Cardiovascular System: Blood, Heart, and Blood Vessels – Study Guide

Ch. 17: Blood

General Characteristics and Functions of Blood

Blood is a specialized connective tissue that plays a vital role in transporting substances, regulating physiological processes, and protecting the body.

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

• General Characteristics: Blood is composed of plasma (the liquid matrix) and formed elements (red blood cells, white blood cells, and platelets). It is viscous, sticky, and has a temperature of about 38°C (100.4°F).

• Blood Typing: Blood types are determined by the presence or absence of specific antigens (A, B, AB, O) and the Rh factor on the surface of red blood cells (RBCs).

• Functions of Blood:

  • Transport of gases (O2, CO2), nutrients, hormones, and waste products

  • Regulation of pH, body temperature, and fluid balance

  • Protection against blood loss (clotting) and infection (immune response)

Red Blood Cells (RBCs) and Hemoglobin

• Sickle Cell Anemia: A genetic disorder where abnormal hemoglobin (HbS) causes RBCs to become sickle-shaped, leading to blockages and pain during a sickling episode.

• Structural Characteristics of RBCs: Biconcave shape increases surface area for gas exchange and flexibility to pass through capillaries.

• Hemoglobin: Each RBC contains about 250 million hemoglobin molecules. Each hemoglobin can carry four oxygen molecules.

• Hemoglobin Equation: $\text{Hb} + 4\text{O}_2 \rightarrow \text{Hb(O}_2)_4$

Blood Plasma and Regulation

• Blood Plasma: The liquid component of blood, making up about 55% of total blood volume. Contains water, proteins (albumin, globulins, fibrinogen), electrolytes, nutrients, and waste products.

• Regulation of RBC Production: The hormone erythropoietin (produced by the kidneys) stimulates RBC production in response to low oxygen levels.

Ch. 18: The Heart

Structure and Function of the Heart

The heart is a muscular organ responsible for pumping blood throughout the body via the circulatory system.

• Myocardial Cells: Specialized muscle cells that contract to propel blood.

• Blood Flow Through the Heart: Blood flows through the right atrium, right ventricle, pulmonary arteries, lungs, pulmonary veins, left atrium, left ventricle, and out through the aorta.

• Systemic and Pulmonary Circulation:

  • Pulmonary circulation: Right side of the heart pumps deoxygenated blood to the lungs.

  • Systemic circulation: Left side of the heart pumps oxygenated blood to the body.

Cardiac Conduction System

• Conduction System Pathway: The sequence is: Sinoatrial (SA) node → Atrioventricular (AV) node → Bundle of His → Right and left bundle branches → Purkinje fibers.

• Action Potential: Electrical impulses that trigger heart muscle contraction.

Cardiac Cycle and Heart Valves

• Three Steps in the Cardiac Cycle:

  1. Atrial systole (atria contract)

  2. Ventricular systole (ventricles contract)

  3. Diastole (relaxation of all chambers)

• Heart Valves: Ensure unidirectional blood flow. Valves open and close in response to pressure changes during the cardiac cycle.

• Left vs. Right Ventricle: The left ventricle has a thicker wall to pump blood throughout the body, while the right ventricle pumps blood to the lungs.

• Angina Pectoris vs. Myocardial Infarction:

  • Angina pectoris: Chest pain due to temporary reduced blood flow to the heart.

  • Myocardial infarction: Heart attack caused by prolonged blockage and death of heart muscle tissue.

Heart Rate and Heart Sounds

• Factors Affecting Heart Rate: Autonomic nervous system, hormones, fitness level, age.

• Factors Affecting Venous Return: Blood volume, venous pressure, muscle activity, respiratory movements.

• Heart Block: A condition where the electrical conduction is partially or completely blocked.

• Normal Heart Sounds: "Lub-dub" sounds produced by the closing of heart valves.

• Foramen Ovale: An opening in the fetal heart that allows blood to bypass the lungs; closes after birth.

Ch. 19: Blood Vessels and Circulation

Types and Functions of Blood Vessels

• Capillaries: Three types—continuous, fenestrated, and sinusoidal. They facilitate exchange of gases, nutrients, and waste between blood and tissues. Continuous capillaries are the most common.

• Arteries: Carry blood away from the heart; have thick, elastic walls to withstand high pressure.

• Veins: Carry blood toward the heart; have thinner walls and valves to prevent backflow.

• Arterioles: Small arteries that regulate blood flow into capillaries.

Blood Pressure and Regulation

• Baroreceptors: Sensory receptors that detect changes in blood pressure and help regulate it via the nervous system.

• Factors Influencing Blood Pressure: Cardiac output, blood volume, resistance of blood vessels, viscosity of blood.

• Blood Pressure Equation: $\text{Blood Pressure} = \text{Cardiac Output} \times \text{Peripheral Resistance}$

• Pulse Pressure: The difference between systolic and diastolic blood pressure. $\text{Pulse Pressure} = \text{Systolic BP} - \text{Diastolic BP}$

Capillary Exchange and Tissue Perfusion

• Bulk Flow in Capillaries: Movement of fluid and solutes driven by hydrostatic and osmotic pressures.

• Hormonal Regulation: Hormones such as epinephrine, norepinephrine, antidiuretic hormone (ADH), and angiotensin II affect blood pressure.

• Types of Arteries: Elastic (conducting), muscular (distributing), and arterioles (resistance vessels).

• Blood Flow Through Skin: Important for thermoregulation; skin blood flow can change rapidly in response to temperature.

• Tissue Perfusion: The process of delivering blood to a capillary bed in tissue. Influenced by blood pressure, vessel diameter, and local metabolic activity.

Summary Table: Types of Blood Vessels

Vessel Type	Main Function	Key Characteristics
Arteries	Carry blood away from heart	Thick, elastic walls; high pressure
Arterioles	Regulate blood flow to capillaries	Small diameter; smooth muscle
Capillaries	Exchange of gases, nutrients, wastes	Thin walls; three types (continuous, fenestrated, sinusoidal)
Venules	Collect blood from capillaries	Thin walls; merge to form veins
Veins	Return blood to heart	Thinner walls; valves prevent backflow

Additional info:

• Some explanations and definitions were expanded for clarity and completeness.

• Table content was inferred and organized based on standard textbook knowledge.