Chapter 11: The Cardiovascular System – Blood (Anatomy & Physiology Study Notes)

Chapter 11: The Cardiovascular System – Blood

Ch 11-1 Blood: Functions and Characteristics

Blood is a specialized connective tissue that plays a vital role in maintaining homeostasis and supporting the functions of all body systems. It consists of plasma and formed elements (cells and cell fragments).

• Functions of Blood:

  • Transportation: Delivers oxygen, nutrients, hormones, and removes waste products (e.g., carbon dioxide, urea).

  • Regulation: Maintains pH, body temperature, and fluid balance.

  • Protection: Defends against pathogens and prevents blood loss through clotting.

  • Homeostasis: Maintains internal environment stability.

  • Communication: Transports signaling molecules (e.g., hormones).

• Physical Characteristics of Blood:

  • Temperature: Blood temperature is approximately 38°C (100.4°F), slightly higher than body temperature.

  • Viscosity: Blood is about 5 times more viscous than water due to the presence of cells and plasma proteins.

  • pH: Blood is slightly alkaline, with a normal pH range of 7.35–7.45.

Ch 11-2 Plasma

Plasma is the liquid component of blood, making up about 55% of total blood volume. It serves as the medium for transporting substances throughout the body.

• Components of Plasma:

  • Water: ~92% of plasma; acts as a solvent and helps regulate temperature.

  • Plasma Proteins: ~7% of plasma; includes albumins, globulins, and fibrinogen.

  • Other Solutes: ~1%; includes electrolytes, nutrients, gases, hormones, and waste products.

• Major Plasma Proteins and Their Functions:

  • Albumins: Maintain osmotic pressure and transport substances such as fatty acids and hormones.

  • Globulins: Include antibodies (immunoglobulins) for immune defense and transport globulins for carrying ions, hormones, and lipids.

  • Fibrinogen: Essential for blood clotting; converted to fibrin during coagulation.

Ch 11-3 Red Blood Cells (RBCs)

Red blood cells, or erythrocytes, are the most abundant formed elements in blood and are specialized for oxygen transport.

• RBC Count: There are approximately 4.5–6.3 million RBCs per microliter (µl) of blood in males and 4.2–5.5 million/µl in females. A single drop of blood contains millions of RBCs.

• Unique Characteristics of RBCs:

  • Biconcave disc shape increases surface area for gas exchange.

  • Lack nuclei and most organelles, maximizing space for hemoglobin.

  • Flexible membrane allows passage through narrow capillaries.

• Hemoglobin and Oxygen Binding: The iron ion (Fe2+) in the heme group of hemoglobin binds oxygen molecules.

• RBC Lifespan and Recycling: Old RBCs are removed by the spleen and liver. Iron and amino acids are recycled; heme is converted to bilirubin and excreted.

• Erythropoiesis (RBC Formation):

  • Occurs in red bone marrow.

  • Requires vitamin B12 for DNA synthesis.

  • Stimulated by the hormone erythropoietin (EPO), which is released by the kidneys in response to low oxygen levels (hypoxia).

Ch 11-4 ABO Blood System

The ABO blood group system is based on the presence or absence of specific antigens on the surface of RBCs and corresponding antibodies in plasma.

• Antigen: A molecule (usually a protein or carbohydrate) found on the surface of RBCs that can trigger an immune response.

• Antibody: A protein found in plasma that binds to specific antigens and can cause agglutination (clumping) if incompatible blood types are mixed.

• Major Blood Group Antigens: A, B, and D (Rh factor).

Blood Type	Antigens Present	Antibodies Present
A negative	A	Anti-B, Anti-D
A positive	A, D	Anti-B
B negative	B	Anti-A, Anti-D
B positive	B, D	Anti-A
AB negative	A, B	Anti-D
AB positive	A, B, D	None
O negative	None	Anti-A, Anti-B, Anti-D
O positive	D	Anti-A, Anti-B

• Agglutination: The clumping of RBCs due to antibody-antigen reactions, which can block blood vessels and cause hemolysis.

• Cause of Agglutination: Occurs when incompatible blood types are mixed, leading to immune response against foreign antigens.

Ch 11-5 White Blood Cells (WBCs)

White blood cells, or leukocytes, are immune cells that protect the body against infection and foreign invaders.

• Comparison of WBCs and RBCs:

Criteria	WBC	RBC
Size	Larger	Smaller
Presence of Organelles	Yes	No
Presence of Hemoglobin	No	Yes
Number in a µl of blood	5,000–10,000	4.5–6.3 million

• Four Characteristics of WBCs:

  • Amoeboid movement (can move through tissues)

  • Diapedesis (can leave blood vessels)

  • Chemotaxis (attracted to chemical signals)

  • Phagocytosis (some can engulf pathogens)

• WBCs in Order of Abundance (Differential Count and Function):

WBC Type	Differential Count (%)	Function
Neutrophils	50–70%	Phagocytize bacteria and debris
Lymphocytes	20–40%	Produce antibodies, regulate immune response
Monocytes	2–8%	Become macrophages, phagocytize pathogens
Eosinophils	1–4%	Attack parasites, modulate allergic responses
Basophils	0.5–1%	Release histamine, mediate inflammation

• WBC Production: Produced in red bone marrow and lymphatic tissues (e.g., lymph nodes, spleen).

Ch 11-6 Platelets

Platelets, or thrombocytes, are small cell fragments derived from megakaryocytes in the bone marrow. They play a crucial role in blood clotting.

• Description: Platelets are disc-shaped, lack nuclei, and contain enzymes and granules essential for clotting.

Ch 11-7 Hemostasis

Hemostasis is the process that stops bleeding and maintains blood in a fluid state within the vascular system.

• Definition: Hemostasis is the cessation of bleeding following vascular injury.

• Three Phases of Hemostasis:

  1. Vascular Phase: Blood vessel constricts to reduce blood flow.

  2. Platelet Phase: Platelets adhere to the injury site and form a temporary plug.

  3. Coagulation Phase: Fibrinogen is converted to fibrin, forming a stable blood clot.

• Extrinsic vs. Intrinsic Pathways in Clotting:

  • Extrinsic Pathway: Initiated by external trauma that causes blood to escape from the vascular system; involves tissue factor.

  • Intrinsic Pathway: Initiated by trauma inside the vascular system; involves clotting factors present in the blood.

• Fate of Clots After Healing: Clots are dissolved by the process of fibrinolysis, where plasmin digests fibrin threads.

Example: If a person with type A negative blood receives type B positive blood, their anti-B and anti-D antibodies will cause agglutination, leading to a dangerous transfusion reaction.

Additional info: The above notes expand on the guided questions by providing definitions, context, and examples to ensure a comprehensive understanding of blood anatomy and physiology for exam preparation.