Capillary Function Flashcards
What is a metarteriole
Connects terminal arterioles, precapillary sphincters directly to the capillary bed
Describe the order of the vessels in the microcirculation
- Small arteries
- First-order arterioles
- Terminal arterioles (precapillary spinsters)
- Capillaries
- Venules
What do capillary beds arise from
a single metarteriole
What is a throughfare channel
Bypasses capillary bed
Name some of the local mediators released by the capillary endothelium
Prostacyclin
Nitric Oxide
Endothelin
What are the functions of the local mediators Prostacyclin, Nitric Oxide and Endothelin
Prostacyclin + Nitric Oxide = relaxation of vascular smooth muscle
Endothelin = contraction of vascular smooth muscle
What is the active and passive functions of the capillaries
Active = release of the local mediators Passive = exchange of all that poop
Where can you find continuous capillaries
Skin Lung Fat Muscle Heart Brain
Describe the structure and function of continuous capillaries
The endothelial cell and basal lamina do not form openings, which would allow substances to pass the capillary wall without passing through both the endothelial cell and basal lamina e.g. BBB
Where can you find fenestrated capillaries
Kidney and gut
Describe the structure and function of fenestrated capillaries
The endothelial cell body forms small openings called fenestrations that allow components of the blood and interstitial fluid to bypass the endothelial cells on their way to or from the tissue surrounding the capillary
Describe the structure and function of discontinuous (sinusoidal) capillaries
Formed by fenestrated endothelial cells, the basal lamina is also incomplete. These capillaries form large irregularly shaped vessels (sinusoidal vessels). Found where free excahnge of substances of even cells between the bloodstream and organ is advantageous
Where are discontinuous capillaries found
Liver
Spleen
Red bone marrow
How does movement between blood and interstitial fluid happen
Diffusion
Transcytosis
Bulk Flow
What is the most important method of transport in capillaries
Diffusion
What can substances cross the capillary wall through
Intracellular clefts
Fenestrations
Endothelial cells
What limits diffusion in the BBB
Tight junctions
Where can proteins and even blood cells leave the capillaries/organs/tissues
Sinusoids
What is transcytosis
When a small quantity of material in the blood plasma becomes enclosed within pinocytotic vesicles and enters endothelial cells by endocytosis and leaves by exocytosis
When is transcytosis important
Important mainly for large, lipid soluble molecules that cannot cross capillary walls any other way.
What is bulk flow
It is a passive process in which large numbers of ions, molecules or particles in a fluid move together in the same direction and is based on pressure gradients.
What is bulk flow most important for
For the regulation of relative volumes of blood and interstitial fluid
What is an oedema and how does it happen
This is an excessive accumulation of ECF resulting from
- high blood pressure
- venous obstruction e.g. heart failure
- leakage of plasma proteins into ECF
What is myxoedema
This is an excess production of glycoproteins in the extracellular matrix form hypothyroidism
How can myxoedema occur
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- Hypothyroidism,
- Low plasma protein levels result from liver disease,
- Obstruction of lymphatic drainage
Idk what the powerpoint is trying to say here
