Mapa mental
Blood vessels
Conteúdo do mapa
Blood vessels
Arteries and arterioles
- Thick muscle to withstand high pressures
- Blood carried at high pressures generated by the ventricular systole
- Oxygenated blood
- Except pulmonary and umbilical arteries
- Medium lumen
- Elastic fibres to control pressure --> elastic recoil between contractions
Veins and venules
- Thick collagen in the walls for support
- Little elastic because they carry the blood at lower pressures
- Valves in medium to large sized veins to prevent backflow
- Carry deoxygenated blood except the pulmonary and umbilical ones
- Smooth lining to allow the blood to flow easily
- Large lumen
- Muscle contraction squeezes them and forces the blood back towards the heart and the breathing movement of the chest pumps it back
Capillaries
- One cell thick walls for small diffusion distances
- Blood deoxygenates as it goes through the capillary
- Smallest lumen to slow the flow of the blood right down and maximise the time for diffusion to occur
- Erythrocytes have to go single-file to which increases the time available for exchange