Cardiovascular System and Blood: Key Terms and Concepts

Cardiovascular System

Overview of the Cardiovascular System

The cardiovascular system is responsible for the transport of blood, nutrients, gases, and wastes throughout the body. It consists of the heart, blood vessels, and blood, and plays a crucial role in maintaining homeostasis.

• Heart: Muscular organ that pumps blood through the circulatory system.

• Blood Vessels: Tubular structures (arteries, veins, capillaries) that carry blood throughout the body.

• Blood: Fluid connective tissue composed of plasma and formed elements (red blood cells, white blood cells, platelets).

Heart Structure and Function

The heart is divided into four chambers: two atria and two ventricles. It contains several valves that ensure unidirectional blood flow.

• Atria: Upper chambers that receive blood returning to the heart.

• Ventricles: Lower chambers that pump blood out of the heart.

• Bicuspid (Mitral) Valve: Valve between the left atrium and left ventricle.

• Tricuspid Valve: Valve between the right atrium and right ventricle.

• Semilunar Valves: Valves at the bases of the aorta and pulmonary artery.

• Pericardium: Protective sac surrounding the heart.

Cardiac Cycle and Heart Rate

The cardiac cycle refers to the sequence of events in one heartbeat, including contraction (systole) and relaxation (diastole). Heart rate is the number of heartbeats per minute.

• Systole: Phase of contraction when blood is pumped out of the chambers.

• Diastole: Phase of relaxation when chambers fill with blood.

• Pulse: Rhythmic expansion of arteries with each heartbeat.

• Pacemaker (SA node): Specialized tissue that initiates the heartbeat.

• AV node: Relays electrical impulses from atria to ventricles.

• Bundle of His & Purkinje fibres: Conduct electrical signals for coordinated contraction.

Blood Vessels

Blood vessels are classified based on their function and structure.

• Arteries: Carry blood away from the heart; usually oxygenated except pulmonary artery.

• Veins: Carry blood toward the heart; usually deoxygenated except pulmonary veins.

• Capillaries: Microscopic vessels for exchange of gases, nutrients, and wastes.

• Arterioles & Venules: Small branches of arteries and veins, respectively.

• Superior/Inferior Vena Cava: Major veins returning deoxygenated blood to the right atrium.

Circulatory Pathways

There are two main circulatory pathways: systemic and pulmonary.

• Systemic Circulation: Delivers oxygenated blood from the heart to the body and returns deoxygenated blood.

• Pulmonary Circulation: Carries deoxygenated blood from the heart to the lungs and returns oxygenated blood.

• Cardiac Circulation: Supplies blood to the heart muscle itself via coronary arteries.

Blood Pressure and Hypertension

Blood pressure is the force exerted by blood on vessel walls. Hypertension is abnormally high blood pressure.

• Blood Pressure: Measured in mmHg; normal adult value is about 120/80 mmHg.

• Hypertension: Persistent elevation of blood pressure; risk factor for heart disease.

Cardiovascular Diseases and Treatments

Several conditions affect the cardiovascular system, some requiring medical intervention.

• Heart Attack (Myocardial Infarction): Blockage of blood flow to heart muscle.

• Atherosclerosis: Build-up of fatty deposits in arteries.

• Varicose Veins: Swollen, twisted veins due to faulty valves.

• Angioplasty: Procedure to open blocked arteries.

• Coronary Bypass Surgery: Surgical creation of alternate blood flow routes.

• CPR (Cardiopulmonary Resuscitation): Emergency procedure to restore circulation and breathing.

Diagnostic Tools

Various tools are used to assess heart function and health.

• Echocardiogram: Ultrasound imaging of the heart.

• Electrocardiogram (ECG): Recording of electrical activity of the heart.

Blood and Its Components

Blood Composition

Blood consists of plasma and formed elements, each with specific functions.

• Plasma: Liquid portion containing water, proteins, nutrients, hormones, and waste products.

• Red Blood Cells (Erythrocytes): Transport oxygen using hemoglobin.

• White Blood Cells (Leukocytes): Defend against infection; include lymphocytes, monocytes, granulocytes.

• Platelets: Cell fragments involved in blood clotting.

• Buffy Coat: Layer containing white blood cells and platelets after centrifugation.

Blood Clotting

Blood clotting prevents excessive bleeding after injury.

• Platelet Plug: Initial aggregation of platelets at injury site.

• Fibrin Mesh: Network of protein fibers stabilizing the clot.

• Clotting Factors: Proteins that trigger the clotting cascade.

Blood Cell Types

Blood contains several types of cells, each with unique roles.

• Erythrocytes: Red blood cells; carry oxygen and carbon dioxide.

• Leukocytes: White blood cells; immune defense.

• Lymphocytes: Type of white blood cell; involved in adaptive immunity.

• Monocytes: White blood cells that become macrophages.

• Granulocytes: White blood cells with granules; include neutrophils, eosinophils, basophils.

Hemoglobin

Hemoglobin is the protein in red blood cells that binds oxygen.

• Hemoglobin: Iron-containing protein; each molecule binds up to four oxygen molecules.

• Oxygenated Blood: Blood rich in oxygen, typically found in arteries.

• Deoxygenated Blood: Blood low in oxygen, typically found in veins.

Homeostasis and Feedback Mechanisms

Homeostasis

Homeostasis is the maintenance of stable internal conditions in the body.

• Dynamic Equilibrium: Continuous adjustments to maintain balance.

• Sensor: Detects changes in the environment.

• Effector: Responds to signals to restore balance.

Feedback Loops

Feedback loops regulate physiological processes.

• Negative Feedback Loop: Reduces the effect of a stimulus to maintain homeostasis (e.g., regulation of blood pressure).

• Positive Feedback Loop: Amplifies a response (e.g., blood clotting).

Temperature Regulation

The body maintains temperature through various mechanisms.

• Hyperthermia: Elevated body temperature.

• Hypothermia: Lowered body temperature.

• Vasoconstriction: Narrowing of blood vessels to reduce heat loss.

• Vasodilation: Widening of blood vessels to increase heat loss.

Key Terms Table

The following table summarizes and classifies key terms from the cardiovascular and blood systems:

Term	Category	Function/Description
Aorta	Blood Vessel	Main artery carrying oxygenated blood from heart to body
Angioplasty	Procedure	Opens blocked arteries
Hemoglobin	Protein	Binds and transports oxygen in red blood cells
Leukocytes	Cell	White blood cells; immune defense
Pulse	Measurement	Rhythmic expansion of arteries
Homeostasis	Process	Maintaining stable internal conditions
Negative Feedback Loop	Regulation	Reduces stimulus to maintain balance
Platelets	Cell Fragment	Involved in blood clotting
Vasoconstriction	Process	Narrowing of blood vessels
Vasodilation	Process	Widening of blood vessels

Key Equations

• Blood Pressure Equation:

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

• Cardiac Output Equation:

$\text{Cardiac Output} = \text{Heart Rate} \times \text{Stroke Volume}$

• Oxygen Transport by Hemoglobin:

$\text{Hb} + 4\,\text{O}_2 \rightarrow \text{Hb(O}_2)_4$

Example

Example: During exercise, heart rate and stroke volume increase, leading to higher cardiac output and increased blood flow to muscles.

Additional info: Some terms were grouped and expanded for clarity; definitions and context were added to ensure completeness and academic quality.