SLIDE 1
Structure and Function of Blood Vessels
Peter Takizawa Department of Cell Biology
SLIDE 2 What we’ll talk about…
- Structure of blood vessels and their appearance in
histological samples
- Endothelium and structures that control permeability
- Increasing endothelial permeability and leukocyte
transmigration
- Smooth muscle and vascular repair
- Angiogenesis
SLIDE 3
Blood vessels comprise three functional layers.
SLIDE 4 Endothelial cells perform a variety of structural and biochemical functions.
- Permeability
- Immune response
- Angiogenesis
- Modulate vascular resistance
- Antihaemostatic and haemostatic control
- Enzymatic action on plasma proteins
SLIDE 5
The aorta is an elastic artery that contains numerous elastic fibers in the media.
Media Adventitia Intima Smooth Muscle Cell Elastic Fiber Internal Elastic Lamina Vasa Vasorum Endothelial Cell
SLIDE 6
Muscular arteries contain more smooth muscle and fewer elastic fibers in the media layer.
Media Adventitia Intima Internal Elastic Lamina Endothelial Cell External Elastic Lamina Smooth Muscle Cell
SLIDE 7
Small muscular arteries contain fewer layers of smooth muscle.
Endothelial Cell Smooth Muscle Cell
SLIDE 8
Arterioles control blood flow into capillaries and create the highest resistance in the circulatory system.
Endothelial Cell Smooth Muscle Cell
SLIDE 9
Arterioles have one or two layers of smooth muscle cells.
Endothelial Cell Smooth Muscle Cell
SLIDE 10
Capillaries contain a single layer of endothelial cells and the occasional pericyte.
Endothelial Cell Capillary Lumen Pericyte
SLIDE 11
Permeability of capillaries
SLIDE 12
Small molecules and ions diffuse across capillaries but proteins are restricted in most capillaries.
s Sugars Small Protein Large Protein
SLIDE 13
Capillaries restrict the diffusion of protein to maintain oncotic pressure.
Protein Protein
SLIDE 14 Primary components that regulate permeability of capillaries.
- Structure of endothelial cells
- Basement membrane
- Intercellular junctions between endothelial cells
- Glycocalyx
SLIDE 15
Structure of Endothelial Cells
SLIDE 16 Continuous capillaries contain endothelial cells that
- nly allow passage through intercellular junctions.
Endothelial Cell Intercellular Junctions Pericyte
SLIDE 17
Fenestrated capillaries have endothelial cells with several gaps for diffusion of solutes.
Endothelial Cell Fenestrae Pericyte
SLIDE 18
Discontinuous capillaries contain large pores and lack a basement membrane.
Endothelial Cell Fenestrae Lumen
SLIDE 19
Basement membrane is a negatively-charged barrier on the basal surface of endothelial cells.
Basement Membrane Red Blood Cell Endothelial Cell
SLIDE 20
Junctional complexes restrict paracellular diffusion between endothelial cells.
Lumen Lumen Interstium
SLIDE 21
Glycocalyx restricts diffusion of large, negatively charged molecules.
Glycocalyx Glycocalyx Removed
SLIDE 22
Transcytosis of Proteins
SLIDE 23
Receptor-mediated endocytosis transports specific proteins across endothelium via transcytosis.
Blood Interstitium
SLIDE 24
Transcytosis mediates movement of proteins across endothelial cells.
Lumen Lumen Endocytic Vesicle Endocytic Vesicle Interstitium Release of Material Release of Material Intercellular Junction Interstitium
SLIDE 25
Increasing the Permeability of Blood Vessels
SLIDE 26 Inflammatory molecules and immune cells activate signaling pathways that disrupt junctions.
Kinases Myosin Disrupt Junctions Increase Tension Modify Cadherins
SLIDE 27
Thrombin increase vascular permeability through tension on adhesion junctions.
SLIDE 28
Immune cells must pass across endothelial cells to reach sites of infection.
SLIDE 29 Rolling Adhesion Emigration
Timothy Springer Lab, Harvard Medical School
Leukocyte transmigration consist of three distinct steps.
SLIDE 30 Selectins and integrins mediate rolling and adhesion of immune cells.
Capture Rolling Arrest Transmigration
Selectins Integrins
SLIDE 31
Leukocytes disrupt adhesion junctions to migrate across endothelium.
SLIDE 32
Venules and Veins
SLIDE 33
Venules have an endothelium and relatively thin layer of smooth muscle.
Endothelial Cell Smooth Muscle Cell
SLIDE 34
Venules have thinner medial layers than arteries and tend to lose their shape.
Endothelial Cell Smooth Muscle Cell Artery Venule
SLIDE 35
The vena cava has a thinner media than the aorta with mostly smooth muscle cells and collagen.
Smooth Muscle Cell Intima Media Adventitia
SLIDE 36
Lymphatic vessels have thin walls and lack red blood cells.
Endothelial Cell Lymphatic Vessel Venule Arteriole
SLIDE 37
Vascular Repair
SLIDE 38
Damage recruits smooth muscle cell progenitors to the intima.
Damage Endothelial Cell Smooth Muscle Cell
SLIDE 39 Smooth muscle proliferation can lead to occlusion
- f arteries after insertion of stents.
SLIDE 40
Angiogenesis
SLIDE 41
VEGF triggers morphological changes in endothelial tip cells.
High O2 Low O2
SLIDE 42
Tip cells follow guidance cues to connect to existing vessels.
Semaphorins
SLIDE 43 Tumor cells initiate angiogenesis to increase their blood supply.
VEGF VEGF
Tumor cells Stromal cells
