the heart and others

Describe the flow of blood through the heart and lungs, including the valves.

  • Superior vena cava, inferior vena cava, and coronary sinus → right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → to lungs → to heart → four pulmonary veins → left atrium → mitral valve → left ventricle → aortic semilunar valve → aorta → to body → to heart 

Explain the heart’s location and orientation in the thorax. 

  • Largest organ of the mediastinum

    • Located between the lungs 

  • Apex lies to the left of the midline 

  • Base is the broad posterior surface 

Know the coverings and layers of the heart, from superficial to deep. 

  • Coverings 

    • Pericardium: two primary layers

      • Fibrous pericardium: strong layer of dense connective tissue 

      • Serous pericardium: formed from two layers

        • Parietal layer of the serous pericardium (superficial to the visceral)

        • Visceral (on the organ)  layer of the serous pericardium (epicardium) 

  • Layers 

    • Epicardium: visceral layer of the serous pericardium 

    • Myocardium 

      • Consists of cardiac muscle 

      • Muscle arranged in circular and spiral patterns 

    • Endocardium

      • Endothelium resting on a layer of connective tissue

      • Lines the internal walls of the heart

List the chambers, internal divisions, and external markings discussed in lecture.

  • Chambers 

    • Right and left atria: superior chambers 

    • Right and left ventricles: inferior chambers 

  • Internal divisions

    • Interventricular septum (between the ventricles)

    • Interatrial septum (between the atria) 

  • External markings

    • Coronary sulcus 

    • Anterior interventricular sulcus 

    • Posterior interventricular sulus 

Be able to identify the internal structures that are characteristics of the four chambers.

  • Right atrium 

    • Forms right border of heart

    • Receives oxygen-poor blood from systemic circuit through these vessels

      • Superior vena cava

      • Inferior vena cava

      • Coronary sinus 

    • Pectinate muscles: ridges inside anterior of right atrium 

    • Crista terminalis: landmark used to locate veins entering right atrium 

    • Fossa ovalis: depression in interatrial septum (remnant of foramen ovale)

  • Right Ventricle 

    • Receives blood from right atrium through the right atrioventricular valve (tricuspid valve) 

    • Pumps blood into pulmonary circuit the pulmonary trunk 

    • Internal walls of right ventricle 

      • Trabeculae carneae

      • Papillary muscles

      • Chordae tendineae

    • Pulmonary semilunar valve (pulmonary valve): located at opening of right ventricle and pulmonary trunk 

  • Left atrium 

    • Makes up heart’s posterior surface

    • Receives oxygen-rich blood from lungs through pulmonary veins

    • Opens into the left ventricle through 

      • Left atrioventricular valve (bicuspid valve) 

        • Mitral valve is another name from the left AV valve 

  • Left ventricle 

    • Forms apex of the heart

    • Internal walls of left ventricle 

      • Trabeculae carneae

      • Papillary muscles 

      • Chordae tendineae

    • Pumps blood through systemic circuit via 

      • Aortic semilunar valve (aortic valve) 

Know basic differences between the structure/function of the four valves.

  • Structure 

    • Each valve composed of endocardium with connective tissue core 

    • Atrioventricular (AV) valves

      • Between atria and ventricles 

        • Right AV valve = tricuspid valve

        • Left AV valve = bicuspid (mitral) valve 

    • Aortic and pulmonary valves

      • At junction of ventricles and great arteries 

Explain the two heart sounds and where each valve sound can be heard. 

  • “Lup-dup” sound of valves closing

    • “Lup” = valves closing 

    • “Dup” = semilunar valves closing 

  • Each sound is best heard near a different heart corner 

    • Pulmonary valve: superior left corner

    • Aortic valve: superior right corner

    • Mitral (bicuspid) valve: at the apex

    • Tricuspid valve: inferior right corner 

Define systole and diastole. 

  • Systole: contraction of a heart chamber

  • Diastole: expansion (relaxation) of heart chamber 

Describe how cardiac muscles are connected. 

  • Cells join at intercalated dics

    • Form cellular networks

    • Complex junctions: adjacent sarcholemmas interlock

  • Two distinct regions

    • Fasciae adherens

    • Gap junctions 

  • Cells are separated be delicate endomysium

    • Binds adjacent cardiac fibers 

    • Contains blood vessels and nerves

List the five main components of the heart’s conduction system 

  1. The SA node (pacemaker) generates impulses

  2. The impulses pause (0.1 sec) at the AV node

  3. The AV bundle connects the atria to the ventricles 

  4. The bundle branches conduct the impulses through the interventricular septum 

  5. The subendocardial conducting network stimulates the contractile cells of both ventricles 

Briefly explain parasympathetic and sympathetic innervation of the heart

  • Parasympathetic fibers

    • Branches of vagus nerve

    • Decrease heart rate

    • Restricted to 

      • SA node, AV node, and coronary arteries

  • Sympathetic 

    • Travel to heart from cervical and upper thoracic chain ganglia 

      • Innervate SA node, AV node, cornoary arties

      • Also innervate cardiac musculature throughout the heart

    • Increase heart rate and strength of contraction 

Know the basic organization of the coronary arteries and cardiac veins discussed in lecture.

  • Coronary arteries 

    • Blood supply to the muscular walls and tissues of the hear

      • Right coronary artery 

      • Left coronary artery 

    • Arise from base of the aorta and run in the coronary sulcus 

  • Cardiac veins

    • Carry deoxygenated blood from the heart wall to the right atrium 

    • Occupy sulci on the heart’s surface

      • Coronary