L10: Capillaries Flashcards
What does the rate of diffusion depend on
Concentration gradient
Surface area
Diffusion distance
What happens to the rate of diffusion as the concentration gradient increases
Increases
What happens to the rate of diffusion as surface area increases
Rate increases
What happens to the rate of diffusion as diffusion distance increases
Decreases
What is the surface area determined by
Number of capillaries
How do we maximise a concentration gradient
By maintaining a good blood flow
What happens to the diffusion distance when there is tissue oedema
Diffusion distance increases therefore diffusion rate decreases
What is anaemia
When there is a low haemoglobin count in the blood
What happens to the diffusion distance when there is anaemia
Diffusion distance increases and therefore the rate of diffusion decreases
What is atherosclerosis
When the elastic arteries stiffen as you age so the blood flow decreases
What is a capillary hydrostatic pressure
The pressure that causes the blood to filter into the interstitial space
In an healthy individual do we have an intersitial oncotic pressure
No because the would be no proteins in the intersitial space so it would be 0
What are the forces favouring reabsorption of fluid into the capillaries
Intersitial hydrostatic pressure
Capillary oncotic pressure
In a normal healthy individual what would the intersitial hydostatic pressure be
0
What is the capillary oncotic pressure caused by
Proteins in the capillaries which draws water from the interstitial space
Overall in a healthy individual what are the only 2 forces found in the capillaries
Capillary hydrostatic pressure
Capillary oncotic pressure
What does the area above the oncotic pressure represent
Filtration
What does the are below the oncotic pressure represent
Reabsorption
In a healthy individual what is the hydrostatic pressure at the arteriolar end
35
In a healthy individual what is the capillary hydrostatic pressure at the venule end
15
What is the normal capillary hydrostatic pressure
15 mmHg
What happens to the capillary hydrostatic pressure when there is arterial vasodilation
Increases
What happens to the oncotic pressure when there is a arterial vasodilation
Stays the same at 25 mmhg
What happens to the capillary hydrostatic pressure when there is a arterial vasoconstriction
Hydrostatic pressure decreases
What happens to the capillary oncotic pressure when there is arterial vasoconstriction
Stays the same at 15 mmHg
What happens to the capillary hydrostatic pressure when there is a increased capillary pressure
Increases
What happens to the capillary oncotic pressure when there is an increased capillary pressure
Stays the same at 25mmhg
What happens to the capillary hydrostatic pressure when there is a high venous pressure
The arteriolar end pressure stays the same at 35 mmhg the capillary hydrostatic pressure will increase from 15mmg in the venous side
What would happen to the oncotic pressure when there is an increased venous pressure
Stays the same at 25 mmhg
What happens to the net oncotic pressure when there is increased interstitial protein
Decreases because net oncotic pressure= capillary oncotic pressure- intersitial oncotic pressure
What happens to the hydrostatic pressure when there is an increased intersitial protein
Stays the same from 35 to 15 mmhg
What happens to the net oncotic pressure when there is plasma protein deficiency
Decreases
What happens to the hydrostatic pressure when there is a plasma protein deficiency
Stays the same
What happens to the oncotic pressure in dehydration
Increases
Why does the oncotic pressure increase in dehydration
You have the same amount of protein in the blood but it is in a less volume so there is higher concentration of protein
What happens to the hydrostatic pressure in dehydration
Decreases
