Blood vessels Flashcards
What is angiogenesis & when does it occur
Formation of new arteries & veins
Controlled by pro-angiogenic (VEGFA, hypoxia, FGF2) & anti-angiogenic (angiostatin & PEDF) factors
When does it occur?
Fetal & post-natal development – metabolically active tissue needs to be close to capillary for gaseous exchange
Female reproduction – placental development
Wound healing
Tumour development
Hypoxia
What is anastomosis
If blood flow stops, organs receive collateral supply of blood to avoid necrosis
What is a vascular tree
Each tissue receives fresh blood from heart, not from other tissues
Split into 2 parts:
Systemic circulation
Pulmonary circulation
What is the portal system
Few organs are connected in series
Obtain their blood second hand from venous outflow of another organ
Done to transport solute from one place to another without dilution in general circulation
All vertebrates have hepatic portal vein
From GI to liver
Filter newly absorbed compounds
Renal portal vein in all vertebrate non-mammals
From hind limbs to kidneys
Resorb salt & water
Fill in the table
Describe pressure in arteries
Composed of smooth muscle cells that contract to decrease radius
Decrease in radius results in increase in blood pressure
Contraction of arterioles regulates blood pressure
Describe types of capillaries & pressure in capillaries
Low blood pressure as they are fragile & very permeable (high pressure forces fluid out)
Types of capillaries:
Continuous – continuous lining of endothelial cells except for clefts between cells
Majority of body
Fenestrated – windows where cell membrane is compressed to permit greater fluid transmission
Glomerular capillaries in kidney
Discontinuous sinusoid – wider intercellular gaps that permit increased exchange with surrounding tissues
Liver, bone marrow, lymphoid tissue, endocrine glands
Describe pressure in veins
High collagen & low elastin
Venous return depends on pressure difference between venules & RA
