Arteries

blood vessels

artery - arteriole - capillary - venule - vein

three layers of blood vessels

tunica intima, tunica media, tunica externa

tunica intima

innermost layer of a blood vessel wall, composed of a simple squamous epithelium lining the blood vessel lumen and a subendothelial layer made up of thin layer of areolar connective tissue

tunica media

middle layer of the vessel wall, composed of circularly arranged layers of smooth muscle cells and may have an external elastic lamina, thickest layer

tunica externa

outermost layer of the blood vessel wall, composed of areolar connective tissue that contains elastic and collagen fibers, helps anchor the vessel to other structures, thicker layer in veins

arteries

transport blood away from the heart

arterioles

the smallest arteries, sympathetic innervation causes contraction in the smooth muscle of the arteriole wall, results in vasoconstriction, which raises blood pressure

arteriole vasoconstriction

decreases blood flow into the capillaries (because the vessel lumen is narrower)

arteriole vasodilation

increases blood flow into the capillaries (because the vessel lumen is wider)

capillaries

the smallest blood vessels, connect arterioles to venules, most capillaries consist solely of a tunica intima composed of a very thin, single layer of endothelium and a basement membrane, the thin wall and narrow vessel diameter are optimal for diffusion of gases and nutrients between blood in the capillaries and body tissues, functional units of cardiovascular system

veins

drain capillaries and return the blood to the heart, vein walls are relatively thin, the vein lumen is larger, function as blood reservoirs

venules

the smallest veins, companion vessels with arterioles, because both supply the same areas, venules merge to form veins

3 main branches of the arch of aorta

brachiocephalic trunk, left common carotid artery, and left subclavian artery

brachiocephalic trunk

bifurcates into the right common carotid artery, supplying arterial blood to the right side of the head and neck, and the right subclavian artery supplying the right upper limb and some thoracic structures

left common carotid artery

supplying the left side of the head and neck

left subclavian artery

supplying the left upper limb and some thoracic structures

descending abdominal aorta

bifurcates into left and right common iliac arteries, each divides further into an internal (to supply pelvic and perineal structures) and external (to supply the lower limb) iliac artery

superior vena cava

the veins that drain the head, neck, and upper limbs merge to form the left and right brachiocephalic veins, which merge to form this structure

inferior vena cava

responsible for transporting venous blood toward the heart from lower limbs, pelvis, and perineum, and abdominal structures, drains blood directly to right atrium

external carotid artery

supplies structures external to the skull

internal carotid artery

enters the cranium to supply the anterior and middle cerebral hemispheres

collateral artery

provide alternative routes for blood flow when the main artery is blocked or narrowed

recurrent artery

after branching off from the main artery, they turn back in the opposite direction, often forming connections with other vessels forming anastomosis

anastomosis

connections between different arteries

vertebral arteries

supply the posterior cerebral hemisphere, brain and spine

circle of willis

acts as a crucial backup system, allowing blood flow to continue to the brain should one vessel become blocked

dural venous sinuses

superior sagittal sinus, inferior sagittal sinus, straight sinus, transverse sinus, sigmoid sinus

dural venous sinus function

collect deoxygenated blood from the brain and skull, drain blood into the internal jugular veins

femoral artery

arterial supply to hamstrings

genicular arteries

collateral circulation around the knee, arise from popliteal artery

popliteal artery

bifurcates into anterior and posterior tibial arteries

posterior tibial artery

arterial supply to the plantar foot

anterior tibial artery

muscles of ther anterior compartment of leg and dorsum of foot

internal thoracic artery

supply to the intercostal muscles of respiration, anterior and posterior intercostal arteries originate from here

internal iliac artery

arterial supply to pelvis and gluteal region (bladder, uterus, vagina, rectum)

femoral artery

begins from the external iliac artery when it crosses under the inguinal ligament

superior and inferior gluteal arteries

superior is above piriformis muscle and inferior is below the piriformis muscle