19.5 Development of the Heart
3 min read•june 18, 2024
The heart's journey from a simple tube to a complex four-chambered organ is a marvel of embryonic development. This process, occurring in the first eight weeks of pregnancy, involves intricate folding, looping, and to create distinct chambers and vessels.
After birth, the fetal heart undergoes crucial changes to adapt to life outside the womb. Fetal shunts close, allowing for separate pulmonary and systemic circulations. The coronary system develops fully, ensuring proper blood supply to the heart muscle itself.
Embryonic Heart Development and Fetal Heart Anatomy
Stages of embryonic heart development
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- forms heart tubes
- arise from cardiogenic mesoderm and fuse to form a single heart tube (day 22)
- Heart tube elongates and loops
- Elongation and looping of the heart tube establishes left-right asymmetry (day 23-28)
- contributes to the positioning of the developing heart
- Septa form to divide heart into four chambers
- develops to divide the into left and right atria
- forms to divide the into left and right ventricles
- separates the atria from the ventricles (day 28-56)
- develop into valves and septa
- Tricuspid and mitral valves form between the atria and ventricles from
- Aortic and pulmonary valves develop at the bases of the great arteries from (day 35-56)
- , an extracellular matrix, plays a crucial role in cushion formation
- Outflow tract divides into aorta and pulmonary artery
- separates the into the ascending aorta and pulmonary trunk (day 28-56)
- Coronary vasculature develops from epicardium
- Coronary arteries and veins form from epicardial cells and connect to the aorta and right atrium, respectively (day 56-birth)
Regions of fetal and adult heart
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- Develops into the left and right atria, which receive blood from the lungs and body, respectively
- Primitive ventricle
- Develops into the left and right ventricles, which pump blood to the body and lungs, respectively
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- Develops into the outflow tracts, including the ascending aorta and pulmonary artery
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- Contributes to the formation of the right atrium and sinoatrial node, the heart's pacemaker
- Truncus arteriosus
- Divides into the ascending aorta, which supplies the body, and the pulmonary trunk, which supplies the lungs
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- Fetal shunt between the right and left atria that allows oxygenated blood to bypass the lungs; closes after birth
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- Fetal shunt between the pulmonary artery and aorta that diverts blood away from the lungs; closes after birth
Transformation of fetal to adult cardiac anatomy
- Atrial and ventricular septa formation
- and fuse to divide the primitive atrium into left and right atria
- Muscular and membranous portions of the fuse to divide the primitive ventricle into left and right ventricles
- Valve formation from endocardial cushions
- Tricuspid and mitral valves develop from atrioventricular cushions and regulate blood flow between the atria and ventricles
- Aortic and pulmonary valves develop from outflow tract cushions and regulate blood flow into the aorta and pulmonary artery
- Outflow tract septation
- Aorticopulmonary septum divides the truncus arteriosus into the ascending aorta and pulmonary artery, separating systemic and pulmonary circulation
- Closure of fetal shunts
- Foramen ovale closes to separate the left and right atria, preventing mixing of oxygenated and deoxygenated blood
- constricts and becomes the , a fibrous remnant connecting the aorta and pulmonary artery
- Coronary circulation development
- Coronary arteries and veins form from epicardial cells and connect to the aorta and right atrium, respectively, to supply the heart muscle with oxygenated blood
Cardiac Neural Crest and Fetal Circulation
- cells contribute to the development of the outflow tract and great vessels
- relies on specialized shunts to bypass the non-functional lungs
- Septation of the heart chambers and great vessels is crucial for establishing separate pulmonary and systemic circulations
Key Terms to Review (45)
Aortic valve: The aortic valve is a one-way valve located between the left ventricle of the heart and the aorta, which prevents blood from flowing back into the heart once it has been pumped out. It consists of three cusps that open and close with each heartbeat.
Aortic Valve: The aortic valve is one of the four heart valves responsible for regulating the flow of blood through the heart. It is located between the left ventricle and the aorta, and its primary function is to ensure that blood flows in the correct direction during the cardiac cycle.
Aorticopulmonary Septum: The aorticopulmonary septum is a crucial structure that forms during the development of the heart, separating the aorta and pulmonary artery. This septum plays a vital role in ensuring the proper division of the cardiac outflow tract, allowing for the effective oxygenation of blood by directing it to the correct circulatory pathways.
Atrial Septum: The atrial septum is the wall that separates the right and left atria of the heart. It plays a crucial role in the development and function of the heart, ensuring the proper flow of blood through the cardiac chambers.
Atrioventricular Cushions: The atrioventricular cushions are thickenings of the cardiac jelly that form between the atria and ventricles during the development of the heart. These cushions play a crucial role in the formation of the atrioventricular valves and septa, which are essential components of the mature heart's structure and function.
Atrioventricular Septum: The atrioventricular septum is a critical structure that forms during the development of the heart, separating the atria from the ventricles and allowing for the proper flow of blood through the cardiac chambers.
