Histology- blood vessels and nerves Flashcards
general structure of blood vessel
lumen surrounded by vascular endothelium (simple squamos epithelium) that sits upon a basement membrane, beneath basement membrane lies the tunica intima (made of series of myointimal cells that have combined properties of smooth muscle and fibroblasts- contractile and secreete collagen and elastin), then internal elastic lamina and then tunica media (smooth muscle cells with interspersed sheets of elastin), external elastic lamina (in arteries), then loose fibrous connective tissue contianing blood vessels called vasa vasora supply artey wall with blood supply(also known as tunica adventitia).
elastic arteries
largest arteries close to heart- aorta and pulmonary artery, well developed tunica media
muscular arteries
most common, e.g. brachial artery, femoral artery, radial artery etc., less developed tunica media, less elastin presnt in media and mainly muscle,
arterioles
resistant vessels, have 3 or fewer muscle layers in tunia media, diameter of 30-40 micrometers in diameter, have poorly define elastic laminae
capilaries
lumen, vascular endothelium resting on basement membrane, pericytes present on some capilalries to allow it to contract (regulate diameter), majority have intact endothelium but some areas of body have fenestrated capillaries e.g. in sinusoids (specialised capillary) of liver, or in kidney due to gaps in endothelial lining (leaky)
venules
bigger lumen, smaller wall, often found associated with arterioles, thin walls, have very very thin media, pericytes also present wrapped around
veins
large lumen, vascular endothelium sat on basemnt membrane, resting on tunia intima sat on internal elastic lamina (poorly developed compared to artery), tunica medica (less well developed), adventitia (more well developed than arteries)
large veins
e.g.inferior and superior vena cava, compared to veins and venules are thick walled (still think compared to arteries)
lympatics vessles
thin walled and have similar structure to capillaries and veins, have valves, has not well developed media and internal elastic lamina, contains Eosinophilic lymph and may contain lymphocytes (stains pink)
afferent vs efferent
efferent away from heart and afferent towards heart
peripheral nerves- describe stucture include details about axon insulation
composed of axons and are supported by Schwann cells, most are myelinated creating an insulating sheath (produced by Schwann cells that wrap around axon), a single axon may have multiple schwann cells wrapping around it, myelin is what schwann cells membrane made of, in unmyleinated axons multiple axons can be suported by the same Schawann cell
mylenated peripheral nerve- main 3 types of fibrous connective tissue that support
supported by fibrous connective tissue: endoneurium (present betweeen individual axons), perineurium (surrounds groups of axons to form fascicles), epineurium (binds fascicles together to form nerve fibres)- be able to recognise in photos
neurovascular bundles
arterioles and venule tend to run in pairs alongside an adjacent nerve
purpose of myelin, how’s it produced
insulates axons and icraeses speed of transmission along nerve, myelinated axons are much larger, spiral of apposed Schwann cell membranes, multiple schwann cells per axon but only one axon per schwann cell, small gaps in myelin sheath are called Nodes of Ranvier
peripheral nerves- location of cell bodies of neurones?
motor neurons have cells bodies in grey matter of spinal cord, sensory neurones have their cell body in dorsal root ganglio, sympathetic neurones have cell bodies in grey matter in adjacent sympathtic ganglia, parasympathatic have their cell bodies in brain and local ganglia, cell bodies stain with H and E and silver stains, gangglian look like a lump
