Heart Anatomy & Circulatory System Overview

• Paola Teurlinckx

Heart Anatomy

• A muscular pump circulates blood throughout the body
• Blood vessels are arteries, veins, and capillaries

Arteries

• Arteries carry blood away from the heart to tissues

Veins

• Bring blood back to the heart

Capillaries

• Tiny vessels branching off from arteries to deliver blood to tissues
• Circulatory systems include systemic and pulmonary

AV Valves

• Atrioventricular Valves; tricuspid and mitral-bicuspid
• AV Valves open during the ventricular filling phase, allowing blood to flow from the atria into the ventricles
• These valves close during ventricular contraction to prevent backflow of blood into the atria

Semilunar Valves

• Aortic and Pulmonary Valves
• Open during the ventricular ejection phase, allowing blood to flow from the ventricles into the aorta and pulmonary artery
• These valves close during ventricular relaxation to prevent backflow of blood into the ventricles

Cardiac Cycle

• Consists of two main phases
• Diastole is relaxation and filling (0.62s)
• Systole is contraction and ejection (0.3s)

Stages of Cardiac Cycle

• Ventricular filling, rapid filling with AV valves open
• Diastasis is 20% of ventricular filling
• Atrial systole, contraction
• Isovolumetric ventricular contraction
• Ejection phase, rapid and slow ejection
• Isovolumetric ventricular relaxation

Heart Attack Symptoms

• Chest pain, lightheadedness, pain in jaw/neck/back/arms/shoulders, shortness of breath
• Main risk factors are high blood cholesterol, high blood pressure, smoking

Stroke Risk Factors

• High blood pressure, diabetes, heart disease, smoking, family history, older age, African American heritage

Stroke Symptoms

• One-sided weakness/numbness, vision problems, speech difficulties, confusion, dizziness, severe headache

Effects of Aging on the Heart

• Decreased heart efficiency, especially during physical activity
• Increased arterial stiffness leading to higher blood pressure risk

Heart

• Muscular pump that circulates blood
• Is divided into right, deoxygenated, and left, oxygenated blood sides
• Is enclosed in the pericardium

Heart Chambers

• 4 chambers, two atrium receiving, and two ventricles chambers
• The right side is low-pressure, pulmonary circulation
• The left side is high-pressure, systemic circulation

Right Atrium

• Receives deoxygenated blood from superior vena cava upper body, inferior vena cava lower body, and coronary sinus heart's own blood supply
• Structures include crista terminalis ridge separating smooth and rough areas, sulcus terminalis external groove corresponding to crista terminalis, and fossa ovalis remnant of fetal foramen ovale

Interatrial Septum

• Separates the right and left atria
• Contains fossa ovalis, a remnant of fetal foramen ovale which closes after birth

Left Atrium

• Receives oxygenated blood from 4 pulmonary veins
• It has mostly smooth-walled structures, except for left auricle

Right Ventricle

• Pumps deoxygenated blood to the lungs via the pulmonary artery
• Tricuspid regulates inflow from right atrium
• Muscular ridges strengthen contraction
• Papillary muscles and chordae tendineae prevent tricuspid valve prolapse
• A smooth-walled area that leads to the pulmonary valve
• Three semilunar cusps direct blood into the pulmonary trunk

Left Ventricle

• Pumps oxygenated blood into systemic circulation via the aorta
• Mitral valve bicuspid regulates inflow from the left atrium
• Thickest myocardium for high-pressure pumping
• Trabeculae carneae, papillary muscles, and chordae tendineae
• A smooth-walled part near the aortic valve
• Three semilunar cusps prevent the backflow of blood

Heart Valves

• Ensures unidirectional blood flow
• Types: separate atria from ventricles, regulate outflow to arteries

Atrioventricular Valves

• Valves AV separate atria from ventricles
• Tricuspid valve (RA → RV) has 3 cusps
• Mitral valve bicuspid (LA → LV) has 2 cusps
• AV Valves prevent backflow during ventricular contraction systole

Semilunar Valves

• Function: prevent backflow during ventricular relaxation diastole
• Pulmonary Valve leads to the pulmonary trunk
• Aortic Valve leads to aorta

Atrial Septal Defect ASD and Patent Foramen Ovale PFO

• Failure of foramen ovale to close can cause persistent shunting of blood between atria and cause paradoxical embolism, increasing stroke risk

