Systemic circulation

Systemic circulation is the portion of the cardiovascular system which carries oxygenated blood away from the heart, to the body, and returns deoxygenated blood back to the heart. The term is contrasted with pulmonary circulation.

Contents 1 Course 1.1 Arteries 1.2 Capillaries 1.3 Venules 1.4 Veins 2 Advantage 3 Veins 4 See also

Course

In the systematic circulation, arteries bring oxygenated blood to the tissues. As blood circulates through the body, oxygen diffuses from the blood into cells surrounding the capillaries, and carbon dioxide diffuses into the blood from the capillary cells. Veins bring deoxygenated blood back to the heart.

Arteries

See also: Arterial tree

Oxygenated blood enters the systemic circulation when leaving the left ventricle, through the aortic semi-lunar valve. The first part of the systemic circulation is the artery aorta, a massive and thick-walled artery. The aorta arches and gives off major arteries to the upper body before piercing the diaphragm in order to supply the lower parts of the body with its various branches.

Capillaries

Blood passes from arteries to capillaries, which are the thinnest and most numerous of the blood vessels. These capillaries help to join tissue with arterioles for transportation of nutrition to the cells, which absorb oxygen and nutrients in the blood. Peripheral tissues do not fully deoxygenate the blood, so venous blood does have oxygen, but in a lower concentration than in arterial blood. In addition, carbon dioxide and wastes are added.

Venules

The deoxygenated blood is then collected by venules, from where it flows first into veins, and then into the inferior and superior venae cavae, which return it to the right heart, completing the systemic cycle. The blood is then re-oxygenated through the pulmonary circulation before returning again to the systemic circulation.

Veins

The relatively de-oxygenated blood collects in the venous system which coalesces into two major veins: the superior vena cava (roughly speaking from areas above the heart) and the inferior vena cava (roughly speaking from areas below the heart). These two great vessels exit the systemic circulation by emptying into the right atrium of the heart. The coronary sinus empties the heart's veins themselves into the right atrium.

Advantage

Because the systemic circulation is powered by the left ventricle (which is very muscular), one advantage of this form of circulation - as opposed to open circulation, or the gill system that fishes use to breathe - is that there is simultaneous high-pressure oxygenated blood delivered to all parts of the body.

Veins

The relatively de-oxygenated blood collects in the venous system which coalesces into two major veins: the superior vena cava (roughly speaking from areas above the heart) and the inferior vena cava (roughly speaking from areas below the heart). These two great vessels exit the systemic circulation by emptying into the right atrium of the heart. The coronary sinus empties the heart's veins themselves into the right atrium

See also

• Pulmonary circulation
• Double circulatory system

•  • e Cardiovascular system
Blood  |  Heart  → Aorta → Arteries → Arterioles → Capillaries → Venules → Veins → Vena cava → Heart → Pulmonary arteries → Lungs → Pulmonary vein

•  • e List of arteries of head and neck
Anterior: CC/EC	superior thyroid (superior laryngeal) - lingual (sublingual) facial: cervical branches (ascending palatine, tonsillar, submental, glandular) - facial branches (inferior labial, superior labial, lateral nasal, angular)
Posterior and ascending: CC/EC	occipital - posterior auricular (stylomastoid) - ascending pharyngeal (meningeal branches)
Terminal, superficial temporal: CC/EC	transverse facial - middle temporal (zygomaticoörbital) - anterior auricular - frontal - parietal
Terminal, maxillary: CC/EC	1st part: anterior tympanic - deep auricular - middle meningeal (superior tympanic) - accessory meningeal - inferior alveolar (mylohyoid) 2nd part: deep temporal - pterygoid branches - masseteric - buccal 3rd part: posterior superior alveolar - infraorbital (anterior superior alveolar) - descending palatine - artery of the pterygoid canal - sphenopalatine
portions #1 and 2: CC/IC	cervical portion (carotid sinus) - petrous portion (Vidian, caroticotympanic)
cavernous portion/ophthalmic: CC/IC	orbital group: lacrimal (lateral palpebral) - supraorbital - posterior ethmoidal - anterior ethmoidal - medial palpebral - supratrochlear - dorsal nasal ocular group: central retinal - ciliary (short posterior, long posterior, anterior) - superior hypophysial - inferior hypophysial
cerebral portion: CC/IC	ACA - anterior communicating - MCA (anterolateral central) - posterior communicating - anterior choroidal - circle of Willis
vertebral artery: SC	meningeal branches - posterior spinal - anterior spinal - PICA - basilar (pontine, labyrinthine, AICA, SCA, PCA)
thyrocervical trunk: SC	inferior thyroid (inferior laryngeal, tracheal, esophageal, ascending cervical) - suprascapular - transverse cervical - dorsal scapular

