01 January 2021 01:17
Blood vessel architecture:
Artery
Arteries supply oxygenated blood to organs and body at high pressure. The interior of the artery is
made of endothelial cells which forms the actual barrier in which the blood is transported. The
endothelium is surrounded by various layers of elastic fibres and other materials.
Vein
Veins are capillaries that take blood back to the heart and lungs and it is also composed of quite a
complex structures. Veins have thinner endothelium structures and the blood pressure coming back
to the heart is lower. They have valves to prevent blood flowing backwards as the pressure is low.
Capillary
These are thinner finer vessels involved in the exchange of nutrients, gas and other materials with
the tissues. They consist of one layer made of single layer cells to allow faster diffusion of materials
across the capillaries. The basement membrane is surrounded by pericyte and they are support cells.
They form the barrier for the inner endothelium layer.
If the integrity of the pericyte is destroyed by viral infection, then that will cause haemorrhage and
different types of haemorrhagic viruses can affect the barrier. When parasites such as mosquitoes
draw blood from the capillaries , they are going to be injecting the virus into the blood stream.
Generally, blood borne infections could arise from intravenous drug use or medical interventions.
Through this pathway they get introduction to the viruses into the vein.
Haemorrhage:
The escape of blood from any blood vessel in the body. Eg. bruising which is the loss of blood from
capillaries and entering muscle tissues which shows the reddish skin on individuals who are bruised.
Viral haemorrhage:
• Severe multi-system (multi organs) syndrome characterised by diffuse vascular leakage
• Bleeding often occurs, may or may not be life threatening
• May be mild or life-threatening
Upon damage of tissue, the blood loses from blood vessels into body cavity so that makes it difficult
to
Examples:
- Bruises
- Conjunctivital infection
- Edema
- Epistaxis
- Petechie
Haemorrhagic fever viruses
Blood borne
Filoviruses: Ebola virus, Marburg virus
Air borne
Arenaviruses: Lassa virus
Arthropod-borne
Flaviviruses: dengue virus
Haemorrhagic viruses Page 1