In this essay I am going to talk about the lungs and the stages of their embryonic development. I chose the lungs because they are one of the most important organs for survival -they supply oxygen to cells and release carbon dioxide to the atmosphere. This essay will mostly focus on the different stages of the lung development- the embryonic, the pseudoglandular, the canalicular, the terminal sac, and the postnatal stage.
The successful maturation of the lungs requires the completion of both biochemical and physical processes. The physical one is required for the structure and the biochemical one is required for maintaining such large surface area (surfactant). These two requirements are greatly related and the incomplete development of any of these processes will lead to insufficiency and compromise of the newborn. In the picture below you can see the all the stages summarized:
We know that the human lung starts as a primitive lung bud in the early fetal life and then undergoes many different morphological processes that also continue in the postnatal life. Genetic, hormonal, physical, and environmental factors, as tightly regulated events, together with lung liquid, and fetal breathing movements form a complex that contributes to each stage. The 5 stages of structural lung development occur at progressive times during gestation. The timing of the phases is not exact set since we have disparity between fetuses.
First is the Embryonic Stage (Weeks 4 to 7). This embryonic stage includes the initial formation of the respiratory diverticulum up to the formation of the all the key bronchopulmonary segments. The lung develops as an outgrowth of the ventral wall of the primitive foregut the laryngotracheal groove. Fore...
... middle of paper ...
... postnatal lung maturation showed a key part in the completion and the formation of an absolute functional lung system.
Works Cited
• Development and growth of the lung, Johannes C. Schittny. Peter Burri , Chapter 5 ( http://www.ana.unibe.ch/~schittny/Reprints/Schittny2008Fishman.pdf )
• Lung Development, Peter Rothstein, chapter 12 (http://www.columbia.edu/itc/hs/medical/humandev/2004/Chpt12-LungDev.pdf)
• Prenatal Lung Development, Gail H, Deutsch, MD and Halit Pinar. Chapter 2 (http://www.bcdecker.com/sampleofchapter/1-55009-133-6.pdf)
• Lung growth and Developmtn, Suchita, Joshi, Sailesh Kotecha, Early human development (2007) (http://prontus.uv.cl/pubacademica/pubasignaturas/medicinav/o/organismohumanoiv/site/artic/20110503/asocfile/lung_growth_and_development.pdf)
• Human Embryology and Developmental Biology, B.Carslon, 2008, 4th edition, chapter 15
The fetus begins to develop the type II alveoli at 22nd to 24th week of gestation, however these immature alveoli are incapable of supplying enough surfactant to meet the infant's respiratory needs. The fetus surfactant production begins to become adequate at the middle terminal stage of alveoli development and production becomes optimal at the 34th-to-36th week. (Porth, 1306) There are four types of surfactant produced by the type 2 alveoli known as primary surfactant proteins SP-A, SP-B, SP-C, and SP-D. SP-A and SP-D roles are inhibiting production of surfactant i...
In the lungs gas exchange occurs to re-oxidize the blood. Air travels through the respiratory tract to reach the lungs and back up to be exhaled into the environment. At the termination point of the respiratory tract lays the alveoli. The alveoli have a sac-like structure. In biological systems, the structure and functions of components are related. The alveoli have a structure specialized for efficient gaseous exchange. In the structure of the alveoli (alveolus), it looks as if it has the form of a hollow cavity that is paired with elastic fibers...
asthma and lung cancer, the study of its effects on lung development are quite limited; consequently, there
Person, A. & Mintz, M., (2006), Anatomy and Physiology of the Respiratory Tract, Disorders of the Respiratory Tract, pp. 11-17, New Jersey: Human Press Inc.
The first days and weeks after conception are critical for fetus body formation. The most extensive transformation of life occurs before birth. The fetal period goes through major changes. During the third month male or female sexual organs begin to develop and is visible through ultrasound. During months 4-6, the baby’s heartbeat becomes stronger. The digestive and excretory systems begin to develop. Body parts such as the fingernails, toenails, and buds of teeth begin to form and hair grows. Brain development occurs in every prenatal month, but the first three months are crucial. The central nervous system becomes responsive during middle of the women 's pregnancy, and begins to regulate body functions such as breathing and sucking.
