4. Blood Vessels and Nerves Flashcards
What are the 8 layers of arteries?
- Lumen
- Endothelium
- Basement membrane
- Intima
- Internal elastic lamina
- Media
- External elastic lamina
- Adventitia
What are the elastic arteries?
Arteries near the heart- aorta and pulmonary arteries
What is a key feature of elastic arteries?
The media contains abundant concentric sheets of elastin
What are muscular arteries?
Most arteries with media comprising layers of smooth muscle and little elastin in the media
What are arterioles?
Resistance vessels having 3 or fewer muscle layers in their media
Describe the elastic laminae of arterioles.
Poorly defined
What are the 2 layers of capillaries?
- Basement membrane
- Endothelium
What are present at intervals along capillaries?
Pericytes
How do fenestrated capillaries differ from normal capillaries?
They have tiny openings called pores which allow larger molecules and proteins to move from the blood into organs and glands
Name 2 examples of where you might find fenestrated capillaries.
- Kidney
- Liver
What are the 7 layers of veins?
- Lumen
- Endothelium
- Basement membrane
- Intima
- Internal elastic lamina
- Media
- Adventitia
Describe venules.
Thin walled and associated with arterioles with contractile pericytes wrapped around the outisde of endothelial cells
What is the difference between venules and veins?
Pericytes are replaced by smooth muscle as venules become veins
Compare vein wall thickness to venules and arteries.
Large veins are thick walled compared to venules and thin walled compared to corresponding arteries
What might smooth muscle in vein walls be?
Circular or longitudinal
Describe lymphatics.
Thin walled, similar to capillaries and veins with valves
What do lymphatics contain?
Eosinophilic lymph (possibly lymphocytes too)
What are peripheral nerves composed of?
Axons
What are peripheral nerves supported by?
Schwann cells and most are myelinated
What is myelin produced by?
Schwann cells
What are the 3 components of myelinated peripheral nerves?
- Endoneurium
- Perineurium
- Epineurium
Where is endoneurium located in myelinated peripheral nerves?
Present between individual axons
Where is perineurium located in myelinated peripheral nerves?
Surrounds the groups of axons to form fascicles
Where is epineurium located in myelinated peripheral nerves?
Binds fascicles together to form nerve fibres
What are small peripheral nerve fibres?
Bundles of axons interspersed with endoneurium and surrounded by perineurium and epineurium
What is a small neuro-vascular bundle?
Nerve, arteriole and venule
What does myelin do?
Insulates axons
What are gaps between Schwann cells?
Nodes of Ranvier
How do impulses in myelinated and unmyelinated axons differ?
Myelinated axons transmit impulses faster
Where are motor neurones located?
Cell bodies in grey matter of the spinal cord
Where are sensory neurones located?
Cell bodies in dorsal root ganglion
Where are sympathetic neurones located?
In grey matter of cord and in adjacent sympathetic ganglia
Where are parasympathetic neurones located?
Cell bodies in brain and local ganglia
