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Cardiovascular_system_F2020

Cardiovascular System Overview

  • The cardiovascular system consists of the heart, blood vessels, and blood.

Components of the Cardiovascular System

  • Heart: A powerful pump that circulates blood throughout the body.

    • Muscular four-chambered organ with specific input (veins) and output (arteries) channels.

    • Functions to transport oxygen (O2), nutrients, hormones, and waste products.

  • Arteries: Vessels that carry blood away from the heart.

    • Thicker and stronger compared to veins.

  • Capillaries: Microscopic vessels positioned between arteries and veins.

    • Allow for the exchange of gases and nutrients between blood and interstitial fluid.

  • Veins: Vessels that return blood to the heart.

    • Thinner walls compared to arteries, capable of carrying greater volumes of blood.

Functions of the Cardiovascular System

  • Nutrition: Provides necessary nutrients to cells.

  • Waste Removal: Facilitates the removal of waste products from cellular metabolism.

  • Protection: Ensures functioning of immune cells in blood circulation.

Structure of the Heart

  • Orientation:

    • BASE: Located dorsally, where vessels enter and exit the heart.

    • APEX: The pointed end of the heart, oriented ventrally and caudally.

  • Layers of the Heart:

    • Epicardium: The outer layer, serous membrane.

    • Myocardium: The thick, muscular middle layer responsible for contraction.

    • Endocardium: The inner layer lined with endothelium.

Pericardium

  • A fibroserous sac surrounding the heart and roots of major vessels, consisting of:

    • Fibrous Pericardium: The tough outer layer.

    • Serous Pericardium: Contains parietal pericardium, pericardial cavity, and visceral pericardium.

Heart Chambers

  • Consists of four chambers:

    • Right Atrium

    • Right Ventricle

    • Left Atrium

    • Left Ventricle

Heart Valves

  • Atrioventricular Valves: Prevent backflow into the atria during ventricular contractions.

    • Right AV (tricuspid) valve

    • Left AV (bicuspid) valve (mitral)

  • Semilunar Valves: Prevent backflow into the ventricles.

    • Aortic valve

    • Pulmonary valve

Blood Circulation

  • Pulmonic Circulation: Blood flow from the right side of the heart to the lungs for oxygenation, then returns to the left side.

  • Systemic Circulation: Blood flow from the left side of the heart to the body, delivering oxygenated blood.

Blood Pressure

  • Systole: High pressure during ventricular contraction; AV valves close, causing the first heart sound.

  • Diastole: Low pressure during relaxation; semilunar valves close, causing the second heart sound.

  • Normal blood pressure example: 120/70 mm Hg.

Conduction System

  • Composed of cells that generate their own electrical impulses, ensuring heart rhythm and muscle contraction.

  • Pacemaker Cells: Located in the SA node, initiate heartbeat and regulate rhythm without external triggers due to leaky ion channels.

Blood Vessels

  • Responsible for delivering O2 and nutrients to cells and removing waste products.

  • Three layers of vessel wall:

    • Tunica Intima: Inner layer; smooth endothelial lining.

    • Tunica Media: Middle layer; consists of smooth muscle cells.

    • Tunica Adventitia: Outer layer; connective tissue for protection and support.

  • Types of Blood Vessels:

    • Arteries: Carry blood away from the heart; thicker walls.

    • Capillaries: Exchange sites for gases and nutrients.

    • Veins: Carry blood back to the heart; have valves to prevent backflow.