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BIOL2225 Physiology: Cardiac Anatomy Review

BIOL2225 Physiology: Cardiac Anatomy & Lab 19A Notes

Lab 19A Resources

  • Lab 19A Reading Assignment
  • Lab Ex.19A
  • Lab 19A Activity (cadaver and model anatomy)
  • Lab 19A Heart Model Video: https://youtu.be/r3ZWk9WZpcs

Lab Objectives Overview

At the end of this lab, you should be able to:

  • Identify objects in slides and figures.
  • Describe the function of any item marked with a asterisk (*) in the objectives below.

Histology of Muscle Tissue

(Refer to fig.5.25/5.26/5.27, section 11.7A, table 11.4)

Differentiating Muscle Types

  • Differentiate between cardiac muscle, skeletal muscle, and smooth muscle on a histology slide.

Cardiac Muscle Tissue Identification

In cardiac muscle tissue, identify:

  • Intercalated discs
  • Nuclei
  • Branching cells
  • Striations

Cardiac Muscle Anatomy: Similarities and Differences

  • Describe how cardiac muscle anatomy differs from skeletal muscle and smooth muscle anatomy.
  • List the similarities and differences among these three muscle types.

Cardiac Muscle Cell Characteristics

Describe cardiac muscle cells in terms of:

  • Cell shape: Typically branched.
  • Presence of intercalated discs: Present, facilitating rapid communication and coordinated contraction.
  • Presence of striations: Present, similar to skeletal muscle, due to organized sarcomeres.
  • Method of ATP production: Primarily aerobic respiration.
  • Relative amounts of myoglobin/glycogen/mitochondria: High relative amounts of myoglobin (for oxygen storage), glycogen (for glucose storage), and mitochondria (to support continuous aerobic respiration).
  • Fatigue-resistance: Highly fatigue-resistant due to extensive aerobic metabolism and constant demand for contraction.

Gross Anatomy of the Heart

Anatomical Location

  • Describe the anatomical location of the heart in terms of its relative placement in a specific body cavity. (Refer to section Atlas A A.3b, fig.A.6a, fig. 19.2a/b/c).
    • The heart is located in the thoracic cavity, specifically within the mediastinum, slightly to the left of the midline.

Layers of the Heart

(Refer to section 19.1B/C $\$*$ 19.2A, fig. 19.3)
Place the layers in order of appearance from superficial to deep, and list their functions:

  1. Fibrous Pericardium:

    • Function: Tough, dense connective tissue layer that protects the heart, anchors it to surrounding structures (diaphragm, great vessels), and prevents overfilling of the heart.

  2. Serous Pericardium (*): A thinner, more delicate two-layered serous membrane.

    • Parietal Layer: Lines the inner surface of the fibrous pericardium.
    • Pericardial Cavity (not a layer): The space between the parietal and visceral layers, containing pericardial fluid.
      • Pericardial Fluid: Lubricates the membranes, allowing the heart to beat with minimal friction.
    • Visceral Layer / Epicardium (*): Adheres directly to the surface of the heart, forming the outermost layer of the heart wall.
    • Function (*): The serous pericardium (parietal and visceral layers) with its fluid-filled cavity reduces friction between the heart and its surrounding structures during beating.

  3. Myocardium (*):

    • Composed of: Primarily cardiac muscle tissue.
    • Function (*): Responsible for the contractile function of the heart, pumping blood.

  4. Endocardium (*):

    • Composed of: A thin layer of endothelium (simple squamous epithelium) overlying a thin layer of connective tissue, continuous with the endothelium of blood vessels.
    • Function (*): Forms a smooth, protective inner lining for the heart chambers and valves, minimizing friction as blood passes through the heart.

Clinical Conditions Related to Heart Layers

  • Pericarditis: Inflammation of the pericardium. This can lead to chest pain and, in severe cases, impaired heart function.
  • Cardiac Tamponade: (Refer to section Atlas A, Deeper insight A.1) A life-threatening condition where excessive fluid (blood, pus, etc.) accumulates in the pericardial cavity, compressing the heart and severely restricting its ability to pump blood.

Heart Model and Figure Anatomy

(Refer to fig.19.2c, fig.19.4b, fig.19.5a/b, fig. 19.7a/b, fig. 19.9, fig.19.10a/b and the function sheet in Canvas.)
Identify the following structures (and list function if marked with *):

Heart Chambers & Septa

  • Right Ventricle (*): Receives deoxygenated blood from the right atrium and pumps it into the pulmonary trunk.
  • Left Ventricle (*): Receives oxygenated blood from the left atrium and pumps it into the aorta.
  • Interventricular Septum (*): The muscular wall separating the right and left ventricles; ensures complete separation of oxygenated and deoxygenated blood in the ventricles.
  • Right Atrium (*): Receives deoxygenated blood from the body via the superior and inferior vena cava and the coronary sinus.
  • Fossa Ovalis: A depression in the interatrial septum, a remnant of the foramen ovale, which shunted blood from the right atrium to the left atrium in the fetal heart.
    • (Distinction: Foramen ovale is the opening in the fetal heart; fossa ovalis is its adult remnant.)
  • Left Atrium (*): Receives oxygenated blood from the lungs via the pulmonary veins.
  • Interatrial Septum (*): The wall separating the right and left atria; prevents mixing of blood between the atria.

