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...
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... 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 respiratory system has the function of getting rid of carbon dioxide and acquiring oxygen. It works closely with the circulatory system to feed the body the proper amounts of oxygen it needs to function efficiently. The respiratory system of an American Mink is very similar to that of a human in spite of the fact that there are some minor modifications. Both Humans and Minks have two lungs, the right lung is larger and has three lobes and the left lung has two lobes. The reason why the left lun...
Marieb, E. N., & Hoehn, K. (2013). Human anatomy & physiology (9th ed.). Boston, MA: Pearson.
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...
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).
Houghton, A. M. (2008, October). Common origins of lung cancer and COPD.Nature Medicine [serial online]. doi:10.1038/nm1008-1023
The typical defect that takes place with a human affected is heart problems. In early infancy surgery needs to be taken place to avoid serious issues in the future. Atypica...
1.1 Describe, in-depth, stages of development from conception to birth in groups of 4 weeks i.e. 0-4, 4-8, 8-12...36-40 weeks.
Infants go through many changes in their first two years of life. All are very important and should be monitored, but the physical change in an infant is the most noticeable change. By the
2. Moore, K. L. The Developing Human: Clinically oriented embryology, 4th edition. Philadelphia PA: W.B. Saunders Co., 1988, p.146.
This stage deals with the ages from birth to 1 year. This is the stage when
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.
Parker, Steve. "Chronic Pulmonary Diseases." The Human Body Book. New ed. New York: DK Pub., 2007.
This is the embryonic period, which occurs three weeks after conception and lasts until the eighth week. During the fourth week, the shape of the head begins to form, along with the formation of the eyes, mouth, nose, and mouth. Through the fifth and eighth week the lower body develops, as the legs and arms appear. After the embryonic stage, the fetal stage begins, which is during the ninth week through birth, where the fetus has a physical appearance distinctive to human features compared to when it was an embryo. At birth, one of the earliest signs of motor development is its first reflexes as a newborn coming out the mother’s womb. Newborns reflexes are not learned, rather they are born with these reflexes and act instinctively to protect itself in its first few months of life. At this point both the physical and motor development is starting to develop naturally at the same
The process of human development is very complex. It is a continual process, providing gradual development for the fetus. Some of the most important factors to fetal development such as blood flow, heart beats, muscle development, and brain activity can all be determined within the first seven weeks of pregnancy (Baby Developme...
Klein believed that this splitting during this stage is essential for healthy development in that it enables the infant to take in and retai...