lecture 7 Flashcards
Function of capillaries
site of exchange between blood and tissues
Features of capillaries?
thin walls
large total cross sectional area of capillary bed
slow and smooth blood flow
Function of precapillary sphincters?
Control blood flow into capillary beds of certain organs
What are precapillary sphincters made up of?
smooth muscle
Small lumen of capillaries allows how many red blood cells through at a time?
One red blood cell
Why do capillaries allow one red blood cell at a time?
Slows and smooths blood flow
Allows time for gas exchange to occur
blood contact with vessel walls
Purpose of thin walls in capillaries?
allow for faster diffusion and large cross sectional area as there are many capillaries.
Three types of capillary structures?
continuous
menstruated
sinusoidal
Most common type of capillary in the body?
continuous
Size of continuous capillary
8-10um
Which types of capillaries have intact basement membranes?
Continuous and fenestrated
What is the most ‘leaky’ type of capillary?
sinusoidal
what is an example of where a fenestrated capillary might be found?
Kidneys and small intestine
Where would you find a sinusoidal capillary?
Liver
size of a fenestrated capillary?
8-10um
size of a sinusoidal capillary?
30-40um
What substances can diffuse through capillary cell membrane?
Lipid soluble
How do water soluble substances get transported through capillaries?
through the intercellular clefts found in all capillaries or the fenestrations
Function of the lymphatic system?
Act as an immune response by screening the drainage of excess tissue fluid and plasma proteins before they return to the blood
What is the structure of a lymphatic capillary?
Large and thin, blind ended with valves
Where would you find lacteals?
In the small intestine
what is the function of lacteals?
they are specialised lymphatic vessels that drain fatty lymph into the cisterna chyli
What is the cisterna chyli?
Dilated sac of the thoracic duct
Where do cervical and axillary nodes on the right hand side drain into?
The right subclavian vein (into the blood) Via the right lymphatic duct
Where do the lymphatic nodes excluding the RHS cervical and axillary nodes drain into?
The thoracic duct and then the left subclavian vein
4 functions of the lymph vascular system?
Drains excess tissue fluid and plasma proteins before returning to blood
filters foreign material from the lymph
screens for foreign antigens and conducts an immune response
absorbs fat from intestine and transports it to the blood
