Circulatory System Overview

Overview of the Cardiovascular System

• Comprised of blood, heart, and blood vessels; essential for transportation and homeostasis.
• Blood transports oxygen, carbon dioxide, nutrients, and hormones; regulates pH, temperature, and provides disease protection.

Functions of Blood

• Transportation: Delivers oxygen from lungs to cells and removes carbon dioxide for exhalation.
• Regulation: Maintains pH levels through buffers; regulates body temperature via blood flow.
• Protection: Forms clots to prevent blood loss and white blood cells engage in phagocytosis to combat pathogens.

Physical Characteristics of Blood

• Denser and more viscous than water; slightly sticky texture.
• Normal temperature around 38°C (100.4°F), slightly alkaline pH of 7.35 to 7.45 (average = 7.4).
• Color of blood indicates oxygen saturation: bright red when oxygenated, dark red when deoxygenated.

Formed Elements of Blood

• Red Blood Cells (RBCs/Erythrocytes): Carry oxygen to cells and carbon dioxide back to lungs; lifespan of 120 days, produced in bone marrow.
• White Blood Cells (WBCs/Leukocytes): Protect against pathogens; include neutrophils, basophils, eosinophils, monocytes, lymphocytes (B cells, T cells, NK cells).
• Platelets: Cell fragments crucial for blood clotting; release chemicals that promote vascular spasm.

The Heart

• Pumps blood through vessels, essential for delivering oxygen and nutrients while removing wastes.
• Beats approximately 100,000 times a day; equates to about 35 million beats annually and 2.5 billion over a lifetime.
• Pumps around 5 liters of blood each minute, totaling over 14,000 liters (3,600 gallons) daily.

Anatomy of the Heart

• Located in the mediastinum; shape resembles a fist.
• Dimensions: Length about 12 cm (5 in), Width 9 cm (3.5 in), Depth 6 cm (2.5 in).
• Average mass: 250 g (8 oz) in females, 300 g (10 oz) in males; two-thirds mass left of midline.

Ventricular Characteristics

• The left ventricle forms the apex of the heart, critical for systemic circulation.