Heart structure

Chapter 11a: Cardiovascular - The Heart

Learning Targets (p. 313 - 325)

  • I can…

    • Describe structures and functions associated with heart function.

      • Label the chambers, veins, arteries, and valves.

      • Identify blood flow through the heart.

    • Describe cardiac conductivity.

      • Label structures associated with heart beating.

      • Describe the order of function for these structures.

    • Describe causes and effects of cardiac abnormalities.

      • Explain how high blood pressure, blockages, valvular problems, murmurs, and electrical problems impact heart function.

    • Describe anatomical structure of the heart;

      • Identify size, location, and layers of the heart.

The Cardiovascular System

  • A closed system consisting of:

    • Heart

    • Blood vessels

  • Function: Pump blood through vessels; circulate to all body parts.

  • Red blood cells: Carry oxygen (O2) to cells, while carbon dioxide (CO2) diffuses out of cells into bloodstream.

  • Core Functions of the Cardiovascular System:

    • Deliver oxygen and nutrients.

    • Remove carbon dioxide and waste products.

The Heart: Location, Shape, and Size

  • Location: Thorax between the lungs.

  • Shape: Pointed apex directed toward left hip.

  • Size: Approximately that of a fist.

The Heart: Coverings

  • Pericardium: A double serous membrane.

    • Visceral pericardium: Part of the heart surface.

    • Parietal pericardium: Outside layer.

    • Lubricating serous fluid between layers reduces friction.

  • Pericarditis: Inflammation of the pericardium.

The Heart: Heart Wall

  • Three layers:

    • Epicardium: Outer layer, visceral pericardium; connective tissue layer.

    • Myocardium: Middle layer; composed of cardiac muscle.

    • Endocardium: Inner layer; made of endothelium; continuous with blood vessel lining.

Blood Flow in the Heart

  • Chambers: Right and left sides act as separate pumps; both pump simultaneously.

    • Four Chambers:

      • Atria: Receiving chambers (Right atrium, Left atrium).

      • Ventricles: Discharging chambers (Right ventricle, Left ventricle).

Blood Circulation Pathway (Deoxygenated Blood)

  1. Deoxygenated blood from superior/inferior vena cava enters right atrium.

  2. Blood flows from right atrium to right ventricle.

  3. Right ventricle pumps blood into pulmonary artery.

  4. Blood travels to lungs for oxygenation.

Blood Circulation Pathway (Oxygenated Blood)

  1. Oxygenated blood returns via pulmonary veins to left atrium.

  2. Blood flows from left atrium to left ventricle.

  3. Left ventricle pumps oxygenated blood to aorta and the rest of the body.

The Heart: Valves

  • Function: Allow blood flow in only one direction; prevent backflow.

  • Four valves:

    • Atrioventricular valves:

      • Mitral/Bicuspid valve (left side).

      • Tricuspid valve (right side).

    • Semilunar valves:

      • Pulmonary valve (to pulmonary artery).

      • Aortic valve (to aorta).

  • Valves open/close based on pressure changes during heart contraction (systole) and relaxation (diastole).

  • Chordae tendineae: "Heart strings" holding valves in place; assist in valve function.

Heart Sounds and Conditions

  • Heart Sounds: "Lub-dub" sound due to valve closing.

  • Murmurs: Abnormal heart sounds indicating potential valve problems.

  • Aortic Stenosis: Narrowing of valve causing increased pressure, leading to heart strain.

Heart Rate Regulation

  • Increased heart rate due to:

    • Nervous system activation (low blood pressure, decreased blood volume).

    • Hormonal influence (e.g., epinephrine).

    • Physical exercise demands more oxygen.

  • Normal heart rate for adults: 60-100 beats/minute.

  • Tachycardia: Abnormally high rate.

  • Bradycardia: Abnormally low rate.

The Heart Conduction System

  • Intrinsic conduction system: Auto-regulates heart muscle contraction without nerve impulses.

    • SA node: Pacemaker; initiates heartbeat.

    • AV node: Receives impulse from SA, causing atrial contraction.

    • Bundle of His and Purkinje fibers: Conduct impulses for ventricle contraction.

Electrocardiogram (ECG)

  • Records electrical signals to check for heart conditions.

  • Utilized in diagnosing arrhythmias and other heart issues.

Heart Problems

  • Sudden Cardiac Arrest: Electrical issue.

  • Heart Attack: Plumbing issue (blocked blood flow).

  • Angina: Pain due to inadequate blood flow; can lead to heart attack if severe narrowing occurs.

Summary of Blood Flow

  • Blood moves in specific order through heart chambers and valves during the cardiac cycle, vital for maintaining efficient circulation and oxygen delivery throughout the body.