Vascular Anatomy Flashcards
What is the aorta?
Largest artery in the body
Receives cardiac output form the left ventricle
Distributes blood via the systemic circulation
What are the sub-divisions of the aorta?
Ascending
Arch
Descending (thoracic)
Abdominal
Where does the aorta terminate?
Terminates at L4 (vertebral level) where it divides (bifurcates) into two terminal branches:
Right and Left Common iliac arteries
What are the 5 general classes of blood vessels?
Arteries – arterioles – capillaries – venules – veins
What is the difference between arteries, capillaries and veins?
ARTERIES
Away from heart
Relatively thick muscular wall
Resilient
Arterioles
Oxygenated blood (mostly)
VEINS
Body –> heart
Thin walls
Valves (due to low pressure)
Venules – collect blood from capillary bed
Venous plexuses
Deoxygenated blood (mostly)
CAPILLARIES
Connect arterioles to venules
1 cell thick walls
Important exchange site between blood and surrounding interstitial fluid
What are the key features of arteries?
Elastic and contractile
Responds to changes in blood pressure
Under autonomic control: vasoconstriction and vasodilation
Classification:
Elastic
Muscular
Resistance
What is the importance of elastic arteries?
Aorta and branches – distinguished by greater elasticity
Helps to smooth out fluctuations in BP
Systole: elastic laminae are stretched, reducing BP
Diastole: elastic rebound helps to maintain arterial pressure
What are the layers of the artery?
Tunica intima (TI) may grow with age (arteriorscleorosis)
Tunica media (TM) thickest layer
•Smooth muscle cells
•Elastin
Tunica adventitia (TA) thin connective tissue •Collagen prevents elastic arteries from stretching beyond physiological limits
Vasa vasorum (vv) ‘vessels of the vessels’
What’s the difference between muscular and resistance arteries?
MUSCULAR
Majority of arteries
Less elastic tissue; smooth muscle predominates in TM
TI smaller and TA larger than in elastic arteries
RESISTANCE
Small diameter arteries and arterioles
TM still relatively muscular
TA thinner and TI may disappear
Greatest change in BP between arterioles and capillaries
What are capillaries and what types are there?
Connect arterioles to venules – exchange of nutrients and waste between blood and tissue cells, + interstitial fluid
Single-layered, flattened endothelial cells
Fenestrated: bigger gaps between endothelial cells
What are the differences between arteries and veins?
ARTERIES
Carry blood away from the heart
Thicker wall/diameter ratio
Maintains circular profile
Resistant to higher pressure
No valves
VEINS
Carry blood to the heart (with the exception of portal systems connecting two capillary beds)
Thinner wall/diameter ratio (especially tunica media)
Often collapsed
Valves
Where does the aorta ascend and what arteries does it give off?
Ascending within pericardial sac from the aortic orifice
Gives off the right and left coronary arteries
Where does the aortic arch lie and where does it terminate?
Arch lies behind sternum, in front of the trachea
Arches upwards and backwards
Becomes continuous with descending aorta at level of sternal angle
End at vertebral level T4
What arteries does the aortic branch into? (in order)
Brachiocephalic trunk (divides into right subclavian and right common carotid
Left common carotid
Left subclavian
What do the branches of the aortic arch branch into?
Brachiocephalic trunk = right subclavian artery and right common carotid artery
Left common carotid = internal/external carotid arteries
Left subclavian = vertebral artery
What provides the blood supply to the head and neck?
Majority from carotid and vertebral arteries
Right common carotid: frrom Brachiocephalic trunk
Left common carotid: directly from aortic arch
Both ascend up the neck and bifurcate into internal and external carotid (L and R) at C4
At what point do the left and right common carotid arteries bifurcate?
Both ascend up the neck and bifurcate into internal and external carotid (L and R) at C4
What do the external and internal carotid arteries each supply?
EXTERNAL CAROTID: artery supplies the areas of the head and neck external to the cranium
The artery ends within the parotid gland by dividing into the superficial temporal artery and the maxillary artery
INTERNAL CAROTID: enters the skull and via the carotid canal and supplies the brain, eyes and forehead
How do vertebral arteries enter the brain?
Vertebral arteries arise from the subclavian arteries and enter the cranium via the foramen magnum to eventually supply the brain
Label the arteries of the trunk