Bulbus cordis: The bulbus cordis is a structure in the developing heart of an embryo that contributes to the formation of the right ventricle, part of the outflow tracts, and some portions of the left ventricle. It is crucial for establishing the basic architecture of the heart early in cardiac development.
Bulbus Cordis: The bulbus cordis is a transient embryonic structure that plays a crucial role in the development of the heart. It is a prominent swelling at the arterial end of the primitive heart tube that contributes to the formation of the ventricles and the outflow tract of the mature heart.
Cardiac Jelly: Cardiac jelly is a gelatinous extracellular matrix that forms during the early development of the heart. It plays a crucial role in the formation and shaping of the heart as it transitions from a simple tubular structure to a complex, multi-chambered organ.
Cardiac Looping: Cardiac looping is a crucial embryonic process in the development of the heart, where the initially straight heart tube undergoes a rightward bending and twisting to form the distinct chambers and great vessels of the mature heart. This dynamic morphogenetic event establishes the basic architecture of the heart and lays the foundation for its proper function.
Cardiac Neural Crest: The cardiac neural crest is a specialized population of cells that originates from the dorsal region of the neural tube during embryonic development. These cells migrate and contribute to the formation of various structures within the developing heart, playing a crucial role in the proper development of the cardiovascular system.
Cardiogenic area: The cardiogenic area is the region in the early embryo where heart development begins, identifiable when cells start to differentiate into cardiac tissue. This area sets the foundation for the formation of the heart's structure and function.
Cardiogenic cords: Cardiogenic cords are clusters of cells in the early embryo that eventually develop into the heart. They form from the mesoderm layer and are essential in the initial stages of cardiac development.
Cardiogenic Mesoderm: Cardiogenic mesoderm is a specialized region of the mesoderm germ layer that gives rise to the heart and associated cardiovascular structures during embryonic development. It is a critical component in the formation and patterning of the heart and its surrounding tissues.
Development of Blood Vessels and Fetal Circulation: Development of blood vessels and fetal circulation is the process by which the cardiovascular system forms in a fetus, ensuring that oxygen and nutrients are efficiently delivered from the placenta to the growing tissues. This intricate network evolves through stages, culminating in a specialized circulatory pattern that supports fetal development until birth.
Ductus arteriosus: The ductus arteriosus is a temporary blood vessel in fetal circulation that connects the pulmonary artery to the descending aorta, allowing most of the blood to bypass the lungs which are not yet in use. After birth, it normally closes and becomes the ligamentum arteriosum within a few days.
Ductus Arteriosus: The ductus arteriosus is a temporary blood vessel present in the fetus that connects the pulmonary artery to the aorta, allowing blood to bypass the lungs before birth. It is a crucial structure in the development of the fetal cardiovascular system and the transition to postnatal circulation.
Embryonic Folding: Embryonic folding is a crucial process that occurs during early embryonic development, where the flat embryonic disc undergoes a series of bending and folding movements to form the three-dimensional structure of the embryo. This process is essential for the formation of the major body systems, including the development of the heart, as outlined in the context of 19.5 Development of the Heart.
Endocardial Cushions: Endocardial cushions are thickenings of the endocardium, the innermost layer of the heart, that play a crucial role in the development of the heart's septa and valves during embryonic and fetal development.
Endocardial tubes: Endocardial tubes are embryonic structures that form the early foundation of the heart. They initially develop as separate parallel tubes which later fuse together to create a primitive heart tube.
Fetal Circulation: Fetal circulation refers to the unique circulatory system that develops in the womb to support the growth and development of the unborn baby. It differs from the adult circulatory system in several key ways, allowing the fetus to obtain oxygen and nutrients from the mother's blood supply.
Foramen Ovale: The foramen ovale is an opening in the fetal heart that allows blood to bypass the lungs and flow directly from the right atrium to the left atrium, bypassing the pulmonary circulation. It is a critical feature of fetal cardiovascular development and the transition to postnatal circulation.
Foramen ovale of the middle cranial fossa: The foramen ovale is an oval-shaped opening in the sphenoid bone of the middle cranial fossa through which the mandibular branch of the trigeminal nerve (cranial nerve V3) passes. It serves as a crucial pathway for both nerves and blood vessels connecting the cranium to other parts of the head.
Heart bulge: The heart bulge is a term used to describe the early stage of heart development in the embryo when the primitive heart tube begins to expand and form the initial segment of the heart's chambers. At this stage, distinct regions start to differentiate into what will become the atria and ventricles.
Interventricular septum: The interventricular septum is a thick wall dividing the left and right ventricles of the heart, preventing the mixing of oxygen-rich and oxygen-poor blood. It consists of an upper membranous part and a lower muscular part, playing a crucial role in the heart's function.