At birth the neonate goes through many physical changes (Fraser & Cooper, 2009). The most dramatic and difficult being when the newborn takes its first breath (Meeks & Hallsworth, 2010). This breathing triggers change within the heart, lungs, blood flow and every other system of the neonate (Coad & Dunstall, 2009). During the first few minute until 6 hours of life, the neonate is considered to be transitioning from intrauterine to extra-uterine life (Sinha, Miall, & Jardine, 2012). It is within this time that the neonate needs close observations to evaluate their progress into their new life, thus showing the importance of newborn examinations within neonatal care (Fraser & Cooper, 2009).
The lungs are two large sacs within the human body that optimize gas exchange between the air breathed and the blood. (Lung cancer, 2013) The lungs take in oxygen and release carbon dioxide. The lungs are made of spongy tissue, which allows for expansion and contraction. The lungs occupy most of the thoracic cavity. Because of the location of the heart the right lung is slightly larger than the left lung. The base of the lungs sits on the diaphragm allowing the diaphragm to help with breathing.
Parker, Steve. "Chronic Pulmonary Diseases." The Human Body Book. New ed. New York: DK Pub., 2007.
Bronchopulmonary dysplasia (BPD) is a chronic lung disease that mostly affects premature infants. Premature infants have very few tiny alveoli that are not fully developed for the lungs to function normally. As a result, premature infants need respiratory support to provide oxygen or they need to be under mechanical ventilation in order to support their breathing. However, BPD is a result of the damage to the lungs caused by mechanical ventilation or by the long-term use of supplemental oxygen. This causes dysplasia and scarring of the air sacs and the damage will continue to affect alveoli that develop after birth. It will also affect the blood vessels which make it difficult for blood to go through the lungs, resulting in pulmonary hypertension and even heart failure. Most babies who have BPD are born with respiratory distress syndrome, a breathing disorder wherein fluid builds up in the alveoli which decreases the amount of oxygen reaching the bloodstream resulting in oxygen deprivation. The lungs are not completely formed or are unable to produce adequate surfactant, the liquid that covers the lungs in order to keep them open and aid in breathing once the infant is born. Without adequate surfactant, the lungs can collapse which causes difficulty in breathing. Because of this, the infant is not able to breathe and circulate sufficient levels of oxygen in order to support the other organs of the body. Most common symptoms of BPD are rapid and labored breathing,
"Fetal Development: MedlinePlus Medical Encyclopedia." National Library of Medicine - National Institutes of Health. Web. 06 Mar. 2011. .
Healthy lung tissue is predominately soft, elastic connective tissue, designed to slide easily over the thorax with each breath. The lungs are covered with visceral pleura which glide fluidly over the parietal pleura of the thoracic cavity thanks to the serous secretion of pleural fluid (Marieb, 2006, p. 430). During inhalation, the lungs expand with air, similar to filling a balloon. The pliable latex of the balloon allows it to expand, just as the pliability of lungs and their components allows for expansion. During exhalation, the volume of air decrease causing a deflation, similar to letting air out of the balloon. However, unlike a balloon, the paired lungs are not filled with empty spaces; the bronchi enter the lungs and subdivide progressively smaller into bronchioles, a network of conducting passageways leading to the alveoli (Marieb, 2006, p. 433). Alveoli are small air sacs in the respiratory zone. The respiratory zone also consists of bronchioles and alveolar ducts, and is responsible for the exchange of oxygen and carbon dioxide (Marieb, 2006, p. 433).
In this discussion post we are to describe the structures and functions of the respiratory system. We were asked to include major organs and how they work within the body and to notate symptoms of failure within the respiratory system.
What is the respiratory system? Why do we need to breathe? Can the process be changed or altered? The information in this paper will help you find out how the respiratory system works, what the components are that make the system work, and the many diseases that can change or alter the process.
Serving as the first stage of life, the prenatal and natal phase is the most critical period in relation to ensuring a healthy, lifelong development in a child. During pregnancy, the placenta works to transfer oxygen and nutrients from
Klein believed that this splitting during this stage is essential for healthy development in that it enables the infant to take in and retai...