•  • e List of arteries of upper limbs
Axillary	scapular anastomosis - 1st part superior thoracic - 2nd part thoracoacromial (deltoid branch)- lateral thoracic - 3rd part subscapular (circumflex scapular, thoracodorsal) - anterior humeral circumflex - posterior humeral circumflex
Brachial	profunda brachii (radial collateral, medial collateral) - superior ulnar collateral - inferior ulnar collateral
Radial	forearm: radial recurrent - palmar carpal branch - superficial palmar branch wrist: dorsal carpal branch (dorsal carpal arch, dorsal metacarpal, dorsal digital) hand: princeps pollicis - radial of index finger - deep palmar arch (palmar metacarpal)
Ulnar	forearm: anterior ulnar recurrent - posterior ulnar recurrent - common interosseous (anterior, posterior, recurrent) wrist: palmar carpal branch - dorsal carpal branch hand: superficial palmar arch (common palmar digital, proper palmar digital) - deep palmar branch - palmar carpal arch

•  • e List of arteries of torso - chest
Pulmonary / coronary	right coronary: SA nodal - AV nodal - atrial - right marginal - posterior interventricular left coronary: anterior interventricular - left circumflex - left marginal
Ascending aorta	aortic arch - brachiocephalic (thyreoidea ima) - common carotid
Subclavian	internal thoracic: anterior intercostal - thymic - pericardiacophrenic - terminal (musculophrenic, superior epigastric) costocervical trunk: highest intercostal (posterior intercostal 1-2) - deep cervical
Descending / thoracic aorta	visceral: bronchial - esophageal - mediastinal parietal: posterior intercostal 3-11 - subcostal - superior phrenic

•  • e List of arteries of torso - abdomen
AA: Anterior	celiac left gastric: esophageal branches splenic: pancreatic branches (greater, dorsal) – short gastric – left gastro-omental common hepatic: proper hepatic (cystic), right gastric, gastroduodenal (right gastro-omental, superior pancreaticoduodenal, supraduodenal) SMA inferior pancreaticoduodenal – intestinal (jejunal, ileal, arcades, vasa recta)  – ileocolic (colic, anterior cecal, posterior cecal, ileal branch, appendicular)  – right colic – middle colic IMA left colic – sigmoid – superior rectal – marginal
AA: Posterior	visceral: middle suprarenal – renal (inferior suprarenal, ureteral) – gonadal (testicular ♂/ovarian ♀) parietal: inferior phrenic (superior suprarenal) – lumbar – median sacral terminal: common iliac (IIA, EIA)
IIA: Anterior	umbilical (superior vesical, to ductus deferens) – middle rectal – obturator (anterior branch, posterior branch) - inferior gluteal (accompanying of ischiadic nerve, crucial anastomosis) uterine ♀ (helicine, vaginal of uterine, ovarian of uterine, tubal of uterine) - vaginal ♀/inferior vesical ♂ internal pudendal: inferior rectal - perineal (urethral) - posterior scrotal ♂/labial ♀ - bulb of penis ♂/vestibule ♀ - deep artery of the penis ♂ (helicine)/clitoris ♀ - dorsal of the penis ♂/clitoris ♀
IIA: Posterior	iliolumbar (lumbar, iliac)  – lateral sacral – superior gluteal
EIA	inferior epigastric (cremasteric, round ligament) – deep circumflex iliac – femoral

•  • e List of arteries of lower limbs
EI: Femoral	superficial epigastric - superficial iliac circumflex - external pudendal (superficial, deep/anterior scrotal arteries) - profunda femoris (lateral circumflex femoral, medial circumflex femoral, perforating) - descending genicular
Popliteal	anterior tibial - sural genicular: superior genicular (medial, lateral) - middle genicular - inferior genicular (medial, lateral)
Anterior tibial	dorsalis pedis: tarsal (lateral - medial) - arcuate - dorsal metatarsal/first dorsal metatarsal - deep plantar tibial recurrent (posterior, anterior) anterior malleolar (medial, lateral)
Posterior tibial	circumflex fibular - fibular medial plantar - lateral plantar (plantar arch, plantar metatarsal)