Mitral Valve Disorders

• Mitral stenosis thickened valve causes left atrial enlargement and pulmonary congestion
• Incompetent Valve leads to volume overload in the left atrium and left ventricle

Right Ventricular Hypertrophy RVH

• Causes are pulmonary hypertension and pulmonary valve stenosis
• Signs include right heart failure -adema, ascites, jugular venous distension

Left Ventricular Hypertrophy LVH

• Causes are aorta stenosis and hypertension
• Signs include chest pain and heart failure symptoms

Aortic Valve Disorders

• Aortic stenosis leads to left ventricular hypertrophy and reduced cardiac output
• Aortic regurgitation causes LV volume overload and heart failure

Pulmonary Valve Stenosis

• Obstruction leads to right ventricular hypertrophy and cyanosis

Aorta Anatomy

• The aorta is a cane-shaped delivers oxygen-rich blood
• Pulmonary and loop, systemic loops in circulatory loops

Aorta Structure

• Ascending Aorta, Aortic Arch, Thoracic Aorta, Abdominal Aorta

Ascending Aorta

• Starts from the heart's left ventricle

Aortic Arch

• Curves downward and gives rise to major arteries
• Can be divided into ascending, transverse and descending

Thoracic Aorta

• Descending
• The descending thoracic aorta gives off left bronchial arteries upper and lower and small arteries, not drawn to pericardium, lungs, & esophagus

Abdominal Aorta

• Extends through the abdominal cavity

Veina Cava

• Superior and inferior
• Superior collects deoxygenated blood from the upper body
• Inferior collects deoxygenated blood the lower body

Pulmonary Circulation

• Transports deoxygenated blood from the heart to the lungs

Pulmonary Arteries

• Carry oxygen-poor blood & pulmonary veins return oxygen-rich blood

Anatomy of the Heart

• Features, central organ of circulation, four chambers, artery

Left Coronary Artery

• Supplies the left ventricle/atrium; branches into the anterior descending artery

Right Coronary Artery

• Supplies right ventricle/atrium and conduction system SA/AV nodes

Venous Drainage

• Blood drains into the coronary sinus and directly into the heart chambers

Pulmonary Vein Formation

• Pulmonary veins are formed by lobar veins, which receive tributaries from intra & inter-segmental veins within lung parenchyma and adjacent lung segments, respectively

Pulmonary Artery Pathway

• The pulmonary trunk emerges and splits into the right and left pulmonary arteries, at the level between vertebrae T5 and T6

Coronary Circulation

• Circulation is classified as right & left-dominant

Cardiac Veins

• Located at anterior interventricular sulcus and posterior interventricular groove

Coronary Sinus

• Coronary veins end in the coronary sinus, a large vein that empties into the right atrium
• Deficient coronary artery irrigation
• Examine the heart, with changes in its shape or size indicating disease

Class 63 – Pericardium

• Double-walled sac that encloses the pericardium
• Consisting of the fibrous pericardium and serous pericardium
• The pericardial cavity holds 10-50mL of fluid to reduce friction

Transverse Sinus

• Helpful in surgery, as it separates the arterial vessels from the venous vessels

Oblique Pericardial Sinus

• Allows free movement of the heart

Rapid Fluid Accumulation

• Compress the heart leading to biventricular failure & requires pericardiocentesis

Electrical Activity

• The heart's conducting system ensures coordinated contraction of the atria and the ventricles
• Atria is separated from the ventricle by an insulate and fibrous barrier

Sinoatrial SA Node

• Superior posterolateral wall of the right atrium
• Main ion channels consist of K+, Na+, and Ca2+

Cardiac Muscle

• Have intercalated discs, are rich mitochondria, and contract rhythmically
• The left ventricle has the thickest myocardium

Electrical Conduction System

• Electrical impulses initiate rhythmical contraction of the heart muscle~
• Conducts electrical impulses rapidly through the heart

Arrhythmias

• Originate in AV node, Purkinje fibers, atrial, or ventricular muscle
• Can occur due to Abnormal rhythmical discharge from ectopic sites or Accessory pathways or retrograde Conduction
• Symptoms can Include tachycardia or bradycardia

Innervations

Sympathetic Activity - Reduces Conduction time from atria to ventricles and facilitates excitation Parasympathetic Activity - Vagus nerve decreases heart rate and Delays excitation while strongly stimulating heart thythem