Interventricular Septum: The interventricular septum is a thick muscular wall that separates the right and left ventricles of the heart. It plays a crucial role in the anatomy and development of the heart, ensuring efficient blood flow and proper heart function.
Ligamentum Arteriosum: The ligamentum arteriosum is a fibrous cord that connects the pulmonary artery to the aorta, forming a remnant of the fetal ductus arteriosus. It plays a crucial role in the development of the heart and the adjustments of the infant at birth and during postnatal stages.
Mitral valve: The mitral valve is a crucial structure in the heart that separates the left atrium from the left ventricle, preventing the backflow of blood during contraction. This valve plays a key role in ensuring that oxygen-rich blood flows efficiently from the lungs to the rest of the body. Its proper function is vital for maintaining effective circulation and overall cardiovascular health.
Outflow Tract Cushions: Outflow tract cushions are specialized mesenchymal tissue structures that play a critical role in the formation of the outflow tracts of the heart during embryonic development. These cushions contribute to the proper separation of the pulmonary artery and aorta, ensuring effective blood flow and preventing congenital heart defects. Their formation and remodeling are vital in establishing the architecture of the heart's great vessels.
Primitive atrium: The primitive atrium is an early embryonic structure in the developing heart that eventually divides to form the right and left atria of the adult heart. It is a crucial part of the cardiovascular system's development during fetal growth.
Primitive Atrium: The primitive atrium is an important structure in the early development of the heart. It is the initial chamber that forms during the embryonic stage, serving as the precursor to the future atria of the fully developed heart.
Primitive heart tube: The primitive heart tube is the early developmental stage of the heart, consisting of a simple tubular structure that eventually forms the chambers and structures of the adult heart. It begins to form in the embryo around the third week of pregnancy, marking the initial phase of cardiovascular development.
Primitive Heart Tubes: Primitive heart tubes refer to the early developmental stage of the heart, where it initially forms as a simple, tubular structure. This fundamental structure is a crucial step in the complex process of cardiac development, ultimately giving rise to the mature, four-chambered heart.
Primitive ventricle: The primitive ventricle is an early developmental stage of the heart where it forms a simple pumping chamber that eventually gives rise to the left and right ventricles of the adult heart. It is a crucial part of heart morphogenesis, the process by which the heart takes on its final shape and structure.
Pulmonary valve: The pulmonary valve is a one-way valve located between the right ventricle and the pulmonary artery that prevents blood from flowing back into the heart once it has been ejected into the pulmonary circulation. It opens to allow deoxygenated blood to be pumped from the heart to the lungs for oxygenation.
Pulmonary Valve: The pulmonary valve is one of the four major valves in the human heart. It is located at the base of the pulmonary artery, responsible for regulating the flow of deoxygenated blood from the right ventricle to the lungs for oxygenation.
Septation: Septation is the process by which the heart divides into distinct chambers through the formation of septa, or walls, during embryonic development. This process is crucial for creating the four chambers of the heart, allowing for efficient separation of oxygenated and deoxygenated blood, which is essential for proper circulatory function.
Septum primum: The septum primum is a thin, crescent-shaped membrane in the developing heart of a fetus that initially forms the partial separation between the right and left atria. It plays a critical role in the development of the heart's structure, eventually contributing to the formation of the atrial septum, which separates these two chambers completely after birth.
Septum Primum: The septum primum is a key structure in the development of the heart, specifically during the formation of the atrial septum. It also plays a crucial role in the adjustments of the infant at birth and during the postnatal stages.
Septum Secundum: The septum secundum is a structure that develops during the embryonic formation of the heart. It is a key component in the proper development and separation of the atria, which are the upper chambers of the heart.
Sinus venosus: The sinus venosus is an embryonic heart chamber that plays a crucial role in the development of the mature heart, particularly in forming part of the right atrium and contributing to the sinoatrial node. It initially serves as the primary collecting chamber for oxygen-depleted blood returning to the heart from the body.
Sinus Venosus: The sinus venosus is a structure that develops during embryonic heart formation and plays a crucial role in the development of the heart's venous drainage system. It serves as a transitional area between the major veins and the developing atria, facilitating the return of deoxygenated blood to the heart.
Tricuspid valve: The tricuspid valve is a valve in the heart located between the right atrium and the right ventricle; it prevents the backflow of blood as it moves from the atrium to the ventricle. It consists of three flaps or cusps, which give it its name.
Tricuspid Valve: The tricuspid valve is one of the four heart valves that regulate blood flow through the heart. It is located between the right atrium and the right ventricle, ensuring that blood flows in the correct direction during the cardiac cycle.
Truncus arteriosus: In the developing heart, the truncus arteriosus is a common arterial trunk that allows blood to exit the heart, which later divides into the pulmonary artery and aorta during normal cardiac development. This structure is critical for directing oxygen-poor and oxygen-rich blood into their respective pathways as the fetus develops.