Complete Guide to Regional Circulation in Human Body | Anatomy + Physiology

Definition:

Regional circulation refers to the blood flow to a specific organ or area of the body, each having special structural & functional adaptations.

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1. CEREBRAL CIRCULATION (Brain)

Key Features:

• Brain gets ~15% of cardiac output
• Highly oxygen-dependent
• Very sensitive to hypoxia or ischemia

Blood Supply:

• Internal carotid arteries
• Vertebral arteries
• Form the Circle of Willis

Regulation:

• Autoregulation is strong (constant flow even if BP varies from 60–160 mmHg)
• ↑ CO₂ → vasodilation
• ↓ O₂ → vasodilation
• Blood-brain barrier protects brain tissue

Clinical:

• Stroke
• Transient ischemic attack (TIA)
• Cerebral edema

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2. PULMONARY CIRCULATION (Lungs)

Key Features:

• Low pressure, high flow system
• Oxygenates blood

Pathway:

• Right ventricle → pulmonary artery → lungs → pulmonary veins → left atrium

Regulation:

• Hypoxia → vasoconstriction (opposite of systemic circulation)
• Maintains proper ventilation/perfusion (V/Q) ratio

Clinical:

• Pulmonary embolism
• Pulmonary hypertension

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3. RENAL CIRCULATION (Kidneys)

Key Features:

• Receives ~20–25% of cardiac output
• Functions in filtration, excretion, BP regulation

Pathway:

• Renal artery → segmental arteries → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries/vasa recta → renal vein

Regulation:

• Autoregulated via:
• Myogenic response
• Tubuloglomerular feedback
• Influenced by RAAS

Clinical:

• Acute kidney injury (AKI)
• Renal hypertension

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4. CUTANEOUS CIRCULATION (Skin)

Key Features:

• Helps in temperature regulation
• Blood supply changes with ambient temperature

Regulation:

• Controlled mainly by sympathetic nerves
• Vasoconstriction in cold
• Vasodilation in heat

Special Feature:

• Arteriovenous anastomoses (AVAs) in fingers, ears, nose (help in thermoregulation)

Clinical:

• Frostbite
• Raynaud’s phenomenon

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5. CORONARY CIRCULATION (Heart)

Key Features:

• Heart receives ~5% of cardiac output
• Most flow occurs during diastole

 Blood Supply:

• Left coronary artery (LCA) → anterior & lateral heart
• Right coronary artery (RCA) → posterior & right heart

Regulation:

• Autoregulation present
• ↑ Heart work → ↑ adenosine → vasodilation

Clinical:

• Angina
• Myocardial infarction (MI)
• Coronary artery disease (CAD)

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Mnemonic to Remember All: "CRuPC-C"

• C – Cerebral
• R – Renal
• P – Pulmonary
• C – Cutaneous
• C – Coronary