SURG 226 Varicose Veins Flashcards
How does blood move along large blood vessels?
by convection
How does blood move through vessel walls?
diffusion
How are the capilliary beds organised? ( vessel order)
arteries –> arterioles –> terminal arterioles –> capilliaries –> post capilliary venules
Which small blood vessels constrict and dilate rhymically (vasomotion) - what is this controlled by?
In the terminal arterioles
Controlled by local metabolic products so blood flow matches metabolism
In inflammation which small blood vessels in the capilliary bed have increased permeability in inflammation?
post-capilliary venules
What molecules in blood are lipophillic?
oxygen and co2 therefore can cross the lipid bilayer of the endothelium
What molecules in blood are hydrophillic?
glucose and other small ions so need to cross wall of continuous capilliaries through gaps between cells
What is molecular sieving?
Only smaller solutes can pass through gaps between cells due to tight junctions and the glycocalyx - slows larger solutes moving through
What are the three types of capilliary?
Continuous
Fenestrated
Sinusoid
Describe continuous capilliaries?
contain flattened endothelial cells with 2/3 junctions
used in skin, lung, connective tissue and the CNS
Describe fenestrated capilliaries?
thin circular regions with gaps in the endothelial cell itself (spoke like)
high filtration and absorption rates
choroid, endocrine glands, guts, joints, kidneys
Describe sinusoid capilliaries?
Gaps between cells usually for RBC movement
e.g. spleen, bone marrow and liver
What is oedema due to?
excess interstitial fluid
capilliary filtration rate must be greater than lymphatic drainage
What are some causes of increased capilliary filtration in oedema?
DVT, inflammation
Right sided HF - high venous pressure
What are some causes of decreased lymphatic drainage??
Filliariasis - chronic lymphoedema with no pitting due to the fibrosis
