Full Exam Simulator โ Heart Anatomy
25 MCQs ยท 20 T/F ยท 25 Definitions. Random order. Score tracked.
๐ฏ TMU Exam Tips โ Heart Unit
Essay Preparation
30 Marks ยท 2 EssaysStudy each question, try to outline your answer mentally, then expand to see the full model answer and marking guide.
Introduction
The heart has four chambers: right atrium, right ventricle, left atrium, and left ventricle โ divided into right (pulmonary) and left (systemic) circulations by the interventricular and interatrial septa.
Right Side โ Pulmonary Circuit
Right atrium receives deoxygenated blood via: superior vena cava (upper body), inferior vena cava (lower body), coronary sinus (cardiac veins). Blood passes through the tricuspid valve (3 cusps: anterior, posterior, septal) into the right ventricle. The crista terminalis divides the smooth sinus venarum from the rough pectinate part.
Right ventricle pumps blood through the pulmonary valve into the pulmonary trunk โ lungs. Contains moderator band (right bundle branch) and coarse trabeculae carneae.
Left Side โ Systemic Circuit
Left atrium receives oxygenated blood via 4 pulmonary veins. Blood passes through the mitral (bicuspid) valve (2 cusps: anterior, posterior) into the left ventricle.
Left ventricle has the thickest wall (~11 mm). Pumps blood through the aortic valve into the ascending aorta for systemic distribution.
Septa
- Interatrial septum โ contains fossa ovalis (remnant of foramen ovale)
- Interventricular septum โ muscular (inferior) + membranous (superior) parts
Components & Locations
1. SA node (pacemaker) โ upper crista terminalis, posterior RA wall near SVC opening. Fires 60โ100/min. Supplied by SA nodal artery (RCA 60%, LCA 40%).
2. AV node โ floor of RA at apex of Triangle of Koch (bounded by: tendon of Todaro, septal tricuspid leaflet, coronary sinus orifice). Delays impulse ~0.1 s to allow atrial completion.
3. AV bundle (Bundle of His) โ runs in membranous IVS. Only electrical bridge between atria and ventricles (fibrous skeleton insulates them).
4. Right bundle branch โ travels via moderator band to anterior papillary muscle of RV โ Purkinje fibres.
5. Left bundle branch โ divides into anterior and posterior fascicles โ LV Purkinje fibres.
6. Purkinje fibres โ terminal branches conducting from endocardium outward โ rapid ventricular contraction from apex upward.
Coordination Sequence
SA fires โ atria contract โ impulse reaches AV node โ 0.1 s delay โ His bundle โ branch blocks โ Purkinje โ apex-first ventricular contraction โ efficient ejection.
Clinical Significance
- SA node damage โ sick sinus syndrome
- AV node damage โ heart block (1ยฐ, 2ยฐ, 3ยฐ)
- LAD occlusion โ RBBB (moderator band ischaemia)