Chapter 2: The Cardiovascular System – Blood (Anatomy & Physiology Study Notes)

The Cardiovascular System

Introduction to the Cardiovascular System

The cardiovascular system is essential for transporting substances throughout the body and maintaining homeostasis. It consists of the heart, blood vessels, and blood, working together to deliver nutrients and remove wastes.

• Transported Substances: Includes nutrients, oxygen, carbon dioxide, hormones, ions, metabolic wastes, and leukocytes (white blood cells).

• Other Functions:

  • Stabilization of body temperature: Blood redistributes heat, similar to a car's cooling system.

  • Prevention of fluid loss: Achieved via the clotting process.

  • Stabilization of pH and electrolyte balance: Blood buffers maintain acid/base homeostasis and keep electrolyte levels consistent in the extracellular fluid (ECF).

Functions and Composition of Blood

Major Components of Blood

Blood is a specialized connective tissue with two primary components: plasma and formed elements.

• Plasma: The liquid matrix of blood, making up about 55% of its volume.

• Formed Elements: Cells and cell fragments suspended in plasma, including:

  • Erythrocytes (red blood cells): Transport oxygen and carbon dioxide.

  • Leukocytes (white blood cells): Defend against pathogens and toxins.

  • Platelets: Prevent blood loss via hemostasis (blood clotting).

Physical Properties and Volume

• Whole blood: Contains all components, is about 5 times as viscous as water.

• Blood volume: 4–6 liters in adults, approximately 7% of body weight.

• Plasma composition: 92% water, 7% proteins, 1% other solutes.

Plasma Composition

Plasma is the fluid portion of blood and contains water, proteins, and other solutes. The proteins in plasma serve various functions, including maintaining osmotic pressure and immune defense.

Plasma Component	Percentage	Main Function
Water	92%	Solvent for carrying other substances; helps regulate temperature
Proteins	7%	Osmotic balance, immune defense, clotting
Other solutes	1%	Electrolytes, nutrients, organic wastes

Plasma Proteins

Plasma proteins are crucial for blood function and are classified into several groups:

Protein	Percentage of Plasma Proteins	Function
Albumins	60%	Major contributor to osmotic pressure; transports lipids and steroid hormones
Globulins	35%	Transport ions, hormones; immune function (antibodies)
Fibrinogen	4%	Essential for blood clotting; can be converted to insoluble fibrin
Regulatory proteins	<1%	Enzymes, proenzymes, hormones

Other Plasma Solutes

• Electrolytes: Maintain membrane potentials and osmotic balance (e.g., Na+, K+, Ca2+).

• Organic nutrients: Used for ATP production, growth, and cell maintenance (e.g., glucose, amino acids).

• Organic wastes: Carried to sites of excretion (e.g., urea, creatinine).

Comparison: Plasma vs. Interstitial Fluid

Both plasma and interstitial fluid are components of the extracellular fluid (ECF), but they differ in composition:

• Oxygen concentration: Higher in plasma than interstitial fluid; oxygen diffuses from blood into tissues.

• Carbon dioxide concentration: Lower in plasma, higher in interstitial fluid; CO2 diffuses from tissues into blood.

• Protein concentration: Much higher in plasma; large plasma proteins cannot cross capillary walls.

Summary Table: Plasma vs. Interstitial Fluid

Property	Plasma	Interstitial Fluid
Oxygen	High	Low
Carbon Dioxide	Low	High
Proteins	High	Low

Key Terms and Definitions

• Plasma: The liquid component of blood, containing water, proteins, and solutes.

• Formed elements: The cellular components of blood, including erythrocytes, leukocytes, and platelets.

• Albumin: The most abundant plasma protein, important for osmotic pressure and transport.

• Globulin: Plasma proteins involved in transport and immune defense.

• Fibrinogen: Plasma protein essential for blood clotting.

Example: Clinical Application

• Blood tests: Measurement of plasma proteins (e.g., albumin, globulins) can help diagnose liver disease, immune disorders, and clotting abnormalities.

Additional info: Later sections of the chapter (not shown in these slides) typically cover the formed elements in more detail, including erythrocyte structure, hemoglobin function, leukocyte types, and hematopoiesis.