluid move with positive NET filtration pressure?
into interstitial fluid
Where will fluid move when -ve NET filtration pressure?
reabsorption into capillary
What happens to Capillary hydrostatic pressure (CHP) from arteriole to venous end?
It decreases from 35 to 18
What is the mmHg pressure value of Cpillary hydrostatic pressure?
35
What is interstitial hydrostaTIC PRESsure mmHg value?
0
What is the typical BLOOD colloid osmotic pressure?
25 (across all capillary)
What is the typical mmHg interstitial colloid osmotic pressure?
0
WHAT is net Hydrosattic pressure value in mmHg?
35 to 18 to venule end
What is net colloid osmotic pressure value in mmHg?
25 across all capillary (25 - 0)
Why is FILTRATION greater than reabsorption overall?
Because net HYDROSTRATIC pressure is 35 compared to net OSMOTIC pressure which is 25, so more fluid exit the capillaries than it is reabsorbed to overall during the day
What is the typical net filtration pressure?
NFP = NHP - NCOP = 10
How does hypertension affect the net filtration pressure at arteriole end?
- Increased net filtration pressure to 20 (45 - 25 instead of 35 - 25)
- High BP = Higher CHP which means more filtration
- which collects in extremities
- leads to systemic oedema
How would haemorrhage affect net filtration pressure at venous end?
- Haemorrhage = lower BP = Lower CHP = 5 instead of 18
instead 18 - 25, its 5-25 = -20 net filtration pressure, so more fluid is reabsorbed into blood
- leads to increase in BP and CO