Heart Valves

  • Aortic Valve (*): A semilunar valve located between the left ventricle and the aorta; prevents backflow of blood into the left ventricle during ventricular diastole.
  • Pulmonary Valve (*): A semilunar valve located between the right ventricle and the pulmonary trunk; prevents backflow of blood into the right ventricle during ventricular diastole.
  • Right AV Valve (Tricuspid Valve) (*): An atrioventricular valve located between the right atrium and the right ventricle; prevents backflow of blood into the right atrium during ventricular systole.
  • Left AV Valve (Bicuspid Valve or Mitral Valve) (*): An atrioventricular valve located between the left atrium and the left ventricle; prevents backflow of blood into the left atrium during ventricular systole.

Structures Associated with Ventricles & Valves

  • Papillary Muscle (+): Cone-shaped muscle projections in the ventricles to which the chordae tendineae are attached.
  • Chordae Tendineae (*): Tendinous cords that connect the papillary muscles to the cusps of the AV valves; they prevent the valve cusps from everting into the atria during ventricular contraction.
  • Trabeculae Carneae (*): Irregular ridges of muscle on the internal surfaces of the ventricles; they contribute to the pumping efficiency of the ventricles.
  • Pectinate Muscle (*): Ridges of muscle found in the anterior wall of the atria (especially the right atrium); they increase the contractile force of the atria.

Great Vessels

  • Pulmonary Trunk (*): Arises from the right ventricle and divides into the right and left pulmonary arteries; carries deoxygenated blood to the lungs.
  • Left and Right Pulmonary Arteries (*): Branches of the pulmonary trunk that carry deoxygenated blood to the lungs.
  • Left and Right Pulmonary Veins (*): Carry oxygenated blood from the lungs to the left atrium.
  • Aorta (*): The largest artery in the body, arising from the left ventricle; distributes oxygenated blood to the entire body.
  • Inferior Vena Cava (*): Large vein that carries deoxygenated blood from the lower body and trunk to the right atrium.
  • Superior Vena Cava (*): Large vein that carries deoxygenated blood from the upper body (head, arms, chest) to the right atrium.

External Heart Landmarks & Coronary Circulation

  • Apex (+): The blunt, rounded point of the heart, directed inferiorly and to the left.
  • Base (+): The broad superior portion of the heart, where the great vessels attach.
  • Anterior Interventricular Sulcus (+): A groove on the anterior surface of the heart marking the boundary between the right and left ventricles; contains the anterior interventricular artery and great cardiac vein.
  • Posterior Interventricular Sulcus (+): A groove on the posterior surface of the heart marking the boundary between the right and left ventricles; contains the posterior interventricular artery and middle cardiac vein.
  • Anterior Interventricular Artery (same as the anterior interventricular branch of LCA) (+): Supplies blood to both ventricles.
  • Posterior Interventricular Artery (same as posterior interventricular branch of RCA) (*): Supplies blood to the posterior portions of both ventricles and the interventricular septum.
  • Left Coronary Artery (LCA) (+): Arises from the aorta; supplies the left side of the heart, including the left atrium, left ventricle, and interventricular septum.
  • Right Coronary Artery (RCA) (+): Arises from the aorta; supplies the right side of the heart, including the right atrium, right ventricle, and parts of the interventricular septum.
  • Coronary Sinus (*): A large vein on the posterior surface of the heart that collects deoxygenated blood from the heart muscle itself and empties it into the right atrium.
  • Coronary Sulcus (+): A groove on the external surface of the heart that marks the division between the atria and the ventricles; contains the main coronary arteries and veins.

Blood Flow Through the Heart

Describe the path of blood flow from the superior and inferior vena cava to the aorta:

  1. Deoxygenated blood from the body enters the Right Atrium via the Superior Vena Cava (from upper body), Inferior Vena Cava (from lower body), and Coronary Sinus (from heart muscle).
  2. From the Right Atrium, blood passes through the Right AV Valve (Tricuspid Valve) into the Right Ventricle.
  3. The Right Ventricle contracts, pumping blood through the Pulmonary Valve into the Pulmonary Trunk.
  4. The Pulmonary Trunk divides into the Left and Right Pulmonary Arteries, which carry deoxygenated blood to the lungs.
  5. In the lungs, blood releases carbon dioxide and picks up oxygen (pulmonary circulation).
  6. Oxygenated blood returns from the lungs to the Left Atrium via the Left and Right Pulmonary Veins.
  7. From the Left Atrium, blood passes through the Left AV Valve (Bicuspid/Mitral Valve) into the Left Ventricle.
  8. The Left Ventricle contracts, pumping blood through the Aortic Valve into the Aorta.
  9. The Aorta then distributes oxygenated blood to the rest of the body (systemic circulation).