CVS (Systems of the body 2)

📌 Introduction & Core Components

🫀 Cardiovascular system = body’s transport network.

Components:

❤️ Heart (pump)

🩸 Blood vessels (arteries, veins, capillaries)

🩸 Blood

Function: transport O₂, nutrients, hormones + remove waste (CO₂).

🖇 The Heart

📍 Location: Thoracic cavity

📏 Size: ~ size of a closed fist

🔹 Structure

4 Chambers:

Right Atrium

Right Ventricle

Left Atrium

Left Ventricle

Walls:

Endocardium: inner smooth lining

Myocardium: muscular middle layer (contraction)

Pericardium: protective double sac (pericardial sac)

🔹 Valves (one-way blood flow):

Atrioventricular: Tricuspid (R), Mitral/Bicuspid (L)

Semilunar: Pulmonary (RV → pulmonary artery), Aortic (LV → aorta)

🔹 Blood Supply

Coronary arteries: supply myocardium

Cardiac veins: drain deoxygenated blood

🖇 Blood Vessels: Structure & Relationship

Arteries & veins often run together.

Small arteries ↔ venae comitantes.

🔗 Anastomosis:

Connection between vessels → alternative blood flow routes.

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📌 Types of Arterio-Venous Communications

1️⃣ Capillaries

Smallest, most numerous vessels.

Wall: single endothelial layer.

Site of gas, nutrient, and waste exchange.

Found in almost all tissues (e.g., alveolar plexuses).

2️⃣ Blood Sinusoids

Specialized capillaries: wide lumen, discontinuous porous walls.

Allow passage of large molecules & cells.

Sites: Liver, spleen, bone marrow.

3️⃣ Arteriovenous Anastomosis (Shunt)

Direct artery → vein connection (bypassing capillaries).

Smooth muscle controlled (open ↔ close).

🔥 Functions: Thermoregulation, blood flow regulation.

Sites: Skin dermis, nose, ear pinna, tongue, lips, erectile tissues (penis, vestibule), intestine.

4️⃣ Cavernous Tissue:

Specialized vascular tissue rich in AV anastomoses.

Blood engorgement → rigidity (e.g., penis).

📌 Clinical Importance

Anastomoses ensure blood supply even if one vessel is blocked.

Portal circulation vital for nutrient metabolism & detox.

AV anastomoses help in thermoregulation and erectile function.