BIOL 2402 Cardiovascular System Lecture Updated 2-4-25 - Tagged

The Cardiovascular System

Basic Concepts

• Arteries:

  • Carry blood away from the heart.

  • Systemic arteries: Colored red to indicate high levels of oxygen (O2), as they transport oxygen-rich blood from the heart to the body's tissues.

  • Pulmonary arteries: Colored blue, carrying oxygen-poor blood (low O2 levels) from the heart to the lungs for oxygenation.

  • Fetal umbilical arteries: Also blue, reflecting the low oxygen content of blood returning from the placenta.

• Veins:

  • Carry blood towards the heart.

  • Systemic veins: Colored blue, transporting oxygen-poor blood back to the heart from the body's periphery.

  • Pulmonary veins: Colored red, these veins bring oxygen-rich blood from the lungs back to the heart.

  • Fetal umbilical veins: Red, carrying oxygen-rich blood from the placenta to the fetus.

Overview of Vertebrate Hearts

• Circulatory Systems:

  • Fish: Feature a single-loop circulatory system; blood travels from the heart to the gills (where it is oxygenated) and then to the rest of the body.

  • Amphibians and some reptiles: Have a mixed blood system within the heart, allowing some degree of oxygen-rich and oxygen-poor blood mixing.

  • Birds and mammals: Possess a more complex, separate pulmonary (lungs) and systemic (body) circulation, facilitating more efficient oxygen delivery.

Heart Anatomy

• Major Structures:

  • Aortic arch: Curved part of the aorta supplying oxygenated blood to the body.

  • Pulmonary artery: Conducts deoxygenated blood from the right ventricle to the lungs.

  • Pulmonary veins: Return oxygenated blood to the left atrium from the lungs.

  • Right/Left atrium: Upper chambers of the heart that receive blood from the body (right) and lungs (left).

  • Right/Left ventricle: Lower chambers that pump blood out to the lungs (right) and the rest of the body (left).

  • Superior/Inferior vena cava: Major veins that return deoxygenated blood from the upper (superior) and lower (inferior) parts of the body to the right atrium.

  • Pulmonary trunk: Divides into the right and left pulmonary arteries, transporting blood to the respective lungs for oxygenation.

Heart Valves

• Key Valves:

  • Aortic valve: Prevents backflow of blood from the aorta into the left ventricle.

  • Pulmonary Semilunar valve: Prevents backflow into the right ventricle from the pulmonary artery.

  • Tricuspid valve: Regulates blood flow from the right atrium to the right ventricle; has three leaflets.

  • Bicuspid valve (Mitral valve): Controls blood flow from the left atrium to the left ventricle; has two leaflets.

  • Chordae Tendinae: Cord-like structures that support the valve leaflets, ensuring they close tightly during contraction to prevent regurgitation.

Heart Structure

• Components Include:

  • Aorta: The largest artery, carrying oxygen-rich blood from the heart to the body.

  • Esophagus and Trachea: Located posterior to the heart; important in the context of anatomical proximity during surgeries.

  • Pulmonary veins: Connect the lungs to the heart, delivering oxygenated blood.

  • Coronary sinus: Drains deoxygenated blood from the heart muscle back to the right atrium.

  • Apex: The tip of the heart; points downward and to the left, crucial during auscultation procedures.

Heart and Vascular Structures

• Key Features Include:

  • Brachiocephalic trunk: First major artery branching from the aorta, supplying blood to the right arm and head.

  • Ascending aorta: Portion of the aorta that rises from the heart.

  • Superior vena cava and left common carotid artery: Major vessels critical for returning deoxygenated blood and supplying the head.

  • Left subclavian artery: Supplies blood to the left arm.

Heart Wall

• Composed of:

  • Myocardium: Cardiac muscle tissue responsible for the heart's contractions.

  • Parietal and Visceral pericardium: Protective layers surrounding the heart, with the visceral layer also forming the outer layer of the heart muscle itself.

  • Endocardium: Smooth inner lining of the heart chambers and valves, providing a frictionless surface for blood flow.

Pericardial Effusion

• Definition: Refers to the abnormal buildup of fluid in the pericardial cavity, which can compress the heart and affect its function, possibly leading to a condition known as cardiac tamponade.

Endocarditis

• Description: Inflammation or infection of the endocardium, particularly affecting heart valves, leading to potential clot formation, severe health risks, and rising incidence associated with healthcare-acquired infections primarily caused by Staphylococcus and Streptococcus bacteria.

Chordae Tendinae and Papillary Muscles

• Function: These structures work together to support heart valves during contraction, preventing them from inverting under pressure.

Blood Flow through the Heart

• Summary: Oxygen-poor blood returns to the right atrium via the superior and inferior vena cava, is pumped into the right ventricle through the tricuspid valve, and then sent to the lungs via the pulmonary trunk for oxygenation. Once oxygen-rich blood returns to the left atrium via the pulmonary veins, it moves to the left ventricle through the bicuspid valve before being circulated to the body.

Heart Rate Factors

• Increase Factors: Sympathetic stimulation (e.g., during stress), increased venous return pressure, and temperature elevation can raise heart rate.

• Decrease Factors: Parasympathetic stimulation (e.g., rest), elevated aortic pressure, and lower body temperature can reduce heart rate.

Electrocardiography (ECG)

• Segments: Normal waveform includes the P wave (atria contraction), QRS complex (ventricular contraction), and T wave (ventricular relaxation), vital for monitoring heart health.

• Heart Rate Abnormalities: Definitions include tachycardia (increased heart rate) and bradycardia (decreased heart rate).
  

Types of Stroke

• Major Types:

  • Hemorrhagic Stroke: Caused by bleeding in the brain, often due to a ruptured aneurysm.

  • Ischemic Stroke: Results from blockage of blood flow to the brain, commonly due to a clot.

  • Transient Ischemic Attack (TIA): A short-lived stroke-like event caused by temporary loss of blood flow to the brain, serving as a warning for potential future strokes.

This detailed information highlights important aspects of the cardiovascular system, covering its anatomy, functions, and related medical conditions.