Human Anatomy: Heart Structure and Function

Cardiovascular System Anatomy

• The cardiovascular system is a closed circular pathway.
• Blood travels in a closed system of vessels.
• The system includes the heart and a network of vessels.

2 Circuits

• Pulmonary Circuit:
  • Blood vessels in the lungs.
  • Includes the right atrium, right ventricle, left atrium, and left ventricle.
• Systemic Circuit:
  • Blood vessels in the head, neck, upper limbs.
  • Blood vessels in the trunk and lower limbs.

Heart

• Transport system pump.
• Location & Position:
  • Thoracic cavity between lungs.
  • 2nd and 5th rib, slightly left.
• Size = Fist.
• Weight ≈ 1 lb.
• Base.
• Ribs.
• Apex.

Coronary Circulation

• Continuously supplies cardiac muscle with oxygen/nutrients.
• Extensive blood supply from systemic circulation directly into right atrium.
• Coronary arteries arise from ascending aorta.
• Coronary veins drain into coronary sinus or directly into right atrium.

Heart Chambers

• Superior Chambers:
  • Right and Left Atria.
  • Receive blood.
• Inferior Chambers:
  • Right and Left Ventricles.
  • Pump blood out.

Anatomy of Heart - Atria

• Atria: Receiving chambers.
• Atrium = entryway.
• Blood returning to the heart from the circulation.
  • Superior Vena Cava.
  • Inferior Vena Cava.
  • Coronary Sinus.

Anatomy of Heart - Ventricles

• Ventricles: Discharging chambers.
• Make up most volume of heart.
• Pumps of the heart.
• Massive walls (Reflect function of pumping blood into circulation).

Surface Anatomy of Heart

• Coronary Sulcus:
  • Groove separating atria and ventricles.
• Interventricular Sulcus:
  • Groove marking boundary between the two ventricles.

Blood Flow Regulation

• AV valves open: Atrial pressure > ventricular pressure.
• AV valves close: Atrial pressure < ventricular pressure.
• Semilunar valves open: Ventricular pressure > pulmonary/aortic pressure.
• Semilunar valves close: Ventricular pressure < pulmonary/aortic pressure.

Interatrial Septum

• Separates L & R atria.

Interventricular Septum

• Separates L & R ventricles.

Blood Flow Regulation - Chambers

• Why do we need to keep left & right sides of heart separate?

Blood Flow Regulation - Valves

• Valves are important.
  • Prevent blood from going backward.
• Atrioventricular or (AV) valves:
  • Right AV valve (tricuspid).
  • Left AV valve (bicuspid or mitral).
• Semilunar Valves:
  • At exit of each ventricle.
  • Pulmonary semilunar valve.
  • Aortic semilunar valve.

Pericardium

• Double-walled sac (peri=around, cardi = heart).
  • Fibrous pericardium = outermost layer.
  • Serous pericardium:
    • Parietal layer.
    • Visceral layer.
• Cavity = space between layers of serous.
  • Pericardial fluid.

Layers of Heart Wall

• Epicardium:
  • Visceral layer of serous pericardium.
• Myocardium:
  • Muscle wall of heart (contractile).
  • Forms bulk of heart.
• Endocardium:
  • White sheet of endothelium.
  • Lines heart chambers.
  • Covers valves.

Retention Check

1. Which is the deepest part of the pericardium? - Visceral Layer
2. Blood leaves from right atrium and empties into where? - Right ventricle.
3. What are the three layers of the heart wall? - Epicardium, myocardium, endocardium.

Major Arteries of Systemic Circulation

• Aorta - Largest artery in the body.
  • Ascending aorta.
  • Arches to the left as aortic arch.
    • In the thorax this aorta is called descending thoracic aorta.
  • Thoracic aorta passes through the diaphragm into the abdominopelvic cavity and is now known as abdominal aorta.

Branches of the Aortic Arch

• Three elastic arteries:
  • Brachiocephalic trunk/artery.
  • Right subclavian artery.
  • Right common carotid artery.
  • Left common carotid artery.
  • Left subclavian artery.

Branches of the Right Subclavian Artery

• Internal thoracic artery (internal mammary artery).
• Supplies pericardium and anterior chest wall.
• Vertebral artery.
• Supplies brain and spinal cord.

Arteries and veins of the upper limb

• Axillary artery - crosses axilla to enter the arm.
• Brachial artery - supplies upper limb (in the upper arm gives rise to deep brachial artery, supplies deep structures, and ulnar collateral arteries, supplies elbow area).
• Brachial artery - branches into radial and ulnar arteries.

Branches of the Common Iliac Artery

• External iliac artery - As it enters the lower limb becomes the femoral artery; Branches off to form deep femoral artery.
• Deep femoral artery - Forms femoral circumflex arteries (supply ventral and lateral skin and deep muscles of the thigh).
• Posterior tibial artery (gives rise to fibular- peroneal artery).
• Anterior tibial artery (descending genicular).

Arteries of the Foot

• Dorsal pedis.
• Dorsal arch.
• Plantar arch.

Veins of the Lower Limbs

• Small saphenous vein - merges with popliteal vein to form the femoral vein.
• Great saphenous vein.
• Deep femoral vein.
• Femoral circumflex vein.
• External iliac vein.
• Internal iliac vein.

Blood Flow Charts

• Blood supply to the upper limbs (steps and diagrams).
• Blood supply to the systemic circuit (diagrams and steps).
• Blood supply from the common iliacs (diagram and steps).
• Blood return from the upper limbs (diagram).
• Thoracic blood return to the heart (diagram).
• Blood return from the abdomen and pelvis (diagram).
• Blood return from the lower limbs (diagram).

Anatomy and Histology Videos

• Heart 101 video.
• Information about valves and their importance.

Test your knowledge on the anatomical structures of the heart and their functions. This quiz covers key components such as valves, layers, and blood flow order. Perfect for students studying human anatomy or cardiology.