Vascular System Flashcards
What are the 3 main functions of the Vascular System?
Transport nutrients (blood/sugar) Maintain internal conditions Protect and fight against disease
What is the structural make up of the vascular system?
A large network of blood vessels
What is the role of arteries?
Carry blood away from the heart towards the arterioles under the highest pressure
What is the structure of arteries?
Thick, muscular elastic walls
What is the role of arterioles?
Carry blood from arteries to capillaries, controlling the pressure and distribution of the blood
How do arterioles control the distribution and pressure of blood?
They can change their internal size via vasomotor control (vasodilate or vasoconstrict), with the aid of pre capillary sphincters
What are pre-capillary sphincters and how are they controlled?
A ring of smooth muscle that behaves like a gate
Using sympathetic nervous stimulation
What is the role of capillaries?
Carry blood at the lowest pressure from arterioles to venules, and surround the structure of important muscles and organs
What is the structure of capillaries?
The thinnest blood vessel, walls are 1 cell thick
Which blood vessel is the site of substance exchange?
Capillaries (oxygen passes through capillary walls into tissue, CO2 passes from tissue into blood through capillary walls)
What is the role of venules?
Act as a link vessel, they carry blood from capillaries to veins
What is the role of veins?
Veins are responsible for venous return They carry (deox) blood at the lowest pressure (furthest from the heart)
What are the venous return mechanisms at rest (3)?
Pocket valves
Smooth muscle
Gravity
What are the venous return mechanisms during exercise (2)?
Muscle pump
Respiratory pump
What is the role of pocket valves (venous return mechanism)?
Prevent the back flow of blood within veins
What is the role of the smooth muscle (venous return mechanism)?
Vasoconstrict to create vasomotor tone (tension in walls) to push blood towards the heart
What is the role of gravity (venous return mechanism)?
Blood in the upper body (above heart) is aided by gravity to return to the heart
What is the role of the muscle pump (venous return mechanism)?
Squeezes blood back to the heart (with help of pocket valves)
What is the role of the respiratory pump (venous return mechanism)?
Return blood in the thoracic cavity and abdomen back to